Phylogenetic reconstruction of the genus Branchypodium P-Beauv. (Poaceae) from combined sequences of chloroplast ndhF gene and nuclear ITS

A phylogenetic reconstruction of eight species of the genus Brachypodium P. Beauv. (Poaceae) has been obtained combining sequence data from the chloroplast ndhF gene and the nuclear ITS, and using five representatives of tribes Triticeae (Secale), Poeae (Lolium), Meliceae (Melica, Glyceria) and Oryzeae (Oryza) as outgroups. Similar numbers of informative substitutions for the ingroup species were provided by both the 3' region of the chloroplast ndhF gene and the nuclear ITS region. The Mediterranean annual Brachypodium distachyon appears to be the basal lineage, followed by the divergence of the New World non-rhizomatous B. mexicanum, which antedates the separation of a core of six European and Eurosiberian rhizomatous perennials (Brachypodium arbuscula, B. retusum, B. rupestre, B. phoenicoides, B. pinnatum, and B. sylvaticum). The evolutionary reconstruction based on sequences of the chloroplast and the nuclear genomes is congruent with topologies obtained from analysis of RAPD data.