Pathway and genotypes proposed for Vitis sex evolution. The first mutation must occur in the So gene that gives the male individuals which had as a consequence the appearance of males with viable pollen. Males and hermaphrodites coexist but it was impossible the emergence of females if not occur a second mutation in the Sp gene. Crosses in a mixed population established the dioecy. In blue are the most possible genotypes. Marked in red are other possible genotypes but less likely to occur. So and Sp are two close linked genes.