State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, Zhejiang, 310006, People's Republic of China; Key Laboratory for Zhejiang Super Rice Research, China National Rice Research Institute, Hangzhou, Zhejiang, 310006, People's Republic of China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China.
Plant Sci. 2019 Oct;287:110182. doi: 10.1016/j.plantsci.2019.110182. Epub 2019 Jul 2.
Lesion mimic mutants are ideal genetic materials to study programmed cell death and defense signaling in plants. However, the molecular basis of lesion mimic formation remains largely unknown. Here, we first used a proteomic approach to identify differentially expressed proteins during dynamic lesion mimic formation in the rice oscul3a mutant, then electron microscope observation and physiological assays were used to analyze the mutant. The oscul3a mutant had disrupted cell metabolism balance, and the identified differentially expressed proteins were mainly located in the chloroplast and cytoplasm, which caused enhanced lipid metabolism, but suppressed carbon/nitrogen metabolism with reduced growth and grain quality. The oscul3a mutant had higher salicylic acid (SA) concentration in leaves, and HO was shown to accumulate late in the formation of lesions. The secondary metabolite coumarin induced reactive oxygen species (ROS) and had rice blast resistance activity. Moreover, the cell death initiated lesion mimic formation of oscul3a mutant was light-sensitive, which might be associated with metabolite biosynthesis and accumulation. This study sheds light on the metabolic transition associated with cell death and defense response, which is under tight regulation by OsCUL3a and metabolism-related proteins, and the newly identified chemicals in the secondary metabolic pathway can potentially be used to control disease in crop plants.
病变模拟突变体是研究植物程序性细胞死亡和防御信号的理想遗传材料。然而，病变模拟形成的分子基础在很大程度上仍然未知。在这里，我们首先使用蛋白质组学方法来鉴定在水稻 oscul3a 突变体中动态病变模拟形成过程中差异表达的蛋白质，然后使用电子显微镜观察和生理测定来分析突变体。oscul3a 突变体破坏了细胞代谢平衡，鉴定出的差异表达蛋白主要位于叶绿体和细胞质中，导致脂质代谢增强，但碳/氮代谢受到抑制，生长和籽粒品质降低。oscul3a 突变体叶片中水杨酸（SA）浓度较高，HO 在病变形成后期积累。次生代谢物香豆素诱导活性氧（ROS）并具有稻瘟病抗性活性。此外，oscul3a 突变体细胞死亡引发的病变模拟形成对光敏感，这可能与代谢物的生物合成和积累有关。本研究揭示了与细胞死亡和防御反应相关的代谢转变，这受到 OsCUL3a 和代谢相关蛋白的严格调控，次生代谢途径中鉴定出的新化学物质可能潜在用于控制作物植物的疾病。
