title: The Arabidopsis bZIP gene AtbZIP63 is a sensitive integrator of transient abscisic acid and glucose signals.
abstract: Glucose modulates plant metabolism, growth, and development. In Arabidopsis (Arabidopsis thaliana), Hexokinase1 (HXK1) is a glucose sensor that may trigger abscisic acid (ABA) synthesis and sensitivity to mediate glucose-induced inhibition of seedling development. Here, we show that the intensity of short-term responses to glucose can vary with ABA activity. We report that the transient (2 h/4 h) repression by 2% glucose of AtbZIP63, a gene encoding a basic-leucine zipper (bZIP) transcription factor partially involved in the Snf1-related kinase KIN10-induced responses to energy limitation, is independent of HXK1 and is not mediated by changes in ABA levels. However, high-concentration (6%) glucose-mediated repression appears to be modulated by ABA, since full repression of AtbZIP63 requires a functional ABA biosynthetic pathway. Furthermore, the combination of glucose and ABA was able to trigger a synergistic repression of AtbZIP63 and its homologue AtbZIP3, revealing a shared regulatory feature consisting of the modulation of glucose sensitivity by ABA. The synergistic regulation of AtbZIP63 was not reproduced by an AtbZIP63 promoter-5'-untranslated region::β-glucuronidase fusion, thus suggesting possible posttranscriptional control. A transcriptional inhibition assay with cordycepin provided further evidence for the regulation of mRNA decay in response to glucose plus ABA. Overall, these results indicate that AtbZIP63 is an important node of the glucose-ABA interaction network. The mechanisms by which AtbZIP63 may participate in the fine-tuning of ABA-mediated abiotic stress responses according to sugar availability (i.e., energy status) are discussed.
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, CP6010 Campinas, Sao Paulo, Brazil.
authors.forename: Cleverson Carlos
authors.initials: CC
authors.lastname: Matiolli
authors.forename: Juarez Pires
authors.initials: JP
authors.lastname: Tomaz
authors.forename: Gustavo Turqueto
authors.initials: GT
authors.lastname: Duarte
authors.forename: Fernanda Manso
authors.initials: FM
authors.lastname: Prado
authors.forename: Luiz Eduardo Vieira
authors.initials: LE
authors.lastname: Del Bem
authors.forename: Amanda Bortolini
authors.initials: AB
authors.lastname: Silveira
authors.forename: Luciane
authors.initials: L
authors.lastname: Gauer
authors.forename: Luiz Gustavo Guedes
authors.initials: LG
authors.lastname: Corrêa
authors.forename: Rodrigo Duarte
authors.initials: RD
authors.lastname: Drumond
authors.forename: Américo José Carvalho
authors.initials: AJ
authors.lastname: Viana
authors.forename: Paolo
authors.initials: P
authors.lastname: Di Mascio
authors.forename: Christian
authors.initials: C
authors.lastname: Meyer
authors.forename: Michel
authors.initials: M
authors.lastname: Vincentz
mesh_terms: D020121:5' Untranslated Regions; D000040:Abscisic Acid / Q000096:biosynthesis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D053898:Biosynthetic Pathways; D018506:Gene Expression Regulation, Plant; D005947:Glucose / Q000378:metabolism*; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020871:RNA Stability; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C098796:Sen1 protein, Arabidopsis; D015534:Trans-Activators; C542093:bZIP34 protein, Arabidopsis; C495668:bZIP63 protein, Arabidopsis; D000040:Abscisic Acid; C071570:SNF1-related protein kinases; D006593:Hexokinase; C473630:ATHXK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D005966:Glucuronidase; D005947:Glucose