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科学网—Current Biology：十字花科植物专食性昆虫小菜蛾的寄主选择机制

花匠小妙招
2024-11-07 23:47

The Molecular Basis of Host Selection in a Crucifer-Specialized Moth

第一作者：Xiao-Long Liu

第一单位：南京农业大学

通讯作者：Markus Knaden

Abstract

大背景：Glucosinolates (GSs) are sulfur-containing secondary metabolites characteristic of cruciferous plants. Their breakdown products, isothiocyanates (ITCs), are released following tissue disruption by insect feeding or other mechanical damages.

小背景：ITCs repel and are toxic to generalist herbivores, while specialist herbivores utilize the volatile ITCs as key signals for localizing host plants.

提出问题：However, the molecular mechanisms underlying detection of ITCs remain open.

主要发现：Here, we report that in the diamondback moth Plutella xylostella, a crucifer specialist, ITCs indeed drive the host preference for Arabidopsis thaliana, and the two olfactory receptors Or35 and Or49 are essential for this behavior.

结果1-表达模式：By performing gene expression analyses, we identified 12 (out of 59 in total) female-biased Ors, suggesting their possible involvement in oviposition choice.

结果2-异位表达：By ectopically expressing these Ors in Xenopus oocytes and screening their responses with 49 odors (including 13 ITCs, 25 general plant volatiles, and 11 sex pheromone components), we found that Or35 and Or49 responded specifically to three ITCs (iberverin, 4-pentenyl ITC, and phenylethyl ITC).

结果3-电生理：The same ITCs also exhibited highest activity in electroantennogram recordings with female antennae and were the strongest oviposition stimulants.

结果4-基因敲除：Knocking out either Or35 or Or49 via CRISPR-Cas9 resulted in a reduced oviposition preference for the ITCs, while double Or knockout females lost their ITC preference completely and were unable to choose between wild-type A. thaliana and a conspecific ITC knockout plant.

结论：We hence conclude that the ITC-based oviposition preference of the diamondback moth for its host A. thaliana is governed by the cooperation of two highly specific olfactory receptors.

摘要

硫代葡萄糖苷（Glucosinolates），也称芥子油苷，是十字花科植物中含硫次生代谢产物。在十字花科植物的组织遭受昆虫啃食或其它机械损伤时，芥子油苷会被分解，形成并释放产物异硫氰酸酯（ITCs）。ITCs对于一般的草食动物是有害的，因而能够帮助植物抵御这些动物的损害；但是有一些专性草食动物会利用挥发性的ITCs作为定位寄主植物的关键信号。然而，这些动物感知挥发性ITCs的分子机制还不清楚。本文中，作者发现对于十字花科专食性小菜蛾（Plutella xylostella）来说，ITCs确实能够驱动小菜蛾对于拟南芥的寄生优先性，并且Or35和Or49两个嗅觉受体对于小菜蛾的这种行为是必须的。通过基因表达分析，作者发现在总共59个Ors基因中，12个Ors基因存在雌性偏好性，说明其可能参与了产卵选择。通过在非洲爪蟾卵母细胞中异位表达这些Ors基因，并测试其对于49个候选气味的响应，主要包括13种ITCs、25种常见植物挥发物以及11种性信息素组分，作者发现Or35和Or49特异性响应于3-(甲硫基)丙基异硫氰酸酯、4-戊烯基-异硫氰酸酯和苯乙基-异硫氰酸酯三种ITCs。另外，电生理试验显示雌性触角对于同样的ITCs表现出最高的活性，并且这些ITCs是最强的产卵刺激剂。通过CRISPR-Cas9技术敲除Or35或者Or49基因会导致ITCs诱导的产卵偏好性降低，而且这两个基因的双突会导致雌性对于ITC的偏好完全丢失，并且不能选择野生型拟南芥与特定的ITC敲除突变体植株。因此，作者总结道在小菜蛾中，基于寄主植物拟南芥释放的ITC的产卵偏好是由两个高度特异性嗅觉受体协同赋予的。

通讯作者

**Markus Knaden**

研究方向：

昆虫基于嗅觉的导航与决策。

doi: 10.1016/j.cub.2020.08.047

Journal: Current Biology

Published date: September 10, 2020

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链接地址：https://blog.sciencenet.cn/blog-3158122-1250888.html

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