Effects of Ionizing Radiation on Roses: Meiotic Studies on Control and Gamma Ray Induced Mutants of Rose Cultivar Montezuma

Rose cultivar ‘Montezuma’ and two of its gamma ray induced mutants presented a marked distinction in their cytological features. Their male meiosis revealed a great variation with regard to chromosome associations at metaphase I which comprised of univalents, bivalents, trivalents and quadrivalents. Ring shaped quadrivalents were more common than the chains. The frequency of quadrivalents was enhanced in mutant plants. The percentage of PMCs with precocious separation, laggards and bridges at anaphases was found to be higher in mutants as compared with the control plants. These results indicate that chromosomal structural changes might also be responsible for the induction of these mutations. The pollen fertility decreased in Pink flowered mutant as compared with control, whereas, an increase was recorded in Reddish-orange flowered mutant. The nature of above mentioned variations in gamma induced mutants may be chromosomal/genic or both.