Effects of gamma radiation and ethylene on protein synthesis in peel of mature grapefruit

Effects of gamma irradiation on protein synthesis in grapefruit peel were studied by incorporating ¹⁴C-leucine into newly synthesized protein. A linear relationship was found between the increase in irradiation doses and the inhibition of protein synthesis. Four hundred krads inhibited almost completely protein synthesis. No recovery of protein synthesis was detected for 5 days after irradiation. Irradiation had little or no effect on total uptake of ¹⁴C-leucine. Senescence of non-irradiated fruits was characterized by a decrease in protein synthesis, while total uptake remained unchanged. Inhibition of protein synthesis by irradiation was not affected by fruit senescence. Ten ppm ethylene did not affect protein synthesis, while 100 ppm inhibited it by 50 per cent. The relationship between protein synthesis, ethylene and irradiation-induced PAL activity is discussed.