(Colorado State University. Libraries, 2008) Broeckling, Corey D., author; Vivanco, Jorge M., advisor
Centaurea maculosa is plant species native to Eurasia which has become invasive in North America, in part through allelopathic behavior. Allelopathy remains a highly debated subject, and a more firm understanding is necessary. C. maculosa is reported to secrete catechin as an allelochemical that is toxic to North American native plants. In this dissertation, a novel colorimetric assay for use in detection of catechin from soils is described and validated. This assay is highly sensitive, selective, and fast, which should allow for more detailed measures of catechin under field conditions, and ultimately a better understanding of the variation in catechin accumulation. To increase the depth of understanding of catechin biosynthesis, I report the cloning and characterization of C. maculosa dihydroflavonol reductase (CmDFR), a gene very likely to be necessary for catechin biosynthesis. To expand our view of metabolism beyond catechin, metabolome analysis is applied to field collected plant material, and demonstrate that the physiology of C. maculosa varies with the surrounding plant community -- plants growing in patches with high C. maculosa density tend to be accumulate higher levels of secondary metabolites than plants growing in the company of few conspecifics. Finally, the results of a study that clarifies the role of root exudates in structuring the soil fungal community are presented in the context of invasion biology.
