Fingerprinting of Released Varieties of Cashew based on DNA Markers

 

Fingerprinting of Released Varieties of Cashew based on DNA Markers

The genetic relationship among 40 varieties of cashew was investigated by analyzing markers derived from ten primers each of RAPD and ISSR and 15 primer sets of cashew SSR. The level of polymorphism in RAPD, ISSR and SSR markers was 71.8%, 87.5% and 93.3% respectively indicated high genetic variation existing among the varieties. Polymorphic information content and marker index computed showed that ISSR and SSR markers as highly informative. The coefficient of genetic similarity (Jaccard) between pair of varieties varied from 0.55-0.96in RAPD, 0.32- 0.94 in ISSR and 0.22 to 0.90 in SSR and an average similarity of 0.53, 0.63 and 0.76 respectively revealed predominance of high genetic similarity than diversity. Better genetic differentiation, was achieved by combining markers data. From a total of 196 bands, polymorphism of 81.6% (160 bands) was observed with an average of 4.6 polymorphic bands per primer. The co-efficient of genetic similarity with combined markers varied from 0.46 to 0.86 with an average similarity of 0.66 also indicated narrow genetic distances and low diversity existing between the varieties. Highest genetic similarity (0.86) observed between V-7 and BPP-5 indicated their close relationship and low genetic divergence. On the other hand, lowest similarity of 0.46 observed between Ullal-1 and Jhargram-1 indicated high genetic divergence with these varieties. Both RAPD and ISSR markers detected high genetic similarity (0.95) between the varieties Goa11/6 and VRI-3 and high diversity between Jhargram-1 and Ullal-1 and Jhargram-1 with Chintamani-1. Dendrograms constructed based on each and combined markers identified essentially 10-12 similar groupings except for some minor differences. There was little or no correspondence in the molecular groupings observed between the varieties originated from the same region or similar morphology. The unique markers identified could be used for differentiating the different varieties and for future breeding work in this crop...