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Woody tissue photosynthesis delays drought stress in Populus tremula trees and maintains starch reserves in branch xylem tissues
Author(s) -
De Roo Linus,
Salomón Roberto Luis,
Oleksyn Jacek,
Steppe Kathy
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16662
Subject(s) - xylem , photosynthesis , botany , biology , drought stress , starch , horticulture , biochemistry
Summary Photosynthesis in woody tissues ( P wt ) is less sensitive to water shortage than in leaves, hence, P wt might be a crucial carbon source to alleviate drought stress. To evaluate the impact of P wt on tree drought tolerance, woody tissues of 4‐m‐tall drought‐stressed Populus tremula trees were subjected to a light‐exclusion treatment across the entire plant to inhibit P wt . Xylem water potential ( Ψ xylem ), sap flow ( F H 2 O ), leaf net photosynthesis ( P n,l ), stem diameter variations (Δ D ), in vivo acoustic emissions in stems (AEs) and nonstructural carbohydrate concentrations ([NSC]) were monitored to comprehensively assess water and carbon relations at whole‐tree level. Under well‐watered conditions, P wt kept Ψ xylem at a higher level, lowered F H 2 Oand had no effect on [NSC]. Under drought, Ψ xylem , F H 2 Oand P n,l in light‐excluded trees rapidly decreased in concert with reductions in branch xylem starch concentration. Moreover, sub‐daily patterns of Δ D , F H 2 Oand AEs were strongly related, suggesting that in vivo AEs may inform not only about embolism events, but also about capacitive release and replenishment of stem water pools. Results highlight the importance of P wt in maintaining xylem hydraulic integrity under drought conditions and in sustaining NSC pools to potentially limit increases in xylem tension.