First Report of Zantedeschia mosaic virus Infecting a Zantedeschia sp. in New Zealand.

Abstract

In February 2004, leaf yellowing, mottling, and mosaics were observed on a few plants of a Zantedeschia sp. (calla lily) growing in Rangiora, Canterbury, New Zealand. Zantedeschia spp. are known to be susceptible to at least 13 virus species (1). No symptoms were observed on Chenopodium amaranticolor, C. quinoa, Cucumis sativus, Gomphrena globosa, Nicotiana benthamiana, N. clevelandii, N. occidentalis, or N. tabacum when inoculated with sap from symptomatic plants. However, electron microscopy of crude sap preparations from a symptomatic Zantedeschia sp. and inoculated N. clevelandii plants revealed the presence of flexuous, filamentous virus particles approximately 700 nm long and 12 nm wide. No virus particles were seen in the other inoculated indicator species. Nucleic acid was extracted from leaves of the infected Zantedeschia sp. and N. clevelandii plants and tested in reverse transcription (RT)-PCR using published potyvirus-specific primers (4). PCR amplicons of the expected size (327 bp) were obtained from both plant species and sequenced directly. The products were identical, and a BLAST search in GenBank showed 99% nucleotide identity with a Taiwanese isolate of the species Zantedeschia mosaic virus (ZaMV) (GenBank Accession No. AY026463). A product of 1,531 bp (GenBank Accession No. EU544542) was amplified from symptomatic Zantedeschia by RT-PCR using novel forward (5'-GCACGGCAGATAAACACGAC-3') and reverse (5'-GTGGGCAACCTTCAACTGTG-3') primers designed to amplify the 3' untranslated region (3'UTR), coat protein (CP), and partial nuclear inclusion b protein (NIb) genes. The product was sequenced and had 94% nucleotide identity with a South Korean ZaMV isolate (GenBank Accession No. AB081519), with 95% nucleotide (97% amino acid) identity in the CP gene. A second crop of Zantedeschia spp. in Tauranga, New Zealand (approximately 700 km north of Rangiora) was observed to have similar disease symptoms. Symptomatic plants tested positive in ELISA using a potyvirus-specific monoclonal antibody (Agdia Inc., Elkhart, IN). Nucleic acid was extracted from leaves of symptomatic plants and tested in RT-PCR using potyvirus-specific primer pairs, PV2I/T7 and D335 and U335 and PV1/SP6, which amplify overlapping regions within the 3'UTR, CP, and NIb genes (2,3). The products were sequenced and a consensus sequence of 1,793 bp was generated (GenBank Accession No. EU532065). A BLAST search showed that the sequence had 78% nucleotide (88% amino acid) identity with Zantedeschia mild mosaic virus (ZaMMV) (GenBank Accession No. AY626825). However, the sequences had only 73% nucleotide (79% amino acid) identity in the CP gene, and therefore, this second virus may be a distinct species. To our knowledge, this is the first report of ZaMV in New Zealand. Cut flowers are an increasingly important commodity in New Zealand and Zantedeschia is one of the most important crops; in 2005, exports of rhizomes and cut flowers of the genus were worth NZ$10.9 million. These viral diseases may require management to ensure that the quality of production is maintained.