Lisianthus (Eustoma exaltatum (L.) Salisb. ex G. Don subsp. russellianum (Hook.) Kartesz) is an economically important ornamental crop in Taiwan. Over the past decade, nine viruses have been identified or detected in lisianthus including: Bean yellow mosaic virus (BYMV), Lisianthus necrosis virus (LNV) (2), Cucumber mosaic virus (CMV) (1), Turnip mosaic virus (TuMV), Tomato spotted wilt virus (TSWV), Broad bean wilt virus (BBWV), Tomato mosaic virus (ToMV), Pepper veinal mottle virus (PVMV), and Ageratum yellow vein virus (AYVV) (4). In May 2007 (late period of growing season) in central Taiwan, systemic necrotic spots, which are similar to that caused by LNV (2), were found on approximately 20% of the lisianthus plants. Spherical virus particles, approximately 32 nm in diameter, were found in the crude sap of infected lisianthus collected from the fields. However, the diseased samples did not react with antisera against domestic lisianthus-infecting spherical viruses, LNV (2) and CMV (1). A virus culture was isolated via mechanical inoculation on Chenopodium quinoa and serologically identified as Carnation mottle virus (CarMV) by ELISA, western blotting, and immunoelectron microscopy using antiserum against the CarMV zantedeschia strain (3). The virus induced necrotic local lesions on the inoculated leaves of C. quinoa, C. amaranticolor, Gomphrena globosa, Cucurbita moschata, Phaseolus angularis, P. vulgaris, and Vigna unguiculata. Lisianthus was previously reported as a local lesion host for CarMV (3). In current studies with 8 of 10 lisianthus plants, the newly isolated virus induced necrotic local lesions on inoculated leaves 20 days post inoculation (dpi). However, systemic necrotic lesions on noninoculated upper leaves, as were observed in the fields, appeared 120 dpi on inoculated plants, indicating that CarMV induces systemic infection in lisianthus during late growth stages. Noninoculated plants did not develop symptoms. Complementary DNA fragments of viral genomic RNA were amplified with a specific primer of the coat protein gene (3) and sets of degenerate primer for CarMV. The amplified cDNA fragments were cloned and sequenced. The full-length sequence was submitted as GenBank Accession No. FJ843021. The genomic RNA consists of 4,003 nucleotides and has an identical genome organization to that reported for members of the genus Carmovirus. The nucleotide sequence of the full-length genome shares more than 95% identity to isolates of CarMV (GenBank Accession Nos. AF192772, AJ304989, AJ811998, NC_001265, and X02986), and the nucleotide and deduced amino acid sequence of coat protein shares more than 98% identity with that of CarMV-TW (AY383566) (3), CarMV-FO25 (EF622206), CarMV-Italy-Ca1 (EF622207), and CarMV-Netherland Ca2 (EF622210). To our knowledge, this is the first report of natural infection of CarMV in lisianthus in Taiwan.
References: (1) C. C. Chen and C. C. Hu, Plant Prot. Bull. 41:179, 1999. (2) C. C. Chen et al. Plant Dis. 84:506, 2000. (3) C. C. Chen et al. Plant Dis. 87:1539, 2003. (4) Y. H. Cheng et al. J. Taiwan Agric. Res. 58:196, 2009.