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. 1977 Aug;60(2):193–196. doi: 10.1104/pp.60.2.193

Oxaloacetate as the Source of Carbon Dioxide for Photosynthesis in Bundle Sheath Cells of the C4 Species Panicum maximum

Thomas B Ray 1, Clanton C Black Jr 1
PMCID: PMC542577  PMID: 16660057

Abstract

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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