Comparative studies on the photosynthesis of higher plants, 1

Abstract The reductive pentose cycle provided by Calvin et al. for the mechanism of the assimilation of carbon dioxide in green plants has been generally appreciated. Kortschak (1), however, reported recently that early photosynthetic products in some plants were malate, oxaloacetate (OAA) and aspartate (Asp) but not 3-phosphoglyceric acid (PGA) stated by Calain et al. Hatch and Slack (2, 3. 4, 5) studied systematicallY the early photosynthetic products and found that plants can be classified to two groups such as tropical grass and temperate grass. Maize, sugar cane and sorghum belong to the former which incorporates CO, into C-4 dicarboxylic acids such as malate, OAA and Asp. Wheat, oats and sugarbeet belong to the latter which incorporates CO2, into PGA. They presented a new hypothesis that the former plant has a proper C-4 dicarboxylic acid pathway shown in Fig. 1 for the assimilation of CO2