Arbuscular mycorrhizal (AM) fungi may help protect plants against herbivores; however, their use for the pest control of woody plants requires further study. Here, we investigated the effect of Glomus mosseae colonization on the interactions between gypsy moth larvae and Populus alba × P. berolinensis seedlings and deciphered the regulatory mechanisms underlying the mycorrhizal-induced resistance in the leaves of mycorrhizal poplar using RNA-seq and nontargeted metabolomics. The resistance assay showed that AM fungus inoculation protected poplar seedlings against gypsy moth larvae, as evidenced by the decreased larval growth and reduced larval survival. A transcriptome analysis revealed that differentially expressed genes (DEGs) were involved in jasmonic acid biosynthesis (lipoxygenase, hydroperoxide dehydratase, and allene oxide cyclase) and signal transduction (jasmonate-ZIM domain and transcription factor MYC2) and identified the genes that were upregulated in mycorrhizal seedlings. Except for chalcone synthase and anthocyanidin synthase, which were downregulated in mycorrhizal seedlings, all DEGs related to flavonoid biosynthesis were upregulated, including 4-coumarate-CoA ligase, chalcone isomerase, flavanone 3-hydroxylase, flavonol synthase, and leucoanthocyanidin reductase. The metabolome analysis showed that several metabolites with insecticidal properties, including coumarin, stachydrine, artocarpin, norizalpinin, abietic acid, 6-formylumbelliferone, and vanillic acid, were significantly accumulated in the mycorrhizal seedlings. These findings suggest the potential of mycorrhiza-induced resistance for use in pest management of woody plants and demonstrate that the priming of JA-dependent responses in poplar seedlings contributes to mycorrhiza-induced resistance to insect pests.

中文翻译：

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丛枝菌根真菌定植杨树幼苗对舞毒蛾幼虫的防御反应：一项多组学研究

丛枝菌根 (AM) 真菌可能有助于保护植物免受食草动物的侵害；然而，它们用于防治木本植物的害虫需要进一步研究。在这里，我们研究了青蒿吉普赛蛾幼虫与白杨 × P. berolinensis并利用 RNA-seq 和非靶向代谢组学破译了菌根诱导的杨树叶片抗性的调控机制。抗性测定表明，AM 真菌接种保护杨树幼苗免受舞毒蛾幼虫的侵害，幼虫生长减少和幼虫存活率降低就是明证。转录组分析显示差异表达基因 (DEG) 参与茉莉酸生物合成（脂氧合酶、氢过氧化物脱水酶和丙二烯氧化环化酶）和信号转导（茉莉酸-ZIM 结构域和转录因子 MYC2），并鉴定出菌根中上调的基因幼苗。除了查尔酮合酶和花青素合酶在菌根幼苗中下调外，所有与类黄酮生物合成相关的 DEG 均上调，包括 4-香豆酸-CoA 连接酶、查耳酮异构酶、黄烷酮 3-羟化酶、黄酮醇合酶和无色花青素还原酶。代谢组学分析表明，几种具有杀虫特性的代谢物，包括香豆素、水苏碱、artocarpin、norizalpinin、枞酸、6-甲酰伞形酮和香草酸，在菌根幼苗中显着积累。这些研究结果表明菌根诱导的抗性可能用于木本植物的害虫管理，并证明杨树幼苗中 JA 依赖性反应的引发有助于菌根诱导的对害虫的抗性。代谢组学分析表明，几种具有杀虫特性的代谢物，包括香豆素、水苏碱、artocarpin、norizalpinin、枞酸、6-甲酰伞形酮和香草酸，在菌根幼苗中显着积累。这些研究结果表明菌根诱导的抗性可能用于木本植物的害虫管理，并证明杨树幼苗中 JA 依赖性反应的引发有助于菌根诱导的对害虫的抗性。代谢组学分析表明，几种具有杀虫特性的代谢物，包括香豆素、水苏碱、artocarpin、norizalpinin、枞酸、6-甲酰伞形酮和香草酸，在菌根幼苗中显着积累。这些研究结果表明菌根诱导的抗性可能用于木本植物的害虫管理，并证明杨树幼苗中 JA 依赖性反应的引发有助于菌根诱导的对害虫的抗性。