Fibroin gene expression and antioxidant enzymes are elevated in Bombyx mori when reared on preferred host plants

Silk fibroin filaments are natural proteins produced by silkworm, Bombyx mori , which is bounded by sericin polymers in silk thread used in the cocoon. Fibroin gene expression and antioxidant enzymes were studied in the midgut of Bombyx mori larvae when reared on tropical mulberry plant varieties (Jorhat, TR10, BC2-59, and Hmute). In this study, the B. mori strain FC2 x FC1 showed a high expression of fibroin at both mRNA and protein levels when reared on four plant varieties. B. mori strains FC1 x FC2 (reared on Local, Jorhat and BC2-59) and CSR4 x CSR2 (reared on Jorhat, TR10 and BC2-59) had a higher level of expression of fibroin protein. The strain FC2 X FC1 showed relatively higher SOD and moderate catalase activities. This study reveals the differential expression of fibroin and tolerance to stress in B. mori strains which might justify the rationality of using the most suitable host plants and economically viable strains (FC2 X FC1) for producing commercially the best quality silk threads.