title: Long noncoding miRNA gene represses wheat β-diketone waxes.
abstract: The cuticle of terrestrial plants functions as a protective barrier against many biotic and abiotic stresses. In wheat and other Triticeae, β-diketone waxes are major components of the epicuticular layer leading to the bluish-white glaucous trait in reproductive-age plants. Glaucousness in durum wheat is controlled by a metabolic gene cluster at theWAX1(W1) locus and a dominant suppressorINHIBITOR of WAX1(Iw1) on chromosome 2B. The wheat D subgenome from progenitorAegilops tauschiicontainsW2andIw2paralogs on chromosome 2D. Here we identify theIw1gene from durum wheat and demonstrate the unique regulatory mechanism by whichIw1acts to suppress a carboxylesterase-like protein gene,W1-COE, within theW1multigene locus.Iw1is a long noncoding RNA (lncRNA) containing an inverted repeat (IR) with >80% identity toW1-COETheIw1transcript forms a miRNA precursor-like long hairpin producing a 21-nt predominant miRNA, miRW1, and smaller numbers of related sRNAs associated with the nonglaucous phenotype. WhenIw1was introduced into glaucous bread wheat, miRW1 accumulated,W1-COEand its paralogW2-COEwere down-regulated, and the phenotype was nonglaucous and β-diketone-depleted. The IR region ofIw1has >94% identity to an IR region on chromosome 2 inAe. tauschiithat also produces miRW1 and lies within the marker-based location ofIw2We propose theIwloci arose from an inverted duplication ofW1-COEand/orW2-COEin ancestral wheat to form evolutionarily young miRNA genes that act to repress the glaucous trait.
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada.
authors.forename: Daiqing
authors.initials: D
authors.lastname: Huang
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada.
authors.forename: J Allan
authors.initials: JA
authors.lastname: Feurtado
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Smith
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada.
authors.forename: Leah K
authors.initials: LK
authors.lastname: Flatman
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada.
authors.forename: Chushin
authors.initials: C
authors.lastname: Koh
authors.affiliation: Wheat Improvement Flagship Program, National Research Council of Canada, Saskatoon, Saskatchewan, SK S7N 0W9, Canada adrian.cutler@nrc-cnrc.gc.ca.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Cutler
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D018506:Gene Expression Regulation, Plant; D007659:Ketones / Q000737:chemistry / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D062085:RNA, Long Noncoding / Q000235:genetics*; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014885:Waxes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007659:Ketones; D035683:MicroRNAs; D010940:Plant Proteins; D062085:RNA, Long Noncoding; D014885:Waxes
keywords: WAX1; glaucous; inhibitor of wax; long noncoding RNA; small RNA