Journal Article

The Arabidopsis bZIP Gene AtbZIP63 Is a Sensitive Integrator of Transient Abscisic Acid and Glucose Signals

Di Mascio, Paolo, Prado, Fernanda Manso, Drumond, Rodrigo Duarte, Meyer, Christian, Duarte, Gustavo Turqueto, Viana, Américo José Carvalho, Corrêa, Luiz Gustavo Guedes, Tomaz, Juarez Pires, Del Bem, Luiz Eduardo Vieira, Silveira, Amanda Bortolini, Gauer, Luciane, Matiolli, Cleverson Carlos, Vincentz, Michel

2011

Overview

Glucose modulates plant metabolism, growth, and development. In Arabidopsis (Arabidopsis thaliana), Hexokinasel (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 AtbZlP63, a gene encoding a basic-leucine zipper (bZIP) transcription factor partially involved in the Snfl-related kinase KINlO-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 AtbZlP63 requires a functional ABA biosynthetic pathway. Furthermore, the combination of glucose and ABA was able to trigger a synergistic repression of AtbZlP63 and its homologue AtbZlP3, revealing a shared regulatory feature consisting of the modulation of glucose sensitivity by ABA. The synergistic regulation of AtbZlP63 was not reproduced by an AtbZlP63 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 finetuning of ABA-mediated abiotic stress responses according to sugar availability (i.e., energy status) are discussed.

• Publisher: American Society of Plant Biologists
• Subject: 5' Untranslated Regions / abiotic stress / abscisic acid / Abscisic Acid - biosynthesis / Abscisic Acid - metabolism / Arabidopsis Proteins / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arabidopsis thaliana / Basic-Leucine Zipper Transcription Factors / Basic-Leucine Zipper Transcription Factors - genetics / Basic-Leucine Zipper Transcription Factors - metabolism / biochemical pathways / Biological and medical sciences / biosynthesis / Biosynthetic Pathways / DEVELOPMENT AND HORMONE ACTION / energy / Fundamental and applied biological sciences. Psychology / Gene expression regulation / Gene Expression Regulation, Plant / Genes / genetics / glucose / Glucose - metabolism / Glucuronidase / Glucuronidase - genetics / Glucuronidase - metabolism / Hexokinase / Hexokinase - metabolism / Messenger RNA / metabolism / Plant cells / Plant physiology and development / Plants / Promoter Regions, Genetic / Protein Serine-Threonine Kinases / Protein-Serine-Threonine Kinases - metabolism / Repression / RNA / RNA Stability / Seedlings / Signal Transduction / stress response / Sugars / Trans-Activators / Trans-Activators - metabolism / transcription factors