The brown planthopper (BPH), Nilaparvata lugens Stål, is one of the major pests of rice. It uses its stylet to penetrate rice phloem, feeding on rice sap and causing direct damage to rice or even plant death. During the feeding process, BPHs secrete saliva into plant tissues, which plays crucial roles in the plant-insect interactions. However, little is known about how the salivary proteins secreted by BPH affect feeding ability and how they induce plant immune responses. Here, we identified an N. lugens Salivary Protein 1 (NlSP1) by screening salivary proteome and characterized its functions in BPH and plants. NlSP1 induces cell death, H₂O₂ accumulation, the expression of defense-related genes, and callose deposition in planta. The active region of NlSP1 that induces plant cell death is located in its N-terminal region. Inhibition of NlSP1 expression in BPHs reduced their feeding ability and had a lethal effect on them. Most importantly, we demonstrated that NlSP1 was able to be secreted into rice plant during feeding process and form a complex with certain interacting partner of rice. These results provide a detailed characterization of a salivary protein from BPHs and offers new insights into our understanding of rice-BPH interaction.

褐飞虱（BPH）， 褐飞虱Stål是水稻的主要害虫之一。它使用管心针穿透水稻韧皮部，以水稻汁液为食，对水稻造成直接损害，甚至导致植物死亡。在摄食过程中，BPH将唾液分泌到植物组织中，这在植物与昆虫的相互作用中起着至关重要的作用。但是，关于由BPH分泌的唾液蛋白如何影响进食能力以及它们如何诱导植物免疫反应的知之甚少。在这里，我们确定了猪笼草唾液蛋白1（NlSP1）通过筛选唾液蛋白质组并表征其在BPH和植物中的功能。NlSP1诱导细胞死亡，H ₂ O ₂积累，防御相关基因的表达和call质沉积在植物。诱导植物细胞死亡的NlSP1活性区域位于其N末端区域。抑制NlSP1BPHs中的表达降低了它们的摄食能力，并对它们具有致死作用。最重要的是，我们证明了NlSP1能够在饲喂过程中分泌到水稻植物中，并与水稻的某些相互作用伙伴形成复合物。这些结果提供了对BPH唾液蛋白的详细表征，并为我们对水稻与BPH相互作用的理解提供了新的见解。