| Heterosis is widely used in the breeding of high-yield silkworm hybrids,which is of great significance to the development of agricultural technology.The heterosis molecular mechanism of is an important topic,but the elaboration of this mechanism is still unclear.In this study,we used purebred and hybrid silkworm as models,combined three hybrid combinations to investigate the heterosis of body weight,silk gland and cocoon layer weight.The molecular mechanism of heterosis in silkworm was investigated by transcriptomics,proteomics,combination analysis,protein interaction network analysis and WGCNA analysis.The differentially expressed genes were verified by q RT-PCR and the differentially expressed proteins were verified by enzyme activity assay.The main conclusions are as follows:(1)Heterosis of the phenotypic traits of the silkworm: in the three hybrid combinations,the weight,silk gland and cocoon shell weight of the hybrid silkworm were significantly higher than those of parent silkworm.The results of the heterosis investigation also showed that the heterosis of phenotypic traits are all overdominant.(2)Transcriptomic analysis of heterosis of silkworm phenotypic traits: in the investigation of heterosis,we found that the phenotypic traits of Bombyx mori were overdominant,but the overdominant genes in transcriptome accounted for a small proportion of the total expressed genes,and the proportion of non-additive genes was larger,which suggested that the relationship between heterosis and gene expression was not consistent.GO and KEGG enrichment analysis showed that the main functions of these genes are catalytic molecules,signal transduction,protein synthesis,activity of related enzymes and serine related metabolic pathways.GO and KEGG annotation and enrichment analysis of non-additive genes showed that these genes are mainly concentrated in the functions of ribonucleoprotein complex,transcription,translation,amino acid metabolism,DNA replication,RNA processing,ribosomal RNA metabolism and transferase activity.Twelve genes were selected from the overdominant and non-additive genes and verified by q RT-PCR.Validation results of 9 genes were consistent with transcriptome sequencing results.(3)Proteomic analysis of silkworm heterosis: proteomics analysis found that overdominant proteins accounted for a small proportion of the total expressed proteins,while non-additive proteins accounted for a larger proportion.It is highly consistent with the results of transcriptome gene pattern analysis.The results of functional analysis of overdominant and non-additive proteins are basically consistent with the analysis results in the transcriptome.Five enzymes were selected for verification of enzyme activity determination,including overdominant proteins QSOX,3-ACPR and non-additive proteins AAT,TPI,AS.The enzyme activity determination results showed that the four enzymes except QSOX were consistent with the proteomic results.(4)Combined analysis of transcriptomics and proteomics: screened genes and proteins with consistent expression patterns in the transcriptome and proteome.The genes and proteins obtained from the transcriptome and proteome screening are jointly analyzed.3 overdominant and 21 nonadditive genes and proteins were obtained.The protein-protein interaction(PPI)network analysis of these proteins revealed that SS3,M1 Pi,ACBP,CKS,CLP,and Cal S are in the central position in the PPI network,and these proteins may be the key proteins of silkworm heterosis.(5)WGCNA analysis: WGCNA analysis was used to link genes with phenotypic information of body weight,silk glands,and cocoon shell weight to explore the influence of genes closely related to phenotypic traits on silkworm heterosis.GO enrichment and KEGG analysis of the 3modular genes that were screened revealed that the functions of these genes were mainly enriched in DNA metabolism,DNA synthesis,enzyme activity,transmembrane signal receptor activity,protein synthesis process,lipid metabolism,Amino acid metabolism,folding,classification and degradation,transport and catabolism.It is confirmed that the increase of enzyme expression leads to the acceleration of metabolism and protein synthesis,which improves heterosis. |
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