Radiosensitivity and polyploidy in some non-tuber bearing Solanum species

Abstract

Twenty-two non-tuber-bearing species of the genus Solanum were investigated cytologically, and their responses to chronic gamma-ray and acute X-ray treatments were studied in terms of induced pollen sterility, growth inhibition and chromosomal aberration, paying special attention to their ploidy levels. The materials used included 2x, 4x and 6x species. The average interphase chromosome volume (ICV) decreases with increasing ploidy. Chronic irradiation of plants revealed no correlation between radiosensitivity and ploidy level, whereas a greater resistance of higher polyploids was observed after acute irradiation of seeds. On the other hand, considerable interspecific differences of sensitivity were seen even in the same ploidy level regardless of irradiation method. The results suggest that the interspecific difference might be mainly attributed to the genotypic constitution specific for each species rather than to the ICV or genetic redundancy. ‘Revised seedling height’ was proposed as an adequate index in determining radiosensitivity based on growth inhibition.