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dc.contributor.advisorDayan, Franck E.
dc.contributor.authorBough, Raven A.
dc.contributor.committeememberGaines, Todd A.
dc.contributor.committeememberHaley, Scott
dc.contributor.committeememberPearce, Stephen
dc.date.accessioned2022-01-07T11:31:13Z
dc.date.available2022-01-07T11:31:13Z
dc.date.issued2021
dc.description2021 Fall.
dc.descriptionIncludes bibliographical references.
dc.description.abstractA new weed management tool in wheat, the CoAXium™ Wheat Production System, incorporates quizalofop-resistant wheat, a specialized formulation of quizalofop (Aggressor™), and a stewardship management program for effective management of annual grasses with otherwise limited control options. The AXigen™ trait confers resistance primarily through a single-point mutation in ACC1. The mutation causes an alanine to valine substitution at position 2004 in wheat acetyl-CoA carboxylase (ACCase) relative to the Alopecurus myosuriodes reference. Through greenhouse and biochemical studies paired with protein homology modelling and simulations, the research presented herein provides strong evidence that a conformational change imparted by the amino acid substitution results in quizalofop-resistant ACCase. Conversely, the mutation conveys negative cross-resistance to haloxyfop, a similar herbicide to quizalofop with a smaller molecular volume. The remaining research objectives focus on quizalofop metabolism in CoAXium™ wheat. Liquid chromatography-mass spectrometry measurements of quizalofop content over time from liquid demonstrate cooler temperature conditions (4.5°C) delay quizalofop metabolism by 4 times compared to warmer temperature conditions (19°C). Reduced temperatures also delay quizalofop metabolism to the same extent in the following annual grass weed species: Aegilops cylindrica, Bromus tectorum, and Secale cereale. Further, additional studies suggest herbicide metabolism mechanisms enhance overall CoAXium™ wheat quizalofop resistance. Despite similar ACCase resistance, resistant winter and spring wheat varieties convey varying degrees of whole-plant resistance. In winter wheat but not spring wheat, increased resistance corresponds to a shorter quizalofop half-life, implying faster metabolism boosts overall resistance. Treatment of resistant spring wheat varieties with cloquintocet, a metabolism-boosting safener, increases overall resistance. Follow-up differential expression analysis of cloquintocet-treated plants may support differential metabolism findings and lead to identification of putative candidate genes associated with upregulated herbicide metabolism, such as cytochrome P450 monooxygenases, glutathione-S-transferases, and glycosyltransferases.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierBough_colostate_0053A_16966.pdf
dc.identifier.urihttps://hdl.handle.net/10217/234317
dc.languageEnglish
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020- CSU Theses and Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectAggressor
dc.subjectacetyl-CoA carboxylase
dc.subjectCoAXium
dc.titleQuizalofop-resistant wheat: biochemical characterization of the AXigen™ trait and corresponding metabolism
dc.typeText
dcterms.rights.dplaThe copyright and related rights status of this Item has not been evaluated (https://rightsstatements.org/vocab/CNE/1.0/). Please refer to the organization that has made the Item available for more information.
thesis.degree.disciplineAgricultural Biology
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)


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