Dong Xiaohua, Lu Xu, Zhu Hai, Zhu Zhengxue, Ji Peiyun, Li Xianglan, Li Tianli, Zhang Xiong, Ai Gan, Dou Daolong
College of Plant Protection, Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, China.
The Key Laboratory of Biology and Genetic Improvement of Oil Crops, The Ministry of Agriculture and Rural Affairs of the PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, China.
Mol Plant. 2025 Mar 3;18(3):485-500. doi: 10.1016/j.molp.2025.01.018. Epub 2025 Jan 24.
Plants possess remarkably durable resistance against non-adapted pathogens in nature. However, the underlying molecular mechanisms remain poorly understood, and it is unclear how the resistance is maintained without coevolution between hosts and non-adapted pathogens. In this study, we used Phytophthora sojae (Ps), a non-adapted pathogen of Nicotiana benthamiana (Nb), as a model and identified an RXLR effector that determines Nb incompatibility to Ps. Knockout of this RXLR effector in Ps enables successful infection of Nb, leading us to name it AvrNb (Avirulence gene in Nb). A systematic screening of Nb NLR genes further revealed that NbPrf, previously reported to be a receptor of bacterial avirulence proteins, is the NLR protein responsible for mediating AvrNb recognition and initiating the hypersensitive response (HR). Mutation in NbPrf makes Nb completely compatible to Ps. We found that AvrNb is structurally conserved among multiple Phytophthora pathogens, and its homologs also induce NbPrf-dependent HR. Remarkably, further inoculation assay showed that NbPrf is also involved in plant immunity to two adapted Phytophthora pathogens, Phytophthora infestans and Phytophthora capsici. Our findings suggest that NbPrf represents a promising resource for breeding resistance to Phytophthora pathogens and implicate that the conserved effectors present in both adapted and non-adapted pathogens may provide sufficient selective pressure to maintain the remarkably durable incompatibility between plants and non-adapted pathogens.
在自然界中，植物对非适应性病原体具有显著持久的抗性。然而，其潜在的分子机制仍知之甚少，并且尚不清楚在宿主与非适应性病原体之间没有共同进化的情况下，这种抗性是如何维持的。在本研究中，我们以大豆疫霉（Ps），一种本氏烟草（Nb）的非适应性病原体为模型，鉴定出一种决定Nb对Ps不亲和性的RXLR效应子。在Ps中敲除这种RXLR效应子可使Ps成功感染Nb，因此我们将其命名为AvrNb（Nb中的无毒基因）。对Nb NLR基因的系统筛选进一步表明，先前报道为细菌无毒蛋白受体的NbPrf是负责介导AvrNb识别并引发超敏反应（HR）的NLR蛋白。NbPrf中的突变使Nb与Ps完全亲和。我们发现AvrNb在多种疫霉病原体中结构保守，并且其同源物也能诱导依赖NbPrf的HR。值得注意的是，进一步的接种试验表明，NbPrf也参与植物对两种适应性疫霉病原体，即致病疫霉和辣椒疫霉的免疫反应。我们的研究结果表明，NbPrf是培育对疫霉病原体抗性的一个有前景的资源，并暗示适应性和非适应性病原体中存在的保守效应子可能提供足够的选择压力，以维持植物与非适应性病原体之间显著持久的不亲和性。
