A Bipartite Geminivirus Infecting Tomatoes in Cuba

Whitefly-transmitted geminiviruses have increased in their distribution and importance during the last decade, apparently due to a wider distribution of their vector Bemisia tabaci (Gennadius). In Cuba, symptoms of geminivirus disease have been observed since the early 1990s. A survey of geminivirus-caused diseases in tomato plants has been conducted since 1994 in the province of La Habana. The most severe symptoms were observed in the commercial varieties Campbell 28, Criollo Quivican, and HC 3880. In some plants the Israeli strain of tomato yellow leaf curl geminivirus (TYLCV) was detected (1). In other cases, a viral DNA with a genome size smaller than that of TYLCV that could not be amplified with primers specific for the Israeli strain was also detected by hybridization. In these samples a polymerase chain reaction amplification with broad-spectrum, degenerate primers designed for whitefly-transmitted bipartite geminivirus (2) was carried out. Two fragments of about 1.1 and 0.6 kb, corresponding to components A and B, respectively, were amplified, indicating that a bipartite geminivirus was present. The 1.1-kb fragment amplified from a sample showing strong leaf yellowing and slight curling was cloned and sequenced. A sequence of 1,174 nucleotides was obtained and compared with geminivirus sequences deposited in the GenBank, by multiple alignment (CLUSTAL W, European Bioinformatics Institute, Hinxton Hall, UK). Genetic distances were calculated by Kimura's two parameters method. Percentages of similarities obtained with the sequence were as follows: tomato mottle virus 78%, abutilon mosaic virus 73.8%, and tomato golden mosaic 61.8%. Partial sequences of the open reading frames AL1 and AR1 and the intergenic region were present. Percentages of similarities obtained with the intergenic region were as follows: tomato mottle virus 78.1%, sida golden mosaic virus 63%, bean dwarf mosaic virus 62.6%, abutilon mosaic virus 57.1%, and tomato golden mosaic virus 32%. These results suggest that we have detected in Cuban tomatoes a new bipartite geminivirus related to tomato mottle virus, and we propose that it be named Havana tomato virus. Frequency of distribution of viruses in commercial varieties and their relationship with the presence of whiteflies are currently being studied. References: (1) Y. Martinez et al. J. Phytopathol. 144:277, 1996. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.