Yin Jinyao, Zhu Xuehuan, Chen Yalong, Lv Yanyang, Shan Jiaxin, Liu Yuhan, Liu Wenbo, Miao Weiguo, Li Xiao
Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, School of Tropical Agriculture and Forestry, Haikou 570228, China.
Danzhou Invasive Species Observation and Research Station of Hainan Province, Hainan University, Danzhou 571737, China.
J Fungi (Basel). 2025 Jan 17;11(1):73. doi: 10.3390/jof11010073.
The exocyst complex in eukaryotic cells modulates secretory vesicle transportation to promote exocytosis. The exocyst is also required for the hyphal growth and pathogenic development of several filamentous phytopathogens. Obligate biotrophic powdery mildew fungi cause considerable damage to many cash crops; however, the exocyst's roles in this group of fungi is not well studied. To verify the functions of the exocyst in powdery mildew fungus, we identified two exocyst subunits, EqSec5 and EqSec6, from , a powdery mildew fungus that infects the rubber tree . When GFP-fused EqSec5 and EqSec6 were introduced into and another phytopathogenic fungus, , they primarily localized to the hyphal tip region. Inducing gene silencing of or caused growth and infection defects, and those defects could not be fully restored under the NADPH oxidase inhibitor treatment to the plant. The silenced strains also induced the host defense response including reactive oxygen species accumulation and callose deposition. The silencing of or also inhibited the secretion of the effector protein EqIsc1, interrupting plant salicylic acid biosynthesis. Yeast two-hybrid and gene overexpression assays suggested that EqSec5 and EqSec6 interact with each other and can complement each other's function during host infection. Overall, our study provides evidence that the exocyst in this powdery mildew fungus facilitates effector secretion, hyphal growth, and infection.
真核细胞中的外泌体复合物调节分泌囊泡运输以促进胞吐作用。外泌体对于几种丝状植物病原体的菌丝生长和致病发育也是必需的。专性活体营养型白粉病真菌对许多经济作物造成了相当大的损害；然而，外泌体在这类真菌中的作用尚未得到充分研究。为了验证外泌体在白粉病真菌中的功能，我们从一种感染橡胶树的白粉病真菌中鉴定出了两个外泌体亚基，EqSec5和EqSec6。当将绿色荧光蛋白融合的EqSec5和EqSec6导入该真菌以及另一种植物病原真菌时，它们主要定位于菌丝尖端区域。诱导EqSec5或EqSec6的基因沉默会导致生长和感染缺陷，并且在对植物进行NADPH氧化酶抑制剂处理的情况下，这些缺陷无法完全恢复。沉默菌株还诱导了宿主防御反应，包括活性氧积累和胼胝质沉积。EqSec5或EqSec6的沉默也抑制了效应蛋白EqIsc1的分泌，从而中断了植物水杨酸的生物合成。酵母双杂交和基因过表达分析表明，EqSec5和EqSec6相互作用，并且在宿主感染过程中可以相互补充功能。总体而言，我们的研究提供了证据，表明白粉病真菌中的外泌体促进了效应蛋白分泌、菌丝生长和感染。
