Assessing the CO2 concentration at the surface of photosynthetic mesophyll cells

Márquez, Diego A., Stuart-Williams, Hilary, Cernusak, Lucas A., and Farquhar, Graham D. (2023) Assessing the CO2 concentration at the surface of photosynthetic mesophyll cells. New Phytologist, 238 (4). pp. 1446-1460.

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Abstract

We present a robust estimation of the CO2 concentration at the surface of photosynthetic mesophyll cells (cw), applicable under reasonable assumptions of assimilation distribution within the leaf. We used Capsicum annuum, Helianthus annuus and Gossypium hirsutumas model plants for our experiments. We introduce calculations to estimate cw using independent adaxial and abaxial gas exchange measurements, and accounting for the mesophyll airspace resistances. The cw was lower than adaxial and abaxial estimated intercellular CO2 concentrations (ci). Differences between cw and the ci of each surface were usually larger than 10 μmol mol−1. Differences between adaxial and abaxial ci ranged from a few μmol mol−1 to almost 50 μmol mol−1, where the largest differences were found at high air saturation deficits (ASD). Differences between adaxial and abaxial ci and the ci estimated by mixing both fluxes ranged from −30 to +20 μmol mol−1, where the largest differences were found under high ASD or high ambient CO2 concentrations. Accounting for cw improves the information that can be extracted from gas exchange experiments, allowing a more detailed description of the CO2 and water vapor gradients within the leaf.

Item ID: 78498
Item Type: Article (Research - C1)
ISSN: 1469-8137
Keywords: abaxial, adaxial, gas exchange, gas exchange parameters, leaf internal CO, concentration 2, mesophyll conductance
Copyright Information: © 2023 The Authors. New Phytologist © 2023 New Phytologist Foundation. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC P210103186
Date Deposited: 02 May 2023 02:39
FoR Codes: 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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