Molecular characterization of a novel botourmiavirus infecting Leptosphaeria biglobosa

Abstract

The phytopathogenic fungus Leptosphaeria biglobosa is the host of diverse mycoviruses. Comprehensive analysis of next-generation sequencing (NGS) data obtained from purified double-stranded RNA (dsRNA) revealed the presence of three single-stranded RNA (ssRNA) molecules. These RNAs, designated ssRNA1, ssRNA2, and ssRNA3, are respectively 2,646, 683, and 575 bp in length. ssRNA1 contains a single open reading frame (ORF) encoding a putative RNA-dependent RNA polymerase (RdRP) and represents the genome of a novel member of the family Botourmiaviridae, designated as “Leptosphaeria biglobosa botourmiavirus 3” (LbBoV-3). Conversely, ssRNA2 and ssRNA3 share identical 3′-termini but no other sequence similarity with ssRNA1, lack substantial ORFs, do not possess poly(A) tails, and are proposed to represent satellite-like RNAs associated with LbBoV-3. To our knowledge, LbBoV-3 is the second member of the genus Magoulivirus associated with two satellite RNAs, expanding the current understanding of mycoviral diversity associated with this economically important phytopathogenic fungus.