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Macroptilium yellow mosaic virus, a New Begomovirus Infecting Macroptilium lathyroides in Cuba

Macroptilium lathyroides (L) is a weed that is widely distributed in Cuba. Frequently, leaves show bright yellow mosaic symptoms, which suggest the incidence of a viral disease. Since begomovirus occurrence in Macroptilium lathyroides has been previously reported in other islands of the Caribbean (1,3), symptomatic plants from three distant places in Cuba (Havana, Villa Clara, and Camaguey), were collected and tested for the presence of begomoviruses. Plant DNA extracts were analyzed by Southern blot hybridization and polymerase chain reaction with two sets of degenerate primers (2). The presence of a bipartite begomovirus was evident through strong hybridization signals obtained with the DNA-A and DNA-B of Taino tomato mottle virus as probes at low stringency. Furthermore, 1.4-kb and 1.2-kb PCR amplified fragments were obtained with DNA-A degenerate primers, PAL1v1978-PAR1c715 and PAL1c1960-PAR1v722, respectively. Both PCR fragments from the samples from the three locations were cloned, and restriction fragment length polymorphism analysis of the 1.4-kb fragments were performed using PstI, EcoRI, HincII, XbaI and BglII. Restriction fragment patterns were the same for the three clones. The DNA-A sequence (GenBank Accession No. AJ344452) of the isolate from Villa Clara was compared with sequences available for other geminiviruses using CLUSTAL program. For the coat protein (CP) gene, the comparisons had the highest percentage of identity with various strains of Bean golden yellow mosaic virus (BGYMV, GenBank Accession Nos. AF173555, M91604, and L01635) (85 to 87% and 93 to 94%, nucleotide and amino acid sequences, respectively). For Rep gene (1,044 nt), the best percentages of identities were with BGYMV (81 to 82% and 80 to 82% nucleotide and amino acid sequences, respectively), Tomato leaf crumple virus (GenBank Accession No. AF101476) (78 and 81%, nucleotide and amino acid sequences, respectively), and Sida golden mosaic virus from Florida (GenBank Accession No. AF049336) (78 and 79%, nucleotide and amino acid sequences, respectively). Finally, the comparative analysis of the intergenic region (i.e. the common region plus the CP gene promoter) had the highest identity with BGYMV (56 to 55%) and Tomato severe rugose virus (GenBank Accession No. AY029750) (49%). Interestingly, this virus has in this region the three G-box elements that are characteristic of BGYMV but it differs in the Rep protein-binding iterative motif that is GGTGA instead of GGAGA, for BGYMV. These data indicate that this virus is a new begomovirus and the name of Macroptilium yellow mosaic virus (MaYMV) is proposed.

References: (1) A. M. Idris et al. Plant Dis. 83:1071, 1999. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993. (3) M. E. Roye et al. Plant Dis. 81:1251, 1997.