Dual role for 14-3-3 proteins and ABF transcription factors in gibberellic acid and abscisic acid signalling in barley (Hordeum vulgare) aleurone cells

• Published in: Plant, cell and environment Vol. 32; no. 5; pp. 439 - 447
• Main Authors: SCHOONHEIM, PETER J, COSTA PEREIRA, DANIEL DA, DE BOER, ALBERTUS H
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.05.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: 14-3-3 Proteins - genetics; 14-3-3 Proteins - metabolism; Abscisic Acid - metabolism; alpha-Amylases - metabolism; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; biolistic transformation; Biological and medical sciences; cereal; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Plant; gibberelin; Gibberellins - metabolism; Hordeum - genetics; Hordeum - metabolism; Hordeum vulgare; PKABA1; Plant Proteins - genetics; Plant Proteins - metabolism; Promoter Regions, Genetic; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Kinases - metabolism; RNA Interference; seed germination; Signal Transduction; yeast two hybrid; Monocotyledones; Microprojectile bombardment; Seeds; Yeast; biolistic transformation; seed germination; Cereal crop; Gramineae; Sesquiterpenes; Angiospermae; Abscisic acid; gibberelin; Plant growth substance; Transcription factor; Cell; Aleurone; Genetic transformation; Hordeum vulgare; Germination; Plant ecology; Hybrid; Gibberellin; Signalling; Protein; PKABA1; cereal; yeast two hybrid; Spermatophyta; Gibberellic acid
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2009.01932.x

The balance of gibberellins [gibberellic acid (GA)] and abscisic acid (ABA) is a determining factor during transition of embryogenesis and seed germination. Recently, we showed that 14-3-3 proteins are important in ABA signalling in barley aleurone cells. Using 14-3-3 RNAi constructs in the barley aleurone transient expression system, we demonstrate here that silencing of each 14-3-3 isoform suppresses GA induction of the α-amylase gene. 14-3-3 Proteins interact with ABA-responsive element (ABRE) binding factors HvABF1, 2 and 3, and here we show that these transcription factors also interact with the ABA-responsive kinase PKABA1, a kinase that mediates cross-talk between the GA and ABA pathway. ABF1 and ABF2 have a function in both signalling pathways as: (1) ectopic expression of wild-type ABF1 and mutant ABF2, lacking the 14-3-3 interaction domain, transactivates the ABA inducible HVA1 gene; and (2) GA induction of the α-amylase gene is repressed by ectopic expression of wild-type ABF1 and 2. Mutant ABF1 and 2 were still effective repressors of GA signalling. In summary, our data provide evidence that 14-3-3 proteins and members of the ABF transcription factor family have a regulatory function in the GA pathway and suggest that PKABA1 and ABF transcription factors are cross-talk intermediates in ABA and GA signalling.