Diversity in Indian and Some Exotic Onion Cultivars as Revealed by Genomic and Mitochondrial DNA

Cytoplasmic genic male sterility in onion has been associated with the mitochondrial genome. Identification of male sterile lines and its maintainers is a major hurdle in exploitation of male sterility in onion hybrid seed production. In this study, we evaluated genomic and mitochondrial genome diversity to identify type of cytoplasm and male sterility among various onion varieties of Indian and exotic origin employing RAPD, SSR and non-radioactive RFLP molecular markers. Among the 68 used random decamer RAPD primers, 39 primers produced 445 total polymorphic bands with an average of 11.40 bands per primer. A total of 16 SSR primers were screened and 11 showed polymorphism and produced 86 polymorphic bands with an average of 8 polymorphic bands per primer. The RFLP studied using non-radioactive gene probes were cox1, cox2, atp6, atp9 and nad6. These studies demonstrate the diversity in the nuclear and mitochondrial genome of onion cultivars.