Complete genome sequence of a new member of the genus Badnavirus infecting nettle (Urtica dioica)

Abstract

A new badnavirus was discovered in nettle plants (Urtica dioica L., family Urticaceae) with vein banding symptoms using high-throughput sequencing. This virus was provisionally named "nettle badnavirus 1" (NBV 1). The complete NBV 1 genome consists of 7598 bp and contains three overlapping open reading frames. NBV 1 found to be was most closely related to green Sichuan pepper vein clearing-associated badnavirus, sharing 73.9% nucleotide sequence identity in the whole genome. These two viruses showed 76.3% nucleotide sequence identity in the region of the genome encoding RT-RNase H. This is lower than the species demarcation cutoff (80%) for the genus Badnavirus of the family Caulimoviridae, suggesting that NBV 1 is a new member of this genus. Phylogenetic analysis based on full-length badnavirus genome sequences showed that NBV 1 belongs to the same clade as a badnavirus whose genome was found to be integrated into chromosome 6 of the nettle genome, sharing 78% identity. Using PCR, NBV 1 was detected in a symptomless nettle plant growing next to symptomatic ones. It is therefore likely that the observed vein banding was due to an idaeovirus or a partitivirus, which were shown to be coinfecting the symptomatic plant. These findings expand the list of viruses infecting nettle.