Transcriptomics and proteomics-based analysis of heterosis on main economic traits of silkworm, Bombyx mori

The application of silkworm hybrids have promoted the innovation and development of agricultural technology, but the mechanism of heterosis in silkworm has not been explained clearly. In this study, the heterosis of silkworm in the aspects of body weight, silk gland and cocoon weight was investigated by means of silkworm hybridization and multi-omics approaches, including transcriptome and proteome. The results showed that heterosis of silkworm body weight, silk gland and cocoon weight was overdominant, but only part of genes and proteins were overdominant, and most of genes and proteins were non-additive. Combined analysis obtained six up-regulated genes and four down-regulated genes that were consistent both in transcriptome and proteome. Gene functional enrichment analysis indicated that most up-regulated genes and proteins were mostly related to metabolism, which led to accelerated metabolism and protein synthesis and contributing to improved heterosis. The up-regulation of 6-phosphate glucose dehydrogenase (G6PDH), phosphatidylethanolamine-binding protein (PEBP) and sHSP20.4, which are involved in metabolism, might be related to silk gland heterosis. SIGNIFICANCE: A combination of transcriptomic and proteomic analysis was used to understand the molecular mechanism of silkworm heterosis. We found that the phenotypic traits of silkworm are overdominant, while the analysis of transcriptome and proteome showed that only part of genes and proteins were overdominant, and most of genes and proteins were non-additive. Some of the genes had unique expression in F1, which was speculated that genes under heterozygous condition may result in rearrangement and cause metabolic changes in the hybrids. Those both up-regulated in transcriptomic and proteomic analysis were found to be involved in various metabolic processes, so as to accelerate metabolism and protein synthesis, thus exhibiting heterosis.