Abstract

Recent work has provided evidence for the occurrence of N-hydroxypipecolic acid (NHP) in Arabidopsis thaliana, characterized its pathogen-inducible biosynthesis by a three-step metabolic sequence from l-lysine, and established a central role for NHP in the regulation of systemic acquired resistance. Here, we show that NHP is biosynthesized in several other plant species in response to microbial attack, generally together with its direct metabolic precursor pipecolic acid and the phenolic immune signal salicylic acid. For example, NHP accumulates locally in inoculated leaves and systemically in distant leaves of cucumber in response to Pseudomonas syringae attack, in Pseudomonas-challenged tobacco and soybean leaves, in tomato inoculated with the oomycete Phytophthora infestans, in leaves of the monocot Brachypodium distachyon infected with bacterial (Xanthomonas translucens) and fungal (Magnaporthe oryzae) pathogens, and in M. oryzae-inoculated barley. Notably, resistance assays indicate that NHP acts as a potent inducer of acquired resistance to bacterial and fungal infection in distinct monocotyledonous and dicotyledonous species. Pronounced systemic accumulation of NHP in leaf phloem sap of locally inoculated cucumber supports a function for NHP as a phloem-mobile immune signal. Our study thus generalizes the existence and function of an NHP resistance pathway in plant systemic acquired resistance.

中文翻译：

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单子叶植物和双子叶植物中系统获得性抗性诱导剂N-羟基哌酸的诱导生物合成和免疫功能。

摘要

最近的工作为拟南芥中N-羟基哌酸（NHP）的发生提供了证据，通过l-赖氨酸的三步代谢序列表征了其病原体诱导的生物合成，并确定了NHP在调节全身性中的重要作用获得性抵抗力。在这里，我们显示了NHP在其他几种植物物种中对微生物的侵袭进行了生物合成，通常与其直接代谢的前体胡椒酸和酚类免疫信号水杨酸一起合成。例如，本地NHP接种叶响应积累和系统性的黄瓜叶遥远到丁香假单胞菌攻击，假单胞菌挑战的烟草和大豆叶片，接种了卵菌疫霉菌的番茄，感染细菌病原体（Xanthomonas translucens）和真菌病原体（Magnaporthe oryzae）的单子叶植物Brachypodium distachyon的叶片以及米曲霉-接种大麦。值得注意的是，耐药性分析表明，NHP在不同的单子叶和双子叶物种中对细菌和真菌感染具有较强的获得性抗性。NHP在局部接种黄瓜叶的韧皮部汁液中的明显系统积累支持NHP作为韧皮部移动免疫信号的功能。因此，我们的研究概括了NHP抗性途径在植物系统获得性抗性中的存在和功能。