Appearance of Tomato yellow leaf curl virus in North Carolina

In the summers of 2000 and 2001, tomato plants (Lycopersicon esculentum) with symptoms of stunting, curling, and marginal chlorosis of leaves, reduced leaf size, and marked reduction in fruit number, similar to those caused by Tomato yellow leaf curl virus (TYLCV), were seen in Henderson County, NC. In 2001, symptomatic plants appeared in a 40-A (18.2 ha) field in 12 foci of ≈12 plants each, at a total incidence of less than 1%. In August 2001, DNA was extracted from leaf samples from four symptomatic plants and tested by polymerase chain reaction (PCR) amplification for the presence of one or more geminiviruses. Two sets of primers were used to test for begomoviruses, AC1048 and PCRv181 (3,4), which amplify a 1,020-bp DNA product from a wide range of monopartite and bipartite (A component only) begomoviruses, and C473 and PTYC1v2406, which preferentially amplifies a 859-bp DNA product from the monopartite TYLCV (1,2). Fragments of the expected size were obtained from all four samples, and all PCR products were sequenced. The sequences of the 1,020-bp PCR product from each of the four samples were compared and found to be 100% identical. The same was found for the 859-bp products. These sequences were compared with equivalent regions of begomoviruses and were identical to sequences of TYLCV. Since the two primer sets amplify overlapping regions of the TYLCV genome, the 1,020 and 859-bp products generated by the two primer sets from one plant were combined to create a 1,464-bp sequence that represented approximately half of the TYLCV genome and encompasses the C4 ORF, the intergenic region, and most of the coat protein gene. This 1,464-bp sequence from North Carolina was 99.2 to 99.6% identical to TYLCV sequences reported from Cuba (GenBank Accession No. AJ223505), the Dominican Republic (GenBank Accession No. AF024715), and Florida, and 96.9 to 98.2% identical to TYLCV sequences reported from the Bahamas, Israel (GenBank Accession No. X15656), Jamaica (GenBank Accession No. U84146), Mexico (GenBank Accession No. AF168709), and Spain (GenBank Accession No. AF071228). Symptomatic plants appeared to be infected with an isolate of TYLCV that is most similar to TYLCV isolates reported from Florida and the northeastern Caribbean. To our knowledge, this is the first report of TYLCV in North Carolina. TYLCV may have been introduced on transplants since the infected plants showed symptoms at an early growth stage. The appearance of infected plants in clusters of limited size suggests no spread or very limited spread in the field. Reports of populations of the whitefly (Bemisia tabaci) vector in the field were not available since whiteflies are not normally a problem in this area due to the higher altitude and relatively cool temperatures characteristic of Henderson County. It is not clear at this time what threat TYLCV poses to tomato production in the county, though its appearance indicates that the geographic range of TYLCV is continuing to expand in the southeastern United States. References: (1) M. Ghanim et al. Virology 240:295, 1998. (2) M. K. Nakhla et al. Phytopathol. Mediterr. 32:163, 1993. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) S. D. Wyatt et al. Phytopathology 86:1288, 1996.