Arabidopsis ABA-INSENSITIVE (ABI) 4 factor acts as a central transcription activator of the expression of its own gene, and for the induction of ABI5 and SBE2.2 genes during sugar signaling

• Published in: The Plant journal : for cell and molecular biology 2009-08, Vol.59 (3), p.359-374
• Main Authors: Bossi, Flavia, Cordoba, Elizabeth, Dupré, Patricia, Mendoza, Mónica Santos, Román, Carolina San, León, Patricia
• Format: Article
• Language: English
• Subjects: ABA signaling; ABI4; Abscisic Acid - metabolism; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Base Sequence; Basic-Leucine Zipper Transcription Factors - metabolism; Binding sites; Biological and medical sciences; Botany; early seedling development; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Plant; Glucose; Glucose - metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Promoter Regions, Genetic; Protein Binding; RNA, Plant - genetics; Seedlings - growth & development; Signal Transduction; sugar regulation; transcription factor; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Initiation Site; Transcription. Transcription factor. Splicing. Rna processing
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2009.03877.x

The transcription factor ABA INSENSITIVE 4 (ABI4), discovered nearly 10 years ago, plays a central role in a variety of functions in plants, including sugar responses. However, not until very recently has its mechanism of action begun to be elucidated. Modulating gene expression is one of the primary mechanisms of sugar regulation in plants. Nevertheless, the transcription factors involved in regulating sugar responses and their role(s) during the signal transduction cascade remain poorly defined. In this paper we analyzed the participation of ABI4, as it is one of the main transcription factors implicated in glucose signaling during early seedling development. Our studies show that ABI4 is an essential activator of its own expression during development, in ABA signaling and in sugar responses. It is also important for the glucose-mediated expression of the genes ABI5 and SBE2.2. We demonstrate that ABI4 binds directly to the promoter region of all three genes and activates their expression in vivo through at CE1-like element. Previous studies found that ABI4 also functions as a transcriptional repressor of sugar-regulated genes, therefore this transcription factor is a versatile protein with dual functions for modulating gene expression.