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Sugars from woody tissue photosynthesis reduce xylem vulnerability to cavitation
Author(s) -
De Baerdemaeker Niels J. F.,
Salomón Roberto Luis,
De Roo Linus,
Steppe Kathy
Publication year - 2017
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.14787
Subject(s) - xylem , cavitation , photosynthesis , botany , biology , woody plant , horticulture , mechanics , physics
Summary Reassimilation of internal CO 2 via woody tissue photosynthesis has a substantial effect on tree carbon income and wood production. However, little is known about its role in xylem vulnerability to cavitation and its implications in drought‐driven tree mortality. Young trees of Populus nigra were subjected to light exclusion at the branch and stem levels. After 40 d, measurements of xylem water potential, diameter variation and acoustic emission ( AE ) were performed in detached branches to obtain acoustic vulnerability curves to cavitation following bench‐top dehydration. Acoustic vulnerability curves and derived AE 50 values (i.e. water potential at which 50% of cavitation‐related acoustic emissions occur) differed significantly between light‐excluded and control branches ( AE 50,light‐excluded = −1.00 ± 0.13 MPa; AE 50,control = −1.45 ± 0.09 MPa; P = 0.007) denoting higher vulnerability to cavitation in light‐excluded trees. Woody tissue photosynthesis represents an alternative and immediate source of nonstructural carbohydrates ( NSC ) that confers lower xylem vulnerability to cavitation via sugar‐mediated mechanisms. Embolism repair and xylem structural changes could not explain this observation as the amount of cumulative AE and basic wood density did not differ between treatments. We suggest that woody tissue assimilates might play a role in the synthesis of xylem surfactants for nanobubble stabilization under tension.