Genetic diversity analysis of the coat protein gene revealed strong evolutionary constraints on Ornithogalum mosaic virus

Ornithogalum mosaic virus (OrMV) has a wide host range and affects the production of a variety of ornamentals. In this study, the coat protein (CP) gene of OrMVwas used to investigate the molecular mechanisms underlying the evolution of this virus. The 36 OrMV isolates fell into two groups which have a significant subpopulation differentiation with an F ST value of 0.470. One isolate was identified as a recombinant and the other 35 recombination-free isolates could be divided into two major clades under different evolutionary constraints with ω -values of 0.055 and 0.028, respectively, indicating a role of purifying selection in the differentiation of OrMV. In addition, the results from molecular variance of analysis (AMOVA) indicated that the effect of host species on the genetic divergence of OrMV is greater than that of geography. In BaTS analysis, OrMV isolates from the genera Ornithogalum, Lachenalia , Diuri tended to group together, indicating that OrMV diversification was maintained, in part, by host-driven adaptation. Furthermore, age calculations suggested that the first divergence event of the OrMV isolates analyzed might take place around 1068 BC.