Effect of continuous far red on betaxanthin and betacyanin synthesis

Seedlings of Celosia plumosa under prolonged irradiation with far red light synthesize chlorophyll α and betaxanthin. Levulinic acid and 2,4-dinitrophenol, inhibitors of chlorophyll synthesis and cyclic photophosphorylation respectively, reduce betaxanthin synthesis. Pigment formation is also inhibited by actinomycin-D and puromycin, but is unaffected by 3-(3,4-dichlorophenyl)-1,1-dimethylurea, an inhibitor of noncyclic photophosphorylation. These findings are evidence of the involvement of photosynthesis through cyclic photophosphorylation, in the far red HER associated with betaxanthin synthesis. Under continuous far red seedlings of Amaranthus tricolor synthesize only chlorophyll α. Lack of betacyanin formation is ascribed to the inactive status of the genes involved in the pigment synthesis.