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Dual role for 14‐3‐3 proteins and ABF transcription factors in gibberellic acid and abscisic acid signalling in barley ( Hordeum vulgare ) aleurone cells
Author(s) -
SCHOONHEIM PETER J.,
COSTA PEREIRA DANIEL DA,
DE BOER ALBERTUS H.
Publication year - 2009
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2009.01932.x
Subject(s) - abscisic acid , aleurone , biology , transcription factor , microbiology and biotechnology , ectopic expression , hordeum vulgare , gibberellic acid , mutant , gibberellin , gene silencing , repressor , gene , biochemistry , genetics , botany , germination , poaceae
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.