The brown planthopper, Nilaparvata lugens, is a pest that threatens rice (Oryza sativa) production worldwide. While feeding on rice plants, planthoppers secrete saliva, which plays crucial roles in nutrient ingestion and modulating plant defense responses, although the specific functions of salivary proteins remain largely unknown. We identified an N. lugens-secreted mucin-like protein (NlMLP) by transcriptome and proteome analyses and characterized its function, both in brown planthopper and in plants. NlMLP is highly expressed in salivary glands and is secreted into rice during feeding. Inhibition of NlMLP expression in planthoppers disturbs the formation of salivary sheaths, thereby reducing their performance. In plants, NlMLP induces cell death, the expression of defense-related genes, and callose deposition. These defense responses are related to Ca2+ mobilization and the MEK2 MAP kinase and jasmonic acid signaling pathways. The active region of NlMLP that elicits plant responses is located in its carboxyl terminus. Our work provides a detailed characterization of a salivary protein from a piercing-sucking insect other than aphids. Our finding that the protein functions in plant immune responses offers new insights into the mechanism underlying interactions between plants and herbivorous insects.

中文翻译：

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饲喂飞虱的粘蛋白样蛋白是必需的，并诱导植物的免疫反应。

褐飞虱Nilaparvata lugens是一种害虫，威胁着世界各地的稻米（Oryza sativa）生产。虽然以唾液蛋白的具体功能仍是未知之数，但以稻米为食的飞虱会分泌唾液，唾液在营养摄入和调节植物防御反应中起着至关重要的作用。我们通过转录组和蛋白质组分析鉴定了一种分泌黄褐藻的粘蛋白样蛋白（NlMLP），并表征了其在褐飞虱和植物中的功能。NlMLP在唾液腺中高度表达，在进食过程中被分泌到水稻中。稻飞虱中N1MLP表达的抑制干扰唾液鞘的形成，从而降低其性能。在植物中，N1MLP诱导细胞死亡，防御相关基因的表达和call质沉积。这些防御反应与Ca2 +动员以及MEK2 MAP激酶和茉莉酸信号通路有关。引起植物应答的N1MLP的活性区位于其羧基末端。我们的工作提供了除蚜虫以外的其他刺吸性昆虫唾液蛋白的详细表征。我们发现蛋白质在植物免疫反应中的功能为发现植物与草食性昆虫之间相互作用的机制提供了新见解。