论文题目：The wheat CC-NBS-LRR protein TaRGA3 confers resistance to stripe rust by suppressing Ascorbate peroxidase 6 activity
论文作者：Nannan Fang, Conghui Jia, Ruolin Chen, Jiarui An, Zhensheng Kang, Jie Liu*
论文摘要：
Nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune receptors that activate innate immune responses upon sensing pathogen attack. However, the molecular mechanisms by which NLR proteins initiate downstream signal transduction pathways to counteract pathogen invasion remain poorly understood. In this study, we identified the wheat (Triticum aestivum) NLR protein Resistance Gene Analogs3 (TaRGA3), which was significantly up-regulated during Puccinia striiformis f. sp. tritici (Pst) infection. TaRGA3 and its coiled-coil (CC) domain, localized to the cytoplasm and nucleus, can induce cell death in Nicotiana benthamiana. Virus-induced gene silencing (VIGS) and overexpression suggested that TaRGA3 contributed to wheat resistance to stripe rust by facilitating reactive oxygen species (ROS) accumulation. Yeast two-hybrid, luciferase complementation imaging, and co-immunoprecipitation assays revealed that TaRGA3 interacted with wheat protein Ascorbate Peroxidase 6 (TaAPX6). Further analysis showed that TaAPX6 specifically targeted the CC domain of TaRGA3. The TaRGA3-TaAPX6 interplay led to reduced enzyme activity of TaAPX6. Notably, TaAPX6 negatively regulated wheat resistance to Pst by removing excessive ROS accompanying Pst-induced hypersensitive responses. Our findings reveal that TaRGA3 responding to Pst infection confers enhanced wheat resistance to stripe rust, possibly by suppressing TaAPX6-modulated ROS scavenging, and demonstrate that TaRGA3 can be used to engineer stripe rust resistance in wheat.
核苷酸结合和富亮氨酸重复序列（NLR）蛋白作为细胞内免疫受体，感知病原体攻击启动免疫反应。激活的NLR蛋白聚合形成抗病小体，诱导程序性细胞凋亡。然而，NLR蛋白启动下游信号转导途径抵抗病原体入侵的分子机制仍然知之甚少。本研究发现，小麦NLR蛋白TaRGA3通过抑制抗坏血酸过氧化物酶TaAPX6活性促进ROS积累以提高小麦对条锈病的抗性。
小麦NLR蛋白TaRGA3在响应条锈菌侵染过程中显著上调表达。TaRGA3全长及CC结构域能够诱导细胞坏死，其定位于细胞质和细胞核。病毒诱导的基因沉默（VIGS）和过表达分析表明，TaRGA3正调控小麦对条锈病的抗性。此外，通过酵母双杂交、荧光素酶互补和免疫共沉淀实验，证实了TaRGA3与小麦抗坏血酸过氧化物酶TaAPX6互作。进一步分析发现，TaRGA3的CC结构域与TaAPX6特异性互作，导致TaAPX6酶活性明显降低。此外，TaAPX6通过清除ROS负调控小麦对条锈菌的抗性。研究结果表明，NLR蛋白TaRGA3可能通过抑制TaAPX6的活性促进ROS积累来增强小麦对条锈病的抗性，并发现过表达TaRGA3并不影响小麦的农艺性状，具有潜在的应用价值。研究成果为作物病害遗传改良提供理论依据和基因资源。
论文链接：https://doi.org/10.1093/plphys/kiae603