Stimulation of chlorophyll synthesis in cucumber cotyledons by benzyladenine

Abstract

When exposed to light, etiolated cucumber cotyledons exhibited a lag phase in chlorophyll biosynthesis. Pretreatment of the cotyledons with benzyladenine (BA) eliminated the lag phase and stimulated chlorophyll formation. In BA-treated cotyledons, the incorporation of 14C-leucine into protein and the total synthesis of protein were higher than in the non-BA-treated controls. After BA treatment and exposure to light, the accumulation of δ-aminolevulinic acid in the cotyledons increased with time and was higher than in the controls, where a lag phase was apparent. These results support our hypothesis that BA affects chlorophyll formation by inducing the production of proteins including ALA-synthetase, the rate-limiting enzyme in chlorophyll biosynthesis.