Dissertation Research: Genetic Architecture of Flower-color Differences in Ipomoea Species

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Flower color is an important ecological trait because it is used by plants to attract pollinators. Differences in flower color between species of Ipomoea (morning glories) will often lead to the presence of different sets of pollinators and a lack of pollen exchange. In order to understand the genetic basis for differences in flower color, one can study the major biosynthetic genes that produce flower pigments. Differences in these genes should be manifest as differences in DNA sequence, expression level, or expression time. A combination of crossing studies, DNA sequencing, and gene expression assays will be used to identify the gene or genes responsible for flower differences between two closely related species of Ipomoea: the white-flowered I. lacunosa and the purple-flowered I. triloba. The number and type of mutations fixed during adaptive evolution is a long-standing question in biology. Recent work has suggested that, contrary to longstanding views, only a few mutations of large effect may be involved in adaptation. Furthermore, with increasing evidence of the conservation of most proteins over long time periods, it has been suggested that important mutations may occur primarily in regulatory sequences. In order to address these issues, the genetic basis of flower color differences between I. lacunosa and I. triloba will be examined.