Comparison of Meiotic Abnormalities Induced by Gamma-rays between a Diploid and a Tetraploid Species of Physalis

Abstract

Radiosensitivity of a diploid (P. ixocarpa) and a tetraploid (P. peruviana) species of Physalis has been studied. Meiotic abnormalities induced by gammarays were compared in both species and found that it was always greater in tetraploid than in diploid species at each corresponding dose. The tetraploid plant due to greater chromosomal volume is more vulnerable to radiation hits and its immediate consequences are expected to contribute to the formation of sterile pollen, but this defect could be overcome by the buffering action of the unaltered genes over the altered ones at multiple loci, which normalizes the induced plant sterility. The diploid P. ixocarpa exhibited higher radiosensitivity than the tetraploid P. peruviana. Comparison between the frequencies of meiotic anomalies of M2 and M1 indicated that the latter has exaggerated values on these at all exposure levels. The lowered values of M2 indicated their elimination through diplontic selection or intrasomatic or competitive elimination during the course of time lapse. © 1985, Japan Mendel Society, International Society of Cytology. All rights reserved.