Effects of Gamma Radiation on Morphological Changes and Nucleic Acid Content in Buds of Potato Tubers

A study was carried out to determine the effect of gamma radiation on the nucleic acid content on buds of potato tubers and the incorporation of 32P into nucleic acid fractions and to observe the morphological changes in buds of irradiated potato tubers.The dead cells were observed in buds of potato tubers irradiated with above 20 Krad, but in the buds of the 10 Krad-tubers they were a little and some giant cells were observed. The contents of sRNA and rRNA in bud disk (bud including cortex tissue) of unirradiated tuber increased from dormant period to breaking period, but they did not increase in bud disk of the tubers irradiated with the doses of 5 and 10 Krad during this physiological turning period of metabolism.The incorporation rates of 32P into sRNA and DNA in bud disk of irradiated tubers were accerelated to some extent at the 5th day after irradiation (dormant period of unirradiated tubers) compared with those in unirradiated ones. It was noted that the incorporation rates of 32P into sRNA and mRNA in the 10 Krad-bud disk decreased between breaking and sprouting period, but not into rRNA and DNA, while the incorporation rates into sRNA, rRNA, DNA and mRNA in bud disk of unirradiated tubers tended to increase respectively. From these results the mechanism of sprout-inhibition of potato tubers by gamma radiation was discussed in a point of nucleic acid metabolism.