REDUCTION OF GRAMINE CONCENTRATION BY GAMMA-IRRADIATION IN SEEDLINGS OF HORDEUM-VULGARE VAR AMAGINIJO

The effects of gamma-irradiation on gramine concentration in seedlings of barley (Hordeum vulgare var. Amaginijo) were investigated. Similar ly to other barley cultivars, this amine appeared in shoots of sprouti ng seedlings and its concentration increased in the course of subseque nt development to attain a maximum around the ninth day. Exposure of t wo-day-old seedlings to gamma-radiation resulted in significant reduct ions of the concentration as compared with non-irradiated control, dep endent upon the radiation dose, whilst the five-day-old seedlings were slightly affected. Seeds were more radioresistant than younger seedli ngs, when the decline in gramine quantity was taken as a marker of rad iation effect. Longer storage of irradiated seeds enhanced the decreas e of this compound in seedlings. At relatively low doses, gramine conc entration was successively recovered to reach the control level during further growth. This decline of gramine content could not be correlat ed solely with water content of seeds and oxygen did not seem to be a critical factor. On the basis of these results, probable mechanisms fo r radiation-induced reduction of the amine concentration are discussed . In these experiments it was found that changing patterns of gramine content were in close parallel with those of growth.