First Report of Hosta virus X Infecting Hosta Plants in China.

Hosta (Hosta spp.) plants showing leaf deformation, puckering, and ink-bleed symptoms were collected in July 2012 from a park at Dongcheng district, Beijing, China. Three out of six samples tested positive for Hosta virus X (HVX) by immunostrip and double-antibody sandwich (DAS)-ELISA with HVX-specific serological reagents from Agdia Inc. (Elkhart, IN, USA). Filamentous viral particles were trapped and observed from the infected hosta leaf sap by immuno-serological electron microscopy (ISEM) (antibodies from Agdia). To confirm HVX infection, three ELISA-positive samples were analyzed by reverse transcription-PCR assay, using virus-specific primers HVXf (5'-ATCCGTTATCTACAGGGGACCAG-3') and HVXr (5'-TAAGTTAGTGGAACGGTTAGCCCGAT-3') that amplified a 1,067-bp fragment including the coat protein (CP) coding region. The CP nucleotide sequence comparisons showed 99% to 100% homology among the three isolates named HVXBJ4, HVXBJ5, and HVXBJ6 (GenBank Accession No. JX535292, JX535293, and JX535294) and with the HVX sequences previously reported in GenBank. HVX has been reported from the United States, Korea, the Netherlands, Poland, France, the Czech Republic, and New Zealand (1,2). To our knowledge, this is the first report of HVX infecting hosta plants in China. As an ornamental and medicinal plant, hosta has been cultivated in China for more than 2,000 years. The presence of HVX in Beijing is a potential threat to the landscape in the city. HVX can be spread by vegetative propagation material or mechanical contact (3). Hence, to cultivate HVX-free hosta and restrict the movement of HVX-infected hosta is vitally important in the future. HVX has become economically important in the world more recently. Globalization of trade in hosta plants has increased the risk of movement of HVX. The national plant protection organization should establish effective quarantine strategy and the growers take proper planting measures to avoid further spreading of this virus. References: (1) S. Currier et al. Plant Dis. 80:1040, 1996. (2) M. H. Park et al. Arch. Virol. 148:2039, 2003. (3) K. H. Ryu et al. Acta Hortic. 722:91, 2006.