The effects of δ -aminolevulinic acid and inhibitors of RNA and protein synthesis on phytochrome mediated chlorophyll accumulation in Sorghum bicolor

Abstract

In 5 - d - old etiolated seedlings of Sorghum bicolor, 12 h of darkness after 5 min in red light eliminated a lag before the accumulation of chlorophylls in subsequent continuous white light. Increasing the dark period to 24 h and 36 h, increased the rate of chlorophyll accumulation in the later stages of greening. Exogenous δ - aminolevulinic acid neither completely removed the lag, nor increased the rate of chlorophyll accumulation. Cycloheximide (25 µg ml^-1) and 6 - methyl purine (5.0 µg ml^-1), given continuously or only until the 12 h dark period following the red light irradiation, restored the lag and decreased the rate of chlorophyll accumulation. D - threo - chloramphenicol (400 µg ml^-1) also decreased the rate of chlorophyll accumulation but did not restore the lag. Addition of these inhibitors even 12 h after red light irradiation decreased the rate of chlorophyll accumulation. Rifampicin (Rifamycin SV, 400 µg ml^-1) did not have such effects.