BACKGROUNDEpichloë endophytes provide many benefits to host plants, including enhanced insect resistance. Fungal alkaloids are usually thought to be responsible for the endophyte‐conferred herbivore resistance. Nonetheless, the fungal alkaloid profiles and concentrations may vary considerably among grass–endophyte systems. This indicates that apart from fungal alkaloids, additional mechanisms such as endophyte‐mediated host defense are likely contributed to endophyte–grass–insect interactions. In this study, we addressed this issue by investigating the effect of Epichloë on the defense responses of Achnatherum sibiricum against locusts.RESULTSThe results showed that Epichloë endophytes increased locust resistance of A. sibiricum in both choice and non‐choice feeding experiments. In no feeding groups, endophyte infection increased the content of jasmonic acid (JA) and ethylene (ET), chitinase activity, and the biosynthetic gene expression of the relevant pathways. Endophyte infection also increased the content of total phenolics and condensed tannins. These indicators were negatively correlated with leaf consumption. In locust feeding groups, endophyte infection increased trypsin inhibitor activity. Exogenous application of phytohormones further proved that JA and ET reduced the consumption of A. sibiricum by locusts.CONCLUSIONThe present study showed that endophyte‐conferred host defense was mainly constitutive, that is, the defense characteristics of host plants were mainly manifested in no feeding groups. Endophyte presence enhanced locust resistance of the host by activating the JA/ET signaling pathway, elevating chitinase activity and phenolic compounds content, thereby improving the defense ability of host plants. © 2024 Society of Chemical Industry.

中文翻译：

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真菌内生菌通过在蝗虫取食前提高 Achnatherum sibiricum 的防御能力来增强抗虫性


背景Epichloë 内生菌为寄主植物提供了许多好处，包括增强抗虫性。真菌生物碱通常被认为是导致内生真菌赋予食草动物抗性的原因。尽管如此，真菌生物碱谱和浓度在草-内生菌系统中可能有很大差异。这表明，除了真菌生物碱外，内生真菌介导的宿主防御等其他机制也可能有助于内生真菌-草-昆虫的相互作用。在这项研究中，我们通过调查 Epichloë 对 Achnatherum sibiricum 对蝗虫的防御反应的影响来解决这个问题。结果结果表明，在选择和非选择喂养实验中，Epichloë 内生菌增加了 A. sibiricum 的蝗虫抗性。在无取食组中，内生真菌侵染增加了茉莉酸 （JA） 和乙烯 （ET） 的含量、几丁质酶活性以及相关途径的生物合成基因表达。内生真菌感染还增加了总酚类和缩合单宁的含量。这些指标与叶片消耗量呈负相关。在蝗虫取食组中，内生真菌感染增加了胰蛋白酶抑制剂活性。植物激素的外源应用进一步证明 JA 和 ET 减少了蝗虫对 A. sibiricum 的消耗。结论本研究表明，内生真菌赋予的寄主防御以组成性为主，即寄主植物的防御特性主要表现为无取食群体。内生真菌的存在通过激活 JA/ET 信号通路、提高几丁质酶活性和酚类化合物含量，从而提高寄主植物的防御能力，从而增强寄主植物的防御能力。© 2024 化工学会.