The genus HordeumL. (barley genus) occurs with about 32 species in temperate climates in most parts of the world. Hordeumis divided in four mostly morphologically defined sections. Four basic genomes were described within Hordeumspecies (H, I, X, Y) that, however, do not correspond to the sections of the genus. To elucidate phylogenetic relationships in Hordeum,intron 3 of the nuclear phospholipase D gene was used to analyze species and genome relationships in the genus, together with several closely related outgroup species. The intron sequences provide sufficient informative positions to analyze species relationships, making phospholipase D a suitable nuclear marker gene for phylogenetic inference.

Key words: Hordeum, phospholipase D, Phylogenetic analysis, PLD, Poaceae