ORCID Profile
0000-0003-3442-1711
Current Organisations
University of Bordeaux
,
Radboud Universiteit Nijmegen
,
INRA Bordeaux
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Ecology | Ecological Physiology | Crop and Pasture Biochemistry and Physiology | Biological Adaptation
Climate Change Adaptation Measures | Forest and Woodlands Water Management | Wheat |
Publisher: Wiley
Date: 21-10-2013
Publisher: Wiley
Date: 16-06-2016
DOI: 10.1111/PCE.12758
Abstract: Research in plant hydraulics has provided important insights into plant responses to drought and species absolute drought tolerance. However, our ability to predict when plants will die from hydraulic failure under extreme drought is limited by a lack of knowledge with regards to the dynamics of plant desiccation following stomatal closure. Thus, we develop a simple hydraulics model based on branch-level traits that incorporates key aspects of allometry, rates of water loss and resistance to embolism thresholds in order to define species differences in the time it takes plants to desiccate from stomatal closure to lethal levels of drought stress.
Publisher: Proceedings of the National Academy of Sciences
Date: 03-2021
Abstract: A fundamental association between sustained water transport and downstream tissue survival should select for xylem that avoids embolism in long-lived woody plants. Previous studies suggest that long-vessel species, such as oaks and vines, are more susceptible to drought-induced loss of function than other species. We show that western North American oaks—even those occurring in wet temperate forest—possess xylem capable of tolerating substantial water stress. Evolutionary relationships between drought tolerance traits combined with plant–climate interactions yield positive hydraulic safety margins in oaks from erse habitats, demonstrating that these key species are not yet on the verge of hydraulically mediated loss of function. Quantifying physical tolerance limits to desiccation is imperative for predicting ecological consequences of future droughts.
Publisher: Oxford University Press (OUP)
Date: 06-07-2017
DOI: 10.1104/PP.17.00552
Publisher: Oxford University Press (OUP)
Date: 09-09-2016
DOI: 10.1104/PP.16.01079
Publisher: Springer Science and Business Media LLC
Date: 09-03-2020
Publisher: Oxford University Press (OUP)
Date: 15-03-0011
Abstract: Xylem anatomy may change in response to environmental or biotic stresses. Vascular occlusion, an anatomical modification of mature xylem, contributes to plant resistance and susceptibility to different stresses. In woody organs, xylem occlusions have been examined as part of the senescence process, but their presence and function in leaves remain obscure. In grapevine, many stresses are associated with premature leaf senescence inducing discolorations and scorched tissue in leaves. However, we still do not know whether the leaf senescence process follows the same sequence of physiological events and whether leaf xylem anatomy is affected in similar ways. In this study, we quantified vascular occlusions in midribs from leaves with symptoms of the grapevine disease esca, magnesium deficiency and autumn senescence. We found higher amounts of vascular occlusions in leaves with esca symptoms (in 27% of xylem vessels on average), whereas the leaves with other symptoms (as well as the asymptomatic controls) had far fewer occlusions (in 3% of vessels). Therefore, we assessed the relationship between xylem occlusions and esca leaf symptoms in four different countries (California in the USA, France, Italy and Spain) and eight different cultivars. We monitored the plants over the course of the growing season, confirming that vascular occlusions do not evolve with symptom age. Finally, we investigated the hydraulic integrity of leaf xylem vessels by optical visualization of embolism propagation during dehydration. We found that the occlusions lead to hydraulic dysfunction mainly in the peripheral veins compared with the midribs in esca symptomatic leaves. These results open new perspectives on the role of vascular occlusions during the leaf senescence process, highlighting the uniqueness of esca leaf symptoms and its consequence on leaf physiology.
Publisher: Wiley
Date: 09-12-2022
DOI: 10.1111/NPH.18614
Abstract: Fuel moisture content (FMC) is a crucial driver of forest fires in many regions world‐wide. Yet, the dynamics of FMC in forest canopies as well as their physiological and environmental determinants remain poorly understood, especially under extreme drought. We embedded a FMC module in the trait‐based, plant‐hydraulic SurEau‐Ecos model to provide innovative process‐based predictions of leaf live fuel moisture content (LFMC) and canopy fuel moisture content (CFMC) based on leaf water potential (). SurEau‐Ecos‐FMC relies on pressure–volume ( p‐v ) curves to simulate LFMC and vulnerability curves to cavitation to simulate foliage mortality. SurEau‐Ecos‐FMC accurately reproduced and LFMC dynamics as well as the occurrence of foliage mortality in a Mediterranean Quercus ilex forest. Several traits related to water use (leaf area index, available soil water, and transpiration regulation), vulnerability to cavitation, and p‐v curves (full turgor osmotic potential) had the greatest influence on LFMC and CFMC dynamics. As the climate gets drier, our results showed that drought‐induced foliage mortality is expected to increase, thereby significantly decreasing CFMC. Our results represent an important advance in our capacity to understand and predict the sensitivity of forests to wildfires.
Publisher: Oxford University Press (OUP)
Date: 02-11-2015
DOI: 10.1104/PP.15.00732
Publisher: Cold Spring Harbor Laboratory
Date: 09-06-2023
DOI: 10.1101/2023.06.07.543986
Abstract: Background. Applying good data management and FAIR data principles (Findable, Accessible, Interoperable, and Reusable) in research projects can help disentangle knowledge discovery, study result reproducibility, and data reuse in future studies. Based on the concepts of the original FAIR principles for research data, FAIR principles for research software were recently proposed. FAIR Digital Objects enable discovery and reuse of Research Objects, including computational workflows for both humans and machines. Practical ex les can help promote the adoption of FAIR practices for computational workflows in the research community. We developed a multi-omics data analysis workflow implementing FAIR practices to share it as a FAIR Digital Object. Findings. We conducted a case study investigating shared patterns between multi-omics data and childhood externalizing behavior. The analysis workflow was implemented as a modular pipeline in the workflow manager Nextflow, including containers with software dependencies. We adhered to software development practices like version control, documentation, and licensing. Finally, the workflow was described with rich semantic metadata, packaged as a Research Object Crate, and shared via WorkflowHub. Conclusions. Along with the packaged multi-omics data analysis workflow, we share our experiences adopting various FAIR practices and creating a FAIR Digital Object. We hope our experiences can help other researchers who develop omics data analysis workflows to turn FAIR principles into practice.
Publisher: Wiley
Date: 17-09-2015
DOI: 10.1111/NPH.13646
Abstract: The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well‐known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and spread) should trade off against xylem efficiency (its capacity to transport water). We tested this safety–efficiency hypothesis in branch xylem across 335 angiosperm and 89 gymnosperm species. Safety was considered at three levels: the xylem water potentials where 12%, 50% and 88% of maximal conductivity are lost. Although correlations between safety and efficiency were weak ( r 2 0.086), no species had high efficiency and high safety, supporting the idea for a safety–efficiency tradeoff. However, many species had low efficiency and low safety. Species with low efficiency and low safety were weakly associated ( r 2 0.02 in most cases) with higher wood density, lower leaf‐ to sapwood‐area and shorter stature. There appears to be no persuasive explanation for the considerable number of species with both low efficiency and low safety. These species represent a real challenge for understanding the evolution of xylem.
Publisher: Oxford University Press (OUP)
Date: 06-11-2014
Publisher: Cold Spring Harbor Laboratory
Date: 22-07-2022
DOI: 10.1101/2022.07.21.22277627
Abstract: Mild traumatic brain injury is widely regarded as a misnomer: it is globally a major cause of disability and is hypothesized as a potential causal factor in subsequent neurodegeneration. Commonly arising in sport, mounting evidence of varying degrees of cognitive impairment in retired athletes exposed to repeated concussions motivates close examination of its cumulative effects on the brain. Studying a cohort of 125 retired athletes with a mean of 11 reported concussions and 36 matched controls with none, here we evaluated whole-brain volumetric and subcortical morphological effects with Bayesian regression models and functional connectivity effects with network-based statistics. Estimates of potential cognitive impact were derived from meta-analytic functional mapping based on 13,459 imaging studies. Across the array of brain structural and functional effects identified, regions significantly lower in volume in the concussed group included, in order of greatest effect size, the middle frontal gyrus, hippoc us, supramarginal gyrus, temporal pole, and inferior frontal gyrus. Conversely, brain regions significantly larger within the athlete group included, in order of greatest effect size, the hippoc al and collateral sulcus, middle occipital gyrus, medial orbital gyrus, caudate nucleus, lateral orbital gyrus, and medial segment to the postcentral gyrus (all significant with 95% Bayesian credible interval). Subcortical morphology analysis corroborated these findings, revealing a significant, age-independent relationship between inward deformation of the hippoc us and the number of concussions sustained (corrected- p .0001). Functional connectivity analyses revealed a distinct brain network with significantly increased edge strength in the athlete cohort comprising 150 nodes and 400 edges (corrected- p =0.02), with the highest degree nodes including the pre-central and post-central gyri and right insula. The functional communities of the greatest eigenvector centralities corresponded to motor domains. Numerous edges of this network strengthened in athletes were significantly weakened with increasing bouts of concussion, which included disengagement of the frontal pole, superior frontal, and middle frontal gyri ( p =0.04). Aligned to meta-analytic neuroimaging data, the observed changes suggest possible functional enhancement within the motor, sensory, coordination, balance, and visual processing domains in athletes, attenuated by concussive head injury with a negative impact on memory and language. That such changes are observed many years after retirement from impact sport suggests strong repetition effects and/or underpinning genetic selection factors. These findings suggest that engagement in sport may benefit the brain across numerous domains, but also highlights the potentially damaging effects of concussive head injury.
Publisher: Wiley
Date: 04-12-2022
DOI: 10.1111/NPH.18578
Abstract: Xylem hydraulic failure (HF) has been identified as a ubiquitous factor in triggering drought‐induced tree mortality through the damage induced by the progressive dehydration of plant living cells. However, fundamental evidence of the mechanistic link connecting xylem HF to cell death has not been identified yet. The main aim of this study was to evaluate, at the leaf level, the relationship between loss of hydraulic function due to cavitation and cell death under drought conditions and discern how this relationship varied across species with contrasting resistances to cavitation. Drought was induced by withholding water from potted seedlings, and their leaves were s led to measure their relative water content (RWC) and cell mortality. Vulnerability curves to cavitation at the leaf level were constructed for each species. An increment in cavitation events occurrence precedes the onset of cell mortality. A variation in cells tolerance to dehydration was observed along with the resistance to cavitation. Overall, our results indicate that the onset of cellular mortality occurs at lower RWC than the one for cavitation indicating the role of cavitation in triggering cellular death. They also evidenced a critical RWC for cellular death varying across species with different cavitation resistance.
Publisher: Wiley
Date: 28-07-2010
DOI: 10.1111/J.1469-8137.2010.03393.X
Abstract: • Motivated by the urgent need to understand how water stress-induced embolism limits the survival and recovery of plants during drought, the linkage between water-stress tolerance and xylem cavitation resistance was examined in one of the world's most drought resistant conifer genera, Callitris. • Four species were subjected to drought treatments of -5, -8 and -10 MPa for a period of 3-4 wk, after which plants were rewatered. Transpiration, basal growth and leaf water potential were monitored during and after drought. • Lethal water potential was correlated with the tension producing a 50% loss of stem hydraulic conductivity. The most resilient species suffered minimal embolism and recovered gas exchange within days of rewatering from -10 MPa, while the most sensitive species suffered major embolism and recovered very slowly. The rate of repair of water transport in the latter case was equal to the rate of basal area growth, indicating xylem reiteration as the primary means of hydraulic repair. • The survival of, and recovery from, water stress in Callitris are accurately predicted by the physiology of the stem water-transport system. As the only apparent means of xylem repair after embolism, basal area growth is a critical part of this equation.
Publisher: Springer Science and Business Media LLC
Date: 11-2012
DOI: 10.1038/NATURE11688
Abstract: Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli in the water transport system, which reduces the ability of plants to supply water to leaves for photosynthetic gas exchange and can ultimately result in desiccation and mortality. At present we lack a clear picture of how thresholds to hydraulic failure vary across a broad range of species and environments, despite many in idual experiments. Here we draw together published and unpublished data on the vulnerability of the transport system to drought-induced embolism for a large number of woody species, with a view to examining the likely consequences of climate change for forest biomes. We show that 70% of 226 forest species from 81 sites worldwide operate with narrow (<1 megapascal) hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe. Safety margins are largely independent of mean annual precipitation, showing that there is global convergence in the vulnerability of forests to drought, with all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment. These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk.
Publisher: Brill
Date: 20-10-2023
Publisher: Oxford University Press (OUP)
Date: 26-11-2015
Abstract: The Araucariaceae is an iconic tree family. Once globally important, the Araucariaceae declined dramatically over the Cenozoic period. Increasing aridity is thought to be responsible for extinction and range contraction of Araucariaceae in Australia, yet little is known about how these trees respond to water stress. We examined the response to water stress of the recently discovered tree Wollemia nobilis Jones, W.G., Hill, K.D. & Allen, J.M. (Araucariaceae) and two closely related and widespread tree species, Araucaria bidwillii Hook. and Araucaria cunninghamii Mudie, and the island-endemic species, Araucaria heterophylla (Salisb.) Franco. Leaf water potential in all Araucaria spp. remained remarkably unchanged during both dehydration and rehydration, indicating strong isohydry. The xylem tensions at which shoot and stem hydraulic conductances were reduced to 50% (P50shoot and P50stem) were closely correlated in all species. Among the four species, W. nobilis exhibited greater resistance to xylem hydraulic dysfunction during water stress (as indicated by P50shoot and P50stem). Unexpectedly, W. nobilis also experienced the highest levels of crown mortality in response to dehydration, suggesting that this was the most drought-sensitive species in this study. Our results highlight that single traits (e.g., P50) should not be used in isolation to predict drought survival. Further, we found no clear correlation between species' P50 and rainfall across their distributional range. Diversity in drought response among these closely related Araucariaceae species was surprisingly high, considering their reputation as a functionally conservative family.
Publisher: Wiley
Date: 21-12-2015
DOI: 10.1111/PCE.12680
Abstract: Plants can be highly segmented organisms with an independently redundant design of organs. In the context of plant hydraulics, leaves may be less embolism resistant than stems, allowing hydraulic failure to be restricted to distal organs that can be readily replaced. We quantified drought-induced embolism in needles and stems of Pinus pinaster using high-resolution computed tomography (HRCT). HRCT observations of needles were compared with the rehydration kinetics method to estimate the contribution of extra-xylary pathways to declining hydraulic conductance. High-resolution computed tomography images indicated that the pressure inducing 50% of embolized tracheids was similar between needle and stem xylem (P50 needle xylem = -3.62 MPa, P50 stem xylem = -3.88 MPa). Tracheids in both organs showed no difference in torus overlap of bordered pits. However, estimations of the pressure inducing 50% loss of hydraulic conductance at the whole needle level by the rehydration kinetics method were significantly higher (P50 needle = -1.71 MPa) than P50 needle xylem derived from HRCT. The vulnerability segmentation hypothesis appears to be valid only when considering hydraulic failure at the entire needle level, including extra-xylary pathways. Our findings suggest that native embolism in needles is limited and highlight the importance of imaging techniques for vulnerability curves.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-01-2018
Abstract: Long-term observations in Napa Valley and Bordeaux reveal that grapevines never reach a lethal level of drought.
Publisher: Wiley
Date: 19-09-2022
DOI: 10.1111/NPH.18447
Abstract: Hydraulic failure resulting from drought-induced embolism in the xylem of plants is a key determinant of reduced productivity and mortality. Methods to assess this vulnerability are difficult to achieve at scale, leading to alternative metrics and correlations with more easily measured traits. These efforts have led to the longstanding and pervasive assumed mechanistic link between vessel diameter and vulnerability in angiosperms. However, there are at least two problems with this assumption that requires critical re-evaluation: (1) our current understanding of drought-induced embolism does not provide a mechanistic explanation why increased vessel width should lead to greater vulnerability, and (2) the most recent advancements in nanoscale embolism processes suggest that vessel diameter is not a direct driver. Here, we review data from physiological and comparative wood anatomy studies, highlighting the potential anatomical and physicochemical drivers of embolism formation and spread. We then put forward key knowledge gaps, emphasising what is known, unknown and speculation. A meaningful evaluation of the diameter-vulnerability link will require a better mechanistic understanding of the biophysical processes at the nanoscale level that determine embolism formation and spread, which will in turn lead to more accurate predictions of how water transport in plants is affected by drought.
Publisher: Wiley
Date: 27-06-2016
DOI: 10.1111/NPH.14043
Publisher: Wiley
Date: 08-2023
DOI: 10.1111/PPL.14035
Publisher: Wiley
Date: 13-06-2020
DOI: 10.1111/NPH.16649
Publisher: Wiley
Date: 26-07-2020
DOI: 10.1111/NPH.16746
Abstract: Hydraulic failure of the plant vascular system is a principal cause of forest die‐off under drought. Accurate quantification of this process is essential to our understanding of the physiological mechanisms underpinning plant mortality. Imaging techniques increasingly are applied to estimate xylem cavitation resistance. These techniques allow for in situ measurement of embolism formation in real time, although the benefits and trade‐offs associated with different techniques have not been evaluated in detail. Here we compare two imaging methods, microcomputed tomography (microCT) and optical vulnerability (OV), to standard hydraulic methods for measurement of cavitation resistance in seven woody species representing a ersity of major phylogenetic and xylem anatomical groups. Across the seven species, there was strong agreement between cavitation resistance values (P 50 ) estimated from visualization techniques (microCT and OV) and between visual techniques and hydraulic techniques. The results indicate that visual techniques provide accurate estimates of cavitation resistance and the degree to which xylem hydraulic function is impacted by embolism. Results are discussed in the context of trade‐offs associated with each technique and possible causes of discrepancy between estimates of cavitation resistance provided by visual and hydraulic techniques.
Publisher: Oxford University Press (OUP)
Date: 25-07-2013
DOI: 10.1093/JXB/ERT193
Abstract: Xylem cavitation resistance has profound implications for plant physiology and ecology. This process is characterized by a 'vulnerability curve' (VC) showing the variation of the percentage of cavitation as a function of xylem pressure potential. The shape of this VC varies from 'sigmoidal' to 'exponential'. This review provides a panorama of the techniques that have been used to generate such a curve. The techniques differ by (i) the way cavitation is induced (e.g. bench dehydration, centrifugation, or air injection), and (ii) the way cavitation is measured (e.g. percentage loss of conductivity (PLC) or acoustic emission), and a nomenclature is proposed based on these two methods. A survey of the literature of more than 1200 VCs was used to draw statistics on the usage of these methods and on their reliability and validity. Four methods accounted for more than 96% of all curves produced so far: bench dehydration-PLC, centrifugation-PLC, pressure sleeve-PLC, and Cavitron. How the shape of VCs varies across techniques and species xylem anatomy was also analysed. Strikingly, it was found that the vast majority of curves obtained with the reference bench dehydration-PLC method are 'sigmoidal'. 'Exponential' curves were more typical of the three other methods and were remarkably frequent for species having large xylem conduits (ring-porous), leading to a substantial overestimation of the vulnerability of cavitation for this functional group. We suspect that 'exponential' curves may reflect an open-vessel artefact and call for more precautions with the usage of the pressure sleeve and centrifugation techniques.
Publisher: Wiley
Date: 03-05-2017
DOI: 10.1111/NPH.14589
Abstract: Xylem vulnerability to embolism represents an essential trait for the evaluation of the impact of hydraulics in plant function and ecology. The standard centrifuge technique is widely used for the construction of vulnerability curves, although its accuracy when applied to species with long vessels remains under debate. We developed a simple diagnostic test to determine whether the open‐vessel artefact influences centrifuge estimates of embolism resistance. Xylem s les from three species with differing vessel lengths were exposed to less negative xylem pressures via centrifugation than the minimum pressure the s le had previously experienced. Additional calibration was obtained from non‐invasive measurement of embolism on intact olive plants by X‐ray microtomography. Results showed artefactual decreases in hydraulic conductance ( k ) for s les with open vessels when exposed to a less negative xylem pressure than the minimum pressure they had previously experienced. X‐Ray microtomography indicated that most of the embolism formation in olive occurs at xylem pressures below −4.0 MP a, reaching 50% loss of hydraulic conductivity at −5.3 MP a. The artefactual reductions in k induced by centrifugation underestimate embolism resistance data of species with long vessels. A simple test is suggested to avoid this open vessel artefact and to ensure the reliability of this technique in future studies.
Publisher: Elsevier BV
Date: 04-2019
Publisher: Oxford University Press (OUP)
Date: 27-08-2019
DOI: 10.1104/PP.19.00591
Start Date: 2017
End Date: 12-2020
Amount: $375,500.00
Funder: Australian Research Council
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