The plant genus Prunus (subfamily Amygdaloideae of family Rosaceae) comprises roughly 200 species of trees and shrubs and includes many of the most economically important fruit and nut crops of temperate regions, such as plums/prunes, peaches, cherries, and almonds, as well as many ornamental species and numerous wild species of ethnobotanical importance because of their uses for food, timber, and medicine. Species of Prunus exhibit great morphological diversity of vegetative and reproductive structures. The genus is distributed throughout the north temperate regions of the world and also includes representatives in tropical regions of Asia and America. Recent molecular phylogenetic studies across Rosaceae and within Prunus have raised questions about the traditional circumscription of subfamily Amygdaloideae and have suggested that a revised classification for Prunus is needed. Moreover, species delimitation throughout Prunus is notoriously poorly understood, and no previous systematic study has included adequate representation of the Pygeum group, a group of about 40 species of the Old World tropics. This project is a comprehensive systematic study of Prunus, the specific objectives of which are: 1) to increase collections of herbarium specimens and material for DNA extractions of 60-80 species of Prunus from tropical Asia and America; 2) to reconstruct phylogenetic relationships across Prunus based on nucleotide sequence data from several regions of the nuclear and chloroplast genomes, while also helping to resolve the relationship of Prunus to other genera in Rosaceae; 3) to examine the evolution of morphological characters within the phylogenetic framework; 4) to infer the historical biogeography of Prunus and to compare it to several other well-supported clades within Rosaceae with distributions in the Old and New Worlds in order to assess whether or not there are recurrent biogeographic patterns in the family; 5) to propose a new phylogenetically based infrageneric classification for Prunus; and 6) to revise the taxonomy of the 50-60 tropical Asian species of Prunus, including all species currently classified in the Pygeum group. The project, a collaborative effort coordinated by Dr. Dan Potter (University of California-Davis) with colleagues Dr. Jun Wen (Smithsonian Institution) and Dr. Joey Shaw (University of Tennessee - Chattanooga), will provide a rigorous modern systematic study and new taxonomic treatments for a large, taxonomically complex and economically important genus of flowering plants performed by a team of researchers with complementary expertise and extensive experience with the group. The project's broader impacts include its relevance to germplasm conservation in this economically important group, training of a Southeast Asian graduate student and a U.S. postdoctoral fellow, and development of a short course in molecular systematics to be offered by the investigators at Herbarium Bogoriense in Indonesia. Results of the project will be disseminated via scientific publications and through internet databases and websites, including contributions to GenBank, detailed taxonomic information for other botanists, and materials on Prunus evolution and systematics intended for educators, students, and horticulturists. Data generated by these studies will be valuable to an international consortium of plant geneticists who are developing peach, Prunus persica, as a model for genomic studies in Rosaceae.
