title: ABI4 mediates antagonistic effects of abscisic acid and gibberellins at transcript and protein levels.
abstract: Abscisic acid (ABA) and gibberellins (GAs) are plant hormones which antagonistically mediate numerous physiological processes, and their optimal balance is essential for normal plant development. However, the molecular mechanism underlying ABA and GA antagonism still needs to be determined. Here, we report that ABA-INSENSITIVE 4 (ABI4) is a central factor in GA/ABA homeostasis and antagonism in post-germination stages. ABI4 overexpression in Arabidopsis (OE-ABI4) leads to developmental defects including a decrease in plant height and poor seed production. The transcription of a key ABA biosynthetic gene, NCED6, and of a key GA catabolic gene, GA2ox7, is significantly enhanced by ABI4 overexpression. ABI4 activates NCED6 and GA2ox7 transcription by directly binding to the promoters, and genetic analysis revealed that mutation in these two genes partially rescues the dwarf phenotype of ABI4 overexpressing plants. Consistently, ABI4 overexpressing seedlings have a lower GA/ABA ratio than the wild type. We further show that ABA induces GA2ox7 transcription while GA represses NCED6 expression in an ABI4-dependent manner; and that ABA stabilizes the ABI4 protein whereas GA promotes its degradation. Taken together, these results suggest that ABA and GA antagonize each other by oppositely acting on ABI4 transcript and protein levels.
authors.affiliation: Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.|State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Shu
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Yaorong
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Ruijun
authors.initials: R
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Huawei
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Shengfu
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Sanyuan
authors.initials: S
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.
authors.forename: Wenyu
authors.initials: W
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Cao
authors.affiliation: Department of Biology and Biotechnology 'Charles Darwin', Sapienza University, Rome, 00185, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Serino
authors.affiliation: State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xie
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004336:Drug Antagonism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D058685:Genetic Pleiotropy; D018525:Germination; D005875:Gibberellins / Q000378:metabolism*; D006706:Homeostasis; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C470421:ABI4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D005875:Gibberellins; D010937:Plant Growth Regulators; D014157:Transcription Factors; D000040:Abscisic Acid
keywords: ABA; ABI4; GA; antagonism; transcription factor