Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, 100193, Beijing, China.
Institute of Plant Protection, Hebei Academy of Agriculture and Forestry Sciences, Baoding, 071000, China.
Chemosphere. 2021 May;270:128647. doi: 10.1016/j.chemosphere.2020.128647. Epub 2020 Oct 19.
Odorant degrading carboxylesterases (CXEs) play key roles in the process of odor signal reception via degrading ester odorants. But the functional mechanisms of CXEs in modulating insect behaviors are unclear. Herein, we studied the roles that CXEs played in mating, foraging, and signal receptions of sex pheromones and host volatiles in Grapholita molesta. As a result, 23 candidate CXEs were identified by transcriptome analysis of G. molesta. The GmolCXE1 and 5 highly expressed in the antennae of male moths and GmolCXE14 and 21 abundantly expressed in larval heads, were significantly upregulated after exposure with odors from female adults or fresh ripe fruits respectively. After knockdown of GmolCXE1 and 5, or GmolCXE14 and 21 by RNA interference, the behavioral responses of G. molesta to ester sex pheromones or host volatiles were decreased, by exhibiting an inhibited searching behavior of G. molesta for females or fruits, respectively. Then evidence form GC-MS analysis, showed that the protein GmolCXE1 and GmolCXE5 could metabolize the sex pheromone components (Z/E)-8-dodecenyl acetate to their metabolites products (Z/E)-8-dodecenol, and that GmolCXE14 and GmolCXE21 could metabolize ethyl butanoate and ethyl hexanoate of ripe pears. In addition, fluorescent binding assays verified that GmolCXEs could degrade the free ester odor molecules, but not degrade the odor molecules protected by odorant-binding proteins. Our study not only demonstrated CXEs modulated the mating and foraging behaviors of G. molesta through inactivation of ester sex pheromone and host volatiles, but also discovered great potential molecular targets to develop behavioral inhibitors for pest management.
气味降解羧酸酯酶（CXEs）在通过降解酯类气味物质接收气味信号的过程中发挥关键作用。但是，CXEs 调节昆虫行为的功能机制尚不清楚。在此，我们研究了 CXEs 在性信息素和寄主挥发物的交配、觅食和信号接收中在桃小食心虫中的作用。结果，通过桃小食心虫转录组分析鉴定了 23 个候选 CXEs。GmolCXE1 和 5 在雄蛾触角中高度表达，GmolCXE14 和 21 在幼虫头部中大量表达，分别在暴露于雌成虫或新鲜成熟果实的气味后显著上调。通过 RNA 干扰敲低 GmolCXE1 和 5 或 GmolCXE14 和 21 后，桃小食心虫对酯类性信息素或寄主挥发物的行为反应降低，表现为对雌虫或果实的搜索行为受到抑制。然后，GC-MS 分析的证据表明，蛋白 GmolCXE1 和 GmolCXE5 可以代谢性信息素成分（Z/E）-8-十二碳烯基乙酸酯为其代谢产物（Z/E）-8-十二碳烯醇，GmolCXE14 和 GmolCXE21 可以代谢成熟梨中的乙基丁酸酯和乙基己酸酯。此外，荧光结合测定验证了 GmolCXEs 可以降解游离酯类气味分子，但不能降解被气味结合蛋白保护的气味分子。我们的研究不仅表明 CXEs 通过使酯类性信息素和寄主挥发物失活来调节桃小食心虫的交配和觅食行为，而且还发现了用于害虫管理的行为抑制剂开发的巨大潜在分子靶标。
