Sugars from woody tissue photosynthesis reduce xylem vulnerability to cavitation.

Autor: De Baerdemaeker NJF; Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium., Salomón RL; Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium., De Roo L; Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium., Steppe K; Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000, Ghent, Belgium.
Jazyk: angličtina
Zdroj: The New phytologist [New Phytol] 2017 Nov; Vol. 216 (3), pp. 720-727. Date of Electronic Publication: 2017 Sep 18.
DOI: 10.1111/nph.14787
Abstrakt: 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.
(© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)
Databáze: MEDLINE
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