Brown planthopper (BPH, Nilaparvata lugens), a highly destructive insect pest, poses a serious threat to rice (Oryza sativa) production worldwide. Jasmonates are key phytohormones that regulate plant defences against BPH; however, the molecular link between jasmonates and BPH responses in rice remains largely unknown. Here, we discovered a Poaceae-specific metabolite, mixed-linkage β-1,3;1,4-d-glucan (MLG), which contributes to jasmonate-mediated BPH resistance. MLG levels in rice significantly increased upon BPH attack. Overexpressing OsCslF6, which encodes a glucan synthase that catalyses MLG biosynthesis, significantly enhanced BPH resistance and cell wall thickness in vascular bundles, whereas knockout of OsCslF6 reduced BPH resistance and vascular wall thickness. OsMYC2, a master transcription factor of jasmonate signalling, directly controlled the upregulation of OsCslF6 in response to BPH feeding. The AT-rich domain of the OsCslF6 promoter varies in rice varieties from different locations and natural variants in this domain were associated with BPH resistance. MLG-derived oligosaccharides bound to the plasma membrane-anchored LECTIN RECEPTOR KINASE1 OsLecRK1 and modulated its activity. Thus, our findings suggest that the OsMYC2-OsCslF6 module regulates pest resistance by modulating MLG production to enhance vascular wall thickness and OsLecRK1-mediated defence signalling during rice-BPH interactions.

中文翻译：

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禾本科特异性 β-1,3;1,4-d-葡聚糖在稻褐飞虱相互作用过程中将茉莉酸信号与 OsLecRK1 介导的防御反应联系起来

褐飞虱（BPH，Nilaparvata lugens）是一种极具破坏性的害虫，对全球水稻（ Oryza sativa ）生产构成严重威胁。茉莉酸是调节植物防御良性飞虱的关键植物激素；然而，茉莉酸与水稻中褐飞虱反应之间的分子联系仍然很大程度上未知。在这里，我们发现了一种禾本科特有的代谢产物，混合连接β-1,3;1,4- d-葡聚糖（MLG），它有助于茉莉酸介导的BPH抗性。稻米中的 MLG 水平在 BPH 攻击后显着增加。过表达OsCslF6（编码催化MLG生物合成的葡聚糖合酶）显着增强了BPH抵抗力和维管束中的细胞壁厚度，而OsCslF6的敲除降低了BPH抵抗力和血管壁厚度。OsMYC2 是茉莉酸信号转导的主要转录因子，直接控制OsCslF6响应 BPH 摄食而上调。OsCslF6启动子的富含 AT 的结构域在不同地点的水稻品种中有所不同，并且该结构域的天然变异与 BPH 抗性相关。MLG 衍生的寡糖与质膜锚定的凝集素受体激酶 1 OsLecRK1 结合并调节其活性。因此，我们的研究结果表明，OsMYC2-OsCslF6 模块通过调节 MLG 的产生来调节害虫抗性，从而增强水稻与 BPH 相互作用过程中的血管壁厚度和 OsLecRK1 介导的防御信号。