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

Thomas B. Ray | Zendy; Clanton C. Black | Zendy

Open Access

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

Author(s) -

Thomas B. Ray,

Clanton C. Black

Publication year - 1977

Publication title -

plant physiology

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 3.554

H-Index - 312

eISSN - 1532-2548

pISSN - 0032-0889

DOI - 10.1104/pp.60.2.193

Subject(s) - c4 photosynthesis , panicum , photosynthesis , carbon dioxide , bundle , carbon source , botany , vascular bundle , chemistry , biology , materials science , ecology , biochemistry , composite material

3-Mercaptopicolinic acid (3-MPA), an inhibitor of phosphoenolpyruvate carboxykinase, was employed to study the role of organic acid decarboxylation during C(4) 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 (14)CO(2) burst associated with P. maximum photosynthesis was almost abolished by 5 mm 3-MPA. The turnover rates of malate and aspartate during C(4) photosynthesis were severely reduced as well as the rates of formation of C(3) cycle intermediates in P. maximum leaves treated with 3-MPA. These results are interpreted as direct evidence for the fixation of CO(2), arising from the decarboxylation of oxaloacetate, by the C(3) cycle in bundle sheath cells of P. maximum leaves.

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