Geographic distribution of Vrn-genes in landraces and improved varieties of spring bread wheat

Summary A study of the global Vrn-genes distribution supports the hypothesis that these loci have different breeding values. Evident zonal differences were discovered in percentage of dominant Vrn-genes and genotypes between the sets of varieties from various locations. For the same zone analogous differences were not so manifested between the sets of local and improved varieties. It showed the similar environmental fitness of those sets as a result of natural or artificial selection. Obvious changes in distribution of Vrn-genes were discovered in the history of breeding. Within this century the dominant Vrn3 was introgressed into many modern varieties of countries close to the equator. The main direction of such introgression ran from the Japanese landrace Akakomugi to Italian varieties. Later it came from Italy through Mentana to Mexican semidwarf varieties, and the last ones (especially Sonora 64 and Lerma Rojo 64) promoted wide distribution of that gene all over the world.