Identification and characterization of Lisianthus necrotic ringspot virus, a novel distinct tospovirus species causing necrotic disease of lisianthus (Eustoma grandiflorum)

In 2007, lisianthus (Eustoma grandiflorum) plants with necrotic ringspots on the leaves were found in Kochi Prefecture, Japan. Tospovirus-like spherical enveloped particles with ca. 160 nm in diameter were observed with electron microscopy. The complete nucleotide sequence of the S RNA segment of the virus was determined, and phylogenetic analysis using deduced amino acid sequences of the nucleocapsid protein and the nonstructural S protein indicated that the virus is phylogenetically distinct from any known tospovirus species. The results suggest that the virus is a new member of the genus Tospovirus, in the family Bunyaviridae. The virus is the fifth distinct tospovirus occurring naturally in lisianthus in Japan. The necrotic symptoms were reproduced on lisianthus seedlings after mechanical inoculation. The host range of the virus isolate on several test plants was also examined.