Characterization of virome of Plasmodiophora brassicae in southwest China

Plasmodiophora brassicae is an obligate biotrophic protist that causes clubroot disease in cruciferous crops, leading to severe yield losses worldwide. Despite its economic importance, the viral community associated with P. brassicae remains entirely unexplored. In this study, we collected clubroot samples from 16 different regions in Sichuan Province and Guizhou Province, China, and employed high-throughput sequencing to investigate the viral diversity in P. brassicae resting spores. A total of 29 viruses were identified, belonging to 13 viral families, including 15 positive-sense single-stranded RNA (+ ssRNA) viruses, eight negative-sense single-stranded RNA (-ssRNA) viruses, five double-stranded RNA (dsRNA) viruses, and one DNA virus. Among these, 14 viruses were identified as putative novel viruses showing less than 90% sequence identity with known viruses. The most widely distributed viruses were Cucumber mosaic virus (100%), Turnip yellows virus (91.7%), and Brassica yellows virus 1 (75%). Correlation analysis revealed that the relative abundance of Plasmodiophora brassicae partitivirus 1 (PbPV1) and Brassica virus 1_Nap was significantly positively correlated with clubroot disease incidence ( p  < 0.05). However, no significant correlation was observed between virus alpha diversity and environmental factors including disease incidence, longitude, latitude, and altitude. These findings significantly expand our understanding of the viral diversity associated with P. brassicae and provide a foundation for future studies on the potential roles of these viruses in clubroot disease epidemiology.