Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China.
Department of Biology, University of Saskatchewan, Saskatoon, S7N 5E2, Canada.
Plant Physiol. 2023 Jan 2;191(1):558-574. doi: 10.1093/plphys/kiac400.
The trans-Golgi network (TGN) acts as a central platform for sorting and secreting various cargoes to the cell surface, thus being essential for the full execution of plant immunity. However, the fine-tuned regulation of TGN components in plant defense and stress response has been not fully elucidated. Our study revealed that despite largely compromising penetration resistance, the loss-of-function mutation of the TGN component protein ECHIDNA (ECH) induced enhanced postinvasion resistance to powdery mildew in Arabidopsis thaliana. Genetic and transcriptome analyses and hormone profiling demonstrated that ECH loss resulted in salicylic acid (SA) hyperaccumulation via the ISOCHORISMATE SYNTHASE 1 biosynthesis pathway, thereby constitutively activating SA-dependent innate immunity that was largely responsible for the enhanced postinvasion resistance. Furthermore, the ech mutant displayed accelerated SA-independent spontaneous cell death and constitutive POWDERY MILDEW RESISTANCE 4-mediated callose depositions. In addition, ECH loss led to a chronically prolonged endoplasmic reticulum stress in the ech mutant. These results provide insights into understanding the role of TGN components in the regulation of plant immunity and stress responses.
高尔基体内网络（TGN）作为一种用于对细胞表面进行各种货物分拣和分泌的中央平台，因此对于植物免疫的完全执行至关重要。然而，TGN 成分在植物防御和应激反应中的精细调控尚未完全阐明。我们的研究表明，尽管 TGN 成分蛋白 ECHIDNA（ECH）的功能丧失突变在很大程度上削弱了穿透抗性，但它诱导了拟南芥对白粉病的入侵后抗性增强。遗传和转录组分析以及激素分析表明，ECH 的缺失导致水杨酸（SA）通过异分支酸合成酶 1 （ISOCHORISMATE SYNTHASE 1）生物合成途径的积累，从而使 SA 依赖性先天免疫持续激活，这在很大程度上导致了入侵后抗性的增强。此外，ech 突变体表现出加速的 SA 非依赖性自发细胞死亡和组成型 POWDERY MILDEW RESISTANCE 4 介导的胼胝质沉积。此外，ECH 的缺失导致 ech 突变体中内质网应激的慢性延长。这些结果为理解 TGN 成分在植物免疫和应激反应调控中的作用提供了新的视角。
