Control of chlorophyll production in rapidly greening bean leaves

Abstract

The possible involvement of nucleic acid and protein synthesis in light-regulated chlorophyll formation by rapidly greening leaves has been studied.Removing leaves from illumination during the phase of rapid greening results in a reduction in the rate of pigment synthesis; cessation occurs within 2 to 4 hours. Etiolated leaves which exhibit a lag in pigment synthesis when first placed in the light do not show another lag after a 4 hour interruption of illumination during the phase of rapid greening.Actinomycin D, chloramphenicol, and puromycin inhibit chlorophyll synthesis when applied before or during the phase of rapid greening. Application of delta-amino-levulinic acid partially relieves the inhibition by chloramphenicol.It is suggested that light regulates chlorophyll synthesis by controlling the availability of delta-aminolevulinic acid, possibly by mediating the formation of an enzyme of delta-aminolevulinate synthesis. This process may result from gene activation or derepression; the involvement of RNA synthesis of some sort is suggested by the inhibitory effect of actinomycin D on chlorophyll production by rapidly greening leaves.