title: Conserved cis-regulatory modules in promoters of genes encoding wheat high-molecular-weight glutenin subunits.
abstract: The concentration and composition of the gliadin and glutenin seed storage proteins (SSPs) in wheat flour are the most important determinants of its end-use value. In cereals, the synthesis of SSPs is predominantly regulated at the transcriptional level by a complex network involving at least five cis-elements in gene promoters. The high-molecular-weight glutenin subunits (HMW-GS) are encoded by two tightly linked genes located on the long arms of group 1 chromosomes. Here, we sequenced and annotated the HMW-GS gene promoters of 22 electrophoretic wheat alleles to identify putative cis-regulatory motifs. We focused on 24 motifs known to be involved in SSP gene regulation. Most of them were identified in at least one HMW-GS gene promoter sequence. A common regulatory framework was observed in all the HMW-GS gene promoters, as they shared conserved cis-regulatory modules (CCRMs) including all the five motifs known to regulate the transcription of SSP genes. This common regulatory framework comprises a composite box made of the GATA motifs and GCN4-like Motifs (GLMs) and was shown to be functional as the GLMs are able to bind a bZIP transcriptional factor SPA (Storage Protein Activator). In addition to this regulatory framework, each HMW-GS gene promoter had additional motifs organized differently. The promoters of most highly expressed x-type HMW-GS genes contain an additional box predicted to bind R2R3-MYB transcriptional factors. However, the differences in annotation between promoter alleles could not be related to their level of expression. In summary, we identified a common modular organization of HMW-GS gene promoters but the lack of correlation between the cis-motifs of each HMW-GS gene promoter and their level of expression suggests that other cis-elements or other mechanisms regulate HMW-GS gene expression.
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ravel
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Fiquet
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Boudet
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Mireille
authors.initials: M
authors.lastname: Dardevet
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Vincent
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Marielle
authors.initials: M
authors.lastname: Merlino
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Robin
authors.initials: R
authors.lastname: Michard
authors.affiliation: Institut National de la Recherche Agronomique, UMR1095, Genetics, Diversity and Ecophysiology of Cereals Clermont-Ferrand, France ; UMR1095, Genetics, Diversity and Ecophysiology of Cereals, Department of Biology, Blaise Pascal University Aubière, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Martre
keywords: cis-elements; conserved cis-regulatory modules (CCRMs); high-molecular-weight glutenin subunits (HMW-GS); seed storage proteins (SSPs); transcription factors (TFs); transcriptional regulation; wheat (Triticum aestivum L)