The sexual determination system in Salix L. (Salicaceae)

Abstract

Current knowledge of the sex determination system that has been analyzed in different species of the genus Salix L.is reviewed. In this genus, sexual chromosomes have been recognized and it was proposed that a gene for sexual determination must be present. In the genus Salix there are two systems of sexual determination: one in which the homogametic system is female and the heterogametic is male (XX/XY system) and another in which the homogametic system is male and the heterogametic is female (ZZ/ZW). The evidence is analyzed in relation to phylogenetic considerations and the need to include the analysis to species of other subgenera is raised. The role of the determination system in the hybridization of species with a mixed determination system is discussed, while it is suggested that this characteristic be investigated in the rest of the members of Salicaceae. Both sex determination systems (SDSs) are found in Salix and are of phylogenetic importance because each type of system is found in different phylogenetic groups. The SDS can influence the expression of the sexes in individuals, especially in polyploid species, and at a population level by influencing the sex ratio related to ploidy levels.