Uncovering a Hidden Viral World in Medicinal Plants

A novel double-stranded RNA (dsRNA) virus was discovered in Valeriana jatamansi Jones plants showing brown necrotic stripe symptoms in Kunming, Yunnan Province. This virus was tentatively designated as "Valeriana jatamansi cryptic virus 2" (VJCV2), with GenBank accession numbers PP482523 and PP482524. The complete genome sequence of VJCV2 was determined using metatranscriptomic sequencing and Sanger sequencing. The genome of VJCV2 comprises two dsRNA segments dsRNA1 (PP482523, 2,463 bp) and dsRNA2 (PP482524, 2,170 bp). dsRNA1 is predicted to encode an RNA-dependent RNA polymerase (RdRp) containing 742 amino acids, and dsRNA2 is predicted to encode a coat protein (CP) with a molecular weight of 75.2 kDa. Multiple sequence alignments revealed that the RdRp and CP encoded by VJCV2 shared a high degree of amino acid sequence similarity with numerous members of the genus Betapartitivirus. Specifically, the RdRp and CP of VJCV2 share the most sequence similarity with dill cryptic virus 2 (77.88% identity in the RdRp and 71.17% in the CP), closely followed by cannabis cryptic virus (77.66% identity in the RdRp and 68.50% in the CP). Phylogenetic trees constructed based on RdRp and CP sequences showed that VJCV2 and its closest relatives clustered independently within the genus Betapartitivirus, and VJCV2 formed a separate small branch together with dill cryptic virus 2 and cannabis cryptic virus. These results indicated that VJCV2 should be classified as a novel member of the genus Betapartitivirus in the family Partitiviridae. This is the first report of a betapartitivirus infecting V. jatamansi.