Following a previous microbial inoculation, plants can induce broad-spectrum immunity to pathogen infection, a phenomenon known as systemic acquired resistance (SAR). SAR establishment in Arabidopsis thaliana is regulated by the Lys catabolite pipecolic acid (Pip) and flavin-dependent-monooxygenase1 (FMO1). Here, we show that elevated Pip is sufficient to induce an FMO1-dependent transcriptional reprogramming of leaves that is reminiscent of SAR. In planta and in vitro analyses demonstrate that FMO1 functions as a pipecolate N-hydroxylase, catalyzing the biochemical conversion of Pip to N-hydroxypipecolic acid (NHP). NHP systemically accumulates in plants after microbial attack. When exogenously applied, it overrides the defect of NHP-deficient fmo1 in acquired resistance and acts as a potent inducer of plant immunity to bacterial and oomycete infection. Our work has identified a pathogen-inducible L-Lys catabolic pathway in plants that generates the N-hydroxylated amino acid NHP as a critical regulator of systemic acquired resistance to pathogen infection.

中文翻译：

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黄素单加氧酶产生的N-羟基胡椒酸是植物体内免疫力的关键元素。

在先前的微生物接种之后，植物可以诱导针对病原体感染的广谱免疫力，这种现象被称为系统获得性抗药性（SAR）。拟南芥中的SAR建立受Lys分解代谢物胡椒酸（Pip）和黄素依赖性单加氧酶1（FMO1）的调节。在这里，我们显示升高的Pip足以诱导令人联想到SAR的叶片的FMO1依赖性转录重编程。在植物体内和体外分析表明，FMO1发挥了胡椒碱N-羟化酶的作用，催化Pip向N-羟基胡椒酸（NHP）的生化转化。NHP会在微生物侵袭后系统性地积累在植物中。外用时 它克服了NHP缺乏的fmo1在获得性抗性方面的缺陷，并作为植物抵抗细菌和卵菌感染的有效诱导剂。我们的工作已经确定了植物中病原体可诱导的L-Lys分解代谢途径，该途径可产生N-羟基化氨基酸NHP，作为系统获得性对病原体感染的关键调节剂。