Chemosensory proteins (CSPs) play a crucial role in olfactory recognition in insects. The small white butterfly Pieris rapae—a major pest of Brassicaceae vegetables, which causes enormous economic losses—uses olfaction to locate its host plants. However, the molecular mechanism of olfaction in this species remains unknown. Herein, we performed a genome-wide and transcriptome-wide analysis of CSP genes in P. rapae and identified 21 CSPs (PrapCSP1 to PrapCSP21). Proteins encoded by these genes showed typical characteristics of CSPs—an N-terminal signal peptide and four positionally conserved cysteine residues. BLASTX analysis indicated that most P. rapae CSPs showed high amino acid identity with their respective orthologs in other lepidopterans. Phylogenetic analysis showed that most P. rapae CSPs were well segregated and were clustered into different branches. The 21 genes were located on six genomic scaffolds, and most genes were tandemly arrayed. Quantitative reverse transcription-PCR showed that PrapCSP3, 4, 16 and 21 had the highest expression level in the antennae; PrapCSP7 and PrapCSP18 were mainly expressed in the ovaries, and PrapCSP9 and PrapCSP17 were leg-enriched. PrapCSP11 and PrapCSP20 were found mainly in the heads and testes, respectively. Our findings provide a solid foundation for studying the function of these genes.

化学感觉蛋白（CSP）在昆虫的嗅觉识别中起关键作用。小白蝴蝶菜青虫（一种菜科植物的主要害虫，会造成巨大的经济损失）利用嗅觉来定位其寄主植物。但是，该物种嗅觉的分子机制仍然未知。在本文中，我们进行了全基因组和转录组范围的分析CSP在基因菜粉蝶，并确定21 CSP S（PrapCSP1到PrapCSP21）。这些基因编码的蛋白质表现出CSP的典型特征-N末端信号肽和四个位置保守的半胱氨酸残基。BLASTX分析表明，大多数菜青虫CSP与其他鳞翅目动物的直向同源物显示出高度的氨基酸同一性。系统发育分析表明，大多数菜青虫CSPs很好地隔离并聚集在不同的分支中。21个基因位于六个基因组支架上，并且大多数基因被串联排列。定量逆转录PCR结果显示PrapCSP3，4，16和21具有在天线的最高表达水平; PrapCSP7和PrapCSP18主要在卵巢中表达，PrapCSP9和PrapCSP17富含腿部。PrapCSP11和PrapCSP20主要在头部和睾丸中发现。我们的发现为研究这些基因的功能提供了坚实的基础。