Body of Abstract: Ranunculaceae is a highly diverse basal eudicot family which exhibits extreme diversity in floral form. One aspect of diversity of Ranunculaceae flowers is diversity of the second whorl organs, or petals. Petalous and apetalous species are found alongside one another scattered throughout the Ranunculacea phylogeny, while petalous species exhibit further diversity still in the morphology of their petals. Despite their striking morphologies, petals of Ranunculaceae are believed to be homologous organs, with the exception of Clematis petals, which were re-evolved from outer stamens of an apetalous ancestor. In core eudicots, petal development is specified by the overlapping functions of A-class and B-class genes, as described by the ABC model of floral development. In Ranunculaceae there are 3 paralogs of the B-class gene AP3, and petals are specified by APETALA3-3 (AP3-3), strong knockdowns of which result in complete petal to sepal transformation. Additionally, Ranunculaceae nectaries seem to be specified by the STYLISH gene family.
Aside from these major petal and nectary identity genes, our understanding of Ranunculaceae petal development is limited. Studies in Aquilegia and Nigella have revealed a more detailed picture of petal development in these taxa, but how conserved these developmental genetic pathways are throughout Ranunculaceae is unknown. I am investigating these developmental underpinnings of Ranunculacee petals. Petal development must involve A-function genes, so I am working to identify and characterize A-function genes in Aquilegia. To obtain a more wholistic view of petal development, I will assess the expression of candidate genes in Ranunculaceae, with further detailed expression and functional analysis based on these results.