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Susan Singer
Susan Singer
Department Biology
Carleton College

Research Interests:

My lab is focused on the development and evolution of inflorescence architecture in legumes. A common toolkit of flowering genes is used in different ways to create diverse morphologies that can dramatically affect reproductive success. How are orthologs of Arabidopsis inflorescence architecture genes used in the development of pea inflorescences? A long history of the study of transmission genetics in pea has yielded many developmental mutants that alter flowering. We use this resource and the cloned flowering genes in Arabidopsis to continue a candidate gene approach to identifying key regulatory genes in pea shoot architecture formation.

The current focus in the lab is on three meristem identity genes with redundant function. PIM is the pea ortholog of AP1 in Arabidopsis (Taylor et al., 2002). It regulates floral meristem identity and has a small affect on bract suppression of second order inflorescence branches. COCH affects vegetative and reproductive development, including symmetry of stipules, floral meristem identity, and pod morphology. Floral meristems cannot be inititated in coch w pim-1, emphasizing the critical importance of these two genes in flowering. Phenotypes of six mutant alleles of COCH have many similarities to FUL mutants in Arabidopsis. Vivian Irish and Amy Litt are investigating the molecular evolution of AP1 genes and the closely related family of FUL MADS box genes. We are characterizing the pea ortholog of FUL and asking if it is COCH.

My lab also works on Chamaecrista fasiculata, a basal legume. Progress on the Medicago truncatula genome project holds much promise for work on the evolution of development in legumes. Substantial synteny among legume genomes will aid in our identification of conserved inflorescence genes and exploration of their roles in novel morphologies. Chameacrista is one of the legume species that is being used in comparative mapping efforts. Coupled with the extensive population genetics/evolution studies on Chameacrista from other labs, we believe this herbaceous prairie plant will prove an exciting complement to work on the more highly derived crop species. For example, pim plants have atavistic traits, including bracteoles found in Chameacrista. We are interested in understanding how this highly conserved MADS box gene functions in Chameacrista.

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