title: Overexpressing the ANR1 MADS-box gene in transgenic plants provides new insights into its role in the nitrate regulation of root development.
abstract: The expression of the ANR1 MADS-box gene was manipulated in transgenic plants to investigate its role in the NO(3)(-)-dependent regulation of root development in Arabidopsis thaliana. Constitutive overexpression of ANR1 in roots, achieved using GAL4 enhancer trap lines, resulted in more rapid early seedling development, increased lengths and numbers of lateral roots and increased shoot fresh weight. Based on results obtained with five different enhancer trap lines, the overexpression of ANR1 in the lateral root tips appears to be more important for this phenotype than its level of expression in the developing lateral root primordia. Dexamethasone-mediated induction of ANR1 in lines expressing an ANR1-GR (glucocorticoid receptor) fusion protein stimulated lateral root growth but not primary root growth. Short-term (24 h) dexamethasone treatments led to prolonged stimulation of lateral root growth, whether the lateral roots were already mature or still unemerged at the time of treatment. In split-root experiments, localized application of dexamethasone to half of the root system of an ANR1-GR line elicited a localized increase in both the length and numbers of lateral roots, mimicking the effect of a localized NO(3)(-) treatment. In both types of transgenic line, the root phenotype was strongly dependent on the presence of NO(3)(-), indicating that there are additional components involved in ANR1 function that are NO(3)(-) regulated. The implications of these results for our understanding of ANR1's mode of action in the root response to localized NO(3)(-) are discussed.
authors.affiliation: Centre for Sustainable Agriculture, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Yinbo
authors.initials: Y
authors.lastname: Gan
authors.forename: Andreas
authors.initials: A
authors.lastname: Bernreiter
authors.forename: Sophie
authors.initials: S
authors.lastname: Filleur
authors.forename: Beverley
authors.initials: B
authors.lastname: Abram
authors.forename: Brian G
authors.initials: BG
authors.lastname: Forde
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D003907:Dexamethasone; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D058685:Genetic Pleiotropy; D009566:Nitrates / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C109964:ANR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003470:Culture Media; D009566:Nitrates; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D003907:Dexamethasone