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Infectivity and pathogenicity of two different Plantago asiatica mosaic virus isolates in lilies

Ken Komatsu: Tokyo Univ Agric & Tech (TUAT)

<div><em>Plantago asiatica mosaic virus</em> (PlAMV) is a member of the genus <em>Potexvirus</em> in the family <em>Alphaflexiviridae</em> and was has been isolated from a variety of host plants. In particular, PlAMV isolates from ornamental lilies (<em>Lilium </em>spp.) cause necrotic symptoms, which significantly reduces their commercial value. However, it has not been clear whether PlAMV isolates from other host plants can cause necrotic symptoms in ornamental lilies, because they may differ in their infectivity and pathogenicity in the hosts. Also, it remains unresolved whether growth conditions affect infectivity and pathogenicity. In this study, we inoculated an edible lily variety (<em>Lilium leichtlinii</em>) and seven varieties of ornamental lilies with two PlAMV isolates, an ornamental lily isolate PlAMV-OL and an edible lily isolate PlAMV-Li1. We performed inoculation test at two seasons, in spring and autumn, in two different growth conditions, in a greenhouse and open field. About two month after inoculation, we examined virus infectivity by quantitative reverse-transcription PCR, and virus pathogenicity by observation symptoms exhibited in plants. We found that PlAMV-OL had stronger infectivity and pathogenicity to both edible and ornamental 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 environment including ambient temperatures 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.</div>