title: Systems approach identifies TGA1 and TGA4 transcription factors as important regulatory components of the nitrate response of Arabidopsis thaliana roots.
abstract: Nitrate acts as a potent signal to control global gene expression in Arabidopsis. Using an integrative bioinformatics approach we identified TGA1 and TGA4 as putative regulatory factors that mediate nitrate responses in Arabidopsis roots. We showed that both TGA1 and TGA4 mRNAs accumulate strongly after nitrate treatments in roots. Global gene expression analysis revealed 97% of the genes with altered expression in tga1 tga4 double mutant plants respond to nitrate treatments, indicating that these transcription factors have a specific role in nitrate responses in Arabidopsis root organs. We found TGA1 and TGA4 regulate the expression of nitrate transporter genes NRT2.1 and NRT2.2. Specific binding of TGA1 to its cognate DNA sequence on NRT2.1 and NRT2.2 promoters was confirmed by chromatin immunoprecipitation assays. The tga1 tga4 double mutant plants exhibit nitrate-dependent lateral and primary root phenotypes. Lateral root initiation is affected in both tga1 tga4 and nrt1.2 nrt2.2 double mutants, suggesting TGA1 and TGA4 regulate lateral root development at least partly via NRT2.1 and NRT2.2. Additional root phenotypes of tga1 tga4 double mutants indicate that these transcription factors play an important role in root developmental responses to nitrate. These results identify TGA1 and TGA4 as important regulatory factors of the nitrate response in Arabidopsis roots.
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, FONDAP Center for Genome Regulation, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Nucleus Center for Plant Functional Genomics, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile.
authors.forename: José M
authors.initials: JM
authors.lastname: Alvarez
authors.forename: Eleodoro
authors.initials: E
authors.lastname: Riveras
authors.forename: Elena A
authors.initials: EA
authors.lastname: Vidal
authors.forename: Diana E
authors.initials: DE
authors.lastname: Gras
authors.forename: Orlando
authors.initials: O
authors.lastname: Contreras-López
authors.forename: Karem P
authors.initials: KP
authors.lastname: Tamayo
authors.forename: Felipe
authors.initials: F
authors.lastname: Aceituno
authors.forename: Isabel
authors.initials: I
authors.lastname: Gómez
authors.forename: Sandrine
authors.initials: S
authors.lastname: Ruffel
authors.forename: Laurence
authors.initials: L
authors.lastname: Lejay
authors.forename: Xavier
authors.initials: X
authors.lastname: Jordana
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Gutiérrez
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism; D019295:Computational Biology; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D015398:Signal Transduction; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D009566:Nitrates; C000588817:TGA1 protein, Arabidopsis; C000588818:TGA4 protein, Arabidopsis
keywords: Arabidopsis; TGA1 and TGA4; lateral root growth; nitrate sensing; nitrate signal