title: Rice open beak is a negative regulator of class 1 knox genes and a positive regulator of class B floral homeotic gene.
abstract: Numerous genes are involved in the regulation of plant development, including those that regulate floral homeotic genes, We identified two recessive allelic rice mutants, open beak-1 (opb-1) and opb-2, which exhibited pleiotropic defects in leaf morphogenesis, inflorescence architecture, and floral organ identity. Abnormal cell proliferation was observed in the leaves and spikelets, and ectopic or overexpression of several class 1 knox genes was detected; thus, the abnormal cell proliferation in opb mutants is probably caused by ectopic class 1 knox gene expression. The opb mutants also had defects in floral organ identity, resulting in the development of mosaic organs, including gluminous lodicules, staminoid lodicules, and pistiloid stamens. These results, together with the reduced expression of a class B gene, indicate that OPB positively regulates the expression of class B genes. Map-based cloning revealed that OPB encodes a transcription factor that is orthologous to the Arabidopsis JAGGED gene and is expressed in leaf primordia, inflorescence meristem, rachis branch meristems, floral meristem, and floral organ primordia. Taken together, our data suggest that the OPB gene affects cellular proliferation and floral organ identity through the regulation of class 1 knox genes and floral homeotic genes.
authors.affiliation: Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Horigome
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nagasawa
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ikeda
authors.forename: Momoyo
authors.initials: M
authors.lastname: Ito
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Itoh
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nagato
mesh_terms: D000483:Alleles; D049109:Cell Proliferation; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005801:Genes, Homeobox; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers
chemical_list: D018398:Homeodomain Proteins; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors