Mycoviruses in the Plant Pathogen Ustilaginoidea virens Are Not Correlated with the Genetic Backgrounds of Its Hosts

Abstract

Ustilaginoidea virens, the causal agent of rice false smut, is one of the most devastating grain diseases that causes loss of yield in most rice-growing areas worldwide. In this study, we performed a dsRNA screen to isolate mycoviruses from 35 U. virens strains. The results revealed that 34 of the tested isolates were infected by various dsRNA elements, displaying highly viral diversity and mixed infections. We characterized a 5.3 kbp dsRNA from a typical isolate containing dsRNA segments with sizes ranging from 0.5 to 5.3 kbp. Sequence analysis of its genomic properties indicated that it is a novel victorivirus, named Ustilaginoidea virens RNA virus 5 (UvRV5), that belongs to the family Totiviridae. RT-PCR detection was performed and indicated that not all the dsRNA bands that were 5.3 kbp in size contained UvRV5. Moreover, the genetic relatedness of all the U. virens strains was estimated according to phylogenetic analysis of the partial intergenic spacer region (IGS) sequences. However, concordance was not found between the dsRNA profiles and the IGS-based genetic relatedness of their host fungi.

Characterization of two novel mycoviruses from Penicillium digitatum and the related fungicide resistance analysis

“…Zhong et al . reported 34 U. virens strains with dsRNA mycovirus infection in total 35 samples 24 . Recently, Kotta-Loizou and Coutts reported 16 B. bassiana isolates with such infection in total 75 samples from worldwide locations 10 .…”

“…The infection rates of 39.3% (35/89) suggested a well prevalence of dsRNA mycovirus infection in P. digitatum strains. According to partial sequencing analysis, 24 P. digitatum isolates are infected with mycoviruses, belonging to Totiviridae family and sharing great similarity with PdV1 17 , and 9 P. digitatum isolates are infected with mycoviruses, belonging to Partitivirdae family and sharing great similarity with PsV-S 24 . Here, mycoviruses coinfection was observed in two P. digitatum strains.…”

Co-infection of Four Novel Mycoviruses from Three Lineages Confers Hypovirulence on Phytopathogenic Fungus Ustilaginoidea virens

“…Therefore, the mycoviruses that infect U. virens have attracted our attention for their high efficiency and persistency. To date, only the genome characterization of dsRNA viruses has been reported in U. virens , including Ustilaginoidea virens RNA virus 1-6 (UvRV1-6) (Zhang et al 2013a ; Zhong et al 2014a , b ; Jiang et al 2015 ; Zhong et al 2017 ), Ustilaginoidea virens partitivirus 1-4 (UvPV1-4) (Zhang et al 2013b ; Zhong et al 2014c , 2014a ; Jiang et al 2014 ), Ustilaginoidea virens nonsegmented virus 1-2 (UvNV1-2) (Zhang et al 2014a , 2018 ) and Ustilaginoidea virens unassigned RNA virus HNND-1 (UvURV-HNND-1) (Zhu et al 2015 ). Furthermore, our laboratory previously identified 593 mycovirus-related contigs in 182 U. virens strains by metatranscriptomic sequencing (He et al 2022 ).…”

Molecular characterization of a novel single-stranded RNA mycovirus infecting the plant pathogenic fungus Ustilaginoidea virens

“…None of the mycoviruses identi ed thus far encodes a capsid protein[6]. To date, only dsRNA viruses have been identi ed in U. virens, including Ustilaginoidea virens RNA virus 1-6, Ustilaginoidea virens partitivirus 1-4, Ustilaginoidea virens nonsegmented virus 1-2 and Ustilaginoidea virens unassigned RNA virus HNND-1 [7][8][9][10][11][12][13][14][15]. With the application of high-throughput sequencing, more and more mycoviruses are being explored [16].…”