National Key Laboratory of Plant Molecular Genetics and National Center of Plant Gene Research, Institute of Plant Physiology & Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
National Key Laboratory of Plant Molecular Genetics and National Center of Plant Gene Research, Institute of Plant Physiology & Ecology, Chinese Academy of Sciences, Shanghai 200032, China; State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Cell Host Microbe. 2016 Dec 14;20(6):758-769. doi: 10.1016/j.chom.2016.10.023.
Programmed cell death (PCD) and immunity in plants are tightly controlled to promote antimicrobial defense while preventing autoimmunity. However, the mechanisms contributing to this immune homeostasis are poorly understood. Here, we isolated a rice mutant ebr1 (enhanced blight and blast resistance 1) that shows enhanced broad-spectrum bacterial and fungal disease resistance, but displays spontaneous PCD, autoimmunity, and stunted growth. EBR1 encodes an E3 ubiquitin ligase that interacts with OsBAG4, which belongs to the BAG (Bcl-2-associated athanogene) family that functions in cell death, growth arrest, and immune responses in mammals. EBR1 directly targets OsBAG4 for ubiquitination-mediated degradation. Elevated levels of OsBAG4 in rice are necessary and sufficient to trigger PCD and enhanced disease resistance to pathogenic infection, most likely by activating pathogen-associated molecular patterns-triggered immunity (PTI). Together, our study suggests that an E3-BAG module orchestrates innate immune homeostasis and coordinates the trade-off between defense and growth in plants.
程序性细胞死亡（PCD）和植物的免疫受到严格控制，以促进抗菌防御，同时防止自身免疫。然而，对于有助于这种免疫稳态的机制知之甚少。在这里，我们分离了一个水稻突变体 ebr1（增强的枯萎病和稻瘟病抗性 1），它表现出增强的广谱细菌和真菌疾病抗性，但表现出自发的 PCD、自身免疫和生长迟缓。EBR1 编码一种 E3 泛素连接酶，它与 OsBAG4 相互作用，后者属于 BAG（Bcl-2 相关的 Athanogene）家族，在哺乳动物的细胞死亡、生长抑制和免疫反应中发挥作用。EBR1 直接将 OsBAG4 作为泛素化介导的降解的靶标。水稻中 OsBAG4 水平的升高是触发 PCD 和增强对病原感染的疾病抗性所必需和充分的，这很可能是通过激活病原体相关分子模式触发的免疫（PTI）来实现的。总之，我们的研究表明，E3-BAG 模块协调先天免疫稳态，并协调植物防御和生长之间的权衡。
