State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei Province, China.
The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, China.
Nat Commun. 2024 Oct 30;15(1):9391. doi: 10.1038/s41467-024-53725-0.
Phytopathogens often secrete effectors to enhance their infection of plants. In the case of Sclerotinia sclerotiorum, a necrotrophic phytopathogen, a secreted protein named SsPEIE1 (Sclerotinia sclerotiorum Plant Early Immunosuppressive Effector 1) plays a crucial role in its virulence. During the early stages of infection, SsPEIE1 is significantly up-regulated. Additionally, transgenic plants expressing SsPEIE1 exhibit increased susceptibility to different phytopathogens. Further investigations revealed that SsPEIE1 interacts with a plasma membrane protein known as hypersensitive induced reaction (HIR) that dampens immune responses. SsPEIE1 is required for S. sclerotiorum virulence on wild-type Arabidopsis but not on Arabidopsis hir4 mutants. Moreover, Arabidopsis hir2 and hir4 mutants exhibit suppressed pathogen-associated molecular pattern-triggered reactive oxygen species (ROS) bursts and salicylic acid (SA)-associated immune gene induction, all of which are phenocopied by the SsPEIE1 transgenic plants. We find that the oligomerization of AtHIR4 is essential for its role in mediating immunity, and that SsPEIE1 inhibits its oligomerization through competitively binding to AtHIR4. Remarkably, both Arabidopsis and rapeseed plants overexpress AtHIR4 display significantly increased resistance to S. sclerotiorum. In summary, these results demonstrate that SsPEIE1 inhibits AtHIR4 oligomerization-mediated immune responses by interacting with the key immune factor AtHIR4, thereby promoting S. sclerotiorum infection.
植物病原菌通常会分泌效应子来增强对植物的感染。在坏死性植物病原菌核盘菌的情况下，一种名为 SsPEIE1（核盘菌植物早期免疫抑制效应子 1）的分泌蛋白在其毒力中起着关键作用。在感染的早期阶段，SsPEIE1 显著上调。此外，表达 SsPEIE1 的转基因植物对不同植物病原菌的敏感性增加。进一步的研究表明，SsPEIE1 与一种称为过敏反应诱导反应（HIR）的质膜蛋白相互作用，从而抑制免疫反应。SsPEIE1 是核盘菌在野生型拟南芥上毒力所必需的，但不是在拟南芥 hir4 突变体上。此外，拟南芥 hir2 和 hir4 突变体表现出抑制病原体相关分子模式触发的活性氧（ROS）爆发和水杨酸（SA）相关免疫基因诱导，所有这些都被 SsPEIE1 转基因植物模拟。我们发现 AtHIR4 的寡聚化对于其介导免疫的作用至关重要，而 SsPEIE1 通过竞争性结合 AtHIR4 抑制其寡聚化。值得注意的是，拟南芥和油菜籽植物过表达 AtHIR4 对核盘菌的抗性显著增加。总之，这些结果表明，SsPEIE1 通过与关键免疫因子 AtHIR4 相互作用抑制 AtHIR4 寡聚化介导的免疫反应，从而促进核盘菌的感染。
