背景:昆虫依赖于化学感官知觉,主要是嗅觉,关于伴侣的位置,食物来源,和产卵地点。植物释放的挥发性化合物引导草食性昆虫寻找和定位其寄主植物,进一步帮助他们确定产卵的合适位置。秋季粘虫Spodopterafrugiperda(S.frugiperda)于2019年被发现入侵中国,此后严重威胁多种作物,特别是玉米和水稻。然而,该害虫产卵偏好的化学和分子机制尚未完全了解。这里,研究了S.frugiperda在玉米和水稻植物上的产卵偏好。
结果:使用GC-EAD和GC-MS/MS技术来鉴定玉米和水稻植物的触角活性挥发物。在实验室和现场环境中测试了已确定成分对女性成年的吸引力和产卵刺激。雌性触角上的气味受体(ORs)在非洲爪的卵母细胞中表达,以及通过RNAi评估它们的功能。玉米和水稻的10种和11种化合物,分别,被鉴定为具有来自顶空挥发物的电生理活性。在这些化合物中,与水稻挥发物相比,发现在玉米挥发物中特别存在的(Z)-3-己烯基乙酸酯在吸引雌性和刺激产卵中起关键作用。在两性触角上的克隆OR中,具有高度女性偏向性表达的SfruOR23介导了女性对(Z)-3-己烯基乙酸酯的反应。使用RNAi敲除SfruOR23显着降低了雌性触角的电生理反应和对该化合物的产卵偏好。
结论:(Z)-3-己烯-乙酸酯是介导玉米上的寄主和产卵偏好的关键挥发性物质。(Z)-3-己烯基乙酸酯的嗅觉受体被鉴定为SfruOR23,其主要在S.frugiperda的触角中表达。
Insects rely on chemosensory perception, mainly olfaction, for the location of mates, food sources, and oviposition sites. Plant-released volatile compounds guide herbivorous insects to search for and locate their host plants, further helping them to identify suitable positions for oviposition. The fall armyworm Spodoptera frugiperda (S. frugiperda) was found to invade China in 2019 and has since seriously threatened multiple crops, particularly maize and rice. However, the chemical and molecular mechanisms underlying oviposition preference in this pest are not fully understood. Here, the oviposition preference of S. frugiperda on maize and rice plants was investigated.
GC-EAD and GC-MS/MS techniques were used to identify the antennally active volatiles from maize and rice plants. The attraction and oviposition stimulation of identified components to female adults were tested in both laboratory and field settings. The odorant receptors (ORs) on female antennae were expressed in Xenopus oocytes, and their functions evaluated by RNAi. Ten and eleven compounds of maize and rice plants, respectively, were identified to possess electrophysiological activity from headspace volatiles. Among these compounds, (Z)-3-hexenyl-acetate specifically presented in maize volatiles was found to play a critical role in attracting females and stimulating oviposition compared to rice volatiles. Among the cloned ORs on the antennae of both sexes, SfruOR23 with highly female-biased expression mediated the responses of females to (Z)-3-hexenyl-acetate. Knockdown of SfruOR23 using RNAi markedly reduced the electrophysiological response of female antennae and oviposition preference to the compound.
(Z)-3-Hexenyl-acetate is a key volatile mediating the host and oviposition preference of S. frugiperda on maize. The olfactory receptor of (Z)-3-hexenyl-acetate was identified to be SfruOR23, which is mainly expressed in the antennae of S. frugiperda.