Owen Atkin

Simulated resilience of tropical rainforests to CO2-induced climate change

Publisher: Springer Science and Business Media LLC

Date: 10-03-2013

DOI: 10.1038/NGEO1741

Thermal acclimation of leaf photosynthetic traits in an evergreen woodland, consistent with the coordination hypothesis

Publisher: Copernicus GmbH

Date: 11-06-2018

DOI: 10.5194/BG-15-3461-2018

Abstract: Abstract. Ecosystem models commonly assume that key photosynthetic traits, such as carboxylation capacity measured at a standard temperature, are constant in time. The temperature responses of modelled photosynthetic or respiratory rates then depend entirely on enzyme kinetics. Optimality considerations, however, suggest this assumption may be incorrect. The “coordination hypothesis” (that Rubisco- and electron-transport-limited rates of photosynthesis are co-limiting under typical daytime conditions) predicts, instead, that carboxylation (Vcmax) capacity should acclimate so that it increases somewhat with growth temperature but less steeply than its instantaneous response, implying that Vcmax when normalized to a standard temperature (e.g. 25 ∘C) should decline with growth temperature. With additional assumptions, similar predictions can be made for electron-transport capacity (Jmax) and mitochondrial respiration in the dark (Rdark). To explore these hypotheses, photosynthetic measurements were carried out on woody species during the warm and the cool seasons in the semi-arid Great Western Woodlands, Australia, under broadly similar light environments. A consistent proportionality between Vcmax and Jmax was found across species. Vcmax, Jmax and Rdark increased with temperature in most species, but their values standardized to 25 ∘C declined. The ci:ca ratio increased slightly with temperature. The leaf N : P ratio was lower in the warm season. The slopes of the relationships between log-transformed Vcmax and Jmax and temperature were close to values predicted by the coordination hypothesis but shallower than those predicted by enzyme kinetics.

Range size and growth temperature influence Eucalyptus species responses to an experimental heatwave.

Publisher: Wiley

Date: 10-03-2019

DOI: 10.1111/GCB.14590

Abstract: Understanding forest tree responses to climate warming and heatwaves is important for predicting changes in tree species ersity, forest C uptake, and vegetation-climate interactions. Yet, tree species differences in heatwave tolerance and their plasticity to growth temperature remain poorly understood. In this study, populations of four Eucalyptus species, two with large range sizes and two with comparatively small range sizes, were grown under two temperature treatments (cool and warm) before being exposed to an equivalent experimental heatwave. We tested whether the species with large and small range sizes differed in heatwave tolerance, and whether trees grown under warmer temperatures were more tolerant of heatwave conditions than trees grown under cooler temperatures. Visible heatwave damage was more common and severe in the species with small rather than large range sizes. In general, species that showed less tissue damage maintained higher stomatal conductance, lower leaf temperatures, larger increases in isoprene emissions, and less photosynthetic inhibition than species that showed more damage. Species exhibiting more severe visible damage had larger increases in heat shock proteins (HSPs) and respiratory thermotolerance (T

Xeml Lab: a tool that supports the design of experiments at a graphical interface and generates computer-readable metadata files, which capture information about genotypes, growth conditions, environm

Publisher: Wiley

Date: 09-2009

DOI: 10.1111/J.1365-3040.2009.01964.X

Abstract: Data mining depends on the ability to access machine-readable metadata that describe genotypes, environmental conditions, and s ling times and strategy. This article presents Xeml Lab. The Xeml Interactive Designer provides an interactive graphical interface at which complex experiments can be designed, and concomitantly generates machine-readable metadata files. It uses a new eXtensible Mark-up Language (XML)-derived dialect termed XEML. Xeml Lab includes a new ontology for environmental conditions, called Xeml Environment Ontology. However, to provide versatility, it is designed to be generic and also accepts other commonly used ontology formats, including OBO and OWL. A review summarizing important environmental conditions that need to be controlled, monitored and captured as metadata is posted in a Wiki (www.codeplex.com/XeO) to promote community discussion. The usefulness of Xeml Lab is illustrated by two meta-analyses of a large set of experiments that were performed with Arabidopsis thaliana during 5 years. The first reveals sources of noise that affect measurements of metabolite levels and enzyme activities. The second shows that Arabidopsis maintains remarkably stable levels of sugars and amino acids across a wide range of photoperiod treatments, and that adjustment of starch turnover and the leaf protein content contribute to this metabolic homeostasis.

Responses of leaf respiration to heatwaves

Publisher: Wiley

Date: 15-02-2021

DOI: 10.1111/PCE.14018

Abstract: Mitochondrial respiration ( R ) is central to plant physiology and responds dynamically to daily short‐term temperature changes. In the longer‐term, changes in energy demand and membrane fluidity can decrease leaf R at a common temperature and increase the temperature at which leaf R peaks ( T max ). However, leaf R functionality is more susceptible to short‐term heatwaves. Catalysis increases with rising leaf temperature, driving faster metabolism and leaf R demand, despite declines in photosynthesis restricting assimilate supply and growth. Proteins denature as temperatures increase further, adding to maintenance costs. Excessive heat also inactivates respiratory enzymes, with a concomitant limitation on the capacity of the R system. These competing push‐and‐pull factors are responsible for the diminishing acceleration in leaf R rate as temperature rises. Under extreme heat, membranes become overly fluid, and enzymes such as the cytochrome c oxidase are impaired. Such changes can lead to over‐reduction of the energy system culminating in reactive oxygen species production. This ultimately leads to the total breakdown of leaf R , setting the limit of leaf survival. Understanding the heat stress responses of leaf R is imperative, given the continued rise in frequency and intensity of heatwaves and the importance of R for plant fitness and survival.

Variation in Leaf Respiration Rates at Night Correlates with Carbohydrate and Amino Acid Supply

Publisher: Oxford University Press (OUP)

Date: 14-06-2017

DOI: 10.1104/PP.17.00610

Diurnal and seasonal variation in light and dark respiration in field-grown Eucalyptus pauciflora

Publisher: Oxford University Press (OUP)

Date: 08-2015

DOI: 10.1093/TREEPHYS/TPV065

Abstract: Respiration from vegetation is a substantial part of the global carbon cycle and the responses of plant respiration to daily and seasonal fluctuations in temperature and light must be incorporated in models of terrestrial respiration to accurately predict these CO2 fluxes. We investigated how leaf respiration (R) responded to changes in leaf temperature (T(leaf)) and irradiance in field-grown saplings of an evergreen tree (Eucalyptus pauciflora Sieb. ex Spreng). Seasonal shifts in the thermal sensitivity of leaf R in the dark (R(dark)) and in the light (R(light)) were assessed by allowing T(leaf) to vary over the day in field-grown leaves over a year. The Q10 of R (i.e., the relative increase in R for a 10 °C increase in T(leaf)) was similar for R(light) and R(dark) and had a value of ∼ 2.5 there was little seasonal change in the Q10 of either R(light) or R(dark), indicating that we may be able to use similar functions to model short-term temperature responses of R in the dark and in the light. Overall, rates of R(light) were lower than those of R(dark), and the ratio of R(light)/R(dark) tended to increase with rising T(leaf), such that light suppression of R was reduced at high T(leaf) values, in contrast to earlier work with this species. Our results suggest we cannot assume that R(light)/R(dark) decreases with increasing T(leaf) on daily timescales, and highlights the need for a better mechanistic understanding of what regulates light suppression of R in leaves.

Ventilation Onset Prior to Umbilical Cord Clamping (Physiological-Based Cord Clamping) Improves Systemic and Cerebral Oxygenation in Preterm Lambs

Publisher: Public Library of Science (PLoS)

Date: 17-02-2015

DOI: 10.1371/JOURNAL.PONE.0117504

Wheat photosystem II heat tolerance responds dynamically to short- and long-term warming

Publisher: Oxford University Press (OUP)

Date: 23-05-2022

DOI: 10.1093/JXB/ERAC039

Abstract: Wheat photosynthetic heat tolerance can be characterized using minimal chlorophyll fluorescence to quantify the critical temperature (Tcrit) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat Tcrit under elevated temperature in field and controlled-environment experiments, and assessed whether intraspecies variation mirrored interspecific patterns of global heat tolerance. In the field, wheat Tcrit varied diurnally—declining from noon through to sunrise—and increased with phenological development. Under controlled conditions, heat stress (36 °C) drove a rapid (within 2 h) rise in Tcrit that peaked after 3–4 d. The peak in Tcrit indicated an upper limit to PSII heat tolerance. A global dataset [comprising 183 Triticum and wild wheat (Aegilops) species] generated from the current study and a systematic literature review showed that wheat leaf Tcrit varied by up to 20 °C (roughly two-thirds of reported global plant interspecies variation). However, unlike global patterns of interspecies Tcrit variation that have been linked to latitude of genotype origin, intraspecific variation in wheat Tcrit was unrelated to that. Overall, the observed genotypic variation and plasticity of wheat Tcrit suggest that this trait could be useful in high-throughput phenotyping of wheat photosynthetic heat tolerance.

Does growth irradiance affect temperature dependence and thermal acclimation of leaf respiration? Insights from a Mediterranean tree with long-lived leaves

Publisher: Wiley

Date: 07-2007

DOI: 10.1111/J.1365-3040.2007.01672.X

Abstract: Understanding the response of leaf respiration (R) to changes in irradiance and temperature is a prerequisite for predicting the impacts of climate change on plant function and future atmospheric CO2 concentrations. Little is known, however, about the interactive effects of irradiance and temperature on leaf R. We investigated whether growth irradiance affects the temperature response of leaf R in darkness (Rdark) and in light (Rlight) in seedlings of a broad-leaved evergreen species, Quercus ilex. Two hypotheses concerning Rdark were tested: (1) the Q10 (i.e. the proportional increase in R per 10 degrees C rise in temperature) of leaf Rdark is lower in shaded plants than in high-light-grown plants, and (2) shade-grown plants exhibit a lower degree of thermal acclimation of Rdark than plants exposed to higher growth irradiance. We also assessed whether light inhibition of Rlight differs between leaves exposed to contrasting temperatures and growth irradiances, and whether the degree of thermal acclimation of Rlight is dependent on growth irradiance. We showed that while growth irradiance did impact on photosynthesis, it had no effect on the Q10 of leaf Rdark. Growth irradiance had little impact on thermal acclimation when fully expanded, pre-existing leaves were exposed to contrasting temperatures for several weeks. When Rlight was measured at a common irradiance, Rlight/Rdark ratios were higher in shaded plants due to homeostasis of Rlight between growth irradiance treatments and to the lower Rdark in shaded leaves. We also showed that Rlight does not acclimate to the same degree as Rdark, and that Rlight/Rdark decreases with increasing measuring and growth temperatures, irrespective of the growth irradiance. Collectively, we raised the possibility that predictive carbon cycle models can assume that growth irradiance and photosynthesis do not affect the temperature sensitivity of leaf Rdark of long-lived evergreen leaves, thus simplifying incorporation of leaf R into such models.

Contrasting responses by respiration to elevated CO2 in intact tissue and isolated mitochondria

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/FP06247

Abstract: The question of whether elevated concentrations of CO2 directly inhibit mitochondrial respiration in plants has received considerable attention. Although there is a growing consensus that elevated [CO2] rarely inhibits respiration of intact tissues, past studies have reported that elevated [CO2] does impact on O2 uptake in isolated mitochondria what remains unclear, however, is the site(s) where elevated [CO2] impacts on mitochondrial electron transport (ETC). Here we investigated direct effects of [CO2] on respiratory activity of ETC enzymes, intact mitochondria and whole tissues using potato tubers (Solanum tuberosum L. cv. Desiree). Plots of O2 uptake against the redox poise of the ubiquinone (UQ) pool in isolated mitochondria were used to determine whether elevated [CO2] inhibits UQ-reducing and UQ-oxidising pathways differentially. Our results show that mitochondrial respiration was more inhibited via [CO2]/[HCO3–] effects on cytochrome c oxidase (COX) than on succinate dehydrogenase, with [HCO3–] rather than [CO2] inhibiting COX. However, the inhibitory effects at the mitochondrial level did not translate into inhibitory effects at the tissue level. Alternative oxidase (AOX) activity is normally absent in young potato tubers, as was the case in the present study. Thus, the lack of CO2-mediated inhibition at the tissue level was not the result of increases in AOX activity masking the effects of CO2 elsewhere in the respiratory system. We discuss whether the direct impact of elevated [CO2] on respiration is dependent on the rate of metabolic activity and flux control coefficients in in idual tissues.

Wheat photosystem II heat tolerance: evidence for genotype‐by‐environment interactions

Publisher: Wiley

Date: 26-07-2022

DOI: 10.1111/TPJ.15894

Abstract: High temperature stress inhibits photosynthesis and threatens wheat production. One measure of photosynthetic heat tolerance is T crit – the critical temperature at which incipient damage to photosystem II (PSII) occurs. This trait could be improved in wheat by exploiting genetic variation and genotype‐by‐environment interactions (GEI). Flag leaf T crit of 54 wheat genotypes was evaluated in 12 thermal environments over 3 years in Australia, and analysed using linear mixed models to assess GEI effects. Nine of the 12 environments had significant genetic effects and highly variable broad‐sense heritability ( H 2 ranged from 0.15 to 0.75). T crit GEI was variable, with 55.6% of the genetic variance across environments accounted for by the factor analytic model. Mean daily growth temperature in the month preceding anthesis was the most influential environmental driver of T crit GEI, suggesting biochemical, physiological and structural adjustments to temperature requiring different durations to manifest. These changes help protect or repair PSII upon exposure to heat stress, and may improve carbon assimilation under high temperature. To support breeding efforts to improve wheat performance under high temperature, we identified genotypes superior to commercial cultivars commonly grown by farmers, and demonstrated potential for developing genotypes with greater photosynthetic heat tolerance.

Canopy position affects the relationships between leaf respiration and associated traits in a tropical rainforest in Far North Queensland

Publisher: Oxford University Press (OUP)

Date: 10-04-2014

DOI: 10.1093/TREEPHYS/TPU016

Abstract: We explored the impact of canopy position on leaf respiration (R) and associated traits in tree and shrub species growing in a lowland tropical rainforest in Far North Queensland, Australia. The range of traits quantified included: leaf R in darkness (RD) and in the light (RL estimated using the Kok method) the temperature (T)-sensitivity of RD light-saturated photosynthesis (Asat) leaf dry mass per unit area (LMA) and concentrations of leaf nitrogen (N), phosphorus (P), soluble sugars and starch. We found that LMA, and area-based N, P, sugars and starch concentrations were all higher in sun-exposed/upper canopy leaves, compared with their shaded/lower canopy and deep-shade/understory counterparts similarly, area-based rates of RD, RL and Asat (at 28 °C) were all higher in the upper canopy leaves, indicating higher metabolic capacity in the upper canopy. The extent to which light inhibited R did not differ significantly between upper and lower canopy leaves, with the overall average inhibition being 32% across both canopy levels. Log-log RD-Asat relationships differed between upper and lower canopy leaves, with upper canopy leaves exhibiting higher rates of RD for a given Asat (both on an area and mass basis), as well as higher mass-based rates of RD for a given [N] and [P]. Over the 25-45 °C range, the T-sensitivity of RD was similar in upper and lower canopy leaves, with both canopy positions exhibiting Q10 values near 2.0 (i.e., doubling for every 10 °C rise in T) and Tmax values near 60 °C (i.e., T where RD reached maximal values). Thus, while rates of RD at 28 °C decreased with increasing depth in the canopy, the T-dependence of RD remained constant these findings have important implications for vegetation-climate models that seek to predict carbon fluxes between tropical lowland rainforests and the atmosphere.

Global variability in leaf respiration in relation to climate, plant functional types and leaf traits (vol 206, pg 614, 2015)

Publisher: Wiley

Date: 10-06-2016

DOI: 10.1111/NPH.14055

Mapping local and global variability in plant trait distributions

Publisher: Proceedings of the National Academy of Sciences

Date: 12-2017

DOI: 10.1073/PNAS.1708984114

Abstract: Currently, Earth system models (ESMs) represent variation in plant life through the presence of a small set of plant functional types (PFTs), each of which accounts for hundreds or thousands of species across thousands of vegetated grid cells on land. By expanding plant traits from a single mean value per PFT to a full distribution per PFT that varies among grid cells, the trait variation present in nature is restored and may be propagated to estimates of ecosystem processes. Indeed, critical ecosystem processes tend to depend on the full trait distribution, which therefore needs to be represented accurately. These maps reintroduce substantial local variation and will allow for a more accurate representation of the land surface in ESMs.

Corrigendum

Publisher: Wiley

Date: 02-09-2016

DOI: 10.1111/NPH.14172

Leaf nitrogen from the perspective of optimal plant function

Publisher: Wiley

Date: 08-2022

DOI: 10.1111/1365-2745.13967

Abstract: Leaf dry mass per unit area (LMA), carboxylation capacity ( V cmax ) and leaf nitrogen per unit area (N area ) and mass (N mass ) are key traits for plant functional ecology and ecosystem modelling. There is however no consensus about how these traits are regulated, or how they should be modelled. Here we confirm that observed leaf nitrogen across species and sites can be estimated well from observed LMA and V cmax at 25°C ( V cmax25 ). We then test the hypothesis that global variations of both quantities depend on climate variables in specific ways that are predicted by leaf‐level optimality theory, thus allowing both N area to be predicted as functions of the growth environment. A new global compilation of field measurements was used to quantify the empirical relationships of leaf N to V cmax25 and LMA. Relationships of observed V cmax25 and LMA to climate variables were estimated, and compared to independent theoretical predictions of these relationships. Soil effects were assessed by analysing biases in the theoretical predictions. LMA was the most important predictor of N area (increasing) and N mass (decreasing). About 60% of global variation across species and sites in observed N area , and 31% in N mass , could be explained by observed LMA and V cmax25 . These traits, in turn, were quantitatively related to climate variables, with significant partial relationships similar or indistinguishable from those predicted by optimality theory. Predicted trait values explained 21% of global variation in observed site‐mean V cmax25 , 43% in LMA and 31% in N area . Predicted V cmax25 was biased low on clay‐rich soils but predicted LMA was biased high, with compensating effects on N area . N area was overpredicted on organic soils. Synthesis . Global patterns of variation in observed site‐mean N area can be explained by climate‐induced variations in optimal V cmax25 and LMA. Leaf nitrogen should accordingly be modelled as a consequence (not a cause) of V cmax25 and LMA, both being optimized to the environment. Nitrogen limitation of plant growth would then be modelled principally via whole‐plant carbon allocation, rather than via leaf‐level traits. Further research is required to better understand and model the terrestrial nitrogen and carbon cycles and their coupling.

Unravelling mechanisms and impacts of day respiration in plant leaves: an introduction to a Virtual Issue

Publisher: Wiley

Date: 02-03-2021

DOI: 10.1111/NPH.17164

Increasing Functional Diversity in a Global Land Surface Model Illustrates Uncertainties Related to Parameter Simplification

Publisher: American Geophysical Union (AGU)

Date: 03-2022

DOI: 10.1029/2021JG006606

Abstract: Simulations of the land surface carbon cycle typically compress functional ersity into a small set of plant functional types (PFT), with parameters defined by the average value of measurements of functional traits. In most earth system models, all wild plant life is represented by between five and 14 PFTs and a typical grid cell (≈100 × 100 km) may contain a single PFT. Model logic applied to this coarse representation of ecological functional ersity provides a reasonable proxy for the carbon cycle, but does not capture the non‐linear influence of functional traits on productivity. Here we show through simulations using the Energy Exascale Land Surface Model in 15 erse terrestrial landscapes, that better accounting for functional ersity markedly alters predicted total carbon uptake. The shift in carbon uptake is as great as 30% and 10% in boreal and tropical regions, respectively, when compared to a single PFT parameterized with the trait means. The traits that best predict gross primary production vary based on vegetation phenology, which broadly determines where traits fall within the global distribution. Carbon uptake is more closely associated with specific leaf area for evergreen PFTs and the leaf carbon to nitrogen ratio in deciduous PFTs.

Psychometric validation of the needs assessment tool: progressive disease in interstitial lung disease

Publisher: BMJ

Date: 17-11-2017

DOI: 10.1136/THORAXJNL-2017-210911

Abstract: The inter-rater/test–retest reliability and construct validity of a palliative care needs assessment tool in interstitial lung disease (NAT:PD-ILD) were tested using NAT:PD-ILD-guided video-recorded consultations, and NAT:PD-ILD-guided consultations, and patient and carer-report outcomes (St George’s Respiratory Questionnaire (SGRQ)-ILD, Carer Strain Index (CSI)/Carer Support Needs Assessment Tool (CSNAT)). 11/16 items reached at least fair inter-rater agreement 5 items reached at least moderate test–retest agreement. 4/6 patient constructs demonstrated agreement with SGRQ-I scores (Kendall’s tau-b, 0.24–20.36 P .05). 4/7 carer constructs agreed with the CSI/CSNAT items (kappa, 0.23–20.53). The NAT:PD-ILD is reliable and valid. Clinical effectiveness and implementation are to be evaluated.

Delaying cord clamping until ventilation onset improves cardiovascular function at birth in preterm lambs

Publisher: Wiley

Date: 19-03-2013

DOI: 10.1113/JPHYSIOL.2012.250084

Separating species and environmental determinants of leaf functional traits in temperate rainforest plants along a soil-development chronosequence

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/FP16035

Abstract: We measured a erse range of foliar characteristics in shrub and tree species in temperate rainforest communities along a soil chronosequence (six sites from 8 to 120 000 years) and used multilevel model analysis to attribute the proportion of variance for each trait into genetic (G, here meaning species-level), environmental (E) and residual error components. We hypothesised that differences in leaf traits would be driven primarily by changes in soil nutrient availability during ecosystem progression and retrogression. Several leaf structural, chemical and gas-exchange traits were more strongly driven by G than E effects. For leaf mass per unit area (MA), foliar [N], net CO2 assimilation and dark respiration rates and foliar carbohydrate concentration, the G component accounted for 60–87% of the total variance, with the variability associated with plot, the E effect, much less important. Other traits, such as foliar [P] and N : P, displayed strong E and residual effects. Analyses revealed significant reductions in the slopes of G-only bivariate relationships when compared with raw relationships, indicating that a large proportion of trait–trait relationships is species based, and not a response to environment per se. This should be accounted for when assessing the mechanistic basis for using such relationships in order to make predictions of responses of plants to short-term environmental change.

Leaf‐ and cell‐level carbon cycling responses to a nitrogen and phosphorus gradient in two Arctic tundra species

Publisher: Wiley

Date: 10-2012

DOI: 10.3732/AJB.1200251

Abstract: Consequences of global climate change are detectable in the historically nitrogen- and phosphorus-limited Arctic tundra landscape and have implications for the terrestrial carbon cycle. Warmer temperatures and elevated soil nutrient availability associated with increased microbial activity may influence rates of photosynthesis and respiration. • This study examined leaf-level gas exchange, cellular ultrastructure, and related leaf traits in two dominant tundra species, Betula nana, a woody shrub, and Eriophorum vaginatum, a tussock sedge, under a 3-yr-old treatment gradient of nitrogen (N) and phosphorus (P) fertilization in the North Slope of Alaska. • Respiration increased with N and P addition-the highest rates corresponding to the highest concentrations of leaf N in both species. The inhibition of respiration by light ("Kok effect") significantly reduced respiration rates in both species (P < 0.001), ranged from 12-63% (mean 34%), and generally decreased with fertilization for both species. However, in both species, observed rates of photosynthesis did not increase, and photosynthetic nitrogen use efficiency generally decreased under increasing fertilization. Chloroplast and mitochondrial size and density were highly sensitive to N and P fertilization (P < 0.001), though species interactions indicated ergent cellular organizational strategies. • Results from this study demonstrate a species-specific decoupling of respiration and photosynthesis under N and P fertilization, implying an alteration of the carbon balance of the tundra ecosystem under future conditions.

A test of the 'one-point method' for estimating maximum carboxylation capacity from field-measured, light-saturated photosynthesis

Publisher: Wiley

Date: 31-12-2016

DOI: 10.1111/NPH.13815

Abstract: Simulations of photosynthesis by terrestrial biosphere models typically need a specification of the maximum carboxylation rate ( V cmax ). Estimating this parameter using A – C i curves (net photosynthesis, A , vs intercellular CO 2 concentration, C i ) is laborious, which limits availability of V cmax data. However, many multispecies field datasets include net photosynthetic rate at saturating irradiance and at ambient atmospheric CO 2 concentration ( A sat ) measurements, from which V cmax can be extracted using a ‘one‐point method’. We used a global dataset of A – C i curves (564 species from 46 field sites, covering a range of plant functional types) to test the validity of an alternative approach to estimate V cmax from A sat via this ‘one‐point method’. If leaf respiration during the day ( R day ) is known exactly, V cmax can be estimated with an r 2 value of 0.98 and a root‐mean‐squared error ( RMSE ) of 8.19 μmol m −2 s −1 . However, R day typically must be estimated. Estimating R day as 1.5% of V cmax, we found that V cmax could be estimated with an r 2 of 0.95 and an RMSE of 17.1 μmol m −2 s −1 . The one‐point method provides a robust means to expand current databases of field‐measured V cmax , giving new potential to improve vegetation models and quantify the environmental drivers of V cmax variation.

Acclimation of leaf respiration temperature responses across thermally contrasting biomes

Publisher: Wiley

Date: 14-10-2020

DOI: 10.1111/NPH.16929

Abstract: Short‐term temperature response curves of leaf dark respiration ( R–T ) provide insights into a critical process that influences plant net carbon exchange. This includes how respiratory traits acclimate to sustained changes in the environment. Our study analysed 860 high‐resolution R–T (10–70°C range) curves for: (a) 62 evergreen species measured in two contrasting seasons across several field sites/biomes and (b) 21 species (subset of those s led in the field) grown in glasshouses at 20°C : 15°C, 25°C : 20°C and 30°C : 25°C, day : night. In the field, across all sites/seasons, variations in R 25 (measured at 25°C) and the leaf T where R reached its maximum ( T max ) were explained by growth T (mean air‐ T of 30‐d before measurement), solar irradiance and vapour pressure deficit, with growth T having the strongest influence. R 25 decreased and T max increased with rising growth T across all sites and seasons with the single exception of winter at the cool‐temperate rainforest site where irradiance was low. The glasshouse study confirmed that R 25 and T max thermally acclimated. Collectively, the results suggest: (1) thermal acclimation of leaf R is common in most biomes and (2) the high T threshold of respiration dynamically adjusts upward when plants are challenged with warmer and hotter climates.

Acclimation of leaf respiration consistent with optimal photosynthetic capacity

Publisher: Wiley

Date: 24-02-2020

DOI: 10.1111/GCB.14980

Global convergence in leaf respiration from estimates of thermal acclimation across time and space

Publisher: Wiley

Date: 21-04-2015

DOI: 10.1111/NPH.13417

Abstract: Recent compilations of experimental and observational data have documented global temperature‐dependent patterns of variation in leaf dark respiration ( R ), but it remains unclear whether local adjustments in respiration over time (through thermal acclimation) are consistent with the patterns in R found across geographical temperature gradients. We integrated results from two global empirical syntheses into a simple temperature‐dependent respiration framework to compare the measured effects of respiration acclimation‐over‐time and variation‐across‐space to one another, and to a null model in which acclimation is ignored. Using these models, we projected the influence of thermal acclimation on: seasonal variation in R spatial variation in mean annual R across a global temperature gradient and future increases in R under climate change. The measured strength of acclimation‐over‐time produces differences in annual R across spatial temperature gradients that agree well with global variation‐across‐space. Our models further project that acclimation effects could potentially halve increases in R (compared with the null model) as the climate warms over the 21st Century. Convergence in global temperature‐dependent patterns of R indicates that physiological adjustments arising from thermal acclimation are capable of explaining observed variation in leaf respiration at ambient growth temperatures across the globe.

Wheat respiratory O2 consumption falls with night warming alongside greater respiratory CO2 loss and reduced biomass

Publisher: Oxford University Press (OUP)

Date: 15-10-2021

DOI: 10.1093/JXB/ERAB454

Abstract: Warming nights are correlated with declining wheat growth and yield. As a key determinant of plant biomass, respiration consumes O2 as it produces ATP and releases CO2 and is typically reduced under warming to maintain metabolic efficiency. We compared the response of respiratory O2 and CO2 flux to multiple night and day warming treatments in wheat leaves and roots, using one commercial (Mace) and one breeding cultivar grown in controlled environments. We also examined the effect of night warming and a day heatwave on the capacity of the ATP-uncoupled alternative oxidase (AOX) pathway. Under warm nights, plant biomass fell, respiratory CO2 release measured at a common temperature was unchanged (indicating higher rates of CO2 release at prevailing growth temperature), respiratory O2 consumption at a common temperature declined, and AOX pathway capacity increased. The uncoupling of CO2 and O2 exchange and enhanced AOX pathway capacity suggest a reduction in plant energy demand under warm nights (lower O2 consumption), alongside higher rates of CO2 release under prevailing growth temperature (due to a lack of down-regulation of respiratory CO2 release). Less efficient ATP synthesis, teamed with sustained CO2 flux, could thus be driving observed biomass declines under warm nights.

COVER IMAGE

Publisher: Wiley

Date: 27-06-2021

DOI: 10.1111/PCE.14122

Macromolecular rate theory (MMRT) provides a thermodynamics rationale to underpin the convergent temperature response in plant leaf respiration

Publisher: Wiley

Date: 14-11-2017

DOI: 10.1111/GCB.13936

Abstract: Temperature is a crucial factor in determining the rates of ecosystem processes, for ex le, leaf respiration ( R ) – the flux of plant respired CO 2 from leaves to the atmosphere. Generally, R increases exponentially with temperature and formulations such as the Arrhenius equation are widely used in earth system models. However, experimental observations have shown a consequential and consistent departure from an exponential increase in R . What are the principles that underlie these observed patterns? Here, we demonstrate that macromolecular rate theory ( MMRT ), based on transition state theory (TST) for enzyme‐catalyzed kinetics, provides a thermodynamic explanation for the observed departure and the convergent temperature response of R using a global database. Three meaningful parameters emerge from MMRT analysis: the temperature at which the rate of respiration would theoretically reach a maximum (the optimum temperature, T opt ), the temperature at which the respiration rate is most sensitive to changes in temperature (the inflection temperature, T inf ) and the overall curvature of the log(rate) versus temperature plot (the change in heat capacity for the system, ). On average, the highest potential enzyme‐catalyzed rates of respiratory enzymes for R are predicted to occur at 67.0 ± 1.2°C and the maximum temperature sensitivity at 41.4 ± 0.7°C from MMRT . The average curvature (average negative ) was −1.2 ± 0.1 kJ mol −1 K −1 . Interestingly, T opt , T inf and appear insignificantly different across biomes and plant functional types, suggesting that thermal response of respiratory enzymes in leaves could be conserved. The derived parameters from MMRT can serve as thermal traits for plant leaves that represent the collective temperature response of metabolic respiratory enzymes and could be useful to understand regulations of R under a warmer climate. MMRT extends the classic TST to enzyme‐catalyzed reactions and provides an accurate and mechanistic model for the short‐term temperature response of R around the globe.

TRY plant trait database – enhanced coverage and open access

Publisher: Wiley

Date: 31-12-2019

DOI: 10.1111/GCB.14904

Abstract: Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to bio ersity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on in idual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

The contribution of roots and shoots to whole plant nitrate reduction in fast- and slow-growing grass species

Publisher: Oxford University Press (OUP)

Date: 07-2002

DOI: 10.1093/JXB/ERF008

Abstract: The hypothesis was tested that slow-growing grass species perform a greater proportion of total plant NO3- reduction in their roots than do fast-growing grasses. Eight grass species were selected that differed in maximum relative growth rate (RGR) and net NO3- uptake rate (NNUR). Plants were grown with free access to nutrients in hydroponics under controlled-environment conditions. The site of in vivo NO3- reduction was assessed by combining in vivo NO3- reductase activity (NRA) assays with biomass allocation data, and by analysing the NO3- to amino acid ratio of xylem sap. In vivo NRA of roots and shoots increased significantly with increasing NNUR and RGR. The proportion of total plant NO3- reduction that occurs in roots was found to be independent of RGR and NNUR, with the shoot being the predominant site of NO3- reduction in all species. The theoretical maximum proportion of whole plant nitrogen assimilation that could take place in the roots was calculated using information on root respiration rates, RGR, NNUR, and specific respiratory costs associated with growth, maintenance and ion uptake. The calculated maximum proportion that the roots can contribute to total plant NO3- reduction was 0.37 and 0.23 for the fast-growing Dactylis glomerata L. and the slow-growing Festuca ovina L., respectively. These results indicate that slow-growing grass species perform a similar proportion of total plant NO3- reduction in their roots to that exhibited by fast-growing grasses. Shoots appear to be the predominant site of whole plant NO3- reduction in both fast- and slow-growing grasses when plants are grown with free access to nutrients.

Trait convergence in photosynthetic nutrient-use efficiency along a 2-million year dune chronosequence in a global biodiversity hotspot

Publisher: Wiley

Date: 28-03-2019

DOI: 10.1111/1365-2745.13158

Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

Publisher: Copernicus GmbH

Date: 22-07-2016

DOI: 10.5194/GMD-9-2415-2016

Abstract: Abstract. Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycle–climate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf life spans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the leaf turnover and growth rates to include a trade-off between leaf life span and leaf mass per unit area.Overall, the simulation of gross and net primary productivity (GPP and NPP, respectively) is improved with the nine PFTs when compared to FLUXNET sites, a global GPP data set based on FLUXNET, and MODIS NPP. Compared to the standard five PFTs, the new nine PFTs simulate a higher GPP and NPP, with the exception of C3 grasses in cold environments and C4 grasses that were previously over-productive. On a biome scale, GPP is improved for all eight biomes evaluated and NPP is improved for most biomes – the exceptions being the tropical forests, savannahs, and extratropical mixed forests where simulated NPP is too high. With the new PFTs, the global present-day GPP and NPP are 128 and 62 Pg C year−1, respectively. We conclude that the inclusion of trait-based data and the evergreen/deciduous distinction has substantially improved productivity fluxes in JULES, in particular the representation of GPP. These developments increase the realism of JULES, enabling higher confidence in simulations of vegetation dynamics and carbon storage.

Mesophyll conductance does not contribute to greater photosynthetic rate per unit nitrogen in temperate compared with tropical evergreen wet-forest tree leaves

Publisher: Wiley

Date: 13-02-2018

DOI: 10.1111/NPH.15031

Abstract: Globally, trees originating from high-rainfall tropical regions typically exhibit lower rates of light-saturated net CO

Reduced global plant respiration due to the acclimation of leaf dark respiration coupled with photosynthesis

Publisher: Wiley

Date: 28-10-2023

DOI: 10.1111/NPH.19355

Updated respiration routines alter spatio-temporal patterns of carbon cycling in a global land surface model

Publisher: IOP Publishing

Date: 23-09-2021

DOI: 10.1088/1748-9326/AC2528

Abstract: We updated the routines used to estimate leaf maintenance respiration (MR) in the Energy Land Model (ELM) using a comprehensive global respiration data base. The updated algorithm includes a temperature acclimating base rate, an updated instantaneous temperature response, and new plant functional type specific parameters. The updated MR algorithm resulted in a very large increase in global MR of 16.1 Pg (38%), but the signal was not geographically uniform. The increase was concentrated in the tropics and humid warm-temperate forests. The increase in MR led to large but proportionally smaller decreases in global net primary production (19%) and in average global leaf area index (15%). The effect on global gross primary production (GPP) was a more modest 5.7 Pg (4%). A detailed site level analysis also demonstrated a wide range of effects the updated algorithm can have on the seasonal cycle of GPP. Output from the updated and old models did not differ markedly in how closely they matched a suite of benchmarks. Given the substantial impact on the land surface carbon cycle, a neutral influence on model benchmarks, and better alignment with empirical evidence, an MR algorithm similar to the one presented here should be adopted into ELM.

Improving representation of leaf respiration in large‐scale predictive climate–vegetation models

Publisher: Wiley

Date: 10-04-2014

DOI: 10.1111/NPH.12686

Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration

Publisher: Wiley

Date: 17-11-2023

DOI: 10.1111/NPH.18545

Abstract: The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential () of crops is vital to address these challenges. In this review, we explore a component of that has yet to be optimised – that being improvements in the efficiency with which light energy is converted into biomass () via modifications to CO 2 fixed per unit quantum of light ( α ), efficiency of respiratory ATP production () and efficiency of ATP use (). For α , targets include changes in photoprotective machinery, ribulose bisphosphate carboxylase/oxygenase kinetics and photorespiratory pathways. There is also potential for to be increased via targeted changes to the expression of the alternative oxidase and mitochondrial uncoupling pathways. Similarly, there are possibilities to improve via changes to the ATP costs of phloem loading, nutrient uptake, futile cycles and/or protein/membrane turnover. Recently developed high‐throughput measurements of respiration can serve as a proxy for the cumulative energy cost of these processes. There are thus exciting opportunities to use our growing knowledge of factors influencing the efficiency of photosynthesis and respiration to create a step‐change in yield potential of globally important crops.

Strong thermal acclimation of photosynthesis in tropical and temperate wet‐forest tree species: the importance of altered Rubisco content

Publisher: Wiley

Date: 03-01-2017

DOI: 10.1111/GCB.13566

Abstract: Understanding of the extent of acclimation of light-saturated net photosynthesis (A

Dynamic changes in the mitochondrial electron transport chain underpinning cold acclimation of leaf respiration

Publisher: Wiley

Date: 09-07-2008

DOI: 10.1111/J.1365-3040.2008.01830.X

Abstract: We examined the effect of short- and long-term changes in temperature on gene expression, protein abundance, and the activity of the alternative oxidase and cytochrome oxidase pathways (AOP and COP, respectively) in Arabidopsis thaliana. The AOP was more sensitive to short-term changes in temperature than the COP, with partitioning to the AOP decreasing significantly below a threshold temperature of 20 degrees C. AOP activity was increased in leaves, which had been shifted to the cold for several days, but this response was transient, with AOP activity subsiding (and COP activity increasing) following the development of leaves in the cold. The transient increase in AOP activity in 10-d cold-shifted leaves was not associated with an increase in alternative oxidase (AOX) protein or AOX1a transcript abundance. By contrast, the amount of uncoupling protein was significantly increased in cold-developed leaves. In conjunction with this, transcript levels of the uncoupling protein-encoding gene UCP1 and the external NAD(P)H dehydrogenase-encoding gene NDB2 exhibited sustained increases following growth in the cold. The data suggest a role for each of these alternative non-phosphorylating bypasses of mitochondrial electron transport at different points in time following exposure to cold, with increased AOP activity being important only in the early stages of cold treatment.

Wheat photosystem II heat tolerance responds dynamically to short and long-term warming

Publisher: Cold Spring Harbor Laboratory

Date: 04-11-2021

DOI: 10.1101/2021.11.01.466822

Abstract: Heat-induced inhibition of photosynthesis is a key factor in declining wheat performance and yield. Variation in wheat heat tolerance can be characterised using the critical temperature ( T crit ) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat T crit under elevated temperature in field and controlled environment experiments. We also assessed whether intraspecies variation in wheat T crit mirrors patterns of global interspecies variation in heat tolerance reported for mostly wild, woody plants. In the field, wheat T crit varied through the course of a day, peaking at noon and lowest at sunrise, and increased as plants developed from heading to anthesis and grain filling. Under controlled temperature conditions, heat stress (36°C) was associated with a rapid rise in wheat T crit (i.e. within two hours of heat stress) that peaked after 3–4 days. These peaks in T crit indicate a physiological limitation to photosystem II heat tolerance. Analysis of a global dataset (comprising 183 Triticum and wild wheat ( Aegilops ) species) generated from the current study and a systematic literature review showed that wheat leaf T crit varied by up to 20°C (about two-thirds of reported global plant interspecies variation). However, unlike global patterns of interspecies T crit variation which has been linked to latitude of genotype origin, intraspecific variation in wheat T crit was unrelated to that. Yet, the observed genotypic variation and plasticity of wheat T crit suggests that this trait could be a useful tool for high-throughput phenotyping of wheat photosynthetic heat tolerance.

New Phytologist and the 'fate' of carbon in terrestrial ecosystems

Publisher: Wiley

Date: 26-11-2015

DOI: 10.1111/NPH.13185

Early detection of ventilation-induced brain injury using magnetic resonance spectroscopy and diffusion tensor imaging: An in vivo study in preterm lambs

Publisher: Public Library of Science (PLoS)

Date: 23-04-2014

DOI: 10.1371/JOURNAL.PONE.0095804

Drought‐induced shoot dieback starts with massive root xylem embolism and variable depletion of nonstructural carbohydrates in seedlings of two tree species

Publisher: Wiley

Date: 30-08-2016

DOI: 10.1111/NPH.14150

Abstract: Combining hydraulic‐ and carbon‐related measurements helps to understand drought‐induced plant mortality. Here, we investigated the role that plant respiration ( R ) plays in determining carbon budgets under drought. We measured the hydraulic conductivity of stems and roots, and gas exchange and nonstructural carbohydrate ( NSC ) concentrations of leaves, stems and roots of seedlings of two resprouting species exposed to drought or well‐watered conditions: Ulmus minor (riparian tree) and Quercus ilex (dryland tree). With increasing water stress (occurring more rapidly in larger U. minor ), declines in leaf, stem and root R were less pronounced than that in leaf net photosynthetic CO 2 uptake ( P n ). Daytime whole‐plant carbon gain was negative below −4 and −6 MPa midday xylem water potential in U. minor and Q. ilex , respectively. Relative to controls, seedlings exhibiting shoot dieback suffered c . 80% loss of hydraulic conductivity in both species, and reductions in NSC concentrations in U. minor . Higher drought‐induced depletion of NSC reserves in U. minor was related to higher plant R , faster stomatal closure, and premature leaf‐shedding. Differences in drought resistance relied on the ability to maintain hydraulic conductivity during drought, rather than tolerating conductivity loss. Root hydraulic failure elicited shoot dieback and precluded resprouting without root NSC reserves being apparently limiting for R .

Leaf trait variation is similar among genotypes of Eucalyptus camaldulensis from differing climates and arises in plastic responses to the seasons rather than water avai

Publisher: Wiley

Date: 06-05-2020

DOI: 10.1111/NPH.16579

Thermal acclimation and the dynamic response of plant respiration to temperature

Publisher: Elsevier BV

Date: 07-2003

DOI: 10.1016/S1360-1385(03)00136-5

Respiratory alternative oxidase responds to both low- and high-temperature stress in Quercus rubra leaves along an urban-rural gradient in New York

Publisher: Wiley

Date: 06-06-2011

DOI: 10.1111/J.1365-2435.2011.01875.X

Phenotypic plasticity and the changing environment - Preface

Publisher: Oxford University Press (OUP)

Date: 2006

DOI: 10.1093/JXB/ERJ079

Addressing Research Bottlenecks to Crop Productivity

Publisher: Elsevier BV

Date: 06-2021

DOI: 10.1016/J.TPLANTS.2021.03.011

High thermal acclimation potential of both photosynthesis and respiration in two lowland Plantago species in contrast to an alpine congeneric

Publisher: Wiley

Date: 03-2006

DOI: 10.1111/J.1365-2486.2006.01114.X

Cover Image

Publisher: Wiley

Date: 10-03-2022

DOI: 10.1111/PCE.14306

Acclimation of leaf photosynthesis and respiration to warming in field‐grown wheat

Publisher: Wiley

Date: 11-01-2021

DOI: 10.1111/PCE.13971

Abstract: Climate change and future warming will significantly affect crop yield. The capacity of crops to dynamically adjust physiological processes (i.e., acclimate) to warming might improve overall performance. Understanding and quantifying the degree of acclimation in field crops could ensure better parameterization of crop and Earth System models and predictions of crop performance. We hypothesized that for field‐grown wheat, when measured at a common temperature (25°C), crops grown under warmer conditions would exhibit acclimation, leading to enhanced crop performance and yield. Acclimation was defined as (a) decreased rates of net photosynthesis at 25°C ( A 25 ) coupled with lower maximum carboxylation capacity ( V cmax 25 ), (b) reduced leaf dark respiration at 25°C (both in terms of O 2 consumption R dark _O 2 25 and CO 2 efflux R dark _CO 2 25 ) and (c) lower R dark _CO 2 25 to V cmax 25 ratio. Field experiments were conducted over two seasons with 20 wheat genotypes, sown at three different planting dates, to test these hypotheses. Leaf‐level CO 2 ‐based traits ( A 25 , R dark _CO 2 25 and V cmax 25 ) did not show the classic acclimation responses that we hypothesized by contrast, the hypothesized changes in R dark_ O 2 were observed. These findings have implications for predictive crop models that assume similar temperature response among these physiological processes and for predictions of crop performance in a future warmer world.

Dark respiration rates are not determined by differences in mitochondrial capacity, abundance and ultrastructure in C4 leaves

Publisher: Wiley

Date: 06-02-2022

DOI: 10.1111/PCE.14267

Abstract: Our understanding of the regulation of respiration in C 4 plants, where mitochondria play different roles in the different types of C 4 photosynthetic pathway, remains limited. We examined how leaf dark respiration rates ( R dark ), in the presence and absence of added malate, vary in monocots representing the three classical biochemical types of C 4 photosynthesis (NADP‐ME, NAD‐ME and PCK) using intact leaves and extracted bundle sheath strands. In particular, we explored to what extent rates of R dark are associated with mitochondrial number, volume and ultrastructure. Based on examination of a single species per C 4 type, we found that the respiratory response of NAD‐ME and PCK type bundle sheath strands to added malate was associated with differences in mitochondrial number, volume, and/or ultrastructure, while NADP‐ME type bundle sheath strands did not respond to malate addition. In general, mitochondrial traits reflected the contributions mitochondria make to photosynthesis in the three C 4 types. However, despite the obvious differences in mitochondrial traits, no clear correlation was observed between these traits and R dark . We suggest that R dark is primarily driven by cellular maintenance demands and not mitochondrial composition per se, in a manner that is somewhat independent of mitochondrial organic acid cycling in the light.

Transient shade and drought have divergent impacts on the temperature sensitivity of dark respiration in leaves of Geum urbanum

Publisher: CSIRO Publishing

Date: 2008

DOI: 10.1071/FP08113

Abstract: The respiratory response of plants to temperature is a critical biotic feedback in the study of global climate change. Few studies, however, have investigated the effects of environmental stresses on the short-term temperature response of dark respiration (Rdark) at the leaf level. We investigated the effect of shade and transient drought on the temperature sensitivity (Q10 the proportional increase in respiration per 10°C increase in temperature) of Rdark of Geum urbanum L. in controlled experiments. Shade effects were most pronounced following sustained, near-darkness, when rates of leaf Rdark at a set measuring temperature (25°C) and the Q10 of Rdark were both reduced. By contrast, rates of leaf Rdark and the Q10 of Rdark both increased in response to the onset of severe water stress. Water stress was associated with a rapid (but reversible) decline in rates of light-saturated photosynthesis (Psat), stomatal closure (gs) and progressive wilting. Re-watering resulted in a rapid recovery of Psat, gs and a decline in the Q10 of Rdark (due to larger proportional reductions in the rate of Rdark measured at 25°C compared with those measured at 14°C). The concentration of soluble sugars in leaves did not decline during drought (5–7 day cycles) or shading, but during drought the starch concentration dropped, suggesting starch to sugar conversion helped to maintain homeostatic concentrations of soluble sugars. Thus, the drought and shade induced changes in Rdark were unlikely to be due to stress-induced changes in substrate supply. Collectively, the data highlight the dynamic responses of respiratory Q10 values to changes in water supply and sustained reductions in growth irradiance. If widespread, such changes in the Q10 of leaf respiration could have important implications for predicted rates of ecosystem carbon exchange in the future, particularly in areas that experience more frequent droughts.

Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

Publisher: Copernicus GmbH

Date: 02-2016

DOI: 10.5194/GMD-2016-22

Abstract: Abstract. Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycleclimate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf lifespans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the model phenology to include a trade-off between leaf lifespan and leaf mass per unit area.

Acclimation of light and dark respiration to experimental and seasonal warming are mediated by changes in leaf nitrogen in Eucalyptus globulus

Publisher: Oxford University Press (OUP)

Date: 24-05-2017

DOI: 10.1093/TREEPHYS/TPX052

Abstract: Quantifying the adjustments of leaf respiration in response to seasonal temperature variation and climate warming is crucial because carbon loss from vegetation is a large but uncertain part of the global carbon cycle. We grew fast-growing Eucalyptus globulus Labill. trees exposed to +3 °C warming and elevated CO2 in 10-m tall whole-tree chambers and measured the temperature responses of leaf mitochondrial respiration, both in light (RLight) and in darkness (RDark), over a 20-40 °C temperature range and during two different seasons. RLight was assessed using the Laisk method. Respiration rates measured at a standard temperature (25 °C - R25) were higher in warm-grown trees and in the warm season, related to higher total leaf nitrogen (N) investment with higher temperatures (both experimental and seasonal), indicating that leaf N concentrations modulated the respiratory capacity to changes in temperature. Once differences in leaf N were accounted for, there were no differences in R25 but the Q10 (i.e., short-term temperature sensitivity) was higher in late summer compared with early spring. The variation in RLight between experimental treatments and seasons was positively correlated with carboxylation capacity and photorespiration. RLight was less responsive to short-term changes in temperature than RDark, as shown by a lower Q10 in RLight compared with RDark. The overall light inhibition of R was ∼40%. Our results highlight the dynamic nature of leaf respiration to temperature variation and that the responses of RLight do not simply mirror those of RDark. Therefore, it is important not to assume that RLight is the same as RDark in ecosystem models, as doing so may lead to large errors in predicting plant CO2 release and productivity.

The global spectrum of plant form and function: enhanced species-level trait dataset

Publisher: Springer Science and Business Media LLC

Date: 07-12-2022

DOI: 10.1038/S41597-022-01774-9

Abstract: Here we provide the ‘Global Spectrum of Plant Form and Function Dataset’, containing species mean values for six vascular plant traits. Together, these traits –plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass – define the primary axes of variation in plant form and function. The dataset is based on ca. 1 million trait records received via the TRY database (representing ca. 2,500 original publications) and additional unpublished data. It provides 92,159 species mean values for the six traits, covering 46,047 species. The data are complemented by higher-level taxonomic classification and six categorical traits (woodiness, growth form, succulence, adaptation to terrestrial or aquatic habitats, nutrition type and leaf type). Data quality management is based on a probabilistic approach combined with comprehensive validation against expert knowledge and external information. Intense data acquisition and thorough quality control produced the largest and, to our knowledge, most accurate compilation of empirically observed vascular plant species mean traits to date.

Assessing the relationship between respiratory acclimation to the cold and photosystem II redox poise in Arabidopsis thaliana

Publisher: Wiley

Date: 12-2007

DOI: 10.1111/J.1365-3040.2007.01738.X

Abstract: We examined the effect of manipulating photosystem II (PSII) redox poise on respiratory flux in leaves of Arabidopsis thaliana. Measurements were made on wild-type (WT) plants and npq4 mutant plants deficient in non-photochemical quenching (NPQ). Two experiments were carried out. In the first experiment, WT and mutant warm-grown plants were exposed to three different irradiance regimes [75, 150 and 300 micromol photosynthetically active radiation (PAR)], and leaf dark respiration was measured in conjunction with PSII redox poise. In the second experiment, WT and mutant warm-grown plants were shifted to 5 degrees C and 75, 150 or 300 micromol PAR, and dark respiration was measured alongside PSII redox poise in cold-treated and cold-developed leaves. Despite significant differences in PSII redox poise between genotypes and irradiance treatments, neither genotype nor growth irradiance had any effect upon the rate of respiration in warm-grown, cold-treated or cold-developed leaves. We conclude that changes in PSII redox poise, at least within the range experienced here, have no direct impacts on rates of leaf dark respiration, and that the respiratory cold acclimation response is unrelated to changes in chloroplast redox poise.

Is resource allocation and grain yield of rice altered by inoculation with arbuscular mycorrhizal fungi?

Publisher: Oxford University Press (OUP)

Date: 12-11-2014

DOI: 10.1093/JPE/RTU025

The validity of optimal leaf traits modelled on environmental conditions

Publisher: Wiley

Date: 29-10-2019

DOI: 10.1111/NPH.15495

Abstract: The ratio of leaf intercellular to ambient CO

Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient

Publisher: Wiley

Date: 02-05-2017

DOI: 10.1111/ELE.12771

Abstract: One of the major challenges in ecology is to understand how ecosystems respond to changes in environmental conditions, and how taxonomic and functional ersity mediate these changes. In this study, we use a trait-spectra and in idual-based model, to analyse variation in forest primary productivity along a 3.3 km elevation gradient in the Amazon-Andes. The model accurately predicted the magnitude and trends in forest productivity with elevation, with solar radiation and plant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, and wood density) collectively accounting for productivity variation. Remarkably, explicit representation of temperature variation with elevation was not required to achieve accurate predictions of forest productivity, as trait variation driven by species turnover appears to capture the effect of temperature. Our semi-mechanistic model suggests that spatial variation in traits can potentially be used to estimate spatial variation in productivity at the landscape scale.

Heterogeneity of plant mitochondrial responses underpinning respiratory acclimation to the cold in Arabidopsis thaliana leaves

Publisher: Wiley

Date: 05-2006

DOI: 10.1111/J.1365-3040.2005.01475.X

Abstract: In this study, we investigated whether changes in mitochondrial abundance, ultrastructure and activity are involved in the respiratory cold acclimation response in leaves of the cold-hardy plant Arabidopsis thaliana. Confocal microscopy [using plants with green fluorescence protein (GFP) targeted to the mitochondria] and transmission electron microscopy (TEM) were used to visualize changes in mitochondrial morphology, abundance and ultrastructure. Measurements of respiratory flux in isolated mitochondria and intact leaf tissue were also made. Warm-grown (WG, 25/ 20 degrees C day/night), 3-week cold-treated (CT) and cold-developed (CD) leaves were s led. Although CT leaves exhibited some evidence of acclimation (as evidenced by higher rates of respiration at moderate measurement temperatures), it was only the CD leaves that were able to re-establish respiratory flux within the cold. Associated with the recovery of respiratory flux in the CD leaves were: (1) an increase in the total volume of mitochondria per unit volume of tissue in epidermal cells (2) an increase in the ratio of cristae to matrix within mesophyll cell mitochondria and (3) an increase in the capacity of the energy-producing cytochrome pathway in mitochondria isolated from whole leaf homogenates. Regardless of growth temperature, we found that contrasting cell types exhibited distinct differences in mitochondrial ultrastructure, morphology and abundance. Collectively, our data demonstrated the ersity and tissue-specific nature of mitochondrial responses that underpin respiratory acclimation to the cold, and revealed the heterogeneity of mitochondrial structure and abundance that exists within leaves.

New Phytologist: bridging the 'plant function - climate modelling divide'

Publisher: Wiley

Date: 03-02-2016

DOI: 10.1111/NPH.13876

Rubisco deactivation and chloroplast electron transport rates co-limit photosynthesis above optimal leaf temperature in terrestrial plants

Publisher: Springer Science and Business Media LLC

Date: 17-05-2023

DOI: 10.1038/S41467-023-38496-4

Abstract: Net photosynthetic CO 2 assimilation rate ( A n ) decreases at leaf temperatures above a relatively mild optimum ( T opt ) in most higher plants. This decline is often attributed to reduced CO 2 conductance, increased CO 2 loss from photorespiration and respiration, reduced chloroplast electron transport rate ( J ), or deactivation of Ribulose-1,5-bisphosphate Carboxylase Oxygenase (Rubisco). However, it is unclear which of these factors can best predict species independent declines in A n at high temperature. We show that independent of species, and on a global scale, the observed decline in A n with rising temperatures can be effectively accounted for by Rubisco deactivation and declines in J . Our finding that A n declines with Rubisco deactivation and J supports a coordinated down-regulation of Rubisco and chloroplast electron transport rates to heat stress. We provide a model that, in the absence of CO 2 supply limitations, can predict the response of photosynthesis to short-term increases in leaf temperature.

Scaling leaf respiration with nitrogen and phosphorus in tropical forests across two continents

Publisher: Wiley

Date: 09-05-2016

DOI: 10.1111/NPH.13992

Abstract: Leaf dark respiration ( R dark ) represents an important component controlling the carbon balance in tropical forests. Here, we test how nitrogen (N) and phosphorus (P) affect R dark and its relationship with photosynthesis using three widely separated tropical forests which differ in soil fertility. R dark was measured on 431 rainforest canopy trees, from 182 species, in French Guiana, Peru and Australia. The variation in R dark was examined in relation to leaf N and P content, leaf structure and maximum photosynthetic rates at ambient and saturating atmospheric CO 2 concentration. We found that the site with the lowest fertility (French Guiana) exhibited greater rates of R dark per unit leaf N, P and photosynthesis. The data from Australia, for which there were no phylogenetic overlaps with the s les from the South American sites, yielded the most distinct relationships of R dark with the measured leaf traits. Our data indicate that no single universal scaling relationship accounts for variation in R dark across this large biogeographical space. Variability between sites in the absolute rates of R dark and the R dark : photosynthesis ratio were driven by variations in N‐ and P‐use efficiency, which were related to both taxonomic and environmental variability.

Seasonality of foliar respiration in two dominant plant species from the Arctic tundra: response to long-term warming and short-term temperature variability

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/FP13137

Abstract: Direct measurements of foliar carbon exchange through the growing season in Arctic species are limited, despite the need for accurate estimates of photosynthesis and respiration to characterise carbon cycling in the tundra. We examined seasonal variation in foliar photosynthesis and respiration (measured at 20°C) in two field-grown tundra species, Betula nana L. and Eriophorum vaginatum L., under ambient and long-term warming (LTW) conditions (+5°C), and the relationship of these fluxes to intraseasonal temperature variability. Species and seasonal timing drove most of the variation in photosynthetic parameters (e.g. gross photosynthesis (Agross)), respiration in the dark (Rdark) and light (Rlight), and foliar nitrogen concentration. LTW did not consistently influence fluxes through the season but reduced respiration in both species. Alongside the flatter respiratory response to measurement temperature in LTW leaves, this provided evidence of thermal acclimation. The inhibition of respiration by light increased by ~40%, with Rlight : Rdark values of ~0.8 at leaf out decreasing to ~0.4 after 8 weeks. Though LTW had no effect on inhibition, the cross-taxa seasonal decline in Rlight : Rdark greatly reduced respiratory carbon loss. Values of Rlight : Agross decreased from ~0.3 in both species to ~0.15 (B. nana) and ~0.05 (E. vaginatum), driven by decreases in respiratory rates, as photosynthetic rates remained stable. The influence of short-term temperature variability did not exhibit predictive trends for leaf gas exchange at a common temperature. These results underscore the influence of temperature on foliar carbon cycling, and the importance of respiration in controlling seasonal carbon exchange.

Implications of improved representations of plant respiration in a changing climate

Publisher: Springer Science and Business Media LLC

Date: 17-11-2017

DOI: 10.1038/S41467-017-01774-Z

Abstract: Land-atmosphere exchanges influence atmospheric CO 2 . Emphasis has been on describing photosynthetic CO 2 uptake, but less on respiration losses. New global datasets describe upper canopy dark respiration ( R d ) and temperature dependencies. This allows characterisation of baseline R d , instantaneous temperature responses and longer-term thermal acclimation effects. Here we show the global implications of these parameterisations with a global gridded land model. This model aggregates R d to whole-plant respiration R p , driven with meteorological forcings spanning uncertainty across climate change models. For pre-industrial estimates, new baseline R d increases R p and especially in the tropics. Compared to new baseline, revised instantaneous response decreases R p for mid-latitudes, while acclimation lowers this for the tropics with increases elsewhere. Under global warming, new R d estimates lify modelled respiration increases, although partially lowered by acclimation. Future measurements will refine how R d aggregates to whole-plant respiration. Our analysis suggests R p could be around 30% higher than existing estimates.

Functional trait variation related to gap dynamics in tropical moist forests: A vegetation modelling perspective

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.PPEES.2018.10.004

Contrasting leaf trait scaling relationships in tropical and temperate wet forest species

Publisher: Wiley

Date: 27-02-2013

DOI: 10.1111/1365-2435.12047

Leaf day respiration: low CO2 flux but high significance for metabolism and carbon balance

Publisher: Wiley

Date: 02-10-2017

DOI: 10.1111/NPH.14816

Abstract: It has been 75 yr since leaf respiratory metabolism in the light (day respiration) was identified as a low‐flux metabolic pathway that accompanies photosynthesis. In principle, it provides carbon backbones for nitrogen assimilation and evolves CO 2 and thus impacts on plant carbon and nitrogen balances. However, for a long time, uncertainties have remained as to whether techniques used to measure day respiratory efflux were valid and whether day respiration responded to environmental gaseous conditions. In the past few years, significant advances have been made using carbon isotopes, ‘omics’ analyses and surveys of respiration rates in mesocosms or ecosystems. There is substantial evidence that day respiration should be viewed as a highly dynamic metabolic pathway that interacts with photosynthesis and photorespiration and responds to atmospheric CO 2 mole fraction. The view of leaf day respiration as a constant and/or negligible parameter of net carbon exchange is now outdated and it should now be regarded as a central actor of plant carbon‐use efficiency. Contents Summary 986 I. Introduction 987 II. Pioneering metabolic studies of day respiration with 14 C 987 III. Metabolic flux pattern of day respiration 988 IV. Significance of day respiration for leaf N assimilation 991 V. Significance of day respiration for leaf gas exchange 992 VI. Is day respiration influenced by CO 2 mole fraction? 995 VII. Significance of day respiration at the plant and ecosystem levels 997 VIII. Conclusions and perspectives 998 References 998

AM 251 and β-Funaltrexamine reduce fat intake in a fat-preferring strain of mouse

Publisher: Elsevier BV

Date: 19-07-2007

DOI: 10.1016/J.BBR.2007.03.028

Abstract: This experiment aimed to examine the role of the CB1 and Opioid mu receptors on fat preference by administering the CB1 inverse agonist AM 251 (5mg/kg i.p.) and the opioid mu antagonist beta-Funaltrexamine (15mg/kg s.c.) for 4 days to fat-preferring C57BL/6 mice fed a two-choice high-fat/low-fat diet. Both drugs were found to significantly reduce total energy intake, high-fat diet intake and fat preference during treatment.

Convergence in the temperature response of leaf respiration across biomes and plant functional types

Publisher: Proceedings of the National Academy of Sciences

Date: 21-03-2016

DOI: 10.1073/PNAS.1520282113

Abstract: A major concern for terrestrial biosphere models is accounting for the temperature response of leaf respiration at regional/global scales. Most biosphere models incorrectly assume that respiration increases exponentially with rising temperature, with profound effects for predicted ecosystem carbon exchange. Based on a study of 231 species in 7 biomes, we find that the rise in respiration with temperature can be generalized across biomes and plant types, with temperature sensitivity declining as leaves warm. This finding indicates universally conserved controls on the temperature sensitivity of leaf metabolism. Accounting for the temperature function markedly lowers simulated respiration rates in cold biomes, which has important consequences for estimates of carbon storage in vegetation, predicted concentrations of atmospheric carbon dioxide, and future surface temperatures.

Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance

Publisher: Wiley

Date: 02-02-2018

DOI: 10.1111/GCB.14037

Abstract: Heatwaves are likely to increase in frequency and intensity with climate change, which may impair tree function and forest C uptake. However, we have little information regarding the impact of extreme heatwaves on the physiological performance of large trees in the field. Here, we grew Eucalyptus parramattensis trees for 1 year with experimental warming (+3°C) in a field setting, until they were greater than 6 m tall. We withheld irrigation for 1 month to dry the surface soils and then implemented an extreme heatwave treatment of 4 consecutive days with air temperatures exceeding 43°C, while monitoring whole-canopy exchange of CO

Effects of chest compressions on cardiovascular and cerebral hemodynamics in asphyxiated near-term lambs

Publisher: Springer Science and Business Media LLC

Date: 18-06-2015

DOI: 10.1038/PR.2015.117

Abstract: Chest compressions (CC) and adrenaline administration are recommended in asphyxiated newborns with persistent bradycardia despite effective ventilation. The effects of CC on cerebral blood flow in newborns at birth are unknown. Our aim was to determine the effects of CC, with or without adrenaline administration, on the return of spontaneous circulation, carotid blood flow (CBF), and carotid arterial pressure (CAP) in asphyxiated near-term lambs. Asphyxia was induced in near-term lambs by cl ing the umbilical cord and delaying ventilation onset until spontaneous circulation ceased. Lambs were then resuscitated by positive pressure ventilation along with CC followed by adrenaline administration. CAP and CBF were continuously recorded. Mean CAP did not increase significantly during CC and only increased following adrenaline administration. CC did not increase mean CBF but increased CBF litude due to increased peak flow and the onset of retrograde flow during diastole. Adrenaline increased mean CBF from 1 ± 2 to 15 ± 5 ml/kg/min and abolished retrograde diastolic CBF, leading to the return in spontaneous circulation. We conclude that CC with adrenaline administration was required to increase CBF and restore spontaneous circulation in asphyxiated lambs. Low CBF and retrograde diastolic CBF during CC indicate hypoperfusion to the brain.

Irradiance, temperature and rainfall influence leaf dark respiration in woody plants

Publisher: Wiley

Date: 09-11-2006

DOI: 10.1111/J.1469-8137.2005.01590.X

Abstract: Leaf dark respiration (R) is one of the most fundamental physiological processes in plants and is a major component of terrestrial CO2 input to the atmosphere. Still, it is unclear how predictably species vary in R along broad climate gradients. Data for R and other key leaf traits were compiled for 208 woody species from 20 sites around the world. We quantified relationships between R and site climate, and climate-related variation in relationships between R and other leaf traits. Species at higher-irradiance sites had higher mean R at a given leaf N concentration, specific leaf area (SLA), photosynthetic capacity (Amass) or leaf lifespan than species at lower-irradiance sites. Species at lower-rainfall sites had higher mean R at a given SLA or Amass than species at higher-rainfall sites. On average, estimated field rates of R were higher at warmer sites, while no trend with site temperature was seen when R was adjusted to a standard measurement temperature. Our findings should prove useful for modelling plant nutrient and carbon budgets, and for modelling vegetation shifts with climate change.

Climate-dependent variations in leaf respiration in a dry-land, low productivity Mediterranean forest: the importance of acclimation in both high-light and shaded habitats

Publisher: Wiley

Date: 16-11-2007

DOI: 10.1111/J.1365-2435.2007.01355.X

A molecular approach to drought‐induced reduction in leaf CO ₂ exchange in drought‐resistant Quercus ilex

Publisher: Wiley

Date: 26-11-2017

DOI: 10.1111/PPL.12649

Abstract: Drought-induced reduction of leaf gas exchange entails a complex regulation of the plant leaf metabolism. We used a combined molecular and physiological approach to understand leaf photosynthetic and respiratory responses of 2-year-old Quercus ilex seedlings to drought. Mild drought stress resulted in glucose accumulation while net photosynthetic CO

Reply to Adams et al.: Empirical versus process-based approaches to modeling temperature responses of leaf respiration

Publisher: Proceedings of the National Academy of Sciences

Date: 04-10-2016

DOI: 10.1073/PNAS.1612904113

The hot and the cold: unravelling the variable response of plant respiration to temperature

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/FP03176

Abstract: When predicting the effects of climate change, global carbon circulation models that include a positive feedback effect of climate warming on the carbon cycle often assume that (1) plant respiration increases exponentially with temperature (with a constant Q10) and (2) that there is no acclimation of respiration to long-term changes in temperature. In this review, we show that these two assumptions are incorrect. While Q10 does not respond systematically to elevated atmospheric CO2 concentrations, other factors such as temperature, light, and water availability all have the potential to influence the temperature sensitivity of respiratory CO2 efflux. Roots and leaves can also differ in their Q10 values, as can upper and lower canopy leaves. The consequences of such variable Q10 values need to be fully explored in carbon modelling. Here, we consider the extent of variability in the degree of thermal acclimation of respiration, and discuss in detail the biochemical mechanisms underpinning this variability the response of respiration to long-term changes in temperature is highly dependent on the effect of temperature on plant development, and on interactive effects of temperature and other abiotic factors (e.g. irradiance, drought and nutrient availability). Rather than acclimating to the daily mean temperature, recent studies suggest that other components of the daily temperature regime can be important (e.g. daily minimum and / or night temperature). In some cases, acclimation may simply reflect a passive response to changes in respiratory substrate availability, whereas in others acclimation may be critical in helping plants grow and survive at contrasting temperatures. We also consider the impact of acclimation on the balance between respiration and photosynthesis although environmental factors such as water availability can alter the balance between these two processes, the available data suggests that temperature-mediated differences in dark leaf respiration are closely linked to concomitant differences in leaf photosynthesis. We conclude by highlighting the need for a greater process-based understanding of thermal acclimation of respiration if we are to successfully predict future ecosystem CO2 fluxes and potential feedbacks on atmospheric CO2 concentrations.

Leaf respiration in darkness and in the light under pre-industrial, current and elevated atmospheric CO2 concentrations

Publisher: Elsevier BV

Date: 09-2014

DOI: 10.1016/J.PLANTSCI.2014.05.001

Abstract: Our study sought to understand how past, low atmospheric CO2 concentrations ([CO2]) impact respiration (R) of soybean (Glycine max), when compared to plants grown under current and future [CO2]s. Experiments were conducted using plants grown under 290, 400 and 700 ppm [CO2]. Leaf R was measured in both darkness (RD) and in the light (RL using the Kok method), with short-term changes in measurement [CO2] and [O2] being used to explore the relationship between light inhibition of leaf R and photorespiration. Root R, photosynthesis (A), leaf [N] and biomass allocation traits were also quantified. In contrast to the inhibitory effect of low growth [CO2] on A, growth [CO2] had no significant effect on leaf RD or root R. Irrespective of growth [CO2], RL was always lower than RD, with light inhibiting leaf R by 17-47%. Importantly, the degree of light inhibition of leaf R was lowest in plants grown under low [CO2], with variations in RL being positively correlated with RD and photorespiration. Irrespective of whether leaf R was measured in the light or dark, a greater proportion of the carbon fixed by leaf photosynthesis was released by leaf R in plants grown under low [CO2] than under current/future [CO2]'s. Collectively, our results highlight the differential responses of A and R to growth of plants under low to elevated atmospheric [CO2].

Light inhibition of leaf respiration as soil fertility declines along a post-glacial chronosequence in New Zealand: an analysis using the Kok method

Publisher: Springer Science and Business Media LLC

Date: 07-04-2013

DOI: 10.1007/S11104-013-1686-0

The crucial role of plant mitochondria in orchestrating drought tolerance

Publisher: Oxford University Press (OUP)

Date: 13-06-2008

DOI: 10.1093/AOB/MCN094

Contributions of photosynthetic and non‐photosynthetic cell types to leaf respiration in Vicia faba L. and their responses to growth temperature

Publisher: Wiley

Date: 12-05-2015

DOI: 10.1111/PCE.12544

Abstract: In intact leaves, mitochondrial populations are highly heterogeneous among contrasting cell types how such contrasting populations respond to sustained changes in the environment remains, however, unclear. Here, we examined respiratory rates, mitochondrial protein composition and response to growth temperature in photosynthetic (mesophyll) and non-photosynthetic (epidermal) cells from fully expanded leaves of warm-developed (WD) and cold-developed (CD) broad bean (Vicia faba L.). Rates of respiration were significantly higher in mesophyll cell protoplasts (MCPs) than epidermal cell protoplasts (ECPs), with both protoplast types exhibiting capacity for cytochrome and alternative oxidase activity. Compared with ECPs, MCPs contained greater relative quantities of porin, suggesting higher mitochondrial surface area in mesophyll cells. Nevertheless, the relative quantities of respiratory proteins (normalized to porin) were similar in MCPs and ECPs, suggesting that ECPs have lower numbers of mitochondria yet similar protein complement to MCP mitochondria (albeit with lower abundance serine hydroxymethyltransferase). Several mitochondrial proteins (both non-photorespiratory and photorespiratory) exhibited an increased abundance in response to cold in both protoplast types. Based on estimates of in idual protoplast respiration rates, combined with leaf cell abundance data, epidermal cells make a small but significant (2%) contribution to overall leaf respiration which increases twofold in the cold. Taken together, our data highlight the heterogeneous nature of mitochondrial populations in leaves, both among contrasting cell types and in how those populations respond to growth temperature.

The crucial roles of mitochondria in supporting C₄ photosynthesis

Publisher: Wiley

Date: 13-11-2021

DOI: 10.1111/NPH.17818

Abstract: C 4 photosynthesis involves a series of biochemical and anatomical traits that significantly improve plant productivity under conditions that reduce the efficiency of C 3 photosynthesis. We explore how evolution of the three classical biochemical types of C 4 photosynthesis (NADP‐ME, NAD‐ME and PCK types) has affected the functions and properties of mitochondria. Mitochondria in C 4 NAD‐ME and PCK types play a direct role in decarboxylation of metabolites for C 4 photosynthesis. Mitochondria in C 4 PCK type also provide ATP for C 4 metabolism, although this role for ATP provision is not seen in NAD‐ME type. Such involvement has increased mitochondrial abundance/size and associated enzymatic capacity, led to changes in mitochondrial location and ultrastructure, and altered the role of mitochondria in cellular carbon metabolism in the NAD‐ME and PCK types. By contrast, these changes in mitochondrial properties are absent in the C 4 NADP‐ME type and C 3 leaves, where mitochondria play no direct role in photosynthesis. From an eco‐physiological perspective, rates of leaf respiration in darkness vary considerably among C 4 species but does not differ systematically among the three C 4 types. This review outlines further mitochondrial research in key areas central to the engineering of the C 4 pathway into C 3 plants and to the understanding of variation in rates of C 4 dark respiration.

Pressure-limited sustained inflation vs. gradual tidal inflations for resuscitation in preterm lambs.

Publisher: American Physiological Society

Date: 04-2015

DOI: 10.1152/JAPPLPHYSIOL.00985.2014

Abstract: Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH 2 O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min ( P = 0.017 two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min ( P 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt.

Light inhibition of leaf respiration in field-grown Eucalyptus saligna in whole-tree chambers under elevated atmospheric CO2 and summer drought

Publisher: Wiley

Date: 14-12-2011

DOI: 10.1111/J.1365-3040.2011.02465.X

Abstract: We investigated whether the degree of light inhibition of leaf respiration (R) differs among large Eucalyptus saligna grown in whole-tree chambers and exposed to present and future atmospheric [CO(2) ] and summer drought. Associated with month-to-month changes in temperature were concomitant changes in R in the light (R(light) ) and darkness (R(dark) ), with both processes being more temperature dependent in well-watered trees than under drought. Overall rates of R(light) and R(dark) were not significantly affected by [CO(2) ]. By contrast, overall rates of R(dark) (averaged across both [CO(2) ]) were ca. 25% lower under drought than in well-watered trees. During summer, the degree of light inhibition of leaf R was greater in droughted (ca. 80% inhibition) than well-watered trees (ca. 50% inhibition). Notwithstanding these treatment differences, an overall positive relationship was observed between R(light) and R(dark) when data from all months/treatments were combined (R(2) = 0.8). Variations in R(light) were also positively correlated with rates of Rubisco activity and nitrogen concentration. Light inhibition resulted in a marked decrease in the proportion of light-saturated photosynthesis respired (i.e. reduced R/A(sat) ). Collectively, these results highlight the need to account for light inhibition when assessing impacts of global change drivers on the carbon economy of tree canopies.

Bringing the Kok effect to light: A review on the integration of daytime respiration and net ecosystem exchange

Publisher: Wiley

Date: 08-2013

DOI: 10.1890/ES13-00120.1

Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature

Publisher: Oxford University Press (OUP)

Date: 09-09-2014

DOI: 10.1093/JXB/ERU367

Exploring high temperature responses of photosynthesis and respiration to improve heat tolerance in wheat

Publisher: Oxford University Press (OUP)

Date: 30-05-2019

DOI: 10.1093/JXB/ERZ257

Abstract: The high temperature responses of photosynthesis and respiration in wheat are an underexamined, yet potential avenue to improving heat tolerance and avoiding yield losses in a warming climate.

Respiratory flexibility and efficiency are affected by simulated global change in Arctic plants

Publisher: Wiley

Date: 21-12-2012

DOI: 10.1111/NPH.12083

Abstract: Laboratory studies indicate that, in response to environmental conditions, plants modulate respiratory electron partitioning between the ‘energy‐wasteful’ alternative pathway ( AP ) and the ‘energy‐conserving’ cytochrome pathway ( CP ). Field data, however, are scarce. Here we investigate how 20‐yr field manipulations simulating global change affected electron partitioning in Alaskan Arctic tundra species. We s led leaves from three dominant tundra species – B etula nana , E riophorum vaginatum and R ubus chamaemorus – that had been strongly affected by manipulations of soil nutrients, light availability, and warming. We measured foliar dark respiration, in‐vivo electron partitioning and alternative oxidase/cytochrome c oxidase concentrations in addition to leaf traits and mitochondrial ultrastructure. Changes in leaf traits and ultrastructure were similar across species. Respiration at 20°C ( R 20 ) was reduced 15% in all three species grown at elevated temperature, suggesting thermal acclimation of respiration. In Betula , the species with the largest growth response to added nutrients, CP activity increased from 9.4 ± 0.8 to 16.6 ± 1.6 nmol O 2 g −1 DM s −1 whereas AP activity was unchanged. The ability of Betula to selectively increase CP activity in response to the environment may contribute to its overall ecological success by increasing respiratory energy efficiency, and thus retaining more carbon for growth.

The art of growing plants for experimental purposes: a practical guide for the plant biologist

Publisher: CSIRO Publishing

Date: 2012

DOI: 10.1071/FP12028

Abstract: Every year thousands of experiments are conducted using plants grown under more-or-less controlled environmental conditions. The aim of many such experiments is to compare the phenotype of different species or genotypes in a specific environment, or to study plant performance under a range of suboptimal conditions. Our paper aims to bring together the minimum knowledge necessary for a plant biologist to set up such experiments and apply the environmental conditions that are appropriate to answer the questions of interest. We first focus on the basic choices that have to be made with regard to the experimental setup (e.g. where are the plants grown what rooting medium what pot size). Second, we present practical considerations concerning the number of plants that have to be analysed considering the variability in plant material and the required precision. Third, we discuss eight of the most important environmental factors for plant growth (light quantity, light quality, CO2, nutrients, air humidity, water, temperature and salinity) what critical issues should be taken into account to ensure proper growth conditions in controlled environments and which specific aspects need attention if plants are challenged with a certain a-biotic stress factor. Finally, we propose a simple checklist that could be used for tracking and reporting experimental conditions.

Supplementary material to &quot;Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information&quot;

Publisher: Copernicus GmbH

Date: 02-2016

DOI: 10.5194/GMD-2016-22-SUPPLEMENT

Respiration as a percentage of daily photosynthesis in whole plants is homeostatic at moderate, but not high, growth temperatures

Publisher: Wiley

Date: 22-02-2007

DOI: 10.1111/J.1469-8137.2007.02011.X

Abstract: Here, we investigated the impact of temperature on the carbon economy of two Plantago species from contrasting habitats. The lowland Plantago major and the alpine Plantago euryphylla were grown hydroponically at three constant temperatures: 13, 20 and 27 degrees C. Rates of photosynthetic CO(2) uptake (P) and respiratory CO(2) release (R) in shoots and R in roots were measured at the growth temperature using intact plants. At each growth temperature, air temperatures were changed to establish short-term temperature effects on the ratio of R to P (R/P). In both species, R/P was essentially constant in plants grown at 13 and 20 degrees C. However, R/P was substantially greater in 27 degrees C-grown plants, particularly in P. euryphylla. The increase in R/P at 27 degrees C would have been even greater had biomass allocation to roots not decreased with increasing growth temperature. Short-term increases in air temperature increased R/P in both species, with the effects of air temperature being most pronounced in 13 degrees C-grown plants. We conclude that temperature-mediated changes in biomass allocation play an important role in determining whole-plant R/P values, and, while homeostasis of R/P is achieved across moderate growth temperatures, homeostasis is not maintained when plants are exposed to growth temperatures higher than usually experienced in the natural habitat.

New Phytologist and the Earth System

Publisher: Wiley

Date: 19-06-2013

DOI: 10.1111/NPH.12367

Molecular and physiological responses during thermal acclimation of leaf photosynthesis and respiration in rice.

Publisher: Wiley

Date: 10-01-2020

DOI: 10.1111/PCE.13706

Abstract: To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas-exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with R

Temperature dependence of respiration in roots colonized by arbuscular mycorrhizal fungi

Publisher: Wiley

Date: 24-12-2008

DOI: 10.1111/J.1469-8137.2008.02727.X

Abstract: * The arbuscular mycorrhizal (AM) symbiosis is ubiquitous, and the fungus represents a major pathway for carbon movement in the soil-plant system. Here, we investigated the impacts of AM colonization of Plantago lanceolata and temperature on the regulation of root respiration (R). * Warm-grown AM plants exhibited higher rates of R than did nonAM plants, irrespective of root mass. AM plants exhibited higher maximal rates of R (R(max)-R measured in the presence of an uncoupler and exogenous substrate) and greater proportional use of R(max) as a result of increased energy demand and/or substrate supply. The higher R values exhibited by AM plants were not associated with higher maximal rates of cytochrome c oxidase (COX) or protein abundance of either the COX or the alternative oxidase. * Arbuscular mycorrhizal colonization had no effect on the short-term temperature dependence (Q(10)) of R. Cold-acclimated nonAM plants exhibited higher rates of R than their warm-grown nonAM counterparts. By contrast, chilling had a negligible effect on R of AM-plants. Thus, AM plants exhibited less cold acclimation than their nonAM counterparts. * Overall, these results highlight the way in which AM colonization alters the underlying components of respiratory metabolism and the response of root R to sustained changes in growth temperature.

On the developmental dependence of leaf respiration: responses to short- and long-term changes in growth temperature

Publisher: Wiley

Date: 11-2006

DOI: 10.3732/AJB.93.11.1633

Abstract: Using measurements of leaf respiratory O(2) uptake (R), we investigated whether immature and mature Arabidopsis thaliana (ecotype Columbia) leaves differed in their response to temperature. Confocal microscopy (using plants with mitochondrially targeted green fluorescent protein [GFP]) was used to determine whether ontogenetic changes in R are associated with concomitant changes in mitochondrial morphology/abundance. Comparisons were made of warm-grown (25/20°C) leaves, warm-grown leaves shifted to cold (5°C) for 10 days, and cold-developed leaves. Short-term Q(10) values and the ability to cold-acclimate were determined. In warm-grown plants, rates of R per mass were highest in immature leaves, decreasing as leaves developed. Moreover, although mitochondrial size (5.6-6.5 μm(3)) remained constant during development, mitochondrial number per μm(3) declined from 0.01 to 0.003 as leaves expanded (i.e., mitochondrial density decreased). Immature and mature leaves did not differ in Q(10) values but did differ in their ability to cold-acclimate. Whereas mature leaves had clear evidence of cold acclimation (e.g., when measured at 25°C, R was highest in cold-developed leaves), young leaves had none. Collectively, the results highlight the changes in rates of R, mitochondrial density, and biomass allocation associated with leaf development and that changes in respiratory flux associated with acclimation only take place within mature tissues.

High-resolution temperature responses of leaf respiration in snow gum (Eucalyptus pauciflora) reveal high-temperature limits to respiratory function

Publisher: Wiley

Date: 24-01-2013

DOI: 10.1111/PCE.12057

Abstract: We tested whether snow gum (Eucalyptus pauciflora) trees growing in thermally contrasting environments exhibit generalizable temperature (T) response functions of leaf respiration (R) and fluorescence (Fo). Measurements were made on pot-grown saplings and field-grown trees (growing between 1380 and 2110 m a.s.l.). Using a continuous, high-resolution protocol, we quantified T response curves of R and Fo--these data were used to identify an algorithm for modelling R-T curves at subcritical T's and establish variations in heat tolerance. For the latter, we quantified Tmax [T where R is maximal] and Tcrit [T where Fo rises rapidly]. Tmax ranged from 51 to 57 °C, varying with season (e.g. winter summer). Tcrit ranged from 41 to 49 °C in summer and from 58 to 63 °C in winter. Thus, surprisingly, leaf energy metabolism was more heat-tolerant in trees experiencing ice-encasement in winter than warmer conditions in summer. A polynomial model fitted to log-transformed R data provided the best description of the T-sensitivity of R (between 10 and 45 °C) using these model fits, we found that the negative slope of the Q10 -T relationship was greater in winter than in summer. Collectively, our results (1) highlight high-T limits of energy metabolism in E. pauciflora and (2) provide a framework for improving representation of T-responses of leaf R in predictive models.

AusTraits, a curated plant trait database for the Australian flora

Publisher: Springer Science and Business Media LLC

Date: 30-09-2021

DOI: 10.1038/S41597-021-01006-6

Abstract: We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field c aigns, published literature, taxonomic monographs, and in idual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised in idual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.

Predicting dark respiration rates of wheat leaves from hyperspectral reflectance

Publisher: Wiley

Date: 28-03-2019

DOI: 10.1111/PCE.13544

Abstract: Greater availability of leaf dark respiration (R

Leaf‐level photosynthetic capacity in lowland Amazonian and high‐elevation Andean tropical moist forests of Peru

Publisher: Wiley

Date: 08-07-2016

DOI: 10.1111/NPH.14079

Abstract: We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests ( TMF s) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco ( V cmax ), and the maximum rate of electron transport ( J max )), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area ( M a , N a and P a , respectively), and chlorophyll from 210 species at 18 field sites along a 3300‐m elevation gradient. Western blots were used to quantify the abundance of the CO 2 ‐fixing enzyme Rubisco. Area‐ and N‐based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMF s, underpinned by greater investment of N in photosynthesis in high‐elevation trees. Soil [P] and leaf P a were key explanatory factors for models of area‐based V cmax and J max but did not account for variations in photosynthetic N‐use efficiency. At any given N a and P a , the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil‐ and leaf‐P in defining the photosynthetic capacity of TMF s, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N‐use efficiency of these critically important forests.

The combination of gas-phase fluorophore technology and automation to enable high-throughput analysis of plant respiration

Publisher: Springer Science and Business Media LLC

Date: 21-03-2017

DOI: 10.1186/S13007-017-0169-3

Temperature-dependent changes in respiration rates and redox poise of the ubiquinone pool in protoplasts and isolated mitochondria of potato leaves

Publisher: Wiley

Date: 2007

DOI: 10.1111/J.1399-3054.2006.00823.X

Nitrogen and phosphorus availabilities interact to modulate leaf trait scaling relationships across six plant functional types in a controlled‐environment study

Publisher: Wiley

Date: 15-05-2017

DOI: 10.1111/NPH.14591

Abstract: Nitrogen (N) and phosphorus (P) have key roles in leaf metabolism, resulting in a strong coupling of chemical composition traits to metabolic rates in field‐based studies. However, in such studies, it is difficult to disentangle the effects of nutrient supply per se on trait–trait relationships. Our study assessed how high and low N (5 mM and 0.4 mM, respectively) and P (1 mM and 2 μM, respectively) supply in 37 species from six plant functional types (PTFs) affected photosynthesis ( A ) and respiration ( R ) (in darkness and light) in a controlled environment. Low P supply increased scaling exponents (slopes) of area‐based log–log A –N or R –N relationships when N supply was not limiting, whereas there was no P effect under low N supply. By contrast, scaling exponents of A –P and R –P relationships were altered by P and N supply. Neither R : A nor light inhibition of leaf R was affected by nutrient supply. Light inhibition was 26% across nutrient treatments herbaceous species exhibited a lower degree of light inhibition than woody species. Because N and P supply modulates leaf trait−trait relationships, the next generation of terrestrial biosphere models may need to consider how limitations in N and P availability affect trait−trait relationships when predicting carbon exchange.

The dependence of respiration on photosynthetic substrate supply and temperature: integrating leaf, soil and ecosystem measurements

Publisher: Wiley

Date: 24-07-2006

DOI: 10.1111/J.1365-2486.2006.01214.X

Mycorrhizal respiration: implications for global scaling relationships

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.TPLANTS.2008.08.010

Abstract: Most plant species form mycorrhizas, yet these are neglected by plant physiologists. One consequence of this neglect is reduced ability to predict plant respiration, because respiration rate (R) in mycorrhizal roots might be higher than in non-mycorrhizal roots owing to increased substrate availability associated with enhanced nutrient uptake, coupled with increased respiratory product demand. Other predictions include that mycorrhizal colonization will affect scaling of R with tissue nitrogen concentrations that mycorrhizal and non-mycorrhizal root R differ in their response to nutrient supply and that the impact of colonization on R is related to fungal biomass. Failure to examine properly the role of colonization in determining root R means that current interpretations of root and soil respiration data might be flawed.

Pressure- versus volume-limited sustained inflations at resuscitation of premature newborn lambs.

Publisher: Springer Science and Business Media LLC

Date: 15-02-2014

DOI: 10.1186/1471-2431-14-43

Abstract: Sustained inflations (SI) are advocated for the rapid establishment of FRC after birth in preterm and term infants requiring resuscitation. However, the most appropriate way to deliver a SI is poorly understood. We investigated whether a volume-limited SI improved the establishment of FRC and ventilation homogeneity and reduced lung inflammation/injury compared to a pressure-limited SI. 131 d gestation lambs were resuscitated with either: i) pressure-limited SI (PressSI: 0-40 cmH 2 O over 5 s, maintained until 20 s) or ii) volume-limited SI (VolSI: 0-15 mL/kg over 5 s, maintained until 20 s). Following the SI, all lambs were ventilated using volume-controlled ventilation (7 mL/kg tidal volume) for 15 min. Lung mechanics, regional ventilation distribution (electrical impedance tomography), cerebral tissue oxygenation index (near infrared spectroscopy), arterial pressures and blood gas values were recorded regularly. Pressure-volume curves were performed in-situ post-mortem and early markers of lung injury were assessed. Compared to a pressure-limited SI, a volume-limited SI had increased pressure variability but reduced volume variability. Each SI strategy achieved similar end-inflation lung volumes and regional ventilation homogeneity. Volume-limited SI increased heart-rate and arterial pressure faster than pressure-limited SI lambs, but no differences were observed after 30 s. Volume-limited SI had increased arterial-alveolar oxygen difference due to higher FiO 2 at 15 min (p = 0.01 and p = 0.02 respectively). No other inter-group differences in arterial or cerebral oxygenation, blood pressures or early markers of lung injury were evident. With the exception of inferior oxygenation, a sustained inflation targeting delivery to preterm lambs of 15 mL/kg volume by 5 s did not influence physiological variables or early markers of lung inflammation and injury at 15 min compared to a standard pressure-limited sustained inflation.

A field-compatible method for measuring alternative respiratory pathway activities in vivo using stable O2 isotopes

Publisher: Wiley

Date: 18-04-2012

DOI: 10.1111/J.1365-3040.2012.02507.X

Abstract: Plants can alter rates of electron transport through the alternative oxidase (AOX) pathway in response to environmental cues, thus modulating respiratory efficiency, but the (18)O discrimination method necessary for measuring electron partitioning in vivo has been restricted to laboratory settings. To overcome this limitation, we developed a field-compatible analytical method. Series of plant tissue subs les were incubated in 12 mL septum-capped vials for 0.5-4 h before aliquots of incubation air were injected into 3.7 mL evacuated storage vials. Vials were stored for up to 10 months before analysis by mass spectrometry. Measurements were corrected for unavoidable contamination. Additional mathematical tools were developed for detecting and addressing non-linearity (whether intrinsic or due to contamination) in the data used to estimate discrimination values. Initial contamination in the storage vials was 0.03 ± 0.01 atm storing the gas s les at -17 °C eliminated further contamination effects over 10 months. Discrimination values obtained using our offline incubation and computation method replicated previously reported results over a range of 10-31‰, with precision generally better than ±0.5‰. Our method enables large-scale investigations of plant alternative respiration along natural environmental gradients under field conditions.

Thermal acclimation of leaf photosynthetic traits in an evergreen woodland, consistent with the co-ordination hypothesis

Publisher: Copernicus GmbH

Date: 07-11-2017

DOI: 10.5194/BG-2017-449

Abstract: Abstract. Ecosystem models commonly assume that key photosynthetic traits, such as carboxylation-capacity measured at a standard temperature, are constant in time. The temperature responses of modelled photosynthetic/respiratory rates then depend entirely on enzyme kinetics. Optimality considerations suggest this assumption may be incorrect. The ‘co-ordination hypothesis’ (that Rubisco- and electron-transport limited rates of photosynthesis are co-limiting under typical daytime conditions) predicts instead that carboxylation (Vcmax) and light-harvesting (Jmax) capacities, and mitochondrial respiration in the dark (Rdark), should acclimate so that they increase with growth temperature – but less steeply than their instantaneous response rates. To explore this hypothesis, photosynthetic measurements were carried out on woody species during the warm and the cool seasons in the semi-arid Great Western Woodlands, Australia, under broadly similar light environments. A consistent linear relationship between Vcmax and Jmax was found across species. Vcmax, Jmax and Rdark increased with temperature, but values standardized to 25 ˚C declined. The ci:ca ratio increased slightly with temperature. The leaf N:P ratio was lower in the warm season. The slopes of the relationships of log-transformed Vcmax and Jmax to temperature were close to values predicted by the co-ordination hypothesis, but shallower than those predicted by enzyme kinetics.

Thermal limits of leaf metabolism across biomes

Publisher: Wiley

Date: 14-10-2016

DOI: 10.1111/GCB.13477

Abstract: High-temperature tolerance in plants is important in a warming world, with extreme heat waves predicted to increase in frequency and duration, potentially leading to lethal heating of leaves. Global patterns of high-temperature tolerance are documented in animals, but generally not in plants, limiting our ability to assess risks associated with climate warming. To assess whether there are global patterns in high-temperature tolerance of leaf metabolism, we quantified T

Modulation of respiratory metabolism in response to nutrient changes along a soil chronosequence

Publisher: Wiley

Date: 07-01-2013

DOI: 10.1111/PCE.12047

Abstract: Laboratory studies indicate that plant respiratory efficiency may decrease in response to low nutrient availability due to increased partitioning of electrons to the energy-wasteful alternative oxidase (AOX) however, field confirmation of this hypothesis is lacking. We therefore investigated plant respiratory changes associated with succession and retrogression in soils aged from 10 to 120 000 years along the Franz Josef soil chronosequence, New Zealand. Respiration rates and electron partitioning were determined based on oxygen isotopic fractionation. Leaf structural traits, foliar nutrient status, carbohydrates and species composition were measured as explanatory variables. Although soil nutrient levels and species composition varied by site along the chronosequence, foliar respiration across all sites and species corresponded strongly with leaf nitrogen concentration (r(2) = 0.8). In contrast, electron partitioning declined with increasing nitrogen hosphorus (r(2) = 0.23) and AOX activity correlated with phosphorus (r(2) = 0.64). Independently, total respiration was further associated with foliar Cu, possibly linked to its effect on AOX. Independent control of AOX and cytochrome pathway activities is also discussed. These responses of plant terminal respiratory oxidases - and therefore respiratory carbon efficiency - to multiple nutrient deficiencies demonstrate that modulation of respiratory metabolism may play an important role in plant responses to nutrient gradients.

Effect of sustained inflation duration; resuscitation of near-term asphyxiated lambs.

Publisher: BMJ

Date: 10-07-2013

DOI: 10.1136/ARCHDISCHILD-2012-301787

Abstract: The 2010 ILCOR neonatal resuscitation guidelines do not specify appropriate inflation times for the initial lung inflations in apnoeic newborn infants. The authors compared three ventilation strategies immediately after delivery in asphyxiated newborn lambs. Experimental animal study. Facility for animal research. Eighteen near-term lambs (weight 3.5-3.9 kg) delivered by caesarean section. Asphyxia was induced by occluding the umbilical cord and delaying ventilation onset (10-11 min) until mean carotid blood pressure (CBP) was ≤22 mm Hg. Animals were ided into three groups (n=6) and ventilation started with: (1) inflation times of 0.5 s at a ventilation rate 60/min, (2) five 3 s inflations or (3) a single 30 s inflation. Subsequent ventilation used inflations at 0.5 s at 60/min for all groups. Times to reach a heart rate (HR) of 120 bpm and a mean CBP of 40 mm Hg. Secondary outcome was change in lung compliance. Median time to reach HR 120 bpm and mean CBP 40 mm Hg was significantly shorter in the single 30 s inflation group (8 s and 74 s) versus the 5×3 s inflation group (38 s and 466 s) and the conventional ventilation group (64 s and 264 s). Lung compliance was significantly better in the single 30 s inflation group. A single sustained inflation of 30 s immediately after birth improved speed of circulatory recovery and lung compliance in near-term asphyxiated lambs. This approach for neonatal resuscitation merits further investigation.

Variation in bulk‐leaf 13C discrimination, leaf traits and water‐use efficiency–trait relationships along a continental‐scale climate gradient in Australia

Publisher: Wiley

Date: 24-10-2018

DOI: 10.1111/GCB.13911

Abstract: Large spatial and temporal gradients in rainfall and temperature occur across Australia. This heterogeneity drives ecological differentiation in vegetation structure and ecophysiology. We examined multiple leaf-scale traits, including foliar

Coordination of photosynthetic traits across soil and climate gradients

Publisher: Wiley

Date: 16-11-2022

DOI: 10.1111/GCB.16501

Abstract: “Least‐cost theory” posits that C 3 plants should balance rates of photosynthetic water loss and carboxylation in relation to the relative acquisition and maintenance costs of resources required for these activities. Here we investigated the dependency of photosynthetic traits on climate and soil properties using a new Australia‐wide trait dataset spanning 528 species from 67 sites. We tested the hypotheses that plants on relatively cold or dry sites, or on relatively more fertile sites, would typically operate at greater CO 2 drawdown (lower ratio of leaf internal to ambient CO 2 , C i : C a ) during light‐saturated photosynthesis, and at higher leaf N per area (N area ) and higher carboxylation capacity ( V cmax 25 ) for a given rate of stomatal conductance to water vapour, g sw . These results would be indicative of plants having relatively higher water costs than nutrient costs. In general, our hypotheses were supported. Soil total phosphorus (P) concentration and (more weakly) soil pH exerted positive effects on the N area – g sw and V cmax 25 – g sw slopes, and negative effects on C i : C a . The P effect strengthened when the effect of climate was removed via partial regression. We observed similar trends with increasing soil cation exchange capacity and clay content, which affect soil nutrient availability, and found that soil properties explained similar amounts of variation in the focal traits as climate did. Although climate typically explained more trait variation than soil did, together they explained up to 52% of variation in the slope relationships and soil properties explained up to 30% of the variation in in idual traits. Soils influenced photosynthetic traits as well as their coordination. In particular, the influence of soil P likely reflects the Australia's geologically ancient low‐relief landscapes with highly leached soils. Least‐cost theory provides a valuable framework for understanding trade‐offs between resource costs and use in plants, including limiting soil nutrients.

Plasticity of photosynthetic heat tolerance in plants adapted to thermally contrasting biomes

Publisher: Wiley

Date: 29-01-2018

DOI: 10.1111/PCE.13133

Abstract: In many biomes, plants are subject to heatwaves, potentially causing irreversible damage to the photosynthetic apparatus. Field surveys have documented global, temperature-dependent patterns in photosynthetic heat tolerance (P

Thermal acclimation of shoot respiration in an Arctic woody plant species subjected to 22 years of warming and altered nutrient supply

Publisher: Wiley

Date: 12-04-2014

DOI: 10.1111/GCB.12544

Abstract: Despite concern about the status of carbon (C) in the Arctic tundra, there is currently little information on how plant respiration varies in response to environmental change in this region. We quantified the impact of long-term nitrogen (N) and phosphorus (P) treatments and greenhouse warming on the short-term temperature (T) response and sensitivity of leaf respiration (R), the high-T threshold of R, and associated traits in shoots of the Arctic shrub Betula nana in experimental plots at Toolik Lake, Alaska. Respiration only acclimated to greenhouse warming in plots provided with both N and P (resulting in a ~30% reduction in carbon efflux in shoots measured at 10 and 20 °C), suggesting a nutrient dependence of metabolic adjustment. Neither greenhouse nor N+P treatments impacted on the respiratory sensitivity to T (Q10 ) overall, Q10 values decreased with increasing measuring T, from ~3.0 at 5 °C to ~1.5 at 35 °C. New high-resolution measurements of R across a range of measuring Ts (25-70 °C) yielded insights into the T at which maximal rates of R occurred (Tmax ). Although growth temperature did not affect Tmax , N+P fertilization increased Tmax values ~5 °C, from 53 to 58 °C. N+P fertilized shoots exhibited greater rates of R than nonfertilized shoots, with this effect diminishing under greenhouse warming. Collectively, our results highlight the nutrient dependence of thermal acclimation of leaf R in B. nana, suggesting that the metabolic efficiency allowed via thermal acclimation may be impaired at current levels of soil nutrient availability. This finding has important implications for predicting carbon fluxes in Arctic ecosystems, particularly if soil N and P become more abundant in the future as the tundra warms.

AusTraits – a curated plant trait database for the Australian flora

Publisher: Cold Spring Harbor Laboratory

Date: 07-01-2021

DOI: 10.1101/2021.01.04.425314

Abstract: We introduce the AusTraits database - a compilation of measurements of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 375 traits across 29230 taxa from field c aigns, published literature, taxonomic monographs, and in idual taxa descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological parameters (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised in idual-, species- and genus-level observations coupled to, where available, contextual information on site properties. This data descriptor provides information on version 2.1.0 of AusTraits which contains data for 937243 trait-by-taxa combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data to increase our collective understanding of the Australian flora.

Seasonal acclimation of leaf respiration in Eucalyptus saligna trees: impacts of elevated atmospheric CO2 and summer drought

Publisher: Wiley

Date: 02-11-2010

DOI: 10.1111/J.1365-2486.2010.02325.X

Diel‐ and temperature‐driven variation of leaf dark respiration rates and metabolite levels in rice

Publisher: Wiley

Date: 07-06-2020

DOI: 10.1111/NPH.16661

Impacts of drought on leaf respiration in darkness and light in Eucalyptus saligna exposed to industrial-age atmospheric CO2 and growth temperature

Publisher: Wiley

Date: 22-03-2011

DOI: 10.1111/J.1469-8137.2011.03673.X

Abstract: Our study assessed the impact of a wide range of industrial-age climate scenarios on leaf respiration (R) in Eucalyptus saligna. Well-watered or sustained drought-treated plants were grown in glasshouses differing in atmospheric CO₂ concentration ([CO₂]) (280, 400 and 640 μl l⁻¹) and temperature (26 and 30°C). Rates of R in darkness (R(dark) ) and light (R(light) ), photosynthesis (A) and related leaf traits (mass : area relationships, and nitrogen, phosphorus, starch and sugar concentrations) were measured. Light inhibited R in all cases (R(light) < R(dark) ) (well-watered: 40% drought-treated: 73%). Growth [CO₂] and temperature had little impact on area-based rates of R(dark) or R(light) , with R(light) exhibiting minimal thermal acclimation. By contrast, sustained drought resulted in reduced R(dark), R(light) and A, with the inhibitory effect of drought on A and R(light) (c. 50-70%) greater than that on R(dark) (c. 15%). Drought effects were fully reversible after watering. Variability in R(light) appeared to be dependent on the underlying rate of R(dark) and associated Rubisco activity. Collectively, our data suggest that there is an asynchronous response of leaf carbon metabolism to drought, and a tighter coupling between R(light) and A than between R(dark) and A, under both past and future climate scenarios. These findings have important implications for ecosystem/global models seeking to predict carbon cycling.

Phenotypic plasticity in rice: responses to fertilization and inoculation with arbuscular mycorrhizal fungi

Publisher: Oxford University Press (OUP)

Date: 20-03-2015

DOI: 10.1093/JPE/RTV031

Tracking the origins of the Kok effect, 70 years after its discovery The 18 th New Phytologist Workshop 'The Kok effect: beyond the artefact, emerging leaf mechanisms ( KOALA)' Angers, France, July 2016

Publisher: Wiley

Date: 20-03-2017

DOI: 10.1111/NPH.14527

Differential physiological responses to environmental change promote woody shrub expansion

Publisher: Wiley

Date: 13-03-2013

DOI: 10.1002/ECE3.525

Core principles which explain variation in respiration across biological scales

Publisher: Wiley

Date: 14-12-2019

DOI: 10.1111/NPH.15576

Abstract: Contents Summary 670 I. Introduction 671 II. Principle 1 - Plant respiration performs three distinct functions 673 III. Principle 2 - Metabolic pathway flexibility underlies plant respiratory performance 676 IV. Principle 3 - Supply and demand interact over time to set plant respiration rate 677 V. Principle 4 - Plant respiratory acclimation involves adjustments in enzyme capacities 679 VI. Principle 5 - Respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies 680 VII. Future directions 680 Acknowledgements 682 References 682 SUMMARY: Respiration is a core biological process that has important implications for the biochemistry, physiology, and ecology of plants. The study of plant respiration is thus conducted from several different perspectives by a range of scientific disciplines with dissimilar objectives, such as metabolic engineering, crop breeding, and climate-change modelling. One aspect in common among the different objectives is a need to understand and quantify the variation in respiration across scales of biological organization. The central tenet of this review is that different perspectives on respiration can complement each other when connected. To better accommodate interdisciplinary thinking, we identify distinct mechanisms which encompass the variation in respiratory rates and functions across biological scales. The relevance of these mechanisms towards variation in plant respiration are explained in the context of five core principles: (1) respiration performs three distinct functions (2) metabolic pathway flexibility underlies respiratory performance (3) supply and demand interact over time to set respiration rates (4) acclimation involves adjustments in enzyme capacities and (5) respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies. We argue that each perspective on respiration rests on these principles to varying degrees and that broader appreciation of how respiratory variation occurs can unite research across scales.

Australian National University

Location: No location found

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University Of Toronto

Location: Canada

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Australian National University

Location: Australia

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ARC Centre Of Excellence In Plant Energy Biology

Start Date: 2014

End Date: 2020

Funder: Australian Research Council

Revealing The Impacts Of Super-charged Photosynthesis On Leaf Respiration

Start Date: 2023

End Date: 2026

Funder: Australian Research Council

Achieving A Step Change In The Modeling Of Leaf Respiration-photosynthesis Relationships

Start Date: 2022

End Date: 2025

Funder: Australian Research Council

A National Approach To Improving Heat Tolerance In Wheat Through More Efficient Carbon Allocation

Start Date: 2016

End Date: 2020

Funder: Grains Research and Development Corporation

Improving Yield By Optimising Energy Use Efficiency

Start Date: 2016

End Date: 2018

Funder: Grains Research and Development Corporation

Discovery Projects - Grant ID: DP230103122

Start Date: 11-2023

End Date: 10-2026

Amount: $603,747.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100044

Start Date: 01-2012

End Date: 12-2013

Amount: $650,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1093759

Start Date: 2010

End Date: 12-2012

Amount: $330,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0986823

Start Date: 2009

End Date: 10-2012

Amount: $503,000.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT0991448

Start Date: 10-2009

End Date: 10-2013

Amount: $891,200.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100078

Start Date: 2010

End Date: 12-2010

Amount: $600,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0990330

Start Date: 05-2010

End Date: 05-2013

Amount: $480,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130101252

Start Date: 04-2013

End Date: 03-2016

Amount: $460,000.00

Funder: Australian Research Council

ARC Centres Of Excellence - Grant ID: CE140100008

Start Date: 2014

End Date: 05-2021

Amount: $26,000,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220101882

Start Date: 11-2022

End Date: 10-2025

Amount: $531,213.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP210300506

Start Date: 04-2023

End Date: 04-2028

Amount: $1,231,305.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989408

Start Date: 2009

End Date: 12-2009

Amount: $150,000.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC210100047

Start Date: 09-2022

End Date: 08-2027

Amount: $5,000,000.00

Funder: Australian Research Council