Abstract:  【Aim】 Re-nd, a non-diapause red egg mutant of Bombyx mori, is the only mutant with bright red egg color in non-diapause. This study aims to determine the chromosome and tightly linked location of the mutant gene of Re-nd by genetic linkage analysis and positional cloning, so as to lay a foundation for functional research and application of the Re-nd mutant. 【Methods】 The experimental materials for genetic linkage analysis and positional cloning were prepared by hybridization of the mutant Re-nd and the wild-type Dazao of B. mori. The SNP markers were developed for the whole chromosomes of B. mori and used for genetic linkage analysis with the BC₁ generation population materials to determine the chromosome where the mutant gene of Re-nd is located. Then the SNP markers were developed for this chromosome and used for positional cloning of the mutant gene of Re-nd with the BC₁ generation population materials. 【Results】 The genetic linkage analysis results showed that the mutation phenotype of Re-nd was completely linked to the SNP markers on chromosome 6. The preliminary positional cloning results showed that the mutant gene of Re-nd was located between the SNP markers SNP7 and SNP17, with a physical distance of 4.04 Mb. The fine positional cloning was performed with six SNP markers between the SNP markers SNP7 and SNP17 and 25 recombined individuals screened, and the results showed that the region of the mutant gene of Re-nd was located on nscaf2853 between the SNP markers SNP10 and SNP12, with a physical distance of about 949.3 kb. 【Conclusion】 The mutant gene of Re-nd is located between the SNP markers SNP10 and SNP12 on chromosome 6, with a physical distance of 949.3 kb. This study lays the foundation for the fine positioning and the functional research and application of the Re-nd mutant genes.

Key words: Bombyx mori, non-diapause red egg, marker developing, genetic linkage analysis; positional cloning