ORCID Profile
0000-0001-8491-9310
Current Organisation
E O Lawrence Berkeley National Laboratory
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Publisher: Cold Spring Harbor Laboratory
Date: 24-12-2019
DOI: 10.1101/2019.12.24.887844
Abstract: Plants emit high rates of methanol (meOH), generally assumed to derive from pectin demethylation, and this increases during abiotic stress. In contrast, less is known about the emission and source of acetic acid (AA). In this study, Populus trichocarpa (California poplar) leaves in different developmental stages were desiccated and quantified for total meOH and AA emissions together with bulk cell wall acetylation and methylation content. While young leaves showed high emissions of meOH (140 μmol m −2 ) and AA (42 μmol m −2 ), emissions were reduced in mature (meOH: 69%, AA: 60%) and old (meOH: 83%, AA: 76%) leaves. In contrast, the ratio of AA/meOH emissions increased with leaf development (young: 35%, mature: 43%, old: 82%), mimicking the pattern of O -acetyl/methyl ester ratios of leaf bulk cell walls (young: 35%, mature: 38%, old: 51%), which is driven by an increase in O -acetyl and decrease in methyl ester content with age. The results are consistent with meOH and AA emission sources from cell wall de-esterification, with young expanding tissues producing highly methylated pectin that is progressively demethyl-esterified. We highlight the quantification of AA/meOH emission ratios as a potential tool for rapid phenotype screening of structural carbohydrate esterification patterns.
Publisher: Public Library of Science (PLoS)
Date: 20-05-2020
Publisher: Oxford University Press (OUP)
Date: 23-07-2013
DOI: 10.1093/JXB/ERT202
Publisher: Cold Spring Harbor Laboratory
Date: 18-05-2023
DOI: 10.1101/2023.05.15.540825
Abstract: During oxygenic photosynthesis, oxygen (O 2 ) is generated from water photolysis, which provides reducing power to sustain CO 2 assimilation. To date, traditional leaf gas-exchange experiments have been focused on net CO 2 exchange (A net ), with limited observations of net oxygen production (NOP). Here, we present the first gas-exchange/fluorescence system, coupling CO 2 /H 2 O analysis (photosynthesis and transpiration) with NOP and isoprene emission measurements. This configuration allowed us to calculate the assimilatory quotient (AQ = A net /NOP) and thus obtain a more complete picture of the photosynthetic redox budget via photosynthetic production of O 2 , electron transport rate (ETR), and isoprene biosynthesis. We used cottonwood leaves ( Populus trichocarpa ) and carried out response curves to light, CO 2 and temperature along with 18 O-labelling with 18 O-enriched water. We found that A net and NOP were linearly correlated across environmental variables with AQ of 1.27 +/- 0.12 regardless of light, CO 2 , and temperature. A net and NOP had optimal temperatures (T opt ) of 31°C, while ETR (35°C) and isoprene emissions (39°C) had distinctly higher T opt . Leaves labelled with H 2 18 O produced labeled ( 18 O 16 O) oxygen with the same T opt as ETR (35°C). The results confirm a tight connection between water oxidation and ETR and are consistent with a suppression of A net and NOP at high temperature driven by an acceleration of (photo)respiration. The findings support the view of isoprene biosynthesis primarily driven by excess photosynthetic ATP/NADPH not consumed by the Calvin cycle during photorespiratory conditions as an important thermotolerance mechanism linked with high rates of CO 2 and O 2 recycling. Photosynthesis, net oxygen production, gross oxygen production, H 2 18 O labeling A leaf gas-exchange system is presented enabling a more complete picture of the photosynthetic redox budget and calculation of the assimilatory quotient.
Publisher: MDPI AG
Date: 23-02-2021
Abstract: Upregulation of acetate fermentation in plants has recently been described as an evolutionarily conserved drought survival strategy, with the amount of acetate produced directly correlating to survival. However, destructive measurements are required to evaluate acetate-linked drought responses, limiting the temporal and spatial scales that can be studied. Here, 13C-labeling studies with poplar (Populus trichocarpa) branches confirmed that methyl acetate is produced in plants from the acetate-linked acetylation of methanol. Methyl acetate emissions from detached leaves were strongly stimulated during desiccation, with total emissions decreasing with the leaf developmental stage. In addition, diurnal methyl acetate emissions from whole physiologically active poplar branches increased as a function of temperature, and light-dark transitions resulted in significant emission bursts lasting several hours. During experimental drought treatments of potted poplar saplings, light-dark methyl acetate emission bursts were eliminated while strong enhancements in methyl acetate emissions lasting 6 days were observed with their initiation coinciding with the suppression of transpiration and photosynthesis. The results suggest that methyl acetate emissions represent a novel non-invasive tracer of acetate-mediated temperature and drought survival response in plants. The findings may have important implications for the future understanding of acetate-mediated drought responses to transcription, cellular metabolism, and hormone signaling, as well as its associated changes in carbon cycling and water use from in idual plants to whole ecosystems.
Publisher: Oxford University Press (OUP)
Date: 15-10-2014
Publisher: Elsevier BV
Date: 08-2020
Publisher: Wiley
Date: 21-09-2021
DOI: 10.1111/GCB.15869
Abstract: Increasing severity and frequency of drought is predicted for large portions of the terrestrial biosphere, with major impacts already documented in wet tropical forests. Using a 4‐year rainfall exclusion experiment in the Daintree Rainforest in northeast Australia, we examined canopy tree responses to reduced precipitation and soil water availability by quantifying seasonal changes in plant hydraulic and carbon traits for 11 tree species between control and drought treatments. Even with reduced soil volumetric water content in the upper 1 m of soil in the drought treatment, we found no significant difference between treatments for predawn and midday leaf water potential, photosynthesis, stomatal conductance, foliar stable carbon isotope composition, leaf mass per area, turgor loss point, xylem vessel anatomy, or leaf and stem nonstructural carbohydrates. While empirical measurements of aboveground traits revealed homeostatic maintenance of plant water status and traits in response to reduced soil moisture, modeled belowground dynamics revealed that trees in the drought treatment shifted the depth from which water was acquired to deeper soil layers. These findings reveal that belowground acclimation of tree water uptake depth may buffer tropical rainforests from more severe droughts that may arise in future with climate change.
Publisher: Wiley
Date: 20-10-2022
DOI: 10.1111/PCE.14464
Abstract: Growth suppression and defence signalling are simultaneous strategies that plants invoke to respond to abiotic stress. Here, we show that the drought stress response of poplar trees ( Populus trichocarpa ) is initiated by a suppression in cell wall derived methanol (MeOH) emissions and activation of acetic acid (AA) fermentation defences. Temperature sensitive emissions dominated by MeOH (AA/MeOH %) were observed from physiologically active leaves, branches, detached stems, leaf cell wall isolations and whole ecosystems. In contrast, drought treatment resulted in a suppression of MeOH emissions and strong enhancement in AA emissions together with volatiles acetaldehyde, ethanol, and acetone. These drought‐induced changes coincided with a reduction in stomatal conductance, photosynthesis, transpiration, and leaf water potential. The strong enhancement in AA/MeOH emission ratios during drought (400%–3500%) was associated with an increase in acetate content of whole leaf cell walls, which became significantly 13 C 2 ‐labelled following the delivery of 13 C 2 ‐acetate via the transpiration stream. The results are consistent with both enzymatic and nonenzymatic MeOH and AA production at high temperature in hydrated tissues associated with accelerated primary cell wall growth processes, which are downregulated during drought. While the metabolic source(s) require further investigation, the observations are consistent with drought‐induced activation of aerobic fermentation driving high rates of foliar AA emissions and enhancements in leaf cell wall O ‐acetylation. We suggest that atmospheric AA/MeOH emission ratios could be useful as a highly sensitive signal in studies investigating environmental and biological factors influencing growth‐defence trade‐offs in plants and ecosystems.
Publisher: American Chemical Society (ACS)
Date: 03-08-2021
Location: United States of America
Location: United States of America
Start Date: 2011
End Date: 2014
Funder: U.S. Department of Energy
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