Abstract
During the illumination of dark‐grown barley plants light induces a rapid decrease of a translatable mRNA which codes for a polypeptide of Mr44000. This component was identified as a precursor of the NADPH: protochlorophyllide oxidoreductase. The precursor has an Mrlarger than the authentic protein by approximately 8000. The light‐induced change in the level of translatable mRNA can be induced by a 15‐s red‐light pulse followed by 5 h of darkness. The red‐light effect is reversed by a subsequent far‐red‐light treatment. It is concluded that the light‐induced decline of translatable mRNA for the NADPH: protochlorophyllide oxidoreductase is controlled by phytochrome. The significance of this finding for present concepts of light‐dependent control of chloroplast development and chlorophyll synthesis is discussed.