Evolutionary Characterization and Genetic Structure of Iranian Isolates of Beet Necrotic Yellow Vein Virus Population Based on p25 Protein

Abstract

To study molecular evolutionary characteristics a nd genetics of beet necrotic yellow vein virus (BNYVV) isolates population from Iran , nucleotide sequences of p25 and coat protein (CP) were determined and the amino acids sequences thus deduced were analyzed using phylogenetic and population genetics methods. A survey of BNYVV in Iran indicated the infection of 288 collected sample s out of 392 samples in most beet growing areas and that most of the isolates (92%) were of the A -type and the rest of isolates (8%) were P -type. Our molecular evolutionary analysis showed that CP was highly conserved but allowed to assign all isolates to three distinct groups. Different parts of p25 coding regions were under different evolutionary constraints. The most positive selection was detected at the position 68, the second amino acid of the tetrad motif. Iranian isolates were found to cluster with European isolates into three distinct clusters based on p25 sequences. Population genetics analysis rev ealed that BNYVV populations have low differentiation (Kt= 3.97145) and low diversity ( π T= 0.006, Hd= 0.860) wi th frequent gene flow indicating lack of phylogeogr aphic structure between populations. Keywords : Evolution, Phylogenetic analysis, Plant virus, Positive selection.