Full genome characterization of a novel zetapartitivirus infecting Alternaria tenuissima strain TY-26 associated with muskmelon leaf spot

Abstract

In China, leaf spot disease poses a significant challenge to muskmelon cultivation, with Alternaria tenuissima being identified as the predominant causal pathogen of this disease. In the current study, we identified and characterized a novel zetapartitivirus from A. tenuissima strain TY-26, which was named "Alternaria tenuissima partitivirus 3" (AttPV3). The full genome of AttPV3, the nucleotide sequence of which was determined by metatranscriptome sequencing and RNA-ligase-mediated rapid amplification of cDNA ends (RLM-RACE), comprises two dsRNA segments. The larger dsRNA1 segment is 1,841 nt in length and encodes a putative RNA-dependent RNA polymerase (RdRp), whereas the smaller dsRNA2 segment is 1,644 nt in length and encodes a putative capsid protein (CP). BLASTp searches showed that the RdRp and CP of AttPV3 had the highest amino acid (aa) sequence similarity to the corresponding proteins of Delitschia confertaspora partitivirus 1 (DcPV1), with 90.72% and 76.65% identity, respectively. Phylogenetic analysis of the RdRp aa sequence positioned AttPV3 within a clade alongside DcPV1, indicating its close evolutionary relationship to members of the the proposed genus “Zetapartitivirus” of the family Partitiviridae. This is the first report describing the full genomic characterization of a zetapartitivirus infecting A. tenuissima.