title: Mitochondrial AtTrxo1 is transcriptionally regulated by AtbZIP9 and AtAZF2 and affects seed germination under saline conditions.
abstract: Mitochondrial thioredoxin-o (AtTrxo1) was characterized and its expression examined in different organs of Arabidopsis thaliana. AtTrxo1 transcript levels were particularly high in dry seeds and cotyledons where they reached a maximum 36 h after imbibition with water, coinciding with 50% germination. Expression was lower in seeds germinating in 100 mM NaCl. To gain insight into the transcriptional regulation of the AtTrxo1 gene, a phylogenomic analysis was coupled with the screening of an arrayed library of Arabidopsis transcription factors in yeast. The basic leucine zipper AtbZIP9 and the zinc finger protein AZF2 were identified as putative transcriptional regulators. Transcript regulation of AtbZIP9 and AtAFZ2 during germination was compatible with the proposed role in transcriptional regulation of AtTrxo1. Transient over-expression of AtbZIP9 and AtAZF2 in Nicotiana benthamiana leaves demonstrated an activation effect of AtbZIP9 and a repressor effect of AtAZF2 on AtTrxo1 promoter-driven reporter expression. Although moderate concentrations of salt delayed germination in Arabidopsis wild-type seeds, those of two different AtTrxo1 knock-out mutants germinated faster and accumulated higher H2O2 levels than the wild-type. All these data indicate that AtTrxo1 has a role in redox homeostasis during seed germination under salt conditions.
authors.affiliation: Departamento de Biología del Estrés y Patología Vegetal, CEBAS-CSIC, Campus Universitario de Espinardo, 30100-Murcia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Ortiz-Espín
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (CBGP; UPM-INIA), Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223-Madrid, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Iglesias-Fernández
authors.affiliation: Departamento de Biología del Estrés y Patología Vegetal, CEBAS-CSIC, Campus Universitario de Espinardo, 30100-Murcia, Spain.
authors.forename: Aingeru
authors.initials: A
authors.lastname: Calderón
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (CBGP; UPM-INIA), Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223-Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Carbonero
authors.affiliation: Departamento de Biología del Estrés y Patología Vegetal, CEBAS-CSIC, Campus Universitario de Espinardo, 30100-Murcia, Spain.
authors.forename: Francisca
authors.initials: F
authors.lastname: Sevilla
authors.affiliation: Departamento de Biología del Estrés y Patología Vegetal, CEBAS-CSIC, Campus Universitario de Espinardo, 30100-Murcia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Jiménez
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000187:drug effects / Q000235:genetics; D054712:Salinity; D012639:Seeds / Q000254:growth & development; D013879:Thioredoxins / Q000235:genetics* / Q000378:metabolism
chemical_list: C410087:AZF protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C000624492:Trxo1 protein, Arabidopsis; C000624493:bZip9 protein, Arabidopsis; D013879:Thioredoxins
keywords: Arabidopsis thaliana; AtTrxo gene family; AtTrxo1 gene expression; ROS homeostasis; germination; saline conditions; transcriptional regulation