Evolutionary Characterization and Genetic Structure of Iranian Isolates of Beet Necrotic Yellow Vein Virus Population Based on p۲۵ Protein

To study molecular evolutionary characteristics and genetics of beet necrotic yellow vein virus (BNYVV) isolates population from Iran, nucleotide sequences of p۲۵ 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 ۲۸۸ collected samples out of ۳۹۲ samples in most beet growing areas and that most of the isolates (۹۲%) were of the A-type and the rest of isolates (۸%) 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 p۲۵ coding regions were under different evolutionary constraints. The most positive selection was detected at the position ۶۸, the second amino acid of the tetrad motif. Iranian isolates were found to cluster with European isolates into three distinct clusters based on p۲۵ sequences. Population genetics analysis revealed that BNYVV populations have low differentiation (Kt= ۳.۹۷۱۴۵) and low diversity (πT= ۰.۰۰۶, Hd= ۰.۸۶۰) with frequent gene flow indicating lack of phylogeographic structure between populations.

Keywords:

Evolution , Phylogenetic analysis , Plant virus , Positive selection