title: Time course and amplitude of DNA methylation in the shoot apical meristem are critical points for bolting induction in sugar beet and bolting tolerance between genotypes.
abstract: An epigenetic control of vernalization has been demonstrated in annual plants such as Arabidopsis and cereals, but the situation remains unclear in biennial plants such as sugar beet that has an absolute requirement for vernalization. The role of DNA methylation in flowering induction and the identification of corresponding target loci also need to be clarified. In this context, sugar beet (Beta vulgaris altissima) genotypes differing in bolting tolerance were submitted to various bolting conditions such as different temperatures and/or methylating drugs. DNA hypomethylating treatment was not sufficient to induce bolting while DNA hypermethylation treatment inhibits and delays bolting. Vernalizing and devernalizing temperatures were shown to affect bolting as well as DNA methylation levels in the shoot apical meristem. In addition, a negative correlation was established between bolting and DNA methylation. Genotypes considered as resistant or sensitive to bolting could also be distinguished by their DNA methylation levels. Finally, sugar beet homologues of the Arabidopsis vernalization genes FLC and VIN3 exhibited distinct DNA methylation marks during vernalization independently to the variations of global DNA methylation. These vernalization genes also displayed differences in mRNA accumulation and methylation profiles between genotypes resistant or sensitive to bolting. Taken together, the data suggest that the time course and amplitude of DNA methylation variations are critical points for the induction of sugar beet bolting and represent an epigenetic component of the genotypic bolting tolerance, opening up new perspectives for sugar beet breeding.
authors.affiliation: Université d'Orléans, UFR-Faculté des Sciences, UPRES EA 1207 Laboratoire de Biologie des Ligneux et des Grandes Cultures, rue de Chartres, BP 6759, F-45067 Orléans, France.
authors.forename: Marie-Véronique
authors.initials: MV
authors.lastname: Trap-Gentil
authors.forename: Claire
authors.initials: C
authors.lastname: Hébrard
authors.forename: Clément
authors.initials: C
authors.lastname: Lafon-Placette
authors.forename: Alain
authors.initials: A
authors.lastname: Delaunay
authors.forename: Daniel
authors.initials: D
authors.lastname: Hagège
authors.forename: Claude
authors.initials: C
authors.lastname: Joseph
authors.forename: Franck
authors.initials: F
authors.lastname: Brignolas
authors.forename: Marc
authors.initials: M
authors.lastname: Lefebvre
authors.forename: Steve
authors.initials: S
authors.lastname: Barnes
authors.forename: Stéphane
authors.initials: S
authors.lastname: Maury
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D001483:Base Sequence; D027461:Beta vulgaris / Q000201:enzymology / Q000235:genetics* / Q000502:physiology*; D003080:Cold Temperature; D003596:Cytosine / Q000378:metabolism; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D018519:Meristem / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D003596:Cytosine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases