title: Genome-wide expression profiling of ARABIDOPSIS RESPONSE REGULATOR 7(ARR7) overexpression in cytokinin response.
abstract: The type-A ARRs of cytokinin two-component signaling system act as negative regulators for cytokinin signaling except for ARR4, but the molecular mechanism by which the A-type ARRs regulate cytokinin signaling remain elusive. To get insights into the molecular function of A-type ARR in cytokinin response, we sought to find the components that function downstream of A-type ARR protein by investigating the effects of ARR7 overexpression on cytokinin-regulated gene expression with the Affymetrix full genome array. To examine early cytokinin response, plants were treated with cytokinin for 30 min or 2 h, followed by GeneChip analysis. The hierarchical clustering analysis of our GeneChip data showed that ARR7 overexpression had distinctively repressive impacts on various groups of the cytokinin-regulated genes. In particular, the induction of all A-type ARRs except for ARR22, and AHK(ARABIDOPSIS HISTIDINE KINASE)1 and AHK4 was suppressed by ARR7. Cytokinin-induced expression of most of 12 expansin genes were repressed by ARR7, indicating potential involvement of ARR7 in cell expansion and plant development. Up-regulation of five cytokinin oxidase genes by cytokinins was negatively affected by ARR7. Our GeneChip analysis suggest that ARR7 mainly acts as a transcriptional repressor for a variety of early cytokinin-regulated genes encoding transcription factors, signal transmitters, plant development, and cellular metabolism, which may be responsible for reduced sensitivity of Arabidopsis transgenic plants overexpressing ARR7 to exogenous cytokinins.
authors.affiliation: Department of Plant Biotechnology and Agricultural Plant Stress Research Center, Chonnam National University, Puk-Gu, Gwangju, 500-757, South Korea.
authors.forename: Dong Ju
authors.initials: DJ
authors.lastname: Lee
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Park
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Ku
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Ha
authors.forename: Sunmi
authors.initials: S
authors.lastname: Kim
authors.forename: Myung Duk
authors.initials: MD
authors.lastname: Kim
authors.forename: Man-Ho
authors.initials: MH
authors.lastname: Oh
authors.forename: Jungmook
authors.initials: J
authors.lastname: Kim
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003583:Cytokinins / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004351:Drug Resistance / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D018745:Genome, Plant / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: C507238:ARR7 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; D014157:Transcription Factors