Transcriptomic Profiling Provides Insight into the Molecular Basis of Heterosis in Philippine-Reared Bombyx mori Hybrids

The Bombyx mori parental strains Lat21 and B221 from the Department of Science and Technology - Cordillera Administrative Region (DOST-CAR) Sericulture Facility in La Trinidad, Benguet are crossed to produce the hybrids NC144 (Lat21? X B221?) and CN144 (B221? X Lat21?). These hybrids exhibited heterosis in field studies conducted in the 1980s. This study aims to provide evidence for the observed heterosis in the molecular basis for heterosis in B. mori hybrids NC144 and CN144 through RNA sequencing of whole silkworm larvae. Withe the sequencing data, it was possible to identify differentially expressed genes (DEGs) among: 1) the parental strains and their hybrids, and 2) the two hybrids. DESeq2 found 384 DEGs in the hybrids (reference: Parents; 202 upregulated, 182 downregulated) and 819 DEGs in NC144 (reference: CN144; 66 upregulated, 753 downregulated). Amon these are DEGs encoding for heat shock proteins and antimicrobial peptides, which have potentials use as markers for marker-assisted breeding. Additionally, the inducible nature of these genes in the presence of stressors like extreme temperature and bacteria, suggests that they could also be used as diagnostic tools for stress assessment. Overall design: RNA from whole Bombyx mori larvae of 2 Philippine-reared parental strains and their 2 hybrids, 3 bioreplicates each strain