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Functional characterization of NAC-domain transcription factors implicated in control of vascular cell differentiation in Arabidopsis and Populus

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dc.contributor.authorGrant, Emily H.en
dc.contributor.committeechairBrunner, Amy M.en
dc.contributor.committeecochairBeers, Eric P.en
dc.contributor.committeememberWestwood, James H.en
dc.contributor.committeememberTokuhisa, James G.en
dc.contributor.departmentForestryen
dc.date.accessioned2014-03-14T20:50:35Zen
dc.date.adate2009-01-27en
dc.date.available2014-03-14T20:50:35Zen
dc.date.issued2008-12-10en
dc.date.rdate2010-12-22en
dc.date.sdate2008-12-21en
dc.description.abstractWood has a wide variety of uses and is arguably the most important renewable raw material. The composition of xylem cell types in wood determines the utility of different types of wood for distinct commercial applications. Using expression profiling and phylogenetic analysis, we identified many xylem-associated regulatory genes that may control the differentiation of cells involved in wood formation in Arabidopsis and poplar. Prominent among these are NAC-domain transcription factors (NACs). In addition to their roles as regulators of xylem differentiation, NACs are regulators of meristem development, organ elongation and separation. We studied a subset of Populus and Arabidopsis NACs with putative involvement in xylem cell expansion and elongation (XND1/ANAC104, PopNAC118, PopNAC122, PopNAC128, PopNAC129), and secondary cell wall synthesis (ANAC073, PopNAC105, PopNAC154, PopNAC156, PopNAC157). Using quantitative Real-Time PCR, we evaluated expression of the selected Populus NACs in a developmental gradient and in response to bending stress. We prepared transgenic Arabidopsis and Populus plants with increased or decreased expression of select NAC genes. For dominant repression of target gene expression, we evaluated transgenic plants expressing translational fusions of NAC-EAR (ERF amphiphilic repressor) chimeras through chimeric repressor silencing-technology (CRES-T). XND1 overexpression in Populus and Arabidopsis resulted in severe stunting and suppression of xylem differentiation. Overexpression of PopNAC122, an XND1 ortholog, yielded an analogous phenotype in Arabidopsis. Populus XND1 overexpressors lacked phloem fibers and showed a reduction in cell size and number, vessel number and frequency of rays. Knowledge gained through characterization of these wood-associated regulatory genes can be used to optimize molecular breeding and genetic engineering strategies for improved wood quality and increased biomass.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-12212008-132213en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12212008-132213/en
dc.identifier.urihttp://hdl.handle.net/10919/36373en
dc.publisherVirginia Techen
dc.relation.haspartThesis_Grant2_fixed.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectxylemen
dc.subjectArabidopsis thalianaen
dc.subjectNACsen
dc.subjecttranscription factoren
dc.subjectWooden
dc.subjectPopulus trichocarpaen
dc.titleFunctional characterization of NAC-domain transcription factors implicated in control of vascular cell differentiation in Arabidopsis and Populusen
dc.typeThesisen
thesis.degree.disciplineForestryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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