Anhui Province Key Laboratory of Crop Integrated Pest Management, Anhui Agricultural University, Hefei, China.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.
Nat Commun. 2024 Sep 10;15(1):7891. doi: 10.1038/s41467-024-52204-w.
The identification effector targets and characterization of their functions are crucial for understanding pathogen infection mechanisms and components of plant immunity. Here, we identify the effector UgsL, a ustilaginoidin synthetase with a key role in regulating virulence of the rice false smut fungus Ustilaginoidea virens. Heterologous expression of UgsL in rice (Oryza sativa) enhances plant susceptibility to multiple pathogens, and host-induced gene silencing of UgsL enhances plant resistance to U. virens, indicating that UgsL inhibits rice immunity. UgsL interacts with STRUBBELIG RECEPTOR KINASE 3 (OsSRF3). Genome editing and overexpression of OsSRF3 demonstrate that OsSRF3 plays a pivotal role in the resistance of rice to multiple pathogens. Remarkably, overexpressing OsSRF3 enhances resistance without adversely affecting plant growth or yield. We show that BRASSINOSTEROID RECEPTOR-ASSOCIATED KINASE 1 (OsBAK1) interacts with and phosphorylates OsSRF3 to activate pathogen-triggered immunity, inducing the mitogen-activated protein kinase cascade, a reactive oxygen species burst, callose deposition, and expression of defense-related genes. UgsL interferes with the phosphorylation of OsSRF3 by OsBAK1. Furthermore, UgsL mediates OsSRF3 degradation by facilitating its association with the ubiquitin-26S proteasome. Our results reveal that OsSRF3 positively regulates immunity in rice and that UgsL mediates its degradation, thereby inhibiting the activation of OsBAK1-OsSRF3-mediated immune pathways.
鉴定效应子靶标及其功能特征对于理解病原体感染机制和植物免疫成分至关重要。在这里，我们鉴定了效应子 UgsL，它是一种假高粱腥黑粉菌（Ustilaginoidea virens）中调节毒性的类麦角甾醇合成酶。在水稻（Oryza sativa）中异源表达 UgsL 会增强植物对多种病原体的易感性，而 UgsL 的宿主诱导基因沉默会增强植物对 U. virens 的抗性，表明 UgsL 抑制了水稻的免疫。UgsL 与 STRUBBELIG RECEPTOR KINASE 3（OsSRF3）相互作用。基因组编辑和 OsSRF3 的过表达表明，OsSRF3 在水稻对多种病原体的抗性中起着关键作用。值得注意的是，过表达 OsSRF3 可增强抗性而不会对植物生长或产量产生不利影响。我们表明 BRASSINOSTEROID RECEPTOR-ASSOCIATED KINASE 1（OsBAK1）与 OsSRF3 相互作用并磷酸化 OsSRF3，以激活由病原体触发的免疫，诱导丝裂原激活蛋白激酶级联反应、活性氧爆发、胼胝质沉积和防御相关基因的表达。UgsL 干扰 OsBAK1 对 OsSRF3 的磷酸化。此外，UgsL 通过促进其与泛素-26S 蛋白酶体的结合来介导 OsSRF3 的降解。我们的结果表明，OsSRF3 正向调节水稻中的免疫，而 UgsL 介导其降解，从而抑制 OsBAK1-OsSRF3 介导的免疫途径的激活。
