Effects of Inhibitors of Protein Synthesis on Abscisic Acid Accumulation in Wheat

The accumulation of abscisic acid (ABA) in wheat seedlings in response to drought stress was studied following treatment with cycloheximide, an inhibitor of protein synthesis on cytosol ribosomes, and with chloramphenicol, lincomycin and spectinomycin, inhibitors of protein synthesis on plastid ribosomes. Cycloheximide treatment for 2 h completely inhibited subsequent ABA accumulation, but treatment for 5 h with the three inhibitors of protein synthesis on plastid ribosomes had no effect. It seems likely, therefore, that stress-induced ABA synthesis requires rapid enzyme production in the cytosol but not in the plastid.