Garland chrysanthemum (Chrysanthemum coronarium) and lettuce (Lactuca sativa) are winter vegetables in Taiwan. Turnip mosaic virus (TuMV) and Lettuce mosaic virus (LMV) were potyviruses commonly isolated from garland chrysanthemum and lettuce, respectively (1). Symptoms of mosaic and deformation in leaves and stunting of plants have been observed in both Compositae crops in the fields since 2007 in the Chiayi area and with an increasing incidence in recent years (26 and 33% in garland chrysanthemum and lettuce, respectively). Filamentous virus particles (approximately 780 × 13 nm) in the crude sap and pinwheel inclusions in infected cells can be observed in the preparations of both diseased hosts with electron microscopy. However, TuMV, LMV, and other potyviruses (Bean yellow mosaic virus, Papaya ringspot virus, and Zucchini yellow mosaic virus) were not detectable in diseased samples by ELISA and western blotting tests, indicating a new potyvirus infection. Virus cultures were isolated from infected garland chrysanthemum and lettuce separately via mechanical inoculations in Chenopodium quinoa. Each isolate was mechanically inoculated to their original host individually and all caused symptoms similar to that observed in the field, indicating their pathogenicity to their original host. A cDNA fragment consisting of partial nuclear inclusion (NIb) and coat protein (CP) genes were amplified with potyvirus degenerate primers (forward: 5′-GGBAAYAATAGTGGNCAACC and reverse: 5′-GGGGAGGTGCCGTTCTCDATRCACCA) and was found to share 90% nucleotide sequence identity to that of Bidens mottle virus (BiMoV; GenBank Accession No. AF538686). The sequences of the CP gene and 3′ untranslated region (3′-UTR) of tested viruses were further amplified with a specific primer of BiMoV CP and oligo-dT in reverse transcription-PCR. The amplified fragments were cloned, sequenced, and the combined cDNA sequences were deposited in GenBank (Accession No. AB491763 for isolate garland chrysanthemum and Accession No. AB491764 for isolate lettuce). Sequence analysis showed that both cloned sequences shared more than 97% nucleotide similarity to that of BiMoV. The amino acid sequence of the CP of both isolates shared a 99.3% identity and a 98.9 to 99.3% identity to that of other BiMoV isolates deposited in GenBank. BiMoV was first described to be infecting lettuce and Cichorium endivia in the United States (4) and was first reported in sunflower and calendula in Taiwan recently (2,3). To our knowledge, this is the first report of the occurrence of BiMoV in garland chrysanthemum and lettuce in Taiwan.
References: (1) Y. K. Chen et al. Plant Pathol. Bull. 5:55,1996. (2) C.-H. Huang and F.-J. Jan. Plant Dis. 95:362, 2011. (3) J. Y. Liao et al. Arch. Virol. 154:723, 2009. (4) F. Youssef et al. Arch. Virol 153:227, 2008.