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Photosynthesis can be enhanced by lateral CO 2 diffusion inside leaves over distances of several millimeters
Author(s) -
Pieruschka Roland,
ChavarríaKrauser Andrés,
Cloos Kathrin,
Scharr Hanno,
Schurr Ulrich,
Jahnke Siegfried
Publication year - 2008
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/j.1469-8137.2008.02368.x
Subject(s) - photosynthesis , phaseolus , diffusion , vicia faba , botany , chlorophyll fluorescence , chlorophyll a , chemistry , analytical chemistry (journal) , biology , physics , thermodynamics , chromatography
Summary• This study examines the extent to which lateral gas diffusion can influence intercellular CO 2 concentrations ( c i ) and thus photosynthesis in leaf areas with closed stomata. • Leaves were partly greased to close stomata artificially, and effects of laterally diffusing CO 2 into the greased areas were studied by gas‐exchange measurement and chlorophyll fluorescence imaging. Effective quantum yields (Δ F / F m ′) across the greased areas were analysed with an image‐processing tool and transposed into c i profiles, and lateral CO 2 diffusion coefficients ( D C′lat ), directly proportional to lateral conductivities (), were estimated using a one‐dimensional (1D) diffusion model. • Effective CO 2 diffusion distances in Vicia faba (homobaric), Commelina vulgaris (homobaric) and Phaseolus vulgaris (heterobaric) leaves clearly differed, and were dependent on D C′lat , light intensity, [CO 2 ], and [O 2 ]: largest distances were approx. 7.0 mm for homobaric leaves (with high D C′lat ) and approx. 1.9 mm for heterobaric leaves (low D C′lat ). • Modeled lateral CO 2 fluxes indicate large support of photosynthesis over submillimeter distances for leaves with low D C′lat , whereas in leaves with large D C′lat , photosynthesis can be stimulated over distances of several millimeters. For the plant species investigated, the surplus CO 2 assimilation rates of the greased leaf areas ( A gr ) differed clearly, depending on lateral conductivities of the respective leaves.