Identification and characterization of a new potyvirus infecting Muscari in Hungary

Grape hyacinths (Muscari spp.) are popular spring flowering bulbs in Europe and also in Hungary. In the spring of 2017, we came across grape hyacinth plants showing mosaic symptoms, which indicated viral infection. Currently Hyacinth mosaic virus (genus Potyvirus), a proposed member of the genus named Muscari mosaic virus, Arabis mosaic virus (genus Nepovirus), Cucumber mosaic virus (genus Cucumovirus) and Tobacco rattle virus (genus Tobravirus) are known to infect grape hyacinth. Leaf samples of symptomatic grape hyacinths were observed, collected and the presence of potyviruses was proved with potyvirus specific monoclonal antibody by ELISA and by potyvirus specific RT-PCR. Laboratory host plants and seed grown Muscari plants were inoculated with leaf sap and symptoms were recorded. Nucleotide sequences of the cloned fragments were compared to GenBank data. In the case of Muscari ‘Helena’ the highest nucleotide identity in the coat protein coding region was found with two Muscari mosaic virus isolates (95.51% and 95.79%). In the case of the clones derived from Muscari ‘Pink Sunrise’ plant, the highest identity was recorded with Muscari mosaic virus isolates (57.65% and 57.80%) and with a Tulip breaking virus strain (55.13%) indicating the existence of a novel potyvirus species, tentatively named Muscari chlorotic mottle virus. The coat protein sequences were aligned and Maximum Likelihood trees were built to analyze phylogenetic relationships.