Caracterização molecular de um novo begomovirus que infecta Cnidoscolus urens (L.) Arthur.

Abstract

The Geminiviridae family encompasses phytoviruses with a single-stranded circular DNA genome encapsidated in quasi-icosahedral geminated particles and divided into nine genera (Becurtovirus, Begomovirus, Curtovirus, Eragrovirus, Mastrevirus, Topocuvirus, Turncurtovirus, Grablovirus and Capulavirus) based on the range of hosts, insect vector type, genomic organization and phylogenetic relationship. Begomoviruses are transmitted by the Bemisia tabaci cryptic species complex, with wild / uncultivated hosts playing a relevant epidemiological role, acting as reservoirs of these viruses. The present study aimed to detect and characterize Begomoviruses that infect C. urens in the states of Alagoas and Piauí. Leaf samples of C. urens (fatigue), presenting symptoms indicative of begomovirus infection, were collected in the states of Alagoas and Piauí. Total DNA was extracted and used as template for amplification of the viral genomes by rolling circle. These genomes were cloned and sequenced commercially by first walking. To correctly assign taxonomy to the new isolates, we compared paired comparisons of the complete genome with other previously reported begomoviruses. Multiple nucleotide sequence alignments were prepared for the DNA-A, CP and Rep data set that were used for phylogenetic and recombination analyzes. A total of six clones corresponding to DNA-A were obtained from three C. urens samples and the paired comparisons indicated the presence of two begomovirus species: Cnidoscolus mosaic leaf deformation virus (CnMLDV) from samples collected in Alagoas; and a new species for which the name Cnidoscolus blistering yellow mosaic virus (CnBYMV) was proposed, from the sample collected in Piauí. Bayesian phylogenetic trees showed that the isolates obtained were distributed in two large well-supported groups. Group I comprised the species of CnMLDV obtained in the present study, other isolates from the State of Alagoas and the isolate of PSLDV. While group II encompassed the CnBYMV and begomovirus species described in cultivated and uncultivated plants. A recombination event was detected in RC and in the Rep gene, having CnMLDV and SiMoV as likely parental.

Key words: Geminiviridae. Uncultivated plants. Euphorbiaceae. Tense.