Effect of gamma irradiation on the indole acetic acid synthesizing system and its significance in sprout inhibition of potatoes

Gamma irradiation interfered with the synthesis of the IAA synthesizing system and exogenous application of 20 ppm IAA within 6 hr after irradiation, triggered the synthesis of this enzyme. This fact is ascertained by the inhibition with protein synthesis inhibitors such as actinomycin D, puromycin and cyclohexamide, on the recovery of enzyme activity on treatment with IAA. Irradiation accelerated the degradation of the existing enzyme by activating proteolytic activity. IAA in irradiated potatoes is completely depleted and this is associated with the activation of H₂O₂ dependent IAA oxidase. A 50 per cent decrease in the level of tryptophan, the substrate for IAA synthesis is observed at 24 hr after irradiation.