Caracterização molecular de begomovírus associados a Sida spp. E Blainvillea rhomboidea

Abstract

Begomoviruses are whitefly-transmitted, single-stranded DNA viruses which are often associated with weed plants, which may act as natural reservoirs of viruses that cause epidemics in crop plants. The aim of this study was to characterize the diversity of begomoviruses infecting weeds in Brazil, as a step to access their importance as natural reservoirs of these viruses. Total DNA was extracted from weeds collected in Viçosa (Minas Gerais state) and some municipalities of Alagoas state in 2009 and 2010. The viral genomes were amplified by RCA, cloned and sequenced. The sequences were used for comparisons with other begomoviruses, phylogenetic and recombination analyses. A total of 26 DNA-A clones were obtained. Sequence analysis indicated the presence of ten different begomoviruses. All isolates originating from samples of Blainvillea rhomboidea belonged to a single viral species, Blainvillea yellow spot virus (BlYSV), suggesting that BlYSV may be the only begomovirus present in this ubiquitous weed species. Four viruses represent new species, for which the following names are proposed: Sida yellow net virus (SiYNV) obtained from Sida micrantha, Sida mottle Alagoas virus (SiMoAV) obtained from Sida urens and Sida sp., Sida yellow blotch virus (SiYBV) and Sida yellow mosaic Alagoas virus (SiYMAV) obtained from S. urens. Recombination events were detected in the SiYBV isolates BR:Rla1:10 and BR:Rla2:10, with BR:CPH1:10 (also SiYBV) and an unknown virus as putative parents, and in the SiYNV isolate BR:Vic2:10, with BR:Vsa2:10 (SiMoAV) and Sida mottle virus (SiMoV) as putative parents. These results consitute further evidence that recombination is an important evolutionary process on the generation of genetic variability and on the evolution of begomoviruses.