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The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa

Gas exchange is constrained by the whole-plant hydraulic conductance (K (plant)). Leaves account for an important fraction of K (plant) and may therefore represent a major determinant of plant productivity. Leaf hydraulic conductance (K (leaf)) decreases with increasing water stress, which is due to...

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Autores principales: Laur, Joan, Hacke, Uwe G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236056/
https://www.ncbi.nlm.nih.gov/pubmed/25406088
http://dx.doi.org/10.1371/journal.pone.0111751
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author Laur, Joan
Hacke, Uwe G.
author_facet Laur, Joan
Hacke, Uwe G.
author_sort Laur, Joan
collection PubMed
description Gas exchange is constrained by the whole-plant hydraulic conductance (K (plant)). Leaves account for an important fraction of K (plant) and may therefore represent a major determinant of plant productivity. Leaf hydraulic conductance (K (leaf)) decreases with increasing water stress, which is due to xylem embolism in leaf veins and/or the properties of the extra-xylary pathway. Water flow through living tissues is facilitated and regulated by water channel proteins called aquaporins (AQPs). Here we assessed changes in the hydraulic conductance of Populus trichocarpa leaves during a dehydration-rewatering episode. While leaves were highly sensitive to drought, K (leaf) recovered only 2 hours after plants were rewatered. Recovery of K (leaf) was absent when excised leaves were bench-dried and subsequently xylem-perfused with a solution containing AQP inhibitors. We examined the expression patterns of 12 highly expressed AQP genes during a dehydration-rehydration episode to identify isoforms that may be involved in leaf hydraulic adjustments. Among the AQPs tested, several genes encoding tonoplast intrinsic proteins (TIPs) showed large increases in expression in rehydrated leaves, suggesting that TIPs contribute to reversing drought-induced reductions in K (leaf). TIPs were localized in xylem parenchyma, consistent with a role in facilitating water exchange between xylem vessels and adjacent living cells. Dye uptake experiments suggested that reversible embolism formation in minor leaf veins contributed to the observed changes in K (leaf).
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spelling pubmed-42360562014-11-21 The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa Laur, Joan Hacke, Uwe G. PLoS One Research Article Gas exchange is constrained by the whole-plant hydraulic conductance (K (plant)). Leaves account for an important fraction of K (plant) and may therefore represent a major determinant of plant productivity. Leaf hydraulic conductance (K (leaf)) decreases with increasing water stress, which is due to xylem embolism in leaf veins and/or the properties of the extra-xylary pathway. Water flow through living tissues is facilitated and regulated by water channel proteins called aquaporins (AQPs). Here we assessed changes in the hydraulic conductance of Populus trichocarpa leaves during a dehydration-rewatering episode. While leaves were highly sensitive to drought, K (leaf) recovered only 2 hours after plants were rewatered. Recovery of K (leaf) was absent when excised leaves were bench-dried and subsequently xylem-perfused with a solution containing AQP inhibitors. We examined the expression patterns of 12 highly expressed AQP genes during a dehydration-rehydration episode to identify isoforms that may be involved in leaf hydraulic adjustments. Among the AQPs tested, several genes encoding tonoplast intrinsic proteins (TIPs) showed large increases in expression in rehydrated leaves, suggesting that TIPs contribute to reversing drought-induced reductions in K (leaf). TIPs were localized in xylem parenchyma, consistent with a role in facilitating water exchange between xylem vessels and adjacent living cells. Dye uptake experiments suggested that reversible embolism formation in minor leaf veins contributed to the observed changes in K (leaf). Public Library of Science 2014-11-18 /pmc/articles/PMC4236056/ /pubmed/25406088 http://dx.doi.org/10.1371/journal.pone.0111751 Text en © 2014 Laur, Hacke http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Laur, Joan
Hacke, Uwe G.
The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title_full The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title_fullStr The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title_full_unstemmed The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title_short The Role of Water Channel Proteins in Facilitating Recovery of Leaf Hydraulic Conductance from Water Stress in Populus trichocarpa
title_sort role of water channel proteins in facilitating recovery of leaf hydraulic conductance from water stress in populus trichocarpa
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236056/
https://www.ncbi.nlm.nih.gov/pubmed/25406088
http://dx.doi.org/10.1371/journal.pone.0111751
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