Phytochrome control of acid and alkaline phosphatases in etiolated shoot apices of Sorghum bicolor

Abstract

A short pulse of red light or continuous far-red light enhanced the activities of acid and alkaline phosphatases over the values of the dark controls in 5-day-old etiolated seedlings of Sorghum bicolor. For 30 min after the red light pulse 100% of the red/far-red photoreversibilities was maintained for the acid and 80% for the alkaline phosphatases. Thereafter, the "photoreversibility escape reaction" was fast, being completed within 180 min. Cycloheximide as well as 6-methyl purine markedly inhibited red light enhancement of the activities of the phosphatases, but chloramphenicol, lincomiycin and rifamycin SV were ineffective. In spite of photoregulation of both the phosphatases at the time of de novo synthesis, it appears that control of the acid and alkaline phosphatases may be affected by two independent initial actions of phytochrome.