Decarboxylation of malate by isolated bundle-sheath cells of certain plants having the C4-dicarboxylic acid cycle of photosynthesis

摘要

Bundle-sheath cells isolated by the grinding and filtration procedure of Edwards and Black (1971b) from species of plants having the C4-dicarboxylic acid pathway of photosynthesis were tested for the decarboxylation of malate from the C4-carboxyl position. The bundle-sheath cells, which showed high malic enzyme activity in extracts, decarboxylated 414Cmalate at rates sufficient to be involved in photosynthesis. The malate decarboxylation is dependent on the addition of magnesium or manganese and NADP+. The activity was increased by raising the temperature from 30 to 50°. The evidence supports the idea that malate may be a carboxyl donor to the reductive pentose-phosphate cycle in bundle-sheath cells in certain C4-dicarboxylic acid pathway plants such asZea maysL.,Sorghum bicolorL., andDigitaria sanguinalis(L.) Scop