The family tree relationships and geographic history of the grape family (Vitaceae) will be investigated with a comprehensive approach that integrates data from DNA analyses, developmental studies, as well as the structural form and geographic distribution of both living and fossil representatives. Characteristics of flowers, seeds, pollen, leaves, and stems will be compared to show the similarities and differences among living and extinct fossil species. Developmental studies on living plants will clarify how mature form is achieved in species of different genera. This information will be analyzed collectively to provide an improved understanding of the evolutionary history of grapes as well as an optimal classification of grapes and closely related genera and species. The project has great potential to contribute to the understanding on how fossils, extant morphology and molecules can be integrated into evolutionary and biogeographic analysis.
The project uses an economically and culturally significant plant family as a model for integrating many types of systematic data into one study, providing training opportunities for first-generation college students at the University of Northern Iowa, as well as students abroad during field collections. Colleagues from Nepal and China will also be trained in appropriate molecular techniques and data analyses. Findings from this research will be incorporated into outreach programs in place at the Florida Museum of Natural History and the Smithsonian Institution.
Grapes (Vitis) have been well studied from a horticultural production and physiological perspective because of their economic importance. However, for a number of practical reasons such as their location in underexplored regions of the world, most of the approximately 900 species in the grape family (the Vitaceae) have been neglected by botanists. The German botanist Karl Süssenguth wrote the last major treatment of the family in 1953, and no similar overview of the phylogenetic relationships of the species and genera in the family, the fossil history, and biogeography of the family has been published since. Over the past 25 years my lab has been comparing development of some of the morphological characters that are unique to the Vitaceae at comparable landmark stages across different species and genera in order to understand their origin and evolutionary trends. We have concentrated on the unique leaf-opposed tendrils, the nature and timing of the divergence in developmental pathway of the tendrils and inflorescences from their common uncommitted primordium, and leaf and flower development. The first objective of our collaborative research was to use molecular techniques to create a modern phylogeny of the relationships of the Vitaceae. The next objective was to integrate this hypothesis of relatedness with the morphological evidence from fossils and living species. That would allow us to update the classification of genera and species in the family. One of my contributions was to assemble a greenhouse collection of 27 species representing 8 genera of the family. Over the period of this grant I successfully trained three undergraduate students to take responsibility for maintenance of the Vitaceae collection at University of Northern Iowa (UNI). Duplicates are now also in the greenhouse collection at the Smithsonian Institution. Three undergraduate students completed and presented posters either at UNI or the Iowa Academy of Sciences. In 2009-10 Erin Gitchell compared the tendril pads of Cissus tuberosa and Parthenocissus quinquefolia (Vitaceae). She demonstrated that although they may resemble one another macroscopically, the pads of C. tuberosa differ from those of P. quinquefolia in that they are not adhesive and the cellular organization is random, resembling reaction wood described by Esau. It appears likely that this character has arisen more than once in the Vitaceae. Ashley Summers, working with Prof. Marek Sliwinski in a summer 2010 REU project, attempted to investigate the TFL1 gene family in two species of Cyphostemma, one with terminal inflorescences and one with ‘typical’ vitaceous leaf-opposed inflorescences. She achieved only partial success, as the DNA she generated from degenerate primers, although matching Vitaceae genomic DNA, was not homologous to TFL1 genes. We are continuing this research by taking a transcriptome approach, and by broadening the species that we can examine. Benjamin Doughan completed an MS in 2008, comparing leaf initiation and development in the two North American species of Ampelopsis, A. arborea with compound leaves, and A. cordata with simple leaves. As predicted by previous KNOX gene work on the family, early stages are identical, and are typical for leaves that will be compound at maturity. Undergraduate student Austin Jones continued this study during summer 2011 and documented the timing and nature of the divergence in later stage pathways of these two species. This paper is being prepared for submission in summer 2012. MS student Kristi Cooley began comparing inflorescence initiation and development in species of Cyphostemma with different mature shoot architectures, but the project was aborted in 2010 as the result of family pressures. We completed collection of the morphological data for 59 taxonomically useful characters in 47 species representing all genera and clades in January 2012, and are completing the integration of the molecular and morphological data. Currently we are preparing the resulting manuscripts for publication.
