This project will examine evolutionary relationships among the so-called "spiny Solanums," a group of about 450 species of plants in the Solanaceae (tomato or potato family). Included within this group are economically important fruit crops such as the eggplant (Solanum melongena), the lulo or naranjilla (S. quitoense), and the cocona (S. sessiliflorum) as well as species with potential as sources of glycoalkaloids useful in medicine. The spiny Solanums exhibit much variation in their morphology and reproductive biology and show intriguing biogeographical patterns through the tropics. Despite their potential as economic crops and their use as model systems for the study of biological questions, the taxonomy and phylogeny of the spiny Solanums have been neglected. The primary data for the phylogenetic analyses will come from DNA sequencing of three genes or gene regions, with measures of mutational differences used to define major lineages within the spiny Solanum group. Sequences will be obtained from the nuclear ribosomal and waxy genes and from chloroplast gene regions, from exemplar species samples representing as much of the taxonomic diversity of the group as possible. These data sets will be analyzed separately and in combination to achieve an overall view of evolutionary relationships within the spiny Solanums. Collecting trips to Mexico and Ecuador are planned to gather material for morphological and molecular analyses, in collaboration with local botanists. More detailed sampling will taxa place in two focal groups, the S. mammosum and S. quitoense groups, in order to clarify relationships at the species level and examine evolutionary patterns of floral biology, biogeography, and fruit chemistry and morphology. This project will contribute to teaching and learning by employing post-doctoral associates and undergraduate students who will be trained in taxonomy, molecular methods, and data analysis. Substantial national and international collaboration will result through foreign collecting and herbarium trips and interaction with Solanaceae specialists in the U.S. and abroad. This project will generate extensive DNA sequence data as well as herbarium collections, leaf and DNA samples, and germplasm accessions that will be distributed to international repositories and available for wide dissemination. The scientific information gathered as part of this project is expected to impact humankind by increasing the agronomic potential of important or emerging crop species such as the eggplant, lulo, and cocona and by contributing to conservation of germplasm of economically useful plants.
