title: Rice ABI5-Like1 regulates abscisic acid and auxin responses by affecting the expression of ABRE-containing genes.
abstract: Abscisic acid (ABA) regulates plant development and is crucial for plant responses to biotic and abiotic stresses. Studies have identified the key components of ABA signaling in Arabidopsis (Arabidopsis thaliana), some of which regulate ABA responses by the transcriptional regulation of downstream genes. Here, we report the functional identification of rice (Oryza sativa) ABI5-Like1 (ABL1), which is a basic region/leucine zipper motif transcription factor. ABL1 is expressed in various tissues and is induced by the hormones ABA and indole-3-acetic acid and stress conditions including salinity, drought, and osmotic pressure. The ABL1 deficiency mutant, abl1, shows suppressed ABA responses, and ABL1 expression in the Arabidopsis abi5 mutant rescued the ABA sensitivity. The ABL1 protein is localized to the nucleus and can directly bind ABA-responsive elements (ABREs; G-box) in vitro. A gene expression analysis by DNA chip hybridization confirms that a large proportion of down-regulated genes of abl1 are involved in stress responses, consistent with the transcriptional activating effects of ABL1. Further studies indicate that ABL1 regulates the plant stress responses by regulating a series of ABRE-containing WRKY family genes. In addition, the abl1 mutant is hypersensitive to exogenous indole-3-acetic acid, and some ABRE-containing genes related to auxin metabolism or signaling are altered under ABL1 deficiency, suggesting that ABL1 modulates ABA and auxin responses by directly regulating the ABRE-containing genes.
authors.affiliation: Shanghai Institutes for Biological Sciences-University of California, Berkeley, Joint Center on Molecular Life Sciences, National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China.
authors.forename: Xi
authors.initials: X
authors.lastname: Yang
authors.forename: Ya-Nan
authors.initials: YN
authors.lastname: Yang
authors.forename: Liang-Jiao
authors.initials: LJ
authors.lastname: Xue
authors.forename: Mei-Juan
authors.initials: MJ
authors.lastname: Zou
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Liu
authors.forename: Fan
authors.initials: F
authors.lastname: Chen
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Xue
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D001483:Base Sequence; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008954:Models, Biological; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D020218:Response Elements / Q000235:genetics*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D010940:Plant Proteins; C036483:T-DNA; D000040:Abscisic Acid