Ling Hui, Fu Xueqin, Huang Ning, Zhong Zaofa, Liu Tingting, Cui Haitao, Que Youxiong
Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture; Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops; Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
Guangxi Key Laboratory of Agricultural Resources Chemistry and Biotechnology, College of Intelligent Agriculture, Yulin Normal University, Yulin, Guangxi, China.
Plant Cell Environ. 2025 Jul;48(7):5271-5289. doi: 10.1111/pce.15500. Epub 2025 Apr 1.
The smut fungus Sporisorium scitamineum is a major pathogen in sugarcane, causing significant agricultural losses worldwide. However, the molecular mechanisms by which its effectors facilitate infection and evade host immunity remain largely unclear. In this study, we identified the sugarcane vacuolar sorting receptor 1 gene (ScVSR1), whose expression negatively correlate with several putative S. scitamineum effector genes in a co-expression network. Overexpression of ScVSR1 in Arabidopsis thaliana reduced resistance to a fungal powdery mildew pathogen, indicating the negative role of ScVSR1 in plant defence. Among the co-expressed S. scitamineum effectors, SsPE15, a secreted cerato-platanin-like protein (CPP), physically interacts with ScVSR1 and is sorted into the prevacuolar compartment (PVC) by interacting with ScVSR1 in plant cells. Deletion of SsPE15 in S. scitamineum enhanced fungal virulence, suggesting that SsPE15 acts as an immune elicitor. Furthermore, the C-terminal domain of the SsPE15, containing the VSR sorting signal, was found to facilitate vesicular location. Notably, fusing this C-terminal domain to the bacterial effector AvrRpt2 significantly reduced AvrRpt2-triggered programmed cell death in Arabidopsis, a process partially dependent on AtVSR1 and AtVSR2. These findings reveal an immune evasion strategy by which S. scitamineum effector SsPE15 hijacks the host's vesicular trafficking system to avoid immune detection.
黑粉菌甘蔗黑粉菌是甘蔗中的主要病原菌，在全球范围内造成重大农业损失。然而，其效应子促进感染并逃避宿主免疫的分子机制仍不清楚。在本研究中，我们鉴定了甘蔗液泡分选受体1基因（ScVSR1），其表达在共表达网络中与几个假定的甘蔗黑粉菌效应子基因呈负相关。在拟南芥中过表达ScVSR1降低了对真菌白粉病病原菌的抗性，表明ScVSR1在植物防御中起负作用。在共表达的甘蔗黑粉菌效应子中，SsPE15是一种分泌的类角质素蛋白（CPP），与ScVSR1发生物理相互作用，并通过在植物细胞中与ScVSR1相互作用而被分选到前液泡区室（PVC）中。甘蔗黑粉菌中SsPE15的缺失增强了真菌的毒力，表明SsPE15作为一种免疫激发子。此外，发现含有VSR分选信号的SsPE15的C末端结构域促进囊泡定位。值得注意的是，将该C末端结构域与细菌效应子AvrRpt2融合显著降低了拟南芥中AvrRpt2触发的程序性细胞死亡，这一过程部分依赖于AtVSR1和AtVSR2。这些发现揭示了一种免疫逃避策略，即甘蔗黑粉菌效应子SsPE15劫持宿主的囊泡运输系统以避免免疫检测。
