Identification and Characterization of a Novel Luteovirus Infecting Hosta ventricosa Plants

Hosta ventricosa, also known as blue plantain lily, is an important traditional herbal medicinal and ornamental plant in China. Prior to this study, no virus has been reported to infect H. ventricosa plants. Based on RNA-seq, transmission electron microscopy, and RT-PCR analyses, we have demonstrated that the H. ventricosa plant showing leaf chlorosis, mottle, mosaic, and crinkling symptoms was co-infected with hosta virus X (HVX) and a novel luteovirus, which we tentatively named hosta ventricosa luteovirus (HVLV). The genome of HVLV is a 5723 nt long, positive-sense, and single-stranded RNA with seven open reading frames (ORFs). Phylogenetic analysis based on the amino acid (aa) sequence of the viral RNA-dependent RNA polymerase (RdRp) revealed that HVLV is clustered within the genus Luteovirus. The HVLV RdRp shares 9.75-45.17% aa sequence identity with the 14 closely related luteoviruses. The P1-2 and P3-5 proteins of HVLV were identified as potential viral pathogenicity determinants through the PVX heterologous expression in Nicotiana benthamiana plants. Moreover, P2, P5 and P3-5 proteins of HVLV have been found to exhibit RNA silencing suppression activities. Additionally, we have successfully constructed an infectious cDNA clone of HVLV and uncovered that this infectious cDNA clone can infect N. benthamiana plants through agroinfiltration. These findings have expanded our understanding of luteoviruses and their host range.