Abstract：
Potassium (K+) plays crucial roles in both plant development and immunity. However, the function of K+ in plant-virus interactions remains largely unknown. Here, we utilized Barley yellow striate mosaic virus (BYSMV), an insect-transmitted plant cytorhabdovirus, to investigate the interplay between viral infection and plant K+ homeostasis. The BYSMV accessory P9 protein exhibits viroporin activity by enhancing membrane permeability in Escherichia coli. Additionally, P9 increases K+ uptake in yeast (Saccharomyces cerevisiae) cells, which is disrupted by a point mutation of Glycine 14 to Threonine (P9G14T). Furthermore, BYSMV P9 forms oligomers and targets to both the viral envelope and the plant membrane. Based on the recombinant BYSMV-green fluorescent protein (BYGFP) virus, a P9-deleted mutant (BYGFPΔP9) was rescued and demonstrated infectivity within individual plant cells of Nicotiana benthamiana and insect vectors. However, BYGFPΔP9 failed to infect barley plants after transmission by insect vectors. Furthermore, infection of barley plants was severely impaired for BYGFP-P9G14T lacking P9 K+ channel activity. In vitro assays demonstrate that K+ facilitates virion disassembly and the release of genome RNA for viral mRNA transcription. Altogether, our results show that the K+ channel activity of viroporins is conserved in plant cytorhabdoviruses and plays crucial roles in insect-mediated virus transmission.
摘要：
钾（K）在植物发育和免疫中起着至关重要的作用。然而,K在植物-病毒相互作用中的功能仍然未知。这里,我们利用大麦黄条纹花叶病毒（BYSMV），一种由昆虫传播的植物胞嘧啶病毒,研究病毒感染与植物K+稳态之间的相互作用。BYSMV附件P9蛋白通过增强大肠杆菌中的膜通透性而表现出病毒传播蛋白活性。此外,P9增加酵母（酿酒酵母）细胞中的K+摄取，其被甘氨酸14至苏氨酸(P9G14T)的点突变所破坏。此外，BYSMVP9形成寡聚体并靶向病毒包膜和植物膜。基于重组BYSMV-绿色荧光蛋白(BYGFP)病毒,拯救了P9缺失的突变体（BYGFPΔP9），并证明了其在烟草和昆虫载体的单个植物细胞中的感染性。然而,BYGFPΔP9在通过昆虫载体传播后未能感染大麦植物。此外，缺乏P9K通道活性的BYGFP-P9G14T严重损害了大麦植物的感染。体外测定表明，K有助于病毒体的分解和基因组RNA的释放，以进行病毒mRNA的转录。总之,我们的研究结果表明，病毒的K+通道活性在植物胞嘧啶病毒中是保守的，在昆虫介导的病毒传播中起着至关重要的作用。
