Woody tissue photosynthesis reduces stem CO 2 efflux by half and remains unaffected by drought stress in young Populus tremula trees.

Autor: De Roo L; Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium., Salomón RL; Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium., Steppe K; Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Jazyk: angličtina
Zdroj: Plant, cell & environment [Plant Cell Environ] 2020 Apr; Vol. 43 (4), pp. 981-991. Date of Electronic Publication: 2020 Jan 23.
DOI: 10.1111/pce.13711
Abstrakt: A substantial portion of locally respired CO 2 in stems can be assimilated by chloroplast-containing tissues. Woody tissue photosynthesis (P wt ) therefore plays a major role in the stem carbon balance. To study the impact of P wt on stem carbon cycling along a gradient of water availability, stem CO 2 efflux (E A ), xylem CO 2 concentration ([CO 2 ]), and xylem water potential (Ψ xylem ) were measured in 4-year-old Populus tremula L. trees exposed to drought stress and different regimes of light exclusion of woody tissues. Under well-watered conditions, local P wt decreased E A up to 30%. Axial CO 2 diffusion (D ax ) induced by distant P wt caused an additional decrease in E A of up to 25% and limited xylem [CO 2 ] build-up. Under drought stress, absolute decreases in E A driven by P wt remained stable, denoting that P wt was not affected by drought. At the end of the dry period, when transpiration was low, local P wt and D ax offset 20% and 10% of stem respiration on a daily basis, respectively. These results highlight (a) the importance of P wt for an adequate interpretation of E A measurements and (b) homeostatic P wt along a drought stress gradient, which might play a crucial role to fuel stem metabolism when leaf carbon uptake and phloem transport are limited.
(© 2019 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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