First report of the whole‑genome sequence analysis of Fig badnavirus 2 from China.

Abstract

A novel plant virus was identified in fig trees exhibiting ring spot symptoms through high-throughput sequencing (HTS). The complete genome sequence was successfully determined using PCR and RT-PCR techniques. The virus features a circular DNA genome of 7233 nucleotides (nt) in length, encompassing four open reading frames (ORFs). ORF1 and ORF2 encode hypothetical proteins, while ORF3 encodes a putative polyprotein with conserved domains, including a zinc finger, aspartic protease, reverse transcriptase (RT), and RNase H. ORF4 encodes a putative protein of unknown function. Comparative nucleotide sequence analysis of the RT + RNase H region reveals 84.46% and 78.82% identity with grapevine badnavirus 1 (GBV-1, MF781082.1) and fig badnavirus 1 (FBV-1, MK348055.1), respectively. Notably, this virus's genomic organization diverges from GBV-1 but is similar to FBV-1. Phylogenetic analysis demonstrates that the three isolates of this virus form a distinct clade within the badnaviruses. Based on genomic structure and phylogenetic relationships, this novel virus represents a new member of the genus Badnavirus and is proposed to be named "Fig badnavirus 2" (FBV-2).