Comparative proteomic analysis of the silkworm (Bombyx mori L.) silk gland reveals yield heterosis

Heterosis is a prevalent phenomenon in nature and is widely found in animals and plants, but the molecular mechanism of heterosis is still unclear. As the model insect of Lepidoptera, Bombyx mori is an ideal material to carry out heterosis research. In current study, we employed proteomic and genetic cross approaches to globally identify differentially expressed proteins in parental silkworms JingSong and HaoYue and their F1 hybrids. The results showed that there were significant differences between hybrids and their parents. In all, 28 differentially expressed proteins were successfully identified through MALDI-TOF-TOF mass spectrometry and database searches. Interestingly, three silk-related proteins were also obtained and identified, including fibroin L-chain, Nd-sD mutant fibroin light chain and fibrohexamerin, which were further confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). Consistent trends were also found in other genes. Taken together, our work not only provides the theoretical basis for the study of molecular mechanism of heterosis, but also provides candidate proteins and genes for the improvement of yield of silkworm.