Biochemical and physiological changes in gamma-irradiated wheat during germination

Abstract

A metabolic disturbance, as revealed by impaired seedling growth on germination of wheat irradiated with ⁶⁰Co gamma rays at 20-200 krad dose levels, is observed. Seedling growth is inhibited by 50-62 per cent at low doses from 20 to 40 krad and almost completely at higher doses. Pre-soaking of control and irradiated grains in 2 × 10^-5 m gibberellic acid (GA) for 16 hr results in stimulation of seedling growth and synthesis of alpha-amylase and ribonuclease in control seeds; GA also causes its normal effects despite radiation treatment with low doses. Radiation or/and GA treatment exert no marked effects on 3'-nucleotidase activity. Decreased incorporation of ¹⁴C-leucine in nascent alpha-amylase in irradiated seeds during 4 days germination can be attributed to its impaired de novo synthesis. The relative permeability of ¹⁴C-leucine in wheat is not changed due to radiation treatment. Endogenous amino acids pool sizes are significantly low in irradiated seeds. However, specific activity of ¹⁴C-leucine is high in seeds irradiated at dose levels used in these studies.