Determinação da estrutura genética da metapopulação global dos begomovírus com base no DNA-B

Abstract

Begomoviruses are divided into two major phylogenetically distinct groups: those from the Americas (known as New World begomoviruses) and those from Europe, Asia, Africa, and Oceania (known as Old World begomoviruses). Their genomes may be composed of one or two single-stranded circular DNA molecules called monopartite or bipartite begomoviruses, respectively. Bipartite begomoviruses have genomic components known as DNA-A and DNA- B. The first one contains genes involved in replication and viral encapsidation, while the second one possess genes associated with short- and long-distance movement and symptom expression. Begomovirus populations show high genetic variability, mainly due to high nucleotide substitution rates and the frequent occurrence of recombination. Detailed knowledge about the genetic structure of the global metapopulation of these viruses might provide important information about their epidemiology and evolution. However, no work has been conducted to determine the genetic structure of the global metapopulation based on DNA-B sequences. Thus, the objective of this work was to determine the genetic structure of begomoviruses metapopulation based on complete DNA-B sequences, as well as to contrast the subpopulations determined from their two coding sequences. To infer the composition of the major begomovirus subpopulations, multiple sequence alignments were analysed using the Discriminant Analysis of Principal Components (DAPC). Were simulated two, five and nine viral subpopulations (K = 2, 5 and 9; respectively) using K-means. The begomoviruses might be subdivided into subpopulations that reflected the geographic barriers that restrict gene flow amongst viruses from different (sub)continents. These results indicate that similar to the DNA- A-based analyses, the DNA-B sequences also show strong geographical structuring signal.