Antennal transcriptome analysis and expression profiles of odorant binding proteins in Eogystia hippophaecolus (Lepidoptera: Cossidae)

Background: Eogystia hippophaecolus (Hua et al.) (Lepidoptera: Cossidae) is the major threat to seabuckthorn plantations in China. Specific and highly efficient artificial sex pheromone traps was developed and used to control it. However, the molecular basis for the pheromone recognition is not known. So we established the antennal transcriptome of E. hippophaecolus and characterized the expression profiles of odorant binding proteins. These results establish and improve the basis knowledge of the olfactory receptive system, furthermore provide a theoretical basis for the development of new pest control method.

Results: We identified 29 transcripts encoding putative odorant-binding proteins (OBPs), 18 putative chemosensory proteins (CSPs), 63 odorant receptors (ORs), 13 gustatory receptors (GRs), 12 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Based on phylogenetic analysis, we found one Orco and three pheromone receptors of E. hippophaecolus and found that EhipGR13 detects sugar, EhipGR11 and EhipGR3 detect bitter. Nine OBPs expression profile indicated that most were the highest expression in antennae, consistent with functions of OBPs in binding and transporting odors during the antennal recognition process. OBP6 was external expressed in male genital-biased in, and this locus may be responsible for pheromone binding and recognition as well as mating. OBP1 was the highest and biased expressed in the foot and may function as identification of host plant volatiles.

Conclusions: One hundred thirty-seven chemosensory proteins were identified and the accurate functions and groups of part proteins were obtained by phylogenetic analysis. The most OBPs were antenna-biased expressed, which are involved in antennal recognition. However, few OBP was detected biased expression in the foot and external genitalia, and these loci may function in pheromone recognition, mating, and the recognition of plant volatiles.

背景：沙棘木蠹蛾（Eogystia hippophaecolus (Hua et al.)，鳞翅目：木蠹蛾科）是中国沙棘人工林的主要害虫。科研人员已开发出特异性强、高效的人工合成性信息素诱捕器用于其防控，但目前对其信息素识别的分子机制尚不清楚。为此，本研究构建了沙棘木蠹蛾的触角转录组，并对气味结合蛋白的表达谱进行了表征。本研究结果完善了嗅觉识别系统的相关基础认知，同时为新型害虫防治方法的开发提供了理论依据。

结果：本研究共鉴定出29个编码推定气味结合蛋白（odorant binding proteins, OBPs）的转录本、18个推定化学感受蛋白（chemosensory proteins, CSPs）、63个气味受体（odorant receptors, ORs）、13个味觉受体（gustatory receptors, GRs）、12个离子型受体（ionotropic receptors, IRs）以及2个感觉神经元膜蛋白（sensory neuron membrane proteins, SNMPs）。通过系统发育分析，本研究鉴定出沙棘木蠹蛾的1个气味受体共受体（Orco）和3个信息素受体；同时发现EhipGR13可识别糖类物质，EhipGR11与EhipGR3可识别苦味物质。对9个OBPs的表达谱分析显示，多数OBPs在触角中表达量最高，这与其在触角识别过程中结合并转运气味分子的功能一致。其中，OBP6在雄性外生殖器中偏好性高表达，该基因可能参与信息素的结合与识别以及交配行为；OBP1在足中表达量最高且具有表达偏好性，其功能可能为识别寄主植物挥发物。

结论：本研究共鉴定得到137个化学感受相关蛋白，通过系统发育分析明确了部分蛋白的准确功能与类群。多数OBPs呈触角偏好性表达，参与触角识别过程。但少数OBPs在足与外生殖器中呈现偏好性表达，这类基因可能参与信息素识别、交配行为以及植物挥发物识别过程。