Molecular Characterization of a Distinct Tomato-Infecting Begomovirus Associated with Yellow Leaf Curl Diseased...

Three distinct tomato-infecting begomoviruses have been identified from Indonesia (GenBank Accessions Nos. AB100304, AB100305, and DQ083765). Severe yellow leaf curl epidemics have been observed on tomato on Java Island since the late 1990s. Viral DNA was extracted (2) from one such sample collected in Lembang, West Java in 1998. Polymerase chain reaction with previously described primers was used to detect the presence of geminiviral DNA-A (4), DNA-B (3), and associated satellite DNA (1). The predicted 1.4-kb DNA-A fragment was amplified with the general primer pair PAL1v1978/PAR1c715 and then cloned and sequenced. DNA-B and satellite DNA were not detected in the sample. On the basis of the partial DNA-A sequences, specific primers were designed to amplify and sequence the complete DNA-A component (2,762 nucleotides, GenBank Accession No. AF189018). The DNA-A sequence contained the geminivirus-conserved nanosequence TAATATTAC in the loop of the hairpin structure of the intergenic region and six open reading frames including two in the virus sense and four in the complementary sense. Pairwise comparison of the full-length DNA-A sequence with those of other begomoviruses available in the GenBank database was done by the MegAlign software (DNASTAR, Inc, Madison, WI). Highest nucleotide sequence identity (74.1%) was with Tomato leaf curl Mayotte virus-[Kahani] (GenBank Accession No. AJ865340). Comparison of the full-length DNA-A sequence with the three above mentioned tomato-infecting begomoviruses from Indonesia also showed less than 71% nucleotide sequence identities. Because the DNA-A sequence had less than 89% identity with other begomoviruses, it should be classified as a distinct virus according to the International Committee on Taxonomy of Viruses. The name Tomato yellow leaf curl Indonesia virus-[Lembang] (TYLCIDV-[Lem]) is proposed. The presence of at least four distinct tomato-infecting begeminiviruses on Java Island needs to be considered when developing tomato cultivars with stable resistance to tomato (yellow) leaf curl disease. References: (1) R. W. Briddon et al. Virology 312:106, 2003. (2) R. L. Gilbertson et al. J. Gen. Virol. 72:2843, 1991. (3) S. K. Green et al. Plant Dis. 85:1286, 2001. (4) M. R. Rojas et al. Plant Dis. 77:340, 1993.