Résumé
A sample from a tomato plant which showed mottling, stunting, and leaf deformation was collected in October 1995, from Guadeloupe from an open-sided planthouse in which all the tomato plants present showed symptoms typical of virus infection. DNA was extracted from the sample and amplified with degenerate primers, pAR1c496 and pAL1v1979 (Rojas et al., 1993). Two bands were obtained, one of 1169 bp and the other approximately 1310 bp. The 1169 bp fragment was cloned, sequenced and determined to be a strain of Potato yellow mosaic virus (PYMV). The 1310 bp fragment was cloned, sequenced, and appeared to be unique. A single fragment was amplified with pBL1v 2042 and pCRc154 (580 bp fragment) and determined to be the B component of PYMV. An infectious clone (2741 nt) was obtained from a DNA extract made from the plant sample. The clone was sequenced, initially with degenerate primers and completed with specific primers. The sequence was compared with 7 known geminiviruses, Abutilon mosaic virus, Beet curly top virus, Pepper huasteco virus, Potato yellow mosaic virus, Tomato mottle virus, Tobacco yellow dwarf virus, Tomato yellow leaf curl virus, and Tomato yellow leaf curl virus Sar. The sequence for the orf V1 (coat protein, Cp) fell within the range expected for a begomovirus. The C1 (Rep) region, the V1 (cp) region, and intergenic region (Ir) had greatest homology with Tomato mottle virus (ToMoV), 88%, 86%, and 82% sequence identity, respectively. The clone was biolistically inoculated into Nicotiana benthamiana and tomato Lycopersicon esculentum 'Florida Lanai' with both the A and B components of PYMV, together and separately to determine if the virus was able to replicate independently. The virus clone was able to establish an infection in N. benthamiana and tomato that were inoculated with the clone alone, and in combination with clones of PYMV-A, PYMV-B, and PYMV-A plus PYMV-B. These results demonstated that the infectious clone was that of a monopartite begomovirus. Tissue from the monopartite virus-infected N. benthamiana was grafted to 'Florida Lanai' tomatoes to successfully transmit the virus. In addition, the clone of the monopartite virus was able to infect tomato by biolistic inoculation both alone and in combination with PYMV (as in N. benthamiana). The symptoms produced in N. benthamiana were leaf mottling, upward leaf curling, severe chlorosis, and stunting. The symptoms on 'Florida Lanai' tomato were stunting, leaf curling, and flower abscission and were similar to those of Tomato yellow leaf curl virus. Infection was confirmed in both N. benthamiana and tomato using monopartite specific primers. This is the first report of a monopartite begomovirus from the New World. (Texte intégral)