Assessment of Genetic Diversity in Promising Sugarcane Mutants Developed Through Chemical Mutagenesis

Sugarcane is an important cash crop gaining importance as ideal raw material for bioenergy production. Conventional sugarcane improvement is carried out through intensive crossing and selection breeding within the Saccharum complex. Being highly polyploidy crop the mutation breeding is also integrated for specifically improving the desired genetic trait in sugarcane varieties developed through conventional breeding. In the present work RAPD markers based assessment of genetic diversity and kinship relationships of six promising mutants developed using CoC 671 has been reported. The banding pattern of the PCR amplified products showed polymorphism with the RAPD profile in all six mutants. Mutants CoC 671, TC 2813, TC 2819, TC 2826, TC 2875 formed a separate cluster, and TC 906, TC 922, and TC 906 B formed a separate cluster distinct from the earlier one with the parent (CoC 671) and the standard Check (Co 86023). The genetic distance between the groups was found to be only marginally higher than the respective group distances and the overall mean genetic distance. The similarity indices indicated that there was 15 % genetic dissimilarity between CoC 671 and Co 86032. This may be because CoC 671 was one of the parents for Co 86032. In the present investigation, the genetic similarity value ranged from 0.97 to 0.78 among the mutants. A total of 34 band positions were scored, out of which 15 RAPD bands were polymorphic. From the genetic similarity coefficient based on RAPD band data sharing, it was found that the majority of the clones were almost more than 78% similar to the mother plant. Thus the level of similarity between varieties seemed to be not very high but the mutants could be distinguished from each other easily. RAPD analysis indicated EMS-induced point mutations resulting in specific rectifications without much change in the genetic backbone of genotype CoC 671. Since this analysis was carried out on mutants after multiplying in field for three successive generations, we presume that these mutants/genotypes are stable and express the stable genetic variations.