Functional xylem characteristics associated with drought‐induced embolism in angiosperms

New Phytologist, Journal Year: 2022, Volume and Issue: 236(6), P. 2019 - 2036

Published: Aug. 30, 2022

Hydraulic failure resulting from drought-induced embolism in the xylem of plants is a key determinant reduced productivity and mortality. Methods to assess this vulnerability are difficult achieve at scale, leading alternative metrics correlations with more easily measured traits. These efforts have led longstanding pervasive assumed mechanistic link between vessel diameter angiosperms. However, there least two problems assumption that requires critical re-evaluation: (1) our current understanding does not provide explanation why increased width should lead greater vulnerability, (2) most recent advancements nanoscale processes suggest direct driver. Here, we review data physiological comparative wood anatomy studies, highlighting potential anatomical physicochemical drivers formation spread. We then put forward knowledge gaps, emphasising what known, unknown speculation. A meaningful evaluation diameter-vulnerability will require better biophysical level determine spread, which turn accurate predictions how water transport affected by drought.

Language: Английский

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Burning questions for a warming and changing world: 15 unknowns in plant abiotic stress

The Plant Cell, Journal Year: 2022, Volume and Issue: 35(1), P. 67 - 108

Published: Aug. 26, 2022

We present unresolved questions in plant abiotic stress biology as posed by 15 research groups with expertise spanning eco-physiology to cell and molecular biology. Common themes of these include the need better understand how plants detect water availability, temperature, salinity, rising carbon dioxide (CO2) levels; environmental signals interface endogenous signaling development (e.g. circadian clock flowering time); this integrated controls downstream responses stomatal regulation, proline metabolism, growth versus defense balance). The plasma membrane comes up frequently a site key transport events mechanosensing lipid-derived signaling, aquaporins). Adaptation extremes CO2 affects hydraulic architecture transpiration, well root shoot morphology, ways not fully understood. Environmental adaptation involves tradeoffs that limit ecological distribution crop resilience face changing increasingly unpredictable environments. Exploration diversity within among species can help us know which represent fundamental limits ones be circumvented bringing new trait combinations together. Better defining what constitutes beneficial resistance different contexts making connections between genes phenotypes, laboratory field observations, are overarching challenges.

Language: Английский

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Addressing controversies in the xylem embolism resistance–vessel diameter relationship

New Phytologist, Journal Year: 2023, Volume and Issue: 238(1), P. 283 - 296

Published: Jan. 13, 2023

Summary Although xylem embolism is a key process during drought‐induced tree mortality, its relationship to wood anatomy remains debated. While the functional link between bordered pits and resistance known, there no direct, mechanistic explanation for traditional assumption that wider vessels are more vulnerable than narrow ones. We used data from 20 temperate broad‐leaved species study inter‐ intraspecific of water potential at 50% loss conductivity ( P 50 ) with hydraulically weighted vessel diameter D h tested pit membrane thickness T PM specific K s on level. Embolism‐resistant had thick membranes vessels. was weakly associated , – remained highly significant after accounting . The interspecific pattern mirrored by but evidence an relationship. Our results provide robust across our species. As cause inconsistencies in published relationships, analysis suggests differences range trait values covered, level aggregation (species, or sample level) studied.

Language: Английский

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Drought will not leave your glass empty: Low risk of hydraulic failure revealed by long-term drought observations in world’s top wine regions

Science Advances, Journal Year: 2018, Volume and Issue: 4(1)

Published: Jan. 5, 2018

Long-term observations in Napa Valley and Bordeaux reveal that grapevines never reach a lethal level of drought.

Language: Английский

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Variation in xylem vulnerability to embolism in European beech from geographically marginal populations

Tree Physiology, Journal Year: 2017, Volume and Issue: 38(2), P. 173 - 185

Published: Sept. 23, 2017

Climate change is expected to increase the frequency and intensity of droughts heatwaves in Europe, leading effects on forest growth major dieback events due hydraulic failure caused by xylem embolism. Inter-specific variability embolism resistance has been studied detail, but little known about intra-specific variability, particularly marginal populations. We evaluated 15 European beech populations, mostly from geographically sites species distribution range, focusing populations dry southern margin. found small, significant differences between with pressures causing 50% loss conductivity ranging −2.84 −3.55 MPa. Significant phenotypic clines increasing temperature aridity were observed: southernmost growing a warmer drier climate lower habitat suitability have higher than those Northern Europe more favourable conditions. Previous studies shown that there or no difference core our findings show developed ways protecting their based either evolution plasticity.

Language: Английский

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Xylem embolism in leaves does not occur with open stomata: evidence from direct observations using the optical visualization technique

Journal of Experimental Botany, Journal Year: 2019, Volume and Issue: 71(3), P. 1151 - 1159

Published: Oct. 21, 2019

Drought represents a major abiotic constraint to plant growth and survival. On the one hand, plants keep stomata open for efficient carbon assimilation while, on other they close them prevent permanent hydraulic impairment from xylem embolism. The order of occurrence these two processes (stomatal closure onset leaf embolism) during dehydration has remained controversial, largely due methodological limitations. However, newly developed optical visualization method now allows concurrent monitoring stomatal behaviour embolism formation in intact plants. We used this new approach directly by dehydrating saplings three contrasting tree species indirectly conducting literature survey across greater range taxa. Our results indicate that increasing water stress generates consistently after closure, lag time between (i.e. safety margin) rises with resistance. This suggests stress, embolism-mediated declines conductivity are unlikely act as signal down-regulation. Instead, converge towards strategy closing early loss delay catastrophic dysfunction.

Language: Английский

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Neither xylem collapse, cavitation, or changing leaf conductance drive stomatal closure in wheat

Plant Cell & Environment, Journal Year: 2020, Volume and Issue: 43(4), P. 854 - 865

Published: Jan. 18, 2020

Abstract Identifying the drivers of stomatal closure and leaf damage during stress in grasses is a critical prerequisite for understanding crop resilience. Here, we investigated whether changes conductance ( g s ) dehydration were associated with hydraulic K ), xylem cavitation, collapse, cell turgor wheat Triticum aestivum ). During soil dehydration, decline was concomitant declining under mild water stress. This early not driven by as first cavitation events stem detected well after had declined. Xylem vessel deformation could only account <5% observed dehydration. Thus, concluded that tissues outside responsible majority wheat. However, contribution resistance to whole plant less than other (<35% resistance), this proportion remained constant plants dehydrated, indicating major driver closure.

Language: Английский

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Function and three-dimensional structure of intervessel pit membranes in angiosperms: a review

IAWA Journal, Journal Year: 2019, Volume and Issue: 40(4), P. 673 - 702

Published: Nov. 16, 2019

ABSTRACT Pit membranes in bordered pits of tracheary elements angiosperm xylem represent primary cell walls that undergo structural and chemical modifications, not only during death but also after their role as safety valves for water transport between conduits. Cellulose microfibrils, which are typically grouped aggregates with a diameter 20 to 30 nm, make up main component. While it is clear pectins hemicellulose removed from immature pit hydrolysis, recent observations amphiphilic lipids proteins associated raise important questions about drought-induced embolism formation spread via air-seeding gas-filled Indeed, mechanisms behind remain poorly understood, due part little attention paid the three-dimensional structure earlier studies. Based on perfusion experiments modelling, pore constrictions fibrous estimated be well below 50 smaller than nm. Together low dynamic surface tensions at air-water interfaces membranes, 5 nm line observed potentials values generally induce embolism. Moreover, appear show ideal porous medium properties sap flow promote hydraulic efficiency very high porosity (pore volume fraction), highly interconnected, non-tortuous pathways, occurrence multiple within single pore. This view mesoporous media may explain relationship membrane thickness resistance, largely incompatible earlier, two-dimensional views air-seeding. It hypothesised enable under negative pressure by producing stable, surfactant coated nanobubbles while preventing entry large bubbles would cause

Language: Английский

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Vulnerability and hydraulic segmentations at the stem–leaf transition: coordination across Neotropical trees

New Phytologist, Journal Year: 2020, Volume and Issue: 228(2), P. 512 - 524

Published: June 4, 2020

Summary Hydraulic segmentation at the stem–leaf transition predicts higher hydraulic resistance in leaves than stems. Vulnerability segmentation, however, lower embolism leaves. Both mechanisms should theoretically favour runaway to preserve expensive organs such as stems, and be tested for any potential coordination. We investigated theoretical leaf‐specific conductivity based on an anatomical approach quantify degree of across 21 tropical rainforest tree species. Xylem stems (flow‐centrifugation technique) (optical visualization method) was quantified assess vulnerability segmentation. found a pervasive species, but with strong variability Despite clear continuum eight species showed positive (leaves less resistant stems), whereas remaining studied exhibited negative or no The positively related that segmented promote both hydraulically decouple leaf xylem from stem xylem. To what extent determine drought requires further integration leaf–stem whole‐plant level, including outer tissue.

Language: Английский

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Insights from in vivo micro‐CT analysis: testing the hydraulic vulnerability segmentation in Acer pseudoplatanus and Fagus sylvatica seedlings

New Phytologist, Journal Year: 2018, Volume and Issue: 221(4), P. 1831 - 1842

Published: Oct. 22, 2018

The seedling stage is the most susceptible one during a tree's life. Water relations may be crucial for seedlings due to their small roots, limited water buffers and effects of drought on transport. Despite obvious relevance, studies xylem hydraulics are scarce as respective methodical approaches limited. Micro-CT scans intact Acer pseudoplatanus Fagus sylvatica dehydrated different potentials (Ψ) allowed simultaneous observation gas-filled versus water-filled conduits calculation percentage loss conductivity (PLC) in stems, roots leaves (petioles or main veins). Additionally, anatomical analyses were performed stem PLC measured with hydraulic techniques. In A. pseudoplatanus, petioles showed higher Ψ at 50% (Ψ50 -1.13MPa) than stems (-2.51 MPa) (-1.78 MPa). leaf veins F. had similar Ψ50 values (-2.26 (-2.74 (-2.75 both species, no difference between root was observed. Hydraulic measurements closely matched micro-CT based calculations. indicated species-specific architecture. Vulnerability segmentation, enabling disconnection pathway upon drought, observed but not especially shade-tolerant sylvatica. patterns could partly related traits.

Language: Английский

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