title: Rice HOX12 Regulates Panicle Exsertion by Directly Modulating the Expression of ELONGATED UPPERMOST INTERNODE1.
abstract: Bioactive gibberellins (GAs) are key endogenous regulators of plant growth. Previous work identified ELONGATED UPPERMOST INTERNODE1 (EUI1) as a GA-deactivating enzyme that plays an important role in panicle exsertion from the flag leaf sheath in rice (Oryza sativa). However, the mechanism that regulates EUI1 activity during development is still largely unexplored. In this study, we identified the dominant panicle enclosure mutant regulator of eui1 (ree1-D), whose phenotype is caused by the activation of the homeodomain-leucine zipper transcription factor HOX12. Diminished HOX12 expression by RNA interference enhanced panicle exsertion, mimicking the eui1 phenotype. HOX12 knockdown plants contain higher levels of the major biologically active GAs (such as GA1 and GA4) than the wild type. The expression of EUI1 is elevated in the ree1-D mutant but reduced in HOX12 knockdown plants. Interestingly, both HOX12 and EUI1 are predominantly expressed in panicles, where GA4 is highly accumulated. Yeast one-hybrid, electrophoretic mobility shift assay, and chromatin immunoprecipitation analyses showed that HOX12 physically interacts with the EUI1 promoter both in vitro and in vivo. Furthermore, plants overexpressing HOX12 in the eui1 mutant background retained the elongated uppermost internode phenotype. These results indicate that HOX12 acts directly through EUI1 to regulate panicle exsertion in rice.
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Shaopei
authors.initials: S
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China ccchu@genetics.ac.cn.
authors.forename: Chengcai
authors.identifier: http://orcid.org/0000-0001-8097-6115
authors.initials: C
authors.lastname: Chu
mesh_terms: D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D005875:Gibberellins / Q000378:metabolism*; D018398:Homeodomain Proteins; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D034622:RNA Interference
chemical_list: D005875:Gibberellins; D018398:Homeodomain Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins