中文摘要：

气味结合蛋白（odorant binding proteins， OBPs）在昆虫对寄主气味的感受中起重要作用， 但有关Minus-C OBP及其功能的报道很少。本研究通过基因组数据分析并利用RACE技术， 克隆和鉴定了二化螟Chilo suppressalis （Walker）的一个Minus-C OBP基因， 命名为CsupOBP1（GenBank登录号： KC492498）。CsupOBP1基因的开放阅读框长423 bp， 编码141个氨基酸， 其中N端的18个氨基酸为预测的信号肽序列， 成熟蛋白序列中具有4个保守的半胱氨酸位点。实时定量PCR分析显示， 该基因在幼虫头部及成虫雌雄足、 翅和雄性触角等化感组织中高表达， 其中在雄虫触角内的表达量显著高于雌虫触角。利用荧光竞争结合实验对CsupOBP1重组蛋白与38种化合物的结合特性的测定表明， 重组CsupOBP1与β紫罗兰酮的结合能力最强（Ki=9.53 μmol/L）。触角电位测定表明， 二化螟成虫可对β-紫罗兰酮产生显著的触角电生理反应， 但雄虫反应明显强于雌虫， 与结合试验及雄虫触角中CsupOBP1的表达量显著高于雌虫触角的测定结果相一致。鉴于β-紫罗兰酮是水稻等植物中普遍存在的一种芳香气味组分， 推测CsupOBP1可能通过对该气味的结合和运输， 从而在二化螟对寄主植物的嗅觉定向中起作用。

英文摘要：

Odorant binding proteins （OBPs） play important roles in the perception of host plant volatiles, but Minus-C OBPs （with only four conserved cysteins） and their functions are rarely addressed. In this study, a full-length cDNA of a Minus-C OBP gene from the rice striped stem borer, Chilo suppressalis （Walker）, was cloned and identified by transcriptome analysis and RACE technology, which was named CsupOBP1 （GenBank accession no. KC492498）. The sequence of CsupOBP1 contains a 423 bp open reading frame that encodes 141 amino acids, including a signal peptide of 18 amino acids at the N terminus and the four conserved cysteins of Minus-C OBPs. The results of real-time quantitative PCR （qRT-PCR） showed that CsupOBP1 was highly expressed in the larval heads, adult legs and wings of both sexes, and adult antennae of males. The expression level in female antennae was significantly lower than that in male antennae. Affinities of recombinant CsupOBP1 with 38 ligands were tested by fluorescence competitive binding assay. Beta-ionone showed the highest affinity （Ki=9.53 μmol/L） to CsupOBP1. In the electroantennogram （EAG） recording assay, beta-ionone elicited stronger EAG responses than other tested volatiles, and stronger response in males than in females, consistent with the results of binding assay and male antennae biased expression of CsupOBP1. Considering that beta-ionone is a common fragrant volatile of many host plants of C. suppressalis, we propose that CsupOBP1 functions to bind and transport beta-ionone and thus plays a role in finding host plants in C. suppressalis.