Functional Genomics of Nectar Production in Brassicaceae

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An organ known as the floral nectary is responsible for producing nectar in many plant families. Despite its central role in plant pollination, very little is known about the molecular mechanisms of nectar synthesis and secretion. Indeed, no genes have been shown to directly affect the production or quality of floral nectar. The overall goal of this project is to identify key genes and cellular processes required for nectar production in the agriculturally important Brassicaceae family. In previous studies, seventy genes from the model plant Arabidopsis thaliana were shown to be expressed at greater than 10-fold higher levels in nectaries than in all other tissues examined. The roles these genes play in nectar production will be systematically examined in both Arabidopsis and Brassica rapa (oilseed rape) through gene knockout and overexpression studies. Mutant plants will be subjected to thorough phenotypic characterization that includes evaluation of nectary morphology and ultrastructure, global changes in gene expression within nectaries, and overall impacts on nectar volume and composition. It is expected that these studies will provide new insight into the genes and pathways required for nectar production in plants. BROADER IMPACTSDetermining the molecular basis of nectar production can have enormous impacts on U.S. agriculture, ranging from increasing yields in a wide range of pollinator-dependent crop species to targeted improvements of apiculture. Each year approximately 1.5 million acres of Brassica rapa and related oilseed crops are planted in the U.S. alone. Significantly, B. rapa is almost entirely dependent on the efficient attraction of pollinators to achieve maximal yields. Indeed, poor pollinator visitation can cut yields of Brassica oilseed, as well as unrelated crop species, in half. The long term goals of this project are to elucidate the underlying mechanisms of nectar production in the agriculturally important Brassicaceae family, and how this understanding can be translated into higher yields in multiple crop species. In addition, this project will provide significant research experiences and educational opportunities to a large number of undergraduate students at the University of Minnesota - Duluth, a primarily undergraduate institution. A detailed description and results derived from this project can be readily viewed at http://www.d.umn.edu/~cjcarter/carterlab.html. Microarray data will be deposited at GEO, gene annotations at TAIR, and metabolomics data will be integrated into the metabolomics database developed at Iowa State University (http://www.plantmetabolomics.org). Seed stocks will be available through the project and through the ABRC (http://www.biosci.ohio-state.edu/pcmb/Facilities/abrc/index.html).