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Downregulation of Cinnamyl Alcohol Dehydrogenase or Caffeic Acid O-Methyltransferase Leads to Improved Biological Conversion Efficiency in Brachypodium distachyon

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dc.contributor.advisorSamuel P Hazen
dc.contributor.authorTrabucco, Gina M
dc.contributor.departmentUniversity of Massachusetts Amherst, Molecular & Cellular Biology
dc.date2023-09-23T07:21:27.000
dc.date.accessioned2024-04-26T21:20:12Z
dc.date.available2012-08-22T00:00:00Z
dc.date.issued2012
dc.date.submitted09
dc.description.abstractLignin is a significant recalcitrant in the conversion of plant biomass to bioethanol. Cinnamyl alcohol dehydrogenase (CAD) and caffeic acid O-methyltransferase (COMT) catalyze key steps in the pathway of lignin monomer biosynthesis. Brown midrib mutants in Zea mays and Sorghum bicolor with impaired CAD or COMT activity have attracted considerable agronomic interest for their altered lignin composition and improved digestibility. We identified candidate genes encoding CAD and COMT enzymes in the grass model species Brachypodium distachyon and developed transgenic plants overexpressing artificial microRNA designed to silence BdCAD1 or BdCOMT4. Both transgenes caused altered flowering time and stem count and weight. Downregulation of BdCAD1 caused a leaf brown midrib phenotype, the first time this phenotype has been observed in a C3 plant. While acetyl bromide soluble lignin measurements were equivalent in BdCAD1-silenced and wildtype plants, histochemical staining and thioacidolysis indicated a decrease in lignin syringyl units and reduced syringyl/guaiacyl ratio in the transgenic plants. BdCOMT4-downregulated plants exhibited a decrease in total lignin content, a significant reduction of guaiacyl lignin, and a modest reduction of syringyl lignin. Ethanol yield by microbial fermentation was enhanced in both BdCAD1- and BdCOMT4-downregulated plants. These results have elucidated two key genes in the lignin biosynthetic pathway in B. distachyon that, when perturbed, may result in greater biomass yield and bioconversion efficiency.
dc.description.degreeMaster of Science (M.S.)
dc.identifier.doi10.7275/3247078
dc.identifier.urihttps://hdl.handle.net/20.500.14394/47897
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2041&context=theses&unstamped=1
dc.source.statuspublished
dc.subjectCAD
dc.subjectCOMT
dc.subjectlignin
dc.subjectBrachypodium distachyon
dc.subjectbiofuel
dc.subjectAgriculture
dc.subjectBiology
dc.subjectGenetics
dc.subjectOil, Gas, and Energy
dc.subjectPlant Biology
dc.subjectPlant Breeding and Genetics
dc.subjectSustainability
dc.titleDownregulation of Cinnamyl Alcohol Dehydrogenase or Caffeic Acid O-Methyltransferase Leads to Improved Biological Conversion Efficiency in Brachypodium distachyon
dc.typecampus
dc.typethesis
digcom.contributor.authorisAuthorOfPublication|email:gtrabucc@student.umass.edu|institution:University of Massachusetts Amherst|Trabucco, Gina M
digcom.date.embargo2012-08-22T00:00:00-07:00
digcom.identifiertheses/957
digcom.identifier.contextkey3247078
digcom.identifier.submissionpaththeses/957
dspace.entity.typePublication
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