Jasmonate synthesis and signalling are essential for plant defense upregulation upon herbivore or microbial attacks. Stress‐induced accumulation of jasmonoyl‐isoleucine (JA‐Ile), the bioactive hormonal form triggering transcriptional changes, is dynamic and transient because of the existence of potent removal mechanisms. Two JA‐Ile turnover pathways operate in Arabidopsis, consisting in cytochrome P450 (CYP94)‐mediated oxidation and deconjugation by the amidohydrolases IAR3/ILL6. Understanding their impacts was previously blurred by gene redundancy and compensation mechanisms. Here we address the consequences of blocking these pathways on jasmonate homeostasis and defenses in double‐2ah , triple‐3cyp mutants, and a quintuple‐5ko line deficient in all known JA‐Ile‐degrading activities. These lines reacted differently to either mechanical wounding/insect attack or fungal infection. Both pathways contributed additively to JA‐Ile removal upon wounding, but their impairement had opposite impacts on insect larvae feeding. By contrast, only the ah pathway was essential for JA‐Ile turnover upon infection by Botrytis , yet only 3cyp was more fungus‐resistant. Despite building‐up extreme JA‐Ile levels, 5ko displayed near‐wild‐type resistance in both bioassays. Molecular analysis indicated that restrained JA‐Ile catabolism resulted in enhanced defense/resistance only when genes encoding negative regulators were not simultaneously overstimulated. This occurred in discrete stress‐ and pathway‐specific combinations, providing a framework for future defense‐enhancing strategies.

中文翻译：

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茉莉酸-异亮氨酸（JA-Ile）分解代谢受损对应激信号和途径的影响对防御信号传导和生物胁迫抗性的影响。

茉莉酸酯合成和信号传导对于草食动物或微生物侵袭时植物防御上调至关重要。由于存在有效的清除机制，应力诱导的茉莉单基-异亮氨酸（JA-Ile）的生物活性激素形式触发转录变化的积累是动态的和短暂的。拟南芥中有两个JA-Ile转换途径，包括细胞色素P450（CYP94）介导的氧化和水解，由酰胺水解酶IAR3 / ILL6进行。以前由于基因冗余和补偿机制而模糊不清它们的影响。在这里，我们解决的茉莉稳态和双防御阻止这些途径的后果2AH，三重3cyp突变体，以及一个五元组-5ko在所有已知的JA-Ile降级活动中都缺乏的生产线。这些系对机械性伤口/昆虫袭击或真菌感染的反应不同。两种途径均有助于在受伤时去除JA-Ile，但是它们的危害对昆虫幼虫的摄食有相反的影响。相比之下，只有ah途径对于被葡萄孢属感染的JA-Ile转换至关重要，而只有3cyp具有更高的抗真菌性。尽管建立了极端的JA-Ile级别，但5ko在两种生物测定中均显示出近乎野生型的抗性。分子分析表明，只有当编码负调控因子的基因不会同时被过度刺激时，抑制的JA-Ile分解代谢才能增强防御/抵抗力。这是在离散的压力和特定于路径的组合中发生的，为将来的防御增强策略提供了框架。