title: Variations of DNA methylation in Eucalyptus urophylla×Eucalyptus grandis shoot tips and apical meristems of different physiological ages.
abstract: Global DNA methylation was assessed by high-performance liquid chromatography (HPLC) for the first time in Eucalyptus urophylla×Eucalyptus grandis shoot tips comparing three outdoor and one in vitro sources of related genotypes differing in their physiological age. The DNA methylation levels found were consistent with those reported for other Angiosperms using the same HPLC technology. Notwithstanding noticeable time-related fluctuations within each source of plant material, methylation rate was overall higher for the mature clone (13.7%) than for the rejuvenated line of the same clone (12.6%) and for the juvenile offspring seedlings (11.8%). The in vitro microshoots of the mature clone were less methylated (11.3%) than the other outdoor origins, but the difference with the juvenile seedlings was not significant. Immunofluorescence investigations on shoot apices established that the mature source could be distinguished from the rejuvenated and juvenile origins by a higher density of cells with methylated nuclei in leaf primordia. Shoot apical meristems (SAMs) from the mature clone also showed a greater proportion and more methylated cells than SAMs from the rejuvenated and juvenile origins. The nuclei of these latter were characterized by fewer and more dispersed labeled spots than for the mature source. Our findings establish that physiological ageing induced quantitative and qualitative variations of DNA methylation at shoot tip, SAM and even cellular levels. Overall this DNA methylation increased with maturation and conversely decreased with rejuvenation to reach the lower scores and to show the immunolabeling patterns that characterized juvenile material nuclei.
authors.affiliation: CRDPI, UR Génétique Amélioration Diversité, B.P. 1291 Pointe-Noire, Congo.
authors.forename: François
authors.initials: F
authors.lastname: Mankessi
authors.forename: Aubin R
authors.initials: AR
authors.lastname: Saya
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Favreau
authors.forename: Sylvie
authors.initials: S
authors.lastname: Doulbeau
authors.forename: Geneviève
authors.initials: G
authors.lastname: Conéjéro
authors.forename: Marc
authors.initials: M
authors.lastname: Lartaud
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Verdeil
authors.forename: Olivier
authors.initials: O
authors.lastname: Monteuuis
mesh_terms: D002467:Cell Nucleus / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D019175:DNA Methylation; D018744:DNA, Plant / Q000235:genetics; D005052:Eucalyptus / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D005455:Fluorescent Antibody Technique / Q000379:methods; D005838:Genotype; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018519:Meristem / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000502:physiology
chemical_list: D018744:DNA, Plant