title: Vernalization treatment induces site-specific DNA hypermethylation at the VERNALIZATION-A1 (VRN-A1) locus in hexaploid winter wheat.
abstract: BACKGROUND
  Certain temperate species require prolonged exposure to low temperature to initiate transition from vegetative growth to flowering, a process known as vernalization. In wheat, winter cultivars require vernalization to initiate flowering, making vernalization requirement a trait of key importance in wheat agronomy. The genetic bases of vernalization response have been largely studied in wheat, leading to the characterization of a regulation pathway that involves the key gene VERNALIZATION1 (VRN1). While previous studies in wheat and barley have revealed the functional role of histone modification in setting VRN1 expression, other mechanisms might also be involved. Here, we were interested in determining whether the cold-induced expression of the wheat VRN-A1 gene is associated with a change in DNA methylation.
  
  
  RESULTS
  We provide the first DNA methylation analysis of the VRN-A1 gene, and describe the existence of methylation at CG but also at non CG sites. While CG sites show a bell-shape profile typical of gene-body methylation, non CG methylation is restricted to the large (8.5 kb) intron 1, in a region harboring fragments of transposable elements (TEs). Interestingly, cold induces a site-specific hypermethylation at these non CG sites. This increase in DNA methylation is transmitted through mitosis, and is reset to its original level after sexual reproduction.
  
  
  CONCLUSIONS
  These results demonstrate that VRN-A1 has a particular DNA methylation pattern, exhibiting rapid shift within the life cycle of a winter wheat plant following exposure to particular environmental conditions. The finding that this shift occurs at non CG sites in a TE-rich region opens interesting questions onto the possible consequences of this type of methylation in gene expression.
authors: Abdul Rehman
authors: AR
authors: Khan
authors: Jérôme
authors: J
authors: Enjalbert
authors: Anne-Charlotte
authors: AC
authors: Marsollier
authors: Agnès
authors: A
authors: Rousselet
authors: Isabelle
authors: I
authors: Goldringer
authors: CNRS, UMR de Génétique Végétale, Gif sur Yvette F-91190, France. vitte@moulon.inra.fr.
authors: Clémentine
authors: C
authors: Vitte
mesh_terms: D000483:Alleles; D003080:Cold Temperature; D019175:DNA Methylation / Q000235:genetics*; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics*; D007438:Introns / Q000235:genetics; D008938:Mitosis / Q000235:genetics; D018515:Plant Leaves / Q000235:genetics; D011123:Polyploidy; D012621:Seasons; D014158:Transcription, Genetic; D014908:Triticum / Q000166:cytology / Q000235:genetics* / Q000502:physiology*
chemical_list: D004251:DNA Transposable Elements; D004262:DNA Restriction Enzymes