Molecular Characterization and Phylogenetic relationships of 7 microsporidian isolates from different Lepidopteran pests cross infecting silkworm, Bombyx mori, based on Intergenic spacer sequence analysis

Abstract

The present study is based on molecular characterization of 7 microsporidian isolates extracted from infected Lepidopteran pests, collected from potential zones of sericulture in Karnataka, India. The seven spore isolates viz., NIK-55Dp, NIK-57Sl, NIK-64So, NIK-60Pd, NIK-61Pp, NIK-63Ec and VIK-52Pr, were studied along with the Nosema type species-NIK-1s_mys. These isolates were tested for their pathogenicity, mode of transmission and tissue specificity in laboratory reared CSR2 race of Bombyx mori. PCR based analysis of Intergenic spacer sequence (IGS) was carried out in order to establish spore identity and to derive phylogenetic relationships among the key isolates. A phylogenetic tree was generated for the test isolates using the maximum parsimony method from MEGA-6. Study shows that six spore isolates were clustering along with the genus of Nosema except isolate-VIK-52Pr, which grouped with Vairimorpha species. VIK-52 Pr was also found to be highly pathogenic to the lab host as compared to rest of the test isolates including NIK-1s_mys.