Oxaloacetate as the Source of Carbon Dioxide for Photosynthesis in Bundle Sheath Cells of the C4 Species Panicum maximum
AUTOR(ES)
Ray, Thomas B.
RESUMO
3-Mercaptopicolinic acid (3-MPA), an inhibitor of phosphoenolpyruvate carboxykinase, was employed to study the role of organic acid decarboxylation during C4 photosynthesis. Treatment of detached Panicum maximum leaves with 5 mm 3-MPA inhibited photosynthesis 70 to 75%. Oxygen was found to have no effect on the degree of inhibition. The postillumination 14CO2 burst associated with P. maximum photosynthesis was almost abolished by 5 mm 3-MPA. The turnover rates of malate and aspartate during C4 photosynthesis were severely reduced as well as the rates of formation of C3 cycle intermediates in P. maximum leaves treated with 3-MPA. These results are interpreted as direct evidence for the fixation of CO2, arising from the decarboxylation of oxaloacetate, by the C3 cycle in bundle sheath cells of P. maximum leaves.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=542577Documentos Relacionados
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