Acta Agriculturae Boreali-Sinica ›› 2025, Vol. 40 ›› Issue (3): 141-148. doi: 10.7668/hbnxb.20195221

Special Issue: Rice Plant protection Biotechnology

• Resources & Environment·Plant Protection • Previous Articles     Next Articles

Genome Organization and Functional Analysis of a Novel Mycovirus in Ustilaginoidea virens Strain Uv263

HE Zhenrui1, ZHAO Wenhua1, YANG Yingqing2, YANG Mei1, ZHOU Erxun1,   

  1. 1 College of Plant Protection,South China Agricultural University,Guangdong Province Key Laboratory of Microbial Signals and Disease Control,Guangzhou 510642,China
    2 Institute of Plant Protection,Jiangxi Academy of Agricultural Sciences,Nanchang 330200,China
  • Received:2024-10-18 Published:2025-06-28

Abstract:

In order to deeply explore the diversity of mycoviruses in Ustilaginoidea virens,this study used an abnormal strain Uv263 of U.virens isolated from diseased rice samples collected from Hainan Province as experimental material to identify potential mycoviruses in this strain,and analyze the relationship between the genome organization and function of mycoviruses.The results showed that strain Uv263 was infected by a novel mycovirus named Ustilaginoidea virens RNA virus 7 (UvRV7).UvRV7 was a double stranded RNA virus with 5 082 bp in total length and 60.29% GC content.UvRV7 encoded two large open reading frames (ORF1 and ORF2),which encoded the coat protein (CP) and RNA-dependent RNA polymerase (RdRP),respectively.The BlastP comparison showed that the RdRP amino acid sequence of UvRV7 shared the highest similarity with that of Thelebolus microsporus totivirus 1,at 48.49%.The results of multiple alignment based on the amino acid sequence of UvRV7 RdRP showed that the RdRP sequence contained a total of eight conserved motifs,among which the most typical GDD motif in the RdRP conserved domain was identified in the Ⅵ motif.The phylogenetic analysis showed that UvRV7 was the most closely related to Thelebolus microsporus totivirus 1 and clustered with representative viruses of the genus Victorivirus in the family Totiviridae.The results of genome organization and evolutionary analyses both indicated that UvRV7 was a novel mycovirus in the genus Victorivirus.Transmission electron microscopy observations showed that UvRV7 formed a spherical viral particle of about 45 nm.Horizontal and vertical transmission experiments showed that UvRV7 could be efficiently transmitted vertically by conidia and efficiently transmitted horizontally between vegetatively compatible strains.Taken together,this study elucidated the genome organization and evolutionary relationships of the novel mycovirus UvRV7 in U.virens,and provided a potential biocontrol agent and theoretical basis for the biological control of rice false smut.

Key words: Rice false smut, Mycovirus, Biocontrol, Totiviridae, Victorivirus

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Cite this article

HE Zhenrui, ZHAO Wenhua, YANG Yingqing, YANG Mei, ZHOU Erxun. Genome Organization and Functional Analysis of a Novel Mycovirus in Ustilaginoidea virens Strain Uv263[J]. Acta Agriculturae Boreali-Sinica, 2025, 40(3): 141-148. doi: 10.7668/hbnxb.20195221.

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