XVI International Botanical Congess

Bouteloua s.l. includes 57 species most diverse in Mexico and the southwest U.S. One of the most striking features of the group is the presence of 15 taxa with unisexual spikelets, with sexual forms including dioecy, monoecy, andromonoecy, and gynodioecy. Molecular phylogenetic studies using the ITS and trnL-F regions suggest that unisexual spikelets have evolved multiple times. The sex determination gene Ts2 from maize is currently being examined to determine what role it might have played in evolution of unisexual spikelets in Bouteloua. We have begun to obtain DNA sequences for orthologous copies of Ts2 for several members of Bouteloua. The sequences are variable within the group indicating the potential phylogenetic utility of this gene. A preliminary analysis resulted in a phylogeny congruent with those from the ITS and trnL-F regions.