LEUNIG, LEUNIG HOMOLOG, AND SEUSS ARE TRANSCRIPTIONAL CO-REPRESSORS THAT REGULATE FLOWER DEVELOPMENT, MUCILAGE SECRETION, AND PATHOGEN RESISTANCE

dc.contributor.advisorHiggins, William Jen_US
dc.contributor.authorBui, Minhen_US
dc.contributor.departmentBiologyen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2009-10-06T05:45:10Z
dc.date.available2009-10-06T05:45:10Z
dc.date.issued2009en_US
dc.description.abstractTranscriptional repression is an important regulatory mechanism for development. My thesis focuses on dissecting the function of Groucho (Gro)/Transducin-Like Enhancer of split (TLE) family of transcriptional repressors in plant development. My work characterizes two Arabidopsis thaliana genes, LEUNIG (LUG), first discovered to repress transcription of the floral homeotic gene AGAMOUS (AG), and LEUNIG_HOMOLOG (LUH), a gene with the highest sequence similarity to LUG. To investigate the functional redundancy between LUG and LUH, I constructed and analyzed lug; luh double mutants, and concluded that both LUG and LUH repress AG expression in the flower, with LUG playing a more prominent role than LUH. The double mutant also revealed a previously unknown function of LUG and LUH in embryogenesis because lug-3; luh-1 double mutants are embryo lethal, while the single mutants develop normal embryos. During the course of this study, I developed a new genotyping method called Simple Allele-discriminating PCR (SAP), which is cost-effective, quick, and easy to perform. This method has greatly facilitated my research as well as others in the lab. A second part of my thesis addresses the role of LUG and LUH in other developmental processes besides flower development. My data indicate that these two genes, like their counter parts in fungi and animals, act as "global co-repressors" in various developmental and physiological processes. My thesis work revealed that both co-repressors, together with its interacting protein SEUSS (SEU), repress the Salicylic Acid (SA) pathogen defense pathway. Although lug-3, luh-1, and seu-1> mutants induced PR1 expression at higher levels than wild-type, only lug-3 and seu-1 mutants were pathogen resistant. Furthermore, LUH functions as a positive regulator in seed mucilage secretion, a process important for proper seed germination, hydration, and dispersal. I propose a possible connection between the defect in mucilage secretion and pathogen defense in luh-1 mutant plants and seeds, which places the foundation for further investigation and may uncover mucilage secretion as a major defense mechanism. My thesis has provided important insights into how transcriptional co-repressors regulate diverse developmental and physiological pathways in higher plants.en_US
dc.format.extent14442220 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/9489
dc.language.isoen_US
dc.subject.pqcontrolledBiology, Geneticsen_US
dc.subject.pqcontrolledBiology, Plant Physiologyen_US
dc.subject.pquncontrolledArabidopsisen_US
dc.subject.pquncontrolledLEUNIGen_US
dc.subject.pquncontrolledMucilageen_US
dc.subject.pquncontrolledPathogenen_US
dc.subject.pquncontrolledSEUSSen_US
dc.subject.pquncontrolledTranscriptionen_US
dc.titleLEUNIG, LEUNIG HOMOLOG, AND SEUSS ARE TRANSCRIPTIONAL CO-REPRESSORS THAT REGULATE FLOWER DEVELOPMENT, MUCILAGE SECRETION, AND PATHOGEN RESISTANCEen_US
dc.typeDissertationen_US

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