title: Identification and characterization of wheat drought-responsive MYB transcription factors involved in the regulation of cuticle biosynthesis.
abstract: A plant cuticle forms a hydrophobic layer covering plant organs, and plays an important role in plant development and protection from environmental stresses. We examined epicuticular structure, composition, and a MYB-based regulatory network in two Australian wheat cultivars, RAC875 and Kukri, with contrasting cuticle appearance (glaucousness) and drought tolerance. Metabolomics and microscopic analyses of epicuticular waxes revealed that the content of β-diketones was the major compositional and structural difference between RAC875 and Kukri. The content of β-diketones remained the same while those of alkanes and primary alcohols were increased by drought in both cultivars, suggesting that the interplay of all components rather than a single one defines the difference in drought tolerance between cultivars. Six wheat genes encoding MYB transcription factors (TFs) were cloned; four of them were regulated in flag leaves of both cultivars by rapid dehydration and/or slowly developing cyclic drought. The involvement of selected MYB TFs in the regulation of cuticle biosynthesis was confirmed by a transient expression assay in wheat cell culture, using the promoters of wheat genes encoding cuticle biosynthesis-related enzymes and the SHINE1 (SHN1) TF. Two functional MYB-responsive elements, specifically recognized by TaMYB74 but not by other MYB TFs, were localized in the TdSHN1 promoter. Protein structural determinants underlying the binding specificity of TaMYB74 for functional DNA cis-elements were defined, using 3D protein molecular modelling. A scheme, linking drought-induced expression of the investigated TFs with downstream genes that participate in the synthesis of cuticle components, is proposed.
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Huihui
authors.initials: H
authors.lastname: Bi
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Sukanya
authors.initials: S
authors.lastname: Luang
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Natalia
authors.initials: N
authors.lastname: Bazanova
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Morran
authors.affiliation: W.M.Keck Metabolomics Research Laboratory, Iowa State University, Ames, IA 50011, USA.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Song
authors.affiliation: W.M.Keck Metabolomics Research Laboratory, Iowa State University, Ames, IA 50011, USA.
authors.forename: M Ann
authors.initials: MA
authors.lastname: Perera
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia maria.hrmova@adelaide.edu.au.
authors.forename: Maria
authors.identifier: 0000-0002-3545-0605
authors.initials: M
authors.lastname: Hrmova
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Borisjuk
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
authors.forename: Sergiy
authors.initials: S
authors.lastname: Lopato
mesh_terms: D003681:Dehydration / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014908:Triticum / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014885:Waxes / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D014885:Waxes
keywords: Abiotic stress; MYB and SHINE1 transcription factors; cuticle; drought; molecular model; water deficit; wax; wheat.; β-diketone