An ambitious silkworm genome programme was initiated in 1997 to identify and map useful genes of silkworm using molecular technologies. This will help in breeding better silkworm races and developing transgenic silkworms with desired traits in future. About 500 DNA markers have been developed in silkworm.
A genetic linkage map employing 518 simple sequence repeat or microsatellite markers has been established for the silkworm, Bombyx mori. A second generation consensus silkworm genetic map with a range of 7 to 40 markers per linkage group and a total map length of ~ 3431.9 cM was constructed.
India joined the International Consortium on Lepidopteron Genomics and fulfilled the Indian commitments viz. (a) Construction of high-density linkage map of silkworm (Bombyx mori) (b) Isolation and characterisation of ESTs from non-mulberry silkworms (1400 ESTs from tropical tasar, Antheraea mylitta and 35,000 ESTs from muga silkworm, A. assama).
An EST database ‘Wild Silkbase’ has been developed hosting information on construction, characterisation and analysis of ESTs (about 35,500) from the wild silkworm species. This is the largest EST database developed for any lepidopteran insect after Bombyx mori.
Three high yielding productive hybrids namely – Swarnandhra, Hemavathy and Kalpavatharu of silkworm have been developed with superior quality of silk by adopting a combination of conventional breeding techniques and DNA marker technology. These hybrids are now being used by farmers of Andhra Pradesh, Karnataka and Tamil Nadu.
A Multi-institutional Network Project on identification of DNA marker for NPV resistance in silkworm has been launched involving CDFD, Hyderabad, along with other four institutions of Central Silk Board and State Governments. A collaborative project on identification of DNA markers linked to QTLs (cocoon weight and cocoon shell weight) also launched. A Bomby mori gene that code for anti-viral (BmNPV) protein has been partially characterised.
Improvement of Host Plants
A Web-enabled DNA database on mulberry has been developed for the first time in the world encompassing DNA fingerprinting studies carried out on more than 250 genotypes including 50 selected elite genotypes. Efforts have been initiated for construction of a framework molecular linkage map of mulberry for mapping and identification of useful genes.
A Multi-institutional Network project has been launched on identification of DNA markers associated with disease and pest resistance in mulberry (Morus spp.) involving CCMB, Hyderabad along with four institutions of CSB and state governments.
Five mapping populations of mulberry for Water Use Efficiency (WUE), two mapping populations for root and three introgressed populations were developed. A total of 85 in-house SSR markers in mulberry have been developed. Sixty-seven SSR and 386 ESTs were submitted to NCBI. High throughput screening techniques for phenotyping in mulberry have been developed. Genotyping of trait-specific mapping population of mulberry is in progress.