Expression Profiling of Fibroin Gene in Various Strains of Bivoltine Silkworm, Bombyx mori L

Abstract:

Silk production in the mulberry silkworm, Bombyx mori L., is primarily governed by the synthesis and expression of fibroin genes in the posterior silk gland. Fibroin, the major structural protein of silk, consists of heavy chain (Fib-H), light chain (Fib-L), and P25 proteins, whose coordinated expression determines silk quality and productivity. The present review summarizes the current knowledge on fibroin gene structure, regulation, and expression profiling in silkworms, with particular emphasis on bivoltine strains of B. mori. Studies conducted using molecular, biochemical, transcriptomic, and proteomic approaches have demonstrated that fibroin gene expression is tightly regulated in a spatially and temporally specific manner, particularly during the fifth larval instar. Several investigations have revealed significant variation in fibroin gene expression among silkworm strains, which contributes to differences in cocoon traits, silk yield, and fiber quality. Advances in gene expression analysis, including quantitative PCR, RNA sequencing, and proteomic profiling, have provided valuable insights into the molecular mechanisms underlying silk protein biosynthesis. Understanding the expression dynamics of fibroin genes can facilitate the identification of superior silkworm genotypes with enhanced silk-producing potential and support the development of improved breeding strategies. The information compiled in this review highlights the importance of fibroin gene expression studies for genetic improvement, conservation of germplasm resources, and enhancement of silk productivity in bivoltine silkworms.