Inter Simple Sequence Repeat (ISSR) Markers for Assessment of Genetic Polymorphism and Phylogenetic Relationships of the Silkworm Bombyx mori L.

An attempt was made to understand the genetic polymorphism and phylogenetic relationships among the eighteen silkworm races/breeds comprising six each of bivoltines (BVs), multivoltines (MVs) and autosomal mutants of the silkworm Bombyx mori belonging to both indigenous and exotic origins, which were drawn from the germplasm of the Department. The DNA was extracted from the whole moth and amplification was carried out with inter simple sequence repeat (ISSR) marker technique. Four ISSR primers namely UBC-812, UBC-813, UBC-826 and UBC-827 were utilized of which two primers UBC-812 and UBC-826 generated a total of 88 clear, distinct and reproducible bands ranging from 500bp to 2000bp corresponding to an average of 44 bands/primer. Among 88 bands 18 bands were monomorphic and remaining 70 were polymorphic. Thus, the percentage of polymorphism revealed for UBC-812 primer was 100%, whereas UBC-826 revealed 60.86% indicating the occurrence of genomic variation from the inbred population.
The unweight pair group method with arithmetic means (UPGMA) was constructed from the ISSR marker profiles have clearly discriminated the BVs, whereas MVs and an autosomal mutant namely pre and a BV race namely C108 were genetically inter-linked together in cluster-I and II respectively. The significance of genetic polymorphism and phylogenetic relationships through the ISSR study are herein discussed.