Differences in infectivity and pathogenicity of two Plantago asiatica mosaic virus isolates in lilies

Plantago asiatica mosaic virus (PlAMV) is a member of the genus Potexvirus in the family Alphaflexiviridae and has been isolated from a variety of host plants. In particular, PlAMV isolates from ornamental lilies (Lilium spp.) cause necrotic symptoms in these plants, which significantly reduces their commercial value. However, it has not been clear whether PlAMV isolates from other host plants differ in their infectivity and/or pathogenicity to ornamental lilies, and whether growth conditions affect infectivity and pathogenicity. In this study, we inoculated an edible lily species (Lilium leichtlinii) and seven varieties of ornamental lilies with two PlAMV isolates, an isolate from ornamental lily (PlAMV-OL) and an isolate from edible lily (PlAMV-Li1). We found that PlAMV-OL showed higher infection rates and exhibited necrotic symptoms more frequently in lilies than PlAMV-Li1. Moreover, we observed higher infection rates of PlAMV-OL in open field than in greenhouse, and higher rates of necrotic symptoms in autumn test than in spring test, suggesting that growth conditions and season affect infectivity and pathogenicity of PlAMV in lilies. Our study would provide important information for estimating the risk of necrotic disease caused by PlAMV, as well as for cultivation management preventing the occurrence of the disease.