PHYLOGENETIC ANALYSIS OF THE TRITICEAE (POACEAE) BASED ON RPOA SEQUENCE DATA

A phylogenetic analysis was conducted on 31 diploid species representi ng 21 of the 24 monogenomic genera of the Triticeae. The data used wer e derived from a 1343- to 1358-bp region of the plastid genome spannin g the entire rpoA gene plus minor parts of the petD and rps11 genes an d the two intergenic spacers surrounding rpoA. Bromus inermis (Bromeae ) was used as an outgroup. A total of 68 variable sites, 25 of them ph ylogenetically informative, and seven length mutations were detected. The length mutations occurred in the noncoding regions. Phylogenetic a nalyses were performed on the whole data set and on various subsets. T he analysis of the unweighted data resulted in 48 equally parsimonious trees (length 98, CI = 0.88, RI = 0.92, ti = 0.25). A parsimony jackk nife analysis proved several clades to be well supported. The effect o f transition/transversion weighting was also investigated. In general, congruence with other data sets was negatively effected by weighting. The preferred phylogenetic hypothesis is congruent with a phylogeny b ased on plastid RFLP data including the same taxa, but it is largely i ncongruent with phylogenies derived from nuclear rDNA and morphology. (C) 1997 Academic Press.