Photocontrol of chlorophyll a and phycocyanin synthesis in the cyanobacterium Calothrix crustacea Schousboe

Abstract

Chlorophyll a and phycocyanin synthesis in the cyanobacterium Calothrix crustacea Schousboe (ecophene Rivularia bullata) have been studied in white light after the application of red and green light pulses. The light quality produces a complementary pattern in the pigment synthesis. Chlorophyll synthesis is stimulated by red light pulses whereas phycocyanin synthesis is by green light pulses. Because the effect of red light on chlorophyll synthesis shows some far-red photoreversibility, the action of phytochrome is proposed. The green light effect on phycocyanin synthesis is only partially reversed by far-red light. This reversion is lost after incubation in white light for two hours. The effect of green light on phycocyanin synthesis could not only be due to phytochrome since theoretically in green light the level of the active form of phytochrome is lower than in red light. Thus, the action of a specific green light photoreceptor is proposed.