Identification of genetic variations among silkworm races of Bombyx mori (L) through bio-molecular tools.

摘要

Silkworm races of Bombyx mori (L.) originated from different geographical regions exhibit distinct variations in phenotypic characters, especially in cocoon shape and colour. This information prompted us to study the genetic variations among eight multivoltine silkworm races applying biochemical and molecular markers of ISSR, RAPD and isozymes. These three markers provided sufficient polymorphism and genetic diversity. Highest level of genetic polymorphism was detected in ISSR marker analysis (95.83%) than in RAPD (77.77%) and isozyme (57.14%). The Marker Index (MI) values as a measure of genetic diversity was calculated for each marker and it was found high in ISSR based analysis (2.20) than RAPD (1.70) and isozyme (0.57). Dendrogram analysis showed two distinct cluster groups placing Hosa Mysore and Kolar Gold in one cluster and C.Nichi and Guangnong in another cluster. Hosa Mysore and Kolar Gold clustered together in all the marker analysis due to sharing of a common female parent i.e., Pure Mysore. C.Nichi and Guangnong shared a common cluster because of their exotic origin. Further, in RAPD and isozyme analysis, Sarupat and Moria were placed in a single cluster due to their common origin from Assam state (India). The polymorphism obtained from these three markers was also correlated using Mantel test and the results indicated a positive relationship (r=0.47) between ISSR and RAPD markers.