Tomato yellow leaf curl virus (TYLCV), a member of the family Geminiviridae, is a serious production constraint to tomato worldwide. In the new world, the virus had been identified as the causal agent of tomato yellow leaf curl disease in the Caribbean countries of the Dominican Republic, Cuba, and Guadeloupe and also in Florida and the Yucatan Peninsula (1). Molecular data from these TYLCV isolates identified the virus as the TYLCV prototype from Israel. During April 2004, tomato plants showing symptoms such as chlorotic leaf edges, upward leaf cupping, leaf mottling, and reduced leaf size indicative of TYLCV were observed in commercial fields in Zulia state, Venezuela. Whiteflies (Bemisia tabaci Gennadius) were present in the field and appeared to be associated with the disease. Leaf samples from nine symptomatic plants were collected and brought to the lab at Instituto Venezolano de Investigaciones Científicas (IVIC) for further analyses. Geminivirus infection of samples was confirmed by PCR amplification with the degenerate primer pair PAL1v1978 and PAR1c494 (2). TYLCV coat protein gene-specific primers KL04-06_TYLCV CP F and KL04-07_TYLCV CP R (3) were used to confirm the diagnosis. These primers amplified the expected 842-bp PCR product from the nine symptomatic samples. One of the resulting amplicons was cloned into the pCR-TOPO vector (Invitrogen, Carlsbad, CA) and sequenced (GenBank Accession No. DQ302033). Sequence comparison with those available in the NCBI database indicated that the sequenced portion of the genome shared 99% nucleotide identity with the TYLCV mild strain from Portugal (GenBank Accession No. AF105975) and 98% nucleotide identity with the TYLCV mild strain from Spain (GenBank Accession No. AF071228), TYLCV Israel isolate (GenBank Accession No. AM234066), and TYLCV Mexico isolate (GenBank Accession No. DQ631892). To our knowledge, this is the first report of TYLCV infecting tomato crops in South America. Further studies are needed to clarify how TYLCV has been introduced into Venezuela. References: (1) J. E. Polston and P. K. Anderson. Plant Dis. 81:1358, 1997. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993. (3) K. S. Ling et al. Plant Dis. 90:379, 2006.

We report the complete nucleotide sequence of a begomovirus isolate infecting Euphorbia heterophylla and tomato (Solanum lycopersicum) in central Venezuela. Based on the current taxonomic criteria for the genus Begomovirus, the isolate was shown to represent a novel species, tentatively named Euphorbia mosaic Venezuela virus (EuMVV). Its DNA-A is most closely related to those of Euphorbia-infecting begomoviruses from the Caribbean and Central America. The DNA B component forms a phylogenetic cluster with Euphorbia and Sida-infecting begomoviruses from the squash leaf curl virus (SLCV) cluster. EuMVV is transmissible to S. lycopersicum and Capsicum annuum by biolistics of infectious cloned DNA-A and DNA-B components and induces characteristic leaf downward curling and yellowing in S. lycopersicum and and yellowing and leaf distortion in Capsicum annuum.

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Virus isolate T217L was obtained from a diseased tomato (Solanum lycopersicum) plant showing leaf deformation and chlorotic mottle symptoms near Maracaibo in the state of Zulia, Venezuela. Full-length DNA-A and DNA-B molecules of T217L were cloned and sequenced. The genome organization of T217L was identical to the bipartite genomes of other begomoviruses described from the Americas. Characteristic disease symptoms were reproduced in S. lycopersicum and Capsicum annum plants inoculated using the cloned viral DNA-A and DNA-B components, confirming disease aetiology. A sequence analysis of DNA-A showed that the T217L isolate has the highest sequence identity (84%) with sida yellow mosaic Yucatan virus (SiYMYuV), sida golden mosaic Honduras virus (SiGMHV) and bean dwarf mosaic virus (BDMV) isolates. This is less than the 89% identity in the DNA-A component that has been defined as the threshold value for the demarcation of species in the genus Begomovirus. The molecular data show that isolate T217L belongs to a novel tentative begomovirus species, for which the name tomato chlorotic leaf distortion virus is proposed. TCLDV was also detected in symptomatic C. chinense plants growing near the T217L-infected plant.

Gerbera (Gerbera jamesonii) and Chrysanthemum (family Asteraceae) are two of the top 10 cut flowers of the world, with great commercial value. Since 1998, Venezuela began a floral industry to produce and export fresh cut gerbera and chrysanthemum, with 40% of nurseries concentrated in Altos Mirandinos (Miranda State, north central region of the country). For the past 2 years, greenhouse-grown gerbera and chrysanthemum have been observed displaying symptoms resembling those associated with tospoviruses. Symptomatic plants showed concentric rings, irregular chlorotic blotches, and deformation on leaves. Disease incidence was estimated at 30%. Mechanical inoculation with extracts of symptomatic leaves reproduced the typical concentric ring symptoms on indicator plants Arachis hypogaea L. cv. San Martín, Capsicum chinense, and G. jamesonii 6 to 15 days after inoculation. In initial tests, leaves from each 30 symptomatic gerbera and chrysanthemum species from several greenhouse facilities in Altos Mirandinos reacted positively when tested by DAS-ELISA with polyclonal antisera (ATCC, Rockville, MD) raised against Tomato spotted wilt virus (TSWV). Total RNA was extracted with the RNeasy Plant Mini kit (QIAGEN, Hilden, Germany) from two gerbera and two chrysanthemum ELISA-positive samples. The TSWV coat protein gene was amplified by conventional reverse transcription (RT)-PCR using primers CP1 TSWV (TTAACTTACAGCTGCTTT) and CP2 TSWV (CAAAGCATATAAGAACTT) (1). A single DNA product of ~823 bp was amplified from all samples. RT-PCR products were directly sequenced in both orientations and sequences were deposited in GenBank (Accession Nos. KF146700 and KF146701 derived from chrysanthemum, KF146702 and KF146703 derived from gerbera). The resulting sequences showed over 99% identity with each other. and were found to be closely related (over 99%) with TSWV isolates deposited in GenBank originating from different hosts from France (FR693058, FR693055), Montenegro (GU339506, GU339508, GU355940), Italy (HQ830187), New Zealand (KC494501), South Korea (KC261967), and the United States (AY744476). To our knowledge, this is the first confirmed report of TSWV infecting gerbera and chrysanthemum in Venezuela. The relatively widespread occurrence of TSWV in Miranda State underscores the need for systematic surveys to assess its incidence and impact on ornamental crops so that appropriate management tactics can be developed. Reference: (1) R. A. Mumford et al. J. Virol. Methods 57:109, 1996.