Photocontrol of Anthocyanin Synthesis: Phytochrome, Chlorophyll and Anthocyanin Synthesis*

Abstract —Anthocyanin synthesis in cabbage and mustard seedlings depends upon duration and irradiance of the light treatment. The relative effectiveness of radiation in various spectral regions depends upon the length of the irradiation and decreases with increasing dose. In intermittent light treatments, far‐red light can reverse the promoting action of red light if the dark interval between successive irradiations is longer than one hour. If the length of the dark interval is less than one hour, far‐red applied immediately after each red irradiation, enhances anthocyanin accumulation. Anthocyanin accumulation under various light treatments seems to correlate, to some extent, with the rate of phytochrome decay, but not with chlorophyll production. Anthocyanin accumulation is inhibited by 2,4‐dinitrophenol and by the ammonium ion, but not by DCMU. The ammonium ion inhibits anthocyanin accumulation induced by a single, short red irradiation. This suggest that the ammonium ion may have a wider spectrum of action in vivo than in chloroplast preparations where it acts as a specific uncoupler of photophosphorylation. Streptomycin inhibits chlorophyll synthesis and enhances anthocyanin accumulation. These results suggest that there is very little, if any, interaction between photosynthesis and ‘high‐irradiance‐reaction’ anthocyanin synthesis in cabbage and mustard seedlings.