Proteomic And Transcriptomic Studies On Heterosis Of Silkworm,Bombyx Mori

Heterosis is a common phenomenon in nature and widely found in animals,plants and microorganisms.At present,the research on heterosis is mainly dominated by plants,and the theoretical mechanism is still unclear.As an important economic insect and model insect of Lepidoptera,Bombyx mori is an ideal material to carry out heterosis research.In current study,JingSong?JS,Chinese line?,HaoYue?HY,Japanese line?and their direct cross?JS×HY?,reciprocal cross?HY×JS?F₁ hybrids were used as research materials.Using a combination of trait investigations,proteomic and transcriptomic approaches,we investigated the differential protein and gene expression patterns between F₁ hybrids and their parents from protein and gene levels.Meanwhile,some differentially expressed proteins and genes were further verified by real-time fluorescence quantitative PCR.The main results are as follows:?1?The investigation results of morphological traits:Starting from the fourth instar,with the rapid growth of silkworm,the body weight of the F₁ hybrids increased more rapidly and exceeded their parents significantly at the end of the fifth instar.Compared with the parents,the F₁ hybrids had significant advantages in whole cocoon weight,cocoon shell weight,pupal weight,cocoon shell percentage,dead cocoon rate,moth weight and the number of eggs.Particularly,the body weight,cocoon weight and fecundity of the hybrid F₁ generation displayed obvious super-parental advantages.?2?The two-dimensional electrophoresis?2-DE?and MALDI-TOF-TOF mass spectrometry methods were used to analyze the differentially expressed proteins in the midguts and silk glands between the parents and their hybrids.There were 32 significantly different proteins were identified successfully in silk glands between the F₁ hybrids and their parents,including three proteins closely related to silk production:fibroin L-chain,Nd-sD mutant fibroin light chain and fibrohexamerin-like.GO analysis showed that the differentially expressed proteins were mainly involved in the process of catalysis,metabolic processes,binding processes and cell processes.KEGG analysis showed that the differentially expressed proteins were mainly involved in metabolic processes,genetic information processing,environmental information processing,cell process and organic system process.Thirty significantly different proteins were alos identified in the midguts,including fatty acid-binding protein 1-like isoform X1,vacuolar ATP synthase subunit H and serine protein inhibitor 2.GO analysis of the midguts were consistent with the results of silk glands.KEGG analysis showed that the differentially expressed proteins were mainly involved in metabolism,genetic information processing,environmental information processing,cell process,biological system pathway.Taken together,the differentially expressed proteins in midguts and silk glands were mainly involved in catalytic and metabolic processes.?3?Differences of gene expression at transcriptional levels:The results of transcriptome analysis of silk glands showed that there were 519 differentially expressed genes between JS and HY.There were 473 differentially expressed genes between JS and JS×HY,and there were481 differentially expressed genes between HY and JS×HY.GO analysis showed that genes with significant differences were mainly involved in oxidation-reduction process,metabolic process,oxidoreductase activity,iron ion binding,heme binding and metal ion binding.KEGG analysis showed that significantly different genes mainly participated in endoplasmic reticulum protein processing,longevity regulation pathway,purine metabolism,oxidative phosphorylation,fatty acid degradation,glycine,serine and threonine metabolic.Transcriptome analysis of the midguts showed that there were 586 differentially expressed genes between JS and HY.There were 464 differentially expressed genes between JS and JS×HY,there were 500 differentially expressed genes between HY and JS×HY.GO analysis showed that the significantly different genes mainly had functions of transmembrane transport,extracellular domain,integral component of membrane,catalytic activity and protein binding.The results of KEGG analysis showed that different genes were mainly involved in the process of protein processing in endoplasmic reticulum,metabolism of cytochrome P450,pentose and glucuronate interconversions and glutathione metabolism.To sum up,the differentially expressed genes mainly exhibited heterosis effects through the process of glucose metabolism and amino acid metabolism.In a word,the F₁ hybrids showed obvious super-parental advantages,especially in body weight,whole cocoon weight,cocoon shell weight and pupal weight.The results of proteome and transcriptome among JS,HY and their hybrids demonstrated that the proteins or genes related to metabolism,catalysis,and transport in hybrids showed significantly different expressions.The differentially expressed proteins and genes were mainly involved in glucose,fat and protein metabolic pathways.Furthermore,some differentially expressed proteins related to the metabolism and digestion of the midgut were detected,including fatty acid-binding protein and vacuolar ATP synthase.In silk glands,the different proteins associated with silk synthesis,such as fibroin L-chain,Nd-sD mutant fibroin light chain and fibrohexamerin-like were also identified,which may be related to the yield heterosis of silkworm.