Marker-assisted Selection of Bivoltine Silkworm Genetic Resources for Thermotolerance

Abstract

The aim of the study is identification of bivoltine breeds showing thermotolerance to evaluate for regional abiotic stress conditions to achieve successful bivoltine cocoon production. Study Design: Lepidopteran insect, Bombyx mori silkworm is more prone to crop losses due to hot climatic conditions during summer seasons. In order to produce bivoltine cocoons consistently throughout the year without affecting productivity during hot summer season, high temperature tolerant silkworm breeds are indispensable. The vast silkworm B.mori (L.) germplasm available needs to be screened using reliable molecular markers to select efficient productive breeds with high temperature tolerance. Marker assisted selection (MAS) has been widely used in selection of desired traits for breeding programs. It is believed that selection based on trait linked to DNA marker would be better option than phenotypic selection which is laborious and time consuming. Place and Duration of the Study: The study has been taken up for 3 years in collaboration with Seribiotech Research Laboratory, Kodathi Methodology: The present study has been carried out to screen forty selected bivoltine silkworm B. mori germplasm resources exhibiting higher rate of survival and high productivity using SSR markers (LFL329; LFL1123; S0809; S0813) linked to thermotolerance in silkworm so as to identify thermotolerant breeds. Results: Based on the PCR product resolved in 2% agarose gel and presence of bands corresponding thermotolerance and thermosusceptible markers observed, 10 bivoltine accessions showed 87-100% thermotolerance were selected viz. BBI-0086 (KPG-A), BBE-0184 (SMGS-2), BBI-0301 (YS-7) and BBI-0339 (DD-2) and the accessions spinning dumbbell cocoons- BBI-0044 (NB4D2), BBI-0334 (APS-4), BBI-0336 (APS-8), BBI-0338 (DD-1), BBI-0343 (NK3) and BBI-0358 (CSR26) for further validation through field trials in selected hotspots viz. Tropical - High temperature and low humidity at RSRS, Jammu and REC Chitradurga; Sub tropical - High temperature and high humidity at RSRS Jammu and Temperate at CSRTI, Berhampore. Conclusion: The present study elucidate the impact of temperature and humidity associated stress conditions over economic traits performances of selected bivoltine accessions. The findings of the present study provide a suitable platform for future bivoltine crop improvement through breeding program.