Li L, Zhou Y-T, Tan Y, Zhou X-R, Pang B-P
Research Center for Grassland Entomology, Inner Mongolia Agricultural University,Hohhot,China.
Bull Entomol Res. 2017 Aug;107(4):550-561. doi: 10.1017/S0007485317000402. Epub 2017 Apr 20.
Odorant-binding proteins (OBPs) play a fundamental role in insect olfaction. In recent years, Galeruca daurica (Joannis) (Coleoptera: Chrysomelidae) has become one of the most important insect pests in the Inner Mongolian grasslands of China. This pest only feeds on the species of Allium plants, implying the central role of olfaction in its search for specific host plants. However, the olfaction-related proteins have not been investigated in this beetle. In this study, we identified 29 putative OBP genes, namely GdauOBP1-29, from the transcriptome database of G. daurica assembled in our laboratory by using RNA-Seq. All 29 genes had the full-length open reading frames except GdauOBP29, encoding proteins in length from 119 to 202 amino acids with their predicted molecular weights from 12 to 22 kDa with isoelectric points from 3.88 to 8.84. Predicted signal peptides consisting of 15-22 amino acid residues were found in all except GdauOBP6, GdauOBP13 and GdauOBP29. The amino acid sequence identity between the 29 OBPs ranged 8.33-71.83%. GdauOBP1-12 belongs to the Classic OBPs, while the others belong with the Minus-C OBPs. Phylogenetic analysis indicated that GdauOBPs are the closest to CbowOBPs from Colaphellus bowringi. RT-PCR and qRT-PCR analyses showed that all GdauOBPs were expressed in adult antennae, 11 of which with significant differences in their expression levels between males and females. Most GdauOBPs were also expressed in adult heads (without antennae), thoraxes, abdomens, legs and wings. Moreover, the expression levels of the GdauOBPs varied during the different development stages of G. daurica with most GdauOBPs expressed highly in the adult antennae but scarcely in eggs and pupae. These results provide insights for further research on the molecular mechanisms of chemical communications in G. daurica.
气味结合蛋白(OBPs)在昆虫嗅觉中起着基础性作用。近年来,黄褐丽金龟(鞘翅目:叶甲科)已成为中国内蒙古草原最重要的害虫之一。这种害虫只取食葱属植物,这意味着嗅觉在其寻找特定寄主植物过程中起核心作用。然而,尚未对这种甲虫中与嗅觉相关的蛋白进行研究。在本研究中,我们通过RNA测序从我们实验室组装的黄褐丽金龟转录组数据库中鉴定出29个假定的OBP基因,即GdauOBP1 - 29。除GdauOBP29外,所有29个基因都有全长开放阅读框,其编码的蛋白质长度为119至202个氨基酸,预测分子量为12至22 kDa,等电点为3.88至8.84。除GdauOBP6、GdauOBP13和GdauOBP29外,在所有其他蛋白中都发现了由15 - 22个氨基酸残基组成的预测信号肽。29个OBP之间的氨基酸序列同一性在8.33% - 71.83%之间。GdauOBP1 - 12属于经典OBPs,而其他的属于C末端缺失型OBPs。系统发育分析表明,GdauOBPs与大猿叶虫的CbowOBPs亲缘关系最近。RT - PCR和qRT - PCR分析表明,所有GdauOBPs在成虫触角中均有表达,其中11个在雌雄成虫中的表达水平存在显著差异。大多数GdauOBPs在成虫头部(无触角)、胸部、腹部、腿部和翅膀中也有表达。此外,GdauOBPs的表达水平在黄褐丽金龟的不同发育阶段有所变化,大多数GdauOBPs在成虫触角中高表达,而在卵和蛹中几乎不表达。这些结果为进一步研究黄褐丽金龟化学通讯的分子机制提供了思路。