Regulation and role of the Arabidopsis abscisic acid-insensitive 5 gene in abscisic acid, sugar, and stress response.
Abscisic acid (ABA) and stress response from late embryonic growth through early seedling development is regulated by a signaling network that includes the Arabidopsis ABA-insensitive (ABI)5 gene, which encodes a basic leucine zipper transcription factor. We have characterized genetic, developmental, and environmental regulation of ABI5 expression. Although expressed most strongly in seeds, the ABI5 promoter is also active in vegetative and floral tissue. Vegetative expression is strongly induced by ABA, and weakly by stress treatments during a limited developmental window up to approximately 2 d post-stratification, but ABA and some stresses can induce expression in specific tissues at later stages. ABI5 expression is autoregulated in transgenic plants and yeast (Saccharomyces cerevisiae), and stress response appears to involve ABI5-dependent and -independent mechanisms. To determine whether ABI5 is necessary and/or sufficient for ABA or stress response, we assayed the effects of increased ABI5 expression on growth and gene expression. Although overexpression of ABI5 confers hypersensitivity to ABA and sugar, as previously described for ABI4 and ABI3 overexpression lines, it has relatively limited effects on enhancing ABA-responsive gene expression. Comparison of expression of eight ABI5-homologous genes shows overlapping regulation by ABI3, ABI4, and ABI5, suggestive of a combinatorial network involving positive and negative regulatory interactions.
Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106, USA.
Inès M
IM
Brocard
Tim J
TJ
Lynch
Ruth R
RR
Finkelstein
D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002241:Carbohydrates / Q000494:pharmacology*; D004777:Environment; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D016350:Leucine Zippers / Q000235:genetics / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000502:physiology; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013314:Stress, Mechanical; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism
C409743:ABI5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002241:Carbohydrates; D010940:Plant Proteins; D014157:Transcription Factors; D000040:Abscisic Acid; C087434:ABI1 protein, Arabidopsis; C106443:ABI2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; D001616:beta-Galactosidase