暗黑鳃金龟触角偏好性表达基因HpGSTd1的气味降解功能研究

气味信号终止作为昆虫气味识别和信号传导进程中的关键一环，在保护嗅觉神经元和维持嗅觉灵敏性方面发挥重要作用。尽管早有报道，GSTs是一类潜在的昆虫气味降解酶，但其参与气味降解的分子机制却尚不明确。课题组前期研究发现，暗黑鳃金龟HpGSTd1基因在触角中高水平、特异性表达，且其重组蛋白具有代谢寄主植物挥发物活性，因此，推测HpGSTd1作为关键的气味降解酶，参与气味信号失活进程。据此，本项目拟通过蛋白表达、生化分析和氨基酸定点突变技术，揭示HpGSTd1对气味分子的催化机制；利用生化免疫试验对HpGSTd1进行组织定位；采用RNAi技术，研究暗黑鳃金龟缺失表达HpGSTd1后的电生理与行为反应；应用体外酶活性抑制试验筛选HpGSTd1高效抑制剂，并探明气味降解酶抑制剂对害虫嗅觉的靶向调控作用。该研究将全面解析HpGSTd1降解气味分子的作用机理，为地下害虫暗黑鳃金龟高效、绿色防控开辟新思路。

As a vital process in insect odorant reception and signal construction, the termination of odorant signals plays important roles in the protection of odorant receptor neurons and maintaining olfactory sensitivity. It has been reported that GSTs are potential odorant-degrading enzymes (ODEs) in insects, however, the molecular mechanism of odorant degradation mediated by GSTs remains unclear. Our previous studies showed that HpGSTd1 was highly and specifically expressed in antennae of Holotrichia parallela, and the recombinant protein of HpGSTd1 could metabolize volatiles from host plants, thus, it is speculated that HpGSTd1 is a critical ODE gene participating in the inactivation of odorant signals. In view of these, this project is planned to elucidate the catalytic mechanism of HpGSTd1 for the degradation of odorants through protein expression, biochemical analysis and site-directed mutation; to clarify the tissue localization of HpGSTd1 through biochemical immunoassay; to determine the electrophysiological and behavioral response of H. parallela losing expression of HpGSTd1 using RNA interference; to screen effective inhibitors of HpGSTd1 using enzyme activity inhibition assay, and further investigate the targeted regulation of ODE inhibitors on the olfaction of pests. The results will not only reveal the molecular mechanism of HpGSTd1 in the odorant degradation, but also contribute to develop the effective and green control strategy for the underground pest H. parallela.