Department of Plant Pathology, China Agricultural University, Beijing 100094, People's Republic of China
Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, People's Republic of China
Department of Plant and Environmental Protection Sciences, University of Hawaii, Honolulu 96822
Hibiscus rosa-sinensis Linn., family Malvaceae, is an attractive horticultural plant originating from China. Five viruses infecting H. rosa-sinensis that have been characterized previously are Hibiscus chlorotic ringspot virus (HCRSV, genus Carmovirus), Hibiscus latent ringspot virus (HLRSV, genus Nepovirus), Hibiscus yellow mosaic virus (genus Tobamovirus), Eggplant mottled dwarf virus (EMDV, genus Nucleorhabdovirus), and Okra mosaic virus (OkMV, genus Tymovirus) (2). Recently, two novel tobamoviruses infecting H. rosa-sinensis were characterized in Singapore and Florida (1). In this study, viral symptoms were observed on H. rosa-sinensis in Nanyang City in Henan Province, China. The systemic symptoms included dark and light green mosaic in young leaves, leaf puckering and malformation on older leaves, and significant stunting. Rod-shaped virus particles were isolated from H. rosa-sinensis expressing systemic symptoms. The virus was transmitted mechanically to 10 species from three families. Symptoms expressed on these plants included systemic leaf chlorosis and distortion on Lycopersicum esculentum, systemic mosaic on Capsicum annuum, Nicotiana tabacum, and Physalis floridana, and systemic chlorosis on Glycine max. N. tabacum-Xanthi nc and Datura stramonium were asymptomatic. The virus also produced chlorotic and necrotic local lesions on Chenopodium quinoa, C. amaranticolor, and C. murale. The virus was propagated in L. esculentum, N. tabacum, and P. floridana. Virions purified from systemically infected N. tabacum contained a single-stranded RNA of approximately 6.4 kb and a coat protein (CP) of approximately 17.6 kDa. The double-stranded RNA profile revealed a single band of approximately 6.4 kb. Sap extracted from virus-infected plants reacted positive with an antiserum prepared against Tobacco mosaic virus (TMV) using an antigen-coated plate enzyme-linked immunosorbent assay. The CP gene was amplified by reverse transcription-polymerase chain reaction with primers specific to Tomato mosaic virus (ToMV) and sequence data obtained from the resulting amplification product. The CP gene consisting of 159 amino acids (GenBank Accession No. AY313136) shared 99.37% identity with the ToMV Queensland isolate (GenBank Accession No. AF332868). On the basis of biology, serology, properties of virions, and the sequence of the CP gene, we conclude that the virus isolated from H. rosa-sinensis in China is Tomato mosaic virus(ToMV).
References: (1) S. Adkins et al. Plant Dis. 87:1190, 2003. (2) M. H. V. van Regenmortel et al., eds. Virus Taxonomy. 7th Report of the ICTV, Academic Press, NY, 2000.