title: A rice WRKY gene encodes a transcriptional repressor of the gibberellin signaling pathway in aleurone cells.
abstract: The molecular mechanism by which GA regulates plant growth and development has been a subject of active research. Analyses of the rice (Oryza sativa) genomic sequences identified 77 WRKY genes, among which OsWRKY71 is highly expressed in aleurone cells. Transient expression of OsWRKY71 by particle bombardment specifically represses GA-induced Amy32b alpha-amylase promoter but not abscisic acid-induced HVA22 or HVA1 promoter activity in aleurone cells. Moreover, OsWRKY71 blocks the activation of the Amy32b promoter by the GA-inducible transcriptional activator OsGAMYB. Consistent with its role as a transcriptional repressor, OsWRKY71 is localized to nuclei of aleurone cells and binds specifically to functionally defined TGAC-containing W boxes of the Amy32b promoter in vitro. Mutation of the two W boxes prevents the binding of OsWRKY71 to the mutated promoter, and releases the suppression of the OsGAMYB-activated Amy32b expression by OsWRKY71, suggesting that OsWRKY71 blocks GA signaling by functionally interfering with OsGAMYB. Exogenous GA treatment decreases the steady-state mRNA level of OsWRKY71 and destabilizes the GFP:OsWRKY71 fusion protein. These findings suggest that OsWRKY71 encodes a transcriptional repressor of GA signaling in aleurone cells.
authors.affiliation: Department of Biological Sciences, University of Nevada, 4505 Maryland Parkway, Las Vegas, Nevada 89154, USA.
authors.forename: Zhong-Lin
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xie
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Zou
authors.forename: Jose
authors.initials: J
authors.lastname: Casaretto
authors.forename: Tuan-Hua David
authors.initials: TH
authors.lastname: Ho
authors.forename: Qingxi J
authors.initials: QJ
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005875:Gibberellins / Q000494:pharmacology*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D005875:Gibberellins; D008164:Luminescent Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D000516:alpha-Amylases