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Occurrence of a Strain of Potato Yellow Mosaic Geminivirus Infecting Tomato in the Eastern Caribbean

Viruslike symptoms were observed in epidemic proportions in tomato, Lycopersicon esculentum Mill., in Guadeloupe and Martinique each year since 1992 and 1993, respectively, and in Puerto Rico since 1994 (1,3). Many tomato fields in Guadeloupe and Martinique had more than 70% of plants expressing symptoms of chlorotic mottling, leaf distortion, leaf rolling, and stunting in 1995 and 1996. The B biotype of Bemisia tabaci (aka B. argentifolii) was associated with all these epidemics. Ninety-three samples of tomato were collected from multiple locations from each island (65 samples from Guadeloupe, 11 from Martinique, and 17 from Puerto Rico) and assayed for the presence of geminivirus by polymerase chain reaction (PCR) with broad spectrum primers, PAL1v1978 and PAR1c496 for the A component, and PBL1v2040 and PCRc154 for the B component (4). Most samples tested positive for geminivirus (98% from Guadeloupe, 100% from Martinique, and 82% from Puerto Rico). Restriction analyses of amplified A component fragment with SacI, EcoRI, and AluI, and amplified B component fragment with EcoRI, AluI, VspI, PstI, and HaeIII were conducted on 34 samples (25 from Guadeloupe, six from Martinique, and three from Puerto Rico). All samples produced very similar restriction patterns, suggesting that they were infected by the same virus. One to three clones of amplified fragments of A and B components, obtained from one plant sample from each location, were at least 98.7% identical in sequence to each other and were 89.6% and 75.2 to 75.7% identical to equivalent regions in potato yellow mosaic virus (PYMV) A and B DNA, respectively (GenBank accession nos. D00940 and D00941). This isolate of PYMV was collected from potato in Venezuela in 1985 (2). Infectious full-length genomic clones of A and B component DNA from Guadeloupe were derived from the same tissue as the PCR-generated clones, and nucleotide sequences were found to be 99.1 and 99% identical to the PCR-generated fragments of A and B DNA, respectively. Nucleotide sequences of these full-length clones were 92.6 and 89.4% identical to full-length sequences of PYMV A and B DNA, respectively. The DNA sequence identity of the common regions of the A and B components between the Guadeloupe virus and PYMV was 95.1 and 91.6%, respectively. There was a nucleotide identity of 93% in the first 125 nucleotides of the coat protein gene. The virus found in Guadeloupe, Martinique, and Puerto Rico appears to be a strain of PYMV reported from Venezuela. This strain of PYMV is at least partially responsible for the epidemics in tomato in Guadeloupe, Martinique, and Puerto Rico. The similarity among geminivirus sequences at distant locations (Puerto Rico to Martinique is approximately 600 km) is unexpected and could be due to recent introductions.

References: (1) J. K. Brown et al. Plant Dis. 79:1250, 1995. (2) R. H. A. Coutts et al. J. Gen. Virol. 72:1515, 1991. (3) B. Hostachy et al. Phytoma 456:24, 1993. (4) M. R. Rojas et al. Plant Dis. 77:340, 1993.