灭字脊虎天牛CSP基因的鉴定、表达谱及XquaCSP7基因的功能研究

Identification and expression pattern of chemosensory protein genes from Xylotrechus quadripes Chevrolat (Coleoptera: Cerambycidae) and functional studies of XquaCSP7 gene

基于已发表的灭字脊虎天牛Xylotrechus quadripes的触角转录组数据,采用BLAST同源搜索的方法从转录组中一共鉴定到14个CSP基因,所有CSP均具有全长序列、信号肽序列和4个保守的半胱氨酸。序列比对结果表明,灭字脊虎天牛CSP间氨基酸一致性差异较大(12%~73%),平均值为34%;具有C1-X6-C2-X18-C3-X2-C4的半胱氨酸保守模式。进化分析表明,除XquaCSP8和XquaCSP12外,其余XquaCSPs聚类到不同分支。表达谱分析表明,XquaCSP7基因在触角特异表达;XquaCSP4、CSP5、CSP12和CSP14基因在触角高表达;XquaCSP13基因在足特异表达;其余XquaCSPs基因在多个组织中有表达。结合测定结果发现,XquaCSP7与测试的21种寄主气味结合能力均较弱,荧光取代率在4.5%~13.5%之间,其中与苯乙酮的结合能力最强,荧光取代率为13.5%。研究结果可为后续灭字脊虎天牛CSP基因的功能研究奠定基础。

In this study, we identified 14 chemosensory protein genes from the antennal transcriptome of Xylotrechus quadripes by using a BLAST homology-based approach. All identified XquaCSPs had full-length sequences with signal peptides and four conserved cysteines. Sequence alignment results showed a varied amino acid identities with a range of 12%-73%(mean: 34%) among XquaCSPs. A conserved cysteine pattern of C1-X6-C2-X18-C3-X2-C4 was presented among XquaCSPs. Phylogenetic analysis indicated that XquaCSP8 and XquaCSP12 were grouped into a small clade and others were classified into different clades. Expression pattern analysis revealed that XquaCSP7 showed an antennae-specific expression, while XquaCSP4, CSP5, CSP12 and CSP14 were highly expressed in the antennae;XquaCSP13 expression was limited to legs. The remaining XquaCSP genes had a broad expression in various tissues. Binding assays showed that XquaCSP7 exhibited weak binding affinities to 21 odorants derived from host plants, with a range of fluorescent displacements of 4.5%-13.5%. Among these, acetophenone was the best ligand with a fluorescent displacement of 13.5%. The results laid a foundation for future functional studies of XquaCSP genes in this species.