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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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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The relative area of vessels in xylem correlates with stem embolism resistance within and between genera

Tree Physiology, Journal Year: 2022, Volume and Issue: 43(1), P. 75 - 87

Published: Sept. 7, 2022

The resistance of xylem conduits to embolism is a major factor defining drought tolerance and can set the distributional limits species across rainfall gradients. Recent work suggests that proximity vessels neighbors increases vulnerability conduit. We therefore investigated whether relative vessel area correlates with intra- inter-generic variation in pairs or triplets from genera Acer, Cinnamomum, Ilex, Quercus Persea, adapted environments differing aridity. used optical method assess stems conducted anatomical measurements on which was quantified. Vessel lumen fraction (VLF) correlated within genera. A low VLF likely gas movement between conduits, by diffusion advection, whereas high enhances transport thorough increased conduit-to-conduit connectivity reduced distances likelihood propagation. suggest rate due local pressure differences network central driver propagation angiosperm vessels.

Language: Английский

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Pit characters determine drought-induced embolism resistance of leaf xylem across 18 Neotropical tree species

PLANT PHYSIOLOGY, Journal Year: 2022, Volume and Issue: 190(1), P. 371 - 386

Published: May 10, 2022

Embolism spreading in xylem is an important component of plant drought resistance. Since embolism resistance has been shown to be mechanistically linked pit membrane characters stem xylem, we speculate that similar mechanisms account for leaf xylem. We conducted transmission electron microscopy investigate across 18 Neotropical tree species. also gold perfusion and polar lipid detection experiments on three species covering the full range then related these observations previously published data incorporated membranes link between vulnerability segmentation (i.e. difference resistance) leaf-stem anatomical variation. Maximum thickness (Tpm,max) thickness-to-diameter ratio (Tpm,max/Dpm) were predictive resistance, especially when vestured pits taken into account. Variation Tpm,max/Dpm was only trait leaves stems. Gold particles 5- 10-nm infiltrated species, while entry 50-nm blocked. Moreover, lipids associated with inner conduit walls pits. Our results suggest are determined by Tpm, pore constrictions narrowest bottlenecks along pathways), surfactants, which largely temperate tropical trees. However, our mechanistic understanding propagation functional relevance remains elusive.

Language: Английский

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A unit pipe pneumatic model to simulate gas kinetics during measurements of embolism in excised angiosperm xylem

Tree Physiology, Journal Year: 2022, Volume and Issue: 43(1), P. 88 - 101

Published: Sept. 1, 2022

Abstract The pneumatic method has been introduced to quantify embolism resistance in plant xylem of various organs by applying a partial vacuum cut-open xylem. Despite the similarity vulnerability curves between and other methods, modeling approach is needed investigate if changes during dehydration can be accurately quantified based on gas diffusion kinetics. Therefore, unit pipe (UPPn) model was developed estimate extraction from intact conduits, which were axially interconnected inter-conduit pit membranes conduits. physical laws used included Fick’s law for diffusion, Henry’s concentration partitioning liquid phases at equilibrium ideal law. UPPn showed that 91% extracted came first five series embolized, conduits only 9% aqueous phase after 15 s simulation. Considering alternative sources, measured with pneumatron device systematically overestimated 2–17%, corresponded typical measuring error 0.11 MPa P50 (the water potential equivalent 50% maximum amount extracted). It concluded directly measure due fast movement across interconduit membranes, while sap hydrated cell walls about 100 times slower. We expect will also contribute understanding propagation temporal dynamics.

Language: Английский

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The root of the problem: diverse vulnerability to xylem cavitation found within the root system of wheat plants

New Phytologist, Journal Year: 2023, Volume and Issue: 239(4), P. 1239 - 1252

Published: June 12, 2023

The propagation of xylem embolism throughout the root systems drought-affected plants remains largely unknown, despite this process being comparatively well characterized in aboveground tissues. We used optical and X-ray imaging to capture across intact bread wheat (Triticum aestivum L. 'Krichauff') subjected drying. Patterns vulnerability cavitation were examined investigate whether may vary based on size placement entire system. Individual exhibited similar mean whole system vulnerabilities but showed enormous 6 MPa variation within their component roots (c. 50 per plant). Xylem typically initiated smallest, peripheral parts moved inwards upwards towards collar last, although trend was highly variable. This pattern spread likely results sacrifice replaceable small while preserving function larger, more costly central roots. A distinct embolism-spread belowground has implications for how we understand impact drought as a critical interface between plant soil.

Language: Английский

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Exploring within‐plant hydraulic trait variation: A test of the vulnerability segmentation hypothesis

Plant Cell & Environment, Journal Year: 2023, Volume and Issue: 46(9), P. 2726 - 2746

Published: June 20, 2023

Abstract Observations show vulnerability segmentation between stems and leaves is highly variable within environments. While a number of species exhibit conventional (stem leaf ), others no reverse ). We developed hydraulic model to test hypotheses about how it interacts with other traits impact plant conductance. do this using series experiments across broad parameter space case study two contrasting patterns: Quercus douglasii Populus trichocarpa . found that while helps preserve conductance in stem tissues, can better maintain the combined stem‐leaf pathway, particularly when plants have more vulnerable s greater resistance leaves. These findings impacts are dependent upon traits, notably segmentation, finding could assist interpretation observations segmentation. Further needed examine transpiration rates recovery from water stress.

Language: Английский

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Angiosperms follow a convex trade‐off to optimize hydraulic safety and efficiency

New Phytologist, Journal Year: 2023, Volume and Issue: 240(5), P. 1788 - 1801

Published: Sept. 10, 2023

Intervessel pits are considered to function as valves that avoid embolism spreading and optimize efficient transport of xylem sap across neighbouring vessels. Hydraulic between vessels would therefore follow a safety-efficiency trade-off, which is directly related the total intervessel pit area (Ap ), inversely membrane thickness (TPM ) driven by pressure difference. To test this hypothesis, we modelled relative rate gas (ka water (Q) at level for 23 angiosperm species correlated these parameters with potential 50% occurs (Ψ50 ). We also measured ka 10 using pneumatic measurements. The difference adjacent estimated values Q were Ψ50 , following convex trade-off based on experimental data. Minor changes in TPM Ap exponentially affected flow, respectively. Our results provide clear evidence not linear, but due flow membranes, represent mesoporous media within microporous conduits. Moreover, nature long-distance may contribute an adjustable fluid balance plants, depending environmental conditions.

Language: Английский

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Minimum leaf conductance during drought: unravelling its variability and impact on plant survival

New Phytologist, Journal Year: 2025, Volume and Issue: unknown

Published: March 9, 2025

Leaf water loss after stomatal closure is key to understanding the effects of prolonged drought on vegetation. It therefore important accurately quantify such losses improve physiology-based models drought-induced plant mortality. We measured detached leaves continuously during dehydration in nine woody angiosperm species. computed minimum leaf conductance (gmin) at different potential thresholds along a sequence physiological function losses, spanning from turgor point hydraulic failure. A mechanistic model evaluated impact gmin estimations time failure (THF). Residual not steady and decreases varying rates across species entire process, even correcting for shrinkage vapor pressure deficit shifts. Different had significant THF predicted by model, especially drought-resistant demonstrate that residual variable dehydration, thus, it use or status boundaries its estimation order determine distinct values loss. describe an accurate, repeatable open-source methodology estimate gmin. Such could enhance mortality under drought.

Language: Английский

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Seeing is believing: what visualising bubbles in the xylem has revealed about plant hydraulic function

Functional Plant Biology, Journal Year: 2022, Volume and Issue: 49(9), P. 759 - 772

Published: June 20, 2022

Maintaining water transport in the xylem is critical for vascular plants to grow and survive. The drought-induced accumulation of embolism, when gas enters conduits, causes declines hydraulic conductance (K) ultimately lethal. Several methods can be used estimate degree embolism xylem, from measuring K tissues directly visualising conduits. One method allowing a direct quantification embolised area optical vulnerability (OV) technique. This has been across different organs high spatial temporal resolution. Here, we review studies using OV technique, discuss main advantages disadvantages this method, summarise key advances arising its use. Vulnerability curves generated by are regularly comparable other methods, including centrifuge X-ray microtomography. A major advantage technique over that it simultaneously determine situ formation leaves, stems roots, species spanning phylogeny land plants. experimentally investigate spreading through networks, associate with downstream tissue death, observe field.

Language: Английский

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