Date of Award


Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)


Biology/Molecular, Cellular, and Organismal Biology

First Advisor

Adán Colón-Carmona

Second Advisor

Steven Ackerman

Third Advisor

Katherine E. Gibson


Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants with cytotoxic, teratogenic, and carcinogenic properties. Bioremediation studies with bacteria have led to the identification of dioxygenases (DOXs) in the first step to the degradation of these recalcitrant compounds. In the research presented here, we characterized the role of the Arabidopsis protein AT5G05600, a putative DOX of the flavonol synthase family, in the transformation of PAHs. Phenotypic analysis of loss-of-function mutant lines showed that these plant lines were less sensitive to the toxic effects of phenanthrene, suggesting possible roles of this gene in PAH degradation in vivo. Interestingly, these mutant lines showed less accumulation of H2O2 after PAH exposure. Transgenic lines over-expressing At5g05600 showed a hypersensitive response and more oxidative stress after phenanthrene treatments. Moreover, fluorometric spectral results of biochemical assays with the recombinant His-tagged protein AT5G05600 detected chemical modifications of phenanthrene. Taken together, these results support the hypothesis that AT5G05600 is involved in the catabolism of PAHs and the accumulation of toxic intermediates during PAH biotransformation in plants. This research represents the first step in the design of transgenic plants with the potential to degrade PAHs, leading to the development of vigorous plant species that can reduce the levels of these pollutants entering the food-chain.


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