Studies on the Mutant Systems of the Bombyx mori Gene Bank

Through over ten years of study, more than 1 000 genetic materials including mutant genes,chromosomal variation strains and special genetic materials of Bombyx mori, Linnaeus, collected, introduced or created since 1940s especially late 1980s, have been sorted out and put in order. After identifications and genetic analyses of their morphological, physiological and biochemical characters, the silkworm gene bank was constructed and the preservation system was perfected, and more than 600 silkworm strains were kept in this gene bank. The preserved silkworm mutant genes have covered more than 90% of existent ones across the world, in which, more than 100 are rare and precious mutant genes, and over 60 mutant genes were found and studied for the first time. Through hybrid analyses, linkage tests and three-point gene location tests, a perfect linkage retrieval labeling system of silkworm was established, which included 230 marker genes covering all the 28 linkage groups of Bombyx mori. The gene location system (composite system of recessive genes) of different linkage groups was set up. The intergenic complementation of mutant egg color and third type of maternal heredity egg color have been found, and indicated that the epistatic effect of mutant gene of white egg is universal. Twenty eight independent near isogenic lines murked with morphological mutation gene have been created and a series of novel breeding materials possessing great potential for application such as high feeding efficiency, special sex markers, natural colored silk, resistance to disease, wider feeding range and adjustable parthenogenesis, etc., have been developed. The sustainable maintenance and management technique system of silkworm gene resources were well established.