Wang Hong, Huang Tingting, Ruan Zheyan, Tu Ranran, He Yan, Liu Qunen, Cheng Shihua, He Guanghua, Shen Xihong
State Key Laboratory of Rice Biology and Breeding, Key Laboratory for Zhejiang Super Rice Research, China National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, Zhejiang, China.
Rice Research Institute, Key Laboratory of Crop Molecular Improvement, Academy of Agricultural Sciences, Southwest University, Chongqing, China.
Plant Cell Environ. 2025 Jan 6. doi: 10.1111/pce.15366.
Unraveling the mechanisms behind plant growth and immunity contributes to effective crop improvement. Membrane attack complex/perforin (MACPF) domain proteins play vital roles in innate and adaptive immunity in vertebrates; however, their molecular functions in plants remain largely unexplored. Here, we isolated and characterized a rice mutant, Oryza sativa constitutively activated cell death 1 (oscad1), which exhibited a lesion mimic phenotype and growth inhibition with increased cell death, elevated ROS accumulation, and enhanced resistance to bacterial blight Xanthomonas oryzae pv. Oryzae (Xoo) and Magnaporthe oryzae. OsCAD1 encodes an MACPF protein, OsCAD1/OsMACPF1, localized in the plasma membrane, cytosol, and nucleus, with a broad expression pattern in tissues. An F416L substitution in OsCAD1 affects its stability and abundance. OsCAD1 knockout lines displayed severe lesion mimic leaves, growth retardation, and eventual death. Both oscad1 and OsCAD1 knockout lines showed increased salicylic acid (SA) levels with the latter showing even higher levels, while OsCAD1-overexpressing lines maintained uninduced SA levels during Xoo infection, resulting in decreased resistance. Knockout of the SA biosynthetic enzyme OsPAL4 in the oscad1 mutant partially alleviated the lesion mimic phenotype and growth inhibition without impacting Xoo resistance. Our findings indicate that OsCAD1 negatively regulates SA levels to modulate plant growth and immunity.
揭示植物生长和免疫背后的机制有助于有效的作物改良。膜攻击复合物/穿孔素（MACPF）结构域蛋白在脊椎动物的先天性和适应性免疫中发挥着至关重要的作用；然而，它们在植物中的分子功能在很大程度上仍未被探索。在这里，我们分离并鉴定了一个水稻突变体，即水稻组成型激活细胞死亡1（oscad1），它表现出类病斑表型和生长抑制，细胞死亡增加，活性氧积累升高，对白叶枯病菌稻黄单胞菌稻致病变种（Xoo）和稻瘟病菌的抗性增强。OsCAD1编码一种MACPF蛋白，即OsCAD1/OsMACPF1，定位于质膜、细胞质和细胞核，在组织中具有广泛的表达模式。OsCAD1中的F416L取代影响其稳定性和丰度。OsCAD1敲除系表现出严重的类病斑叶片、生长迟缓并最终死亡。oscad1和OsCAD1敲除系的水杨酸（SA）水平均升高，后者的水平更高，而OsCAD1过表达系在Xoo感染期间维持未诱导的SA水平，导致抗性降低。在oscad1突变体中敲除SA生物合成酶OsPAL4可部分缓解类病斑表型和生长抑制，而不影响对Xoo的抗性。我们的研究结果表明，OsCAD1负调控SA水平以调节植物生长和免疫。
