Zhuang Xinjian, Zhang Wenyi, Xu Shuqi, Yang Wenxuan, Yin Jinlong, Zhou Tong, Kundu Jiban K, Xu Kai
Jiangsu Key Laboratory for Pathogens and Ecosystems, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China.
Jiangsu Key Laboratory for Pathogens and Ecosystems, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China; Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
Virology. 2025 Mar;604:110417. doi: 10.1016/j.virol.2025.110417. Epub 2025 Jan 17.
Clover yellow vein virus (ClYVV), a potyvirus that infects various dicotyledonous plants, poses a significant threat to the cultivation of legumes. Although potyviral NIa-Pro was extensively studied in viral infection cycle and host antiviral responses, the contribution of NIa-Pro protease activity to virus systemic symptoms has not yet been reported. In this study, we developed infectious clones of a ClYVV isolated from Pisum sativum. The rescued ClYVV showed robust infectivity and induced obvious systemic mosaic and necrosis symptoms in the model host Nicotiana benthamiana and natural hosts Pisum sativum and Vicia faba. Using a potato virus X (PVX) vector to express 11 ClYVV proteins in N. benthamiana ectopically, we identified that NIa-Pro is the key determinant in inducing systemic symptoms and causes higher leaf ROS levels and cell death. Further, we found that the protease-inactive mutant NIa-Pro causes significantly reduced systemic symptoms when expressed via the PVX vector and does not induce higher cellular ROS levels and cell death when transiently overexpressed compared to wild-type NIa-Pro. Overall, this study provides evidence supporting that the protease activity of a potyvirus protein NIa-Pro directly contributes to the virus symptoms.
三叶草黄脉病毒（ClYVV）是一种感染多种双子叶植物的马铃薯Y病毒属病毒，对豆类作物的种植构成重大威胁。尽管马铃薯Y病毒属的NIa-Pro在病毒感染周期和宿主抗病毒反应方面得到了广泛研究，但NIa-Pro蛋白酶活性对病毒系统症状的影响尚未见报道。在本研究中，我们构建了从豌豆中分离得到的ClYVV的感染性克隆。拯救出的ClYVV表现出强大的感染性，并在模式宿主本氏烟草以及天然宿主豌豆和蚕豆中诱导出明显的系统花叶和坏死症状。利用马铃薯X病毒（PVX）载体在本氏烟草中异位表达11种ClYVV蛋白，我们确定NIa-Pro是诱导系统症状的关键决定因素，并导致叶片活性氧水平升高和细胞死亡。此外，我们发现与野生型NIa-Pro相比，蛋白酶失活的突变体NIa-Pro通过PVX载体表达时引起的系统症状显著减轻，瞬时过表达时也不会诱导细胞活性氧水平升高和细胞死亡。总体而言，本研究提供了证据支持马铃薯Y病毒属蛋白NIa-Pro的蛋白酶活性直接导致病毒症状。
