The small white butterfly, Pieris rapae (L.), is an important insect pest of Brassica crops. This species utilize olfactory cues to find their hosts and mates. However, the molecular mechanism underlying the olfactory perception in this species remains unclear. Here, we identified 14 odorant-binding proteins (OBP) genes—essential for insect olfaction—in P. rapae by exploring a previously published transcriptome dataset. Proteins encoded by all of these genes contain N-terminal signal peptides and six positionally conserved cysteine residues, which are characteristic of insect OBPs. These OBPs displayed high amino acid identity with their respective orthologs in other lepidopterans, and several conserved motifs were identified within these OBPs. Phylogenetic analysis showed that these OBPs were well segregated from each other and clustered into different branches. PrapOBP1 and PrapOBP2 were clustered into the ‘general odorant-binding protein’ clade, and PrapOBP3 and PrapOBP4 fall into the ‘pheromone-binding protein’ clade. The 14 OBP genes were located on seven genomic scaffolds. Of these, PrapOBP1, 2, 3, and 4 were located on scaffold332, whereas PrapOBP5, 6, 7, 8, and 9 were located on scaffold116. Ten of the 14 genes had antenna-biased expression. Of these, PrapOBP1, 2, 4, and 13 were enriched in male antennae, whereas PrapOBP7 and PrapOBP10 were female-biased. Our findings suggest that these OBPs may be involved in olfactory communication. To the best of our knowledge, this is the first report on the identification and characterization of OBPs in P. rapae, and our findings provide a solid foundation for studying the functions of these genes.

中文翻译：

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菜青虫（鳞翅目：Pieridae）的14种气味结合蛋白基因的鉴定和表达谱。

白色的小蝴蝶菜青虫（Pieris rapae）是芸苔属植物的重要害虫。该物种利用嗅觉线索找到其寄主和伴侣。然而，该物种嗅觉感知的潜在分子机制仍不清楚。在这里，我们鉴定了14个气味增强结合蛋白（OBP）基因-对昆虫嗅觉至关重要-在菜青虫中通过探索先前发布的转录组数据集。由所有这些基因编码的蛋白质均包含N端信号肽和六个位置保守的半胱氨酸残基，它们是昆虫OBP的特征。这些OBP与其他鳞翅目动物的直系同源物显示出高度的氨基酸同一性，并且在这些OBP中鉴定了几个保守的基序。系统发育分析表明，这些OBP彼此之间很好地隔离，并聚集成不同的分支。PrapOBP1和PrapOBP2聚集成“一般气味结合蛋白”进化枝，PrapOBP3和PrapOBP4归入“信息素结合蛋白”进化枝。14个OBP基因位于七个基因组支架上。在这些中，PrapOBP1，2，3和4分别位于scaffold332，而PrapOBP5，6，7，8，和9分别位于scaffold116。14个基因中有10个具有天线偏向表达。在这些中，PrapOBP1，2，4，和13在雄性触角富集，而PrapOBP7和PrapOBP10为女性偏置。我们的发现表明，这些OBP可能参与了嗅觉交流。据我们所知，这是关于菜青虫中OBP的鉴定和表征的第一份报告。，我们的发现为研究这些基因的功能提供了坚实的基础。