The small brown planthopper (Laodelphax striatellus; SBPH) is a piercing-sucking insect that secretes salivary proteins into its plant host during feeding. However, the mechanisms by which these salivary proteins regulate plant defense responses remain poorly understood. Here, we identified the disulfide isomerase (LsPDI1) in the SBPH salivary proteome. LsPDI1 was highly expressed in the SBPH salivary glands and secreted into rice plants during feeding. Transient in planta LsPDI1 expression in the absence of signal peptide induced reactive oxygen species (ROS) burst, cell death, callose deposition, and jasmonic acid (JA) signaling pathway. Deletion mutant analysis revealed that either the a-b-b’ or the b-b’-a’ domains in LsPDI1 are required to induce cell death in plants. LsPDI1 and its orthologs were highly conserved among various planthopper species and strongly induced ROS burst and cell death in plants. Transient in Nicotiana benthamiana LsPDI1 expression impaired the performance of Spodoptera frugiperda and Myzus persicae on host plants. Hence, LsPDI1 is an important salivary elicitor that enhances plant resistance to insects by inducing the calcium, ROS, and JA signaling pathways. The findings of this study provide novel insights into the molecular mechanisms underlying plant-insect interactions.

小褐飞虱（灰飞虱; SBPH）是一种刺吸性昆虫，在进食过程中会将唾液蛋白分泌到植物宿主中。但是，这些唾液蛋白调节植物防御反应的机制仍然知之甚少。在这里，我们确定了SBPH唾液蛋白质组中的二硫键异构酶（LsPDI1）。LsPDI1在SBPH唾液腺中高表达，并在进食期间分泌到水稻中。短暂的在植物LsPDI1表达缺乏信号肽诱导的活性氧（ROS）破裂，细胞死亡，call质沉积和茉莉酸（JA）信号传导途径。缺失突变分析表明，Ab-b'或b-b'-a'结构域位于LsPDI1需要诱导植物中的细胞死亡。LsPDI1及其直系同源物在各种飞虱物种中高度保守，并强烈诱导植物中的ROS爆发和细胞死亡。瞬态烟草 LsPDI1表达削弱了 草地贪夜蛾 和 桃蚜在寄主植物上。因此，LsPDI1是重要的唾液激发子，它通过诱导钙，ROS和JA信号通路来增强植物对昆虫的抗性。这项研究的发现为植物-昆虫相互作用的分子机制提供了新颖的见解。