A Cluster of Genes at the Terminal Region of Chromosome 1 Contributes to Silk Yield in Bombyx Mori.

Abstract

Background: The silk yield is the most economically important trait in sericulture. In the domestication of the silkworm, traits related to silk yield are the main selective targets. In previous studies, linkage and association analyses were performed, which narrowed the region of the locus controlling the cocoon shell weight (CSW), an important index of silk yield, to the interval of 0–134 kb on the 1st chromosome. Results In this study, selection pressure analysis showed that most of the loci in this interval were co-selected during silkworm domestication. Association analysis conducted with 95 strains found that there is a 110 kb region that was significantly associated with CSW. An expression profile correlation analysis of eight genes in the region showed that their expression patterns were very similar. Sequence variation analysis detected mutations in the exon regions of BMgn002066 and BMgn002073, leading to premature termination of translation. The sequence variation was significantly correlated with CSW. In addition, another two genes, BMgn002067 and BMgn002071, had significantly different expression levels in the posterior silk glands of 11 high-yield strains and 11 low-yield strains. Therefore, we speculate that the abovementioned four genes and the gene BmAbl1 detected in previous studies may co-regulate CSW. Conclusions This study is the first to identify the gene clusters that affect CSW by forward genetics, thereby providing new evidence for gene clusters that regulate quantitative traits.