Repair of gamma-ray and neutron-induced lesions in germinating barley seeds.

SummaryBarley seeds were irradiated with gamma-rays or fast neutrons in the resting state and after various periods of germination. When irradiated in the resting state, about 50 krads of gamma-rays or about 1 krad of fast neutrons produced a 50 per cent inhibition of seedling growth. The radiosensitivity increased after pre-soaking and reached a maximum level after 12–15 hours of germination. At this stage the sensitivity to gamma-rays had increased by a factor of 50 and to fast neutrons by a factor of 5.The presence of caffeine (assumed to be a DNA-repair inhibitor) during the first period of germination of seeds irradiated in the resting state led to an enhancement of the gamma-induced damage by a factor of 2, but had little effect on neutron-irradiated seeds. The caffeine effect was also negligible if the gamma-irradiated seeds were allowed to germinate for at least 5 hours in water before the treatment. The effect of caffeine was also considerably lower in seeds pre-soaked for 12–15 hours.The results...

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