Distribution of Asclepias Asymptomatic Virus and Exploration of Possible Effects on the Wild Plant Host, Asclepias viridis

Viruses in wild plants are poorly studied yet important sources of emerging diseases. We surveyed populations of a perennial host, Asclepias viridis, for Asclepias asymptomatic virus (AsAV) in nine sites (two in Oklahoma, seven in Kansas) from 2015 to 2018. All collected leaf samples from A. viridis were tested serologically by dot-immunobinding assays. In Oklahoma, the virus was present and abundant at both sites; in Kansas, the virus was found in four sites, but only one or two plants were infected per site. We followed the fate of individual plants and found little evidence that plant persistence or reproduction differed among plants with and without virus infection. Infected plants were 20% shorter than noninfected plants in two years at one site. No symptoms were evident in virus-infected plants. We observed apparent gains and losses of infection across years in Oklahoma but not in Kansas. The apparent neutral to slightly negative effects of this virus on this wild host emphasize the importance of studying wild plant–wild virus interactions to more fully understand plant virus ecology. Further, the fact that the virus is known to cause symptoms in plants of economically important families emphasizes the applied importance of research on wild viruses.