title: Rice homeobox transcription factor HOX1a positively regulates gibberellin responses by directly suppressing EL1.
abstract: Homeobox transcription factors are involved in various aspects of plant development, including maintenance of the biosynthesis and signaling pathways of different hormones. However, few direct targets of homeobox proteins have been identified. We here show that overexpression of rice homeobox gene HOX1a resulted in enhanced gibberellin (GA) response, indicating a positive effect of HOX1a in GA signaling. HOX1a is induced by GA and encodes a homeobox transcription factor with transcription repression activity. In addition, HOX1a suppresses the transcription of early flowering1 (EL1), a negative regulator of GA signaling, and further electrophoretic mobility shift assay and chromatin immunoprecipitation analysis revealed that HOX1a directly bound to the promoter region of EL1 to suppress its expression and stimulate GA signaling. These results demonstrate that HOX1a functions as a positive regulator of GA signaling by suppressing EL1, providing informative hints on the study of GA signaling.
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Bi-Qing
authors.initials: BQ
authors.lastname: Wen
authors.forename: Mei-Qing
authors.initials: MQ
authors.lastname: Xing
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Cheng
authors.initials: C
authors.lastname: Dai
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Xue
mesh_terms: D005875:Gibberellins / Q000494:pharmacology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D018398:Homeodomain Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins