Zhou Gangqiang, Chen Honglin, Zhou Wenzhe, Shen Rubin, Xie Lizhu, Gao Gao, Situ Junjian, Xi Pinggen, Li Minhui, Li Wen, Hsiang Tom, Jiang Zide, Kong Guanghui
National Key Laboratory of Green Pesticide/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, Guangxi University, Nanning, China.
Mol Plant Pathol. 2025 Sep;26(9):e70154. doi: 10.1111/mpp.70154.
Among eukaryotes, Rab GTPases are critical for intracellular membrane trafficking and possess various functions. Oomycetes, responsible for many devastating plant diseases, pose a significant threat to global agriculture. However, the functions of Rab GTPases in oomycetes are largely uncharted. In this study, we functionally characterised two Rab8 homologues, PlRab8A and PlRab8B, from a plant-pathogenic oomycete, Peronophythora litchii. These genes are crucial for mycelial growth and play significant roles in the production and morphology of sporangia, as well as the formation of zoospores. PlRab8A and PlRab8B also contribute to maintaining cell wall integrity, osmotic stress tolerance and oospore formation, which are vital for the organism's survival and virulence. Moreover, PlRab8A and PlRab8B are essential for the full virulence of P. litchii by influencing laccase activity. We also found that PlRab8B co-localised with lipid droplets (LDs) and negatively affected LD accumulation. Autophagy was enhanced and autophagy-related genes (PlATGs) were up-regulated in PlRab8B mutants. Additionally, PlRab8A was found to interact with PlRab6. Similar to PlRab8, PlRab6 is also required for growth, zoospore formation and pathogenicity of P. litchii. Taken together, this study reported for the first time the functions of three Rab proteins regulating autophagy, LD accumulation and pathogenesis in oomycetes.
在真核生物中，Rab GTP酶对细胞内膜运输至关重要，并具有多种功能。卵菌可引发许多毁灭性的植物病害，对全球农业构成重大威胁。然而，Rab GTP酶在卵菌中的功能在很大程度上尚不清楚。在本研究中，我们对来自植物致病卵菌荔枝霜霉（Peronophythora litchii）的两个Rab8同源物PlRab8A和PlRab8B进行了功能表征。这些基因对菌丝体生长至关重要，在孢子囊的产生和形态以及游动孢子的形成中发挥重要作用。PlRab8A和PlRab8B还有助于维持细胞壁完整性、渗透胁迫耐受性和卵孢子形成，这些对该生物体的存活和毒力至关重要。此外，PlRab8A和PlRab8B通过影响漆酶活性对荔枝霜霉的完全毒力至关重要。我们还发现PlRab8B与脂滴（LDs）共定位，并对LD积累产生负面影响。在PlRab8B突变体中自噬增强，自噬相关基因（PlATGs）上调。此外，发现PlRab8A与PlRab6相互作用。与PlRab8类似，PlRab6对荔枝霜霉的生长、游动孢子形成和致病性也是必需的。综上所述，本研究首次报道了三种Rab蛋白在卵菌中调节自噬、LD积累和致病机制的功能。
