Within the grass family (Poaceae), which includes about 10,000 species, one of the two largest of the twelve subfamilies is the Pooideae, with about 3300 species. This subfamily includes most of the grasses of temperate and boreal regions. Among many other species, it includes wheat, barley, rye, and their relatives of the tribe Triticeae, which has been the focus of intensive study, in terms of its phylogenetic and genomic relationships. The common occurrence of hybridization and polyploidy have been thoroughly documented in this group, in part because of the economic importance of the species in this assemblage. Most species of the subfamily (about 2200) fall within another group, which consists of species formerly assigned to three different tribes (Aveneae, Poeae, and Hainardieae). This group, the APH complex, includes many species of economic importance such as oats, timothy, bentgrass, the fescues, and the bluegrasses. Preliminary data acquired by Prof. Jerrold Davis at Cornell University indicate that the three major tribes previously recognized within the APH complex are intermixed phylogenetically. This suggests that the characters traditionally used to distinguish these groups have arisen in parallel several times or that hybridization among species from different lineages within the group has generated new (possibly polyploid) groups that combine the features of the various parents, as has occurred so frequently in the related Triticeae. In comparison to the Triticeae, the APH group is much larger, and much more poorly known. The main goal of the proposed work is to generate a phylogenetic hypothesis for subfamily Pooideae, with specific attention to the APH complex. To accomplish this, three data sets will be generated and analyzed separately and in combination. The three character sets are a set of linked genes in the plastid genome (ndhF, ndhH, and rbcL), a nuclear-encoded gene (GBSSI), and a structural character set that includes features such as spikelet structure and leaf anatomy. Instances of incongruence among these data sets will be examined to identify evidence of character parallelisms and reversals, and inter-lineage hybridization. One interesting quality of ndhF and ndhH is that they lie near opposite ends of the short single-copy (SSC) region of the plastid genome, near the boundaries of this region with the flanking inverted repeat (IR) regions. In some grasses the 5' end of ndhH extends into the IR region, and thus is duplicated in the genome, while in others the 3' end of ndhF extends into the IR region, and thus is duplicated. In addition to the phylogenetic goals of the work, the distribution of these attributes, the sizes of the duplicated portions, and the dynamics of gene exchange between these regions are topics of research. One of the broader impacts of the proposed work will be the training of undergraduate students, who will be engaged in study of molecular and structural characters of the target group. Also, a website will be developed that will depict the critical structural and anatomical features of the subfamily, and will provide taxon descriptions, data matrices, trees, images, and a classification of the group, with problematic taxa highlighted. The APH group includes numerous species of economic importance, yet, as indicated above, systematic relationships within the group are poorly understood. The species of this group, and of subfamily Pooideae as a whole, are of great interest to investigators in a variety of areas, including genetics, ecology, agronomy, range management, etc., and a website that describes the grasses of this group, and that depicts characteristics of the taxa and relationships among them, will be of interest to many scientists and other persons, and will stimulate additional investigation. Thus, the information generated during the course of the proposed work will be disseminated rapidly to students, professionals, and other persons.
