Photosynthetic Activity in the Developing Cotyledon of Soybean Seeds

Abstract

We examined whether developing cotyledons of soybean seed had photosynthetic activities. The cotyledons evolved oxygen under illumination and the activity was inhibited by 3-(3', 4'-dichlorophenyl)-1, 1-dimethylurea. The rate of oxygen evolution decreased during the development of seeds; about 30 μmol O₂•mg chlorophyll^-1•hr^-1 at the early developing stage and about 10 μmol O₂•mg chlorophyll^-1•-hr^-1 at the late developing stage. The rate of oxygen uptake remained at an almost constant level of 40 μmol O₂•mg chlorophyll^-1•hr^-1 throughout the development. Photosynthetic ¹⁴CO₂-fixation by the cotyledon was observed. Ribulose bisphosphate carboxylase was immunochemically detected in the developing cotyledons. These results show that functional photosynthetic apparatus is present in the developing cotyledons of soybean seeds.