Photosynthesis can be enhanced by lateral CO2 diffusion inside leaves over distances of several millimeters.
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 (Delta 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.
Pieruschka
Roland
R
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.|Carnegie Institution of Washington, Department of Global Ecology, 260 Panama St, 94305 Stanford, CA, USA.
Chavarría-Krauser
Andrés
A
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.|Universität Heidelberg, Institut für Angewandte Mathematik, Im Neuenheimer Feld 294, 69120 Heidelberg, Germany.
Cloos
Kathrin
K
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.
Scharr
Hanno
H
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.
Schurr
Ulrich
U
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.
Jahnke
Siegfried
S
Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre (ICG), ICG-3: Phytosphäre, 52425 Jülich, Germany.|Universität Duisburg-Essen, Fachbereich Biologie und Geographie, 45117 Essen, Germany.
D002245:Carbon Dioxide / Q000378:metabolism*; D034822:Commelina / Q000378:metabolism; D004058:Diffusion; D008027:Light; D008954:Models, Biological; D027805:Phaseolus / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D031307:Vicia faba / Q000378:metabolism
D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide