TOMATO YELLOW VEIN STREAK VIRUS, A NEW BEGOMOVIRUS ON TOMATO FROM BRAZIL: COMPLETE DNA-A SEQUENCE AND SOME MOLECULAR AND BIOLOGICAL FEATURES

In recent years a high incidence of begomoviruses has been reported in different regions of Brazil causing severe losses to tomato crops. In order to study the distribution of begomovirus species in São Paulo State, periodical sampling was undertaken in tomato-growing areas from different municipalities. Plants showing stunting, foliar yellow vein streak, mosaic and malformation were used for sap inoculations, whitefly transmission, electron microscope observations, and DNA extraction, followed by PCR using universal primers for the genus Begomovirus. The fragments amplified were sequenced and compared with other geminivirus sequences in the GenBank. Tomato yellow vein streak virus (ToYVSV) and Tomato rugose mosaic virus (ToRMV) were identified in our samples. Phylogenetic analysis based on the 5' end of the coat protein gene showed a cluster including the ToYVSV isolates. All isolates in the two species identified were whitefly-transmitted, whereas only the ToYVSV isolates from Campinas were also mechanically transmitted. After complete DNA-A component sequencing and comparison with other geminivirus species, the ToYVSV isolate from Monte Mor, SP, was confirmed as a new begomovirus species closely related to Tomato golden mosaic virus (TGMV).