ناحیه مدیترانه‌ای پالئارکتیک و هلال حاصلخیز پیش مرکز تنوع و تکامل تریتیموویروس‌ها در جهان

The genus Tritimovirus is a member of the family Potyviridae, primarily known for infecting graminaceous plants. This genus currently comprises six recognized species, with the Wheat streak mosaic virus (WSMV) as the type species, Oat necrotic mottle virus (ONMV), Brome streak mosaic virus (BStMV), Wheat Eqlid mosaic virus (WEqMV), Yellow oat grass mosaic virus (YOgMV), and Tall oat grass mosaic virus (TOgMV). Members of the genus Tritimovirus are characterized by their flexible filamentous particles and the formation of pinwheel inclusion bodies within the cells of infected hosts. Their mode of transmission involves polyprotein production and transmission by eriophyid mites. It is important to note that the genus Tritimovirus represents a natural monophyletic group. While WSMV has a relatively broad host range, other tritimoviruses typically exhibit a more limited host range. Phylogenetic analyses based on complete nucleotide sequences indicate that ONMV is the closest relative to WSMV, although they share a poor serological relationship. Despite significant biological differences, both viruses appear to have undergone similar evolutionary processes and selective pressures, particularly in the evolution and divergence of the ONMV strain and a divergent Mexican strain of WSMV known as El Batan 3. As a result, they share a common evolutionary history, although ONMV has already diverged. Beyond WSMV, other tritimoviruses tend to associate with wild wheat plants, whereas WSMV has largely adapted to cultivated wheat, particularly its ancestral forms. WSMV has a long history of co-evolution with wheat. In phylogenetic trees, BStMV and WEqMV cluster together, as do TOgMV and YOGMV, reflecting their similarities in biological properties and host ranges. It is hypothesized that both BStMV and WEqMV likely originated from Bromus species, with subsequent transfer of WEqMV to wheat. The Mediterranean basin may serve as the origin of tritimoviruses. Reports indicate that WEqMV has been identified in Fars Province (Iran), BStMV in Germany and France, and ONMV in Germany, Turkey, Canada, and the United States. Current data suggest that WSMV and other tritimoviruses originated in the Fertile Crescent or the Palearctic Mediterranean region and subsequently dispersed radially to other areas. Understanding the origin and evolution of these viruses may provide insights for discovering other potential species and sources of resistance against them.