Benzyladenine as a regulator of chlorophyll synthesis in cucumber cotyledons

Pretreatment of etiolated cucumber cotyledons (4–10 days old) with benzyladenine (BA) increased the amount of chlorophyll produced in light. BA also eliminated the lag phase in chlorophyll formation, which in the water controls lasted for [Formula: see text]. Addition of δ-aminolevulinic acid (ALA) to the etiolated cotyledons resulted in the production of protochlorophyllide (PCHLD) in the dark. The BA-pretreated cotyledons did not make any PCHLD in the dark. The inhibitors of RNA and protein synthesis, actinomycin D, chloramphenicol, and cycloheximide (CH), inhibited BA's effect on chlorophyll production, with CH being the most effective. We propose that BA's effect on increased chlorophyll formation is mediated by inducing production of proteins including ALA synthetase, the rate-limiting enzyme in chlorophyll biosynthesis.