Characterization of a potexvirus infecting Hosta spp.

A previously undescribed potexvirus, named Hosta virus X (HVX), was found in 17 naturally infected hosta (Hosta spp.) cultivars from Minnesota, Indiana, Illinois, Iowa, and Michigan. HVX was readily transmitted mechanically but infected only Nicotiana benthamiana and Hosta spp., in which symptoms ranged from severe mosaic and leaf necrosis to latency. Particles of HVX averaged 530 nm in length, had a buoyant density in cesium chloride of 1.28 gm/cm³, and contained a single genomic species of ssRNA approximately 3 kb in size. The capsid protein of HVX had a molecular mass of approximately 27 kDa. In indirect enzyme immunoassays, HVX reacted with an antiserum to clover yellow mosaic virus (ClYMV), and less strongly with antiserum to hydrangea ringspot virus (HRSV), but not with antisera to any of 14 other potexviruses tested. However, in reciprocal tests, ClYMV reacted only very weakly with HVX antiserum. HVX did not infect any of three cultivars of pea that were susceptible to infection by ClYMV, and ClYMV did not infect any of three hosta cultivars susceptible to infection by HVX. Spread of HVX infection in hosta appears to occur by vegetative propagation and accidental mechanical transmission, and management of the disease can be achieved by virus indexing and cultural practices that minimize the risk of virus spread to susceptible cultivars.