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CO2 diffusion in tobacco: a link between mesophyll conductance and leaf anatomy

journal contribution
posted on 2023-11-03, 02:54 authored by Victoria ClarkeVictoria Clarke, Florence R Danila, Susanne von Caemmerer
The partial pressure of CO2 at the sites of carboxylation within chloroplasts depends on the conductance to CO2 diffusion from intercellular airspace to the sites of carboxylation, termed mesophyll conductance (g m). We investigated how g m varies with leaf age and through a tobacco (Nicotiana tabacum) canopy by combining gas exchange and carbon isotope measurements using tunable diode laser spectroscopy. We combined these measurements with the anatomical characterization of leaves. CO2 assimilation rate, A, and g m decreased as leaves aged and moved lower in the canopy and were linearly correlated. This was accompanied by large anatomical changes including an increase in leaf thickness. Chloroplast surface area exposed to the intercellular airspace per unit leaf area (S c) also decreased lower in the canopy. Older leaves had thicker mesophyll cell walls and g m was inversely proportional to cell wall thickness. We conclude that reduced g m of older leaves lower in the canopy was associated with a reduction in S c and a thickening of mesophyll cell walls.

History

Sub-type

  • Article

Publication title

INTERFACE FOCUS

Medium

Print-Electronic

Volume

11

Issue

2

Article number

ARTN 20200040

Pagination

11

eISSN

2042-8901

ISSN

2042-8898

Department/School

TIA - Research Institute

Publisher

ROYAL SOC

Publication status

  • Published

Place of publication

England

Event Venue

Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia.

Rights statement

Copyright 2021 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.