|Hsu, Hei Ti|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2004
Publication Date: 1/5/2005
Citation: Chen, C.C., Chang, C.A., Tsai, H.T., Hsu, H.T. 2004. Identification of a potyvirus causing latent infection in calla lilies. Plant Disease. 88:1046. Interpretive Summary: Attractive with their brilliant color and long lasting flowers, calla lilies (Zantedeschia spp.) have become very popular worldwide. The crop is highly susceptible to several viruses including Tomato spotted wilt. Turnip mosaic, Zantedeschia mosaic, Konjac mosaic, Dasheen mosaic and Carnation mottle viruses. All of these viral agents induce visual symptoms in infected plants. In this paper, a new virus in the Potyvirus genus causing latent infection in calla lilies is described. The virus was molecularly characterized. Polyclonal antibody reagents were produced using E. coli bacteria-expressed viral coat protein. The discovery of Zantedeschia latent virus in calla lilies is important in that the virus may spread in fields from apparent healthy plants showing no symptoms via vegetative propagation. The work reported in the paper is relevant to National Plant Health Program 303, and is useful to growers, nurseries, extension specialists and quarantine official.
Technical Abstract: A new potyvirus, designated Zantedeschia latent virus (ZLV), was isolated from calla lilies (Zantedeschia spp.) in Taiwan. Different from most calla lily- infecting potyviruses (3), ZLV infects Chenopodium quinoa and develops local lesions on inoculated leaves. Typical potyvirus particles about 780 nm in length were readily detected from ZLV induced C. quinoa local lesions. Attempts to establish ZLV cultures on calla lilies from C. quinoa lesions were not successful. A 1.3-kb DNA product was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) from ZLV-infected calla lilies and C. quinoa using potyvirus degenerate primers (2). The PCR product was subsequently cloned and its sequence analyzed. It was found to consist of 1339 nucleotides corresponding to the genome organization of the 3'-terminal region of potyviruses (GenBank with the accession no. AF469171). The deduced amino acid sequence contains 362 residues encoding the 3'-terminal region of nuclear inclusion b gene (80 residues) and the complete sequence of the coat protein (CP) gene (282 residues). A non-coding region (NCR) of 253 nts was found located at the 3'-terminal region of the DNA. Pair wise comparisons with known sequences of potyviruses available in GenBank, ZLV was identified as a new species of Potyvirus based on its uniqueness in both the coat protein gene (CP) and 3' non-coding region (NCR). Comparative studies show that Soybean mosaic virus and Watermelon mosaic virus 2 are the two potyviruses most similar to ZLV, but they share only about 80% nucleotide identities in CP and NCR. Attempts to purify sufficient quantity of ZLV from C. quinoa for antiserum preparation were not successful. Alternatively, polyclonal antibodies were produced using E. coli-expressed ZLV CP as described (1). The antibodies were found useful in ELISA, SDS-immunodiffusion, immuno-specific electron microscopy, and western blotting for the detection of ZLV and its CP in calla lilies. Field surveys showed that ZLV singly infected calla lily plants always remained symptomless throughout the entire observation period. Occasionally, symptomatic calla lilies were detected but were consistently confirmed to be dually infected by other viruses.