Plant pattern recognition receptors (PRRs) perceive pathogen-associated molecular patterns (PAMPs) to activate immune responses. Medium-chain 3-hydroxy fatty acids (mc-3-OH-FAs), which are widely present in Gram-negative bacteria, were recently shown to be novel PAMPs in Arabidopsis thaliana. The Arabidopsis PRR LIPOOLIGOSACCHARIDE-SPECIFIC REDUCED ELICITATION (LORE) is a G-type lectin receptor-like kinase that recognizes mc-3-OH-FAs and subsequently mounts an immune response; however, the mechanisms underlying LORE activation and downstream signaling are unexplored. Here, we report that one of the mc-3-OH-FAs, 3-OH-C10:0, induces phosphorylation of LORE at tyrosine residue 600 (Y600). Phosphorylated LORE subsequently trans-phosphorylates the receptor-like cytoplasmic kinase PBL34 and its close paralogs, PBL35 and PBL36, and therefore activates plant immunity. Phosphorylation of LORE Y600 is required for downstream phosphorylation of PBL34, PBL35, and PBL36. However, the Pseudomonas syringae effector HopAO1 targets LORE, dephosphorylating the tyrosine-phosphorylated Y600 and therefore suppressing the immune response. These observations uncover the mechanism by which LORE mediates signaling in response to 3-OH-C10:0 in Arabidopsis.

中文翻译：

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凝集素受体样激酶LORE的酪氨酸磷酸化调节植物免疫力。

植物模式识别受体（PRR）感知与病原体相关的分子模式（PAMP）以激活免疫反应。在革兰氏阴性细菌中广泛存在的中链3-羟基脂肪酸（mc-3-OH-FAs）最近被证明是拟南芥中的新型PAMP。拟南芥PRR脂寡糖特异性减少的诱导（LORE）是一种G型凝集素受体样激酶，可识别mc-3-OH-FA，随后引发免疫反应。然而，尚未探究LORE激活和下游信号转导的机制。在这里，我们报告的mc-3-OH-FAs之一，3-OH-C10：0，诱导酪氨酸残基600（Y600）处的LORE磷酸化。磷酸化的LORE随后将受体样胞质激酶PBL34及其紧密旁系同源物PBL35和PBL36反式磷酸化，因此激活了植物的免疫力。LORE Y600的磷酸化对于PBL34，PBL35和PBL36的下游磷酸化是必需的。但是，丁香假单胞菌效应物HopAO1靶向LORE，使酪氨酸磷酸化的Y600去磷酸化，因此抑制了免疫反应。这些发现揭示了LORE介导拟南芥中响应3-OH-C10：0的信号传导的机制。