title: Distinct nuclear organization, DNA methylation pattern and cytokinin distribution mark juvenile, juvenile-like and adult vegetative apical meristems in peach (Prunus persica (L.) Batsch).
abstract: Chromatin organization, nuclear DNA methylation and endogenous zeatin localization were investigated in shoot apical meristems (SAM) during juvenile and adult phases of peach (Prunus persica (L.) Batsch). The aim was to examine the extent to which these parameters could discriminate the juvenile and adult SAMs. Seedlings (juvenile, cannot flower), basal shoots (called juvenile-like, because they exhibit juvenile macroscopic traits) and apical shoots (competent to form flowers) of adult plants were chosen. Nuclear chromatin exhibited chromocentres that were peripherally distributed in SAMs of juvenile and juvenile-like shoots, but were diffusely spread in those of adult shoots. These patterns coincided with a peripheral labelling of DNA methylation in juvenile and juvenile-like meristem nuclei versus a diffuse labelling pattern in adult meristem nuclei. During vegetative growth (from March to June), the level of nuclear DNA methylation was higher in adult meristems than in juvenile and juvenile-like ones. The immunolocalization of zeatin in juvenile SAM was in the subapical region, but adult meristems exhibited a widespread localization or a signal confined within the boundaries of the central zone. The extent to which the acquisition of a strongly zonated pattern of these parameters as markers of floral competence in adult SAMs is discussed.
authors.affiliation: Dipartimento di Ecologia, Università della Calabria, I-87030 Arcavacata di Rende, (CS), Italy. b.bitonti@unical.it
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Bitonti
authors.forename: Radiana
authors.initials: R
authors.lastname: Cozza
authors.forename: Adriana
authors.initials: A
authors.lastname: Chiappetta
authors.forename: Donato
authors.initials: D
authors.lastname: Giannino
authors.forename: Monica
authors.initials: M
authors.lastname: Ruffini Castiglione
authors.forename: Walter
authors.initials: W
authors.lastname: Dewitte
authors.forename: Domenico
authors.initials: D
authors.lastname: Mariotti
authors.forename: Harry
authors.initials: H
authors.lastname: Van Onckelen
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Innocenti
mesh_terms: D002467:Cell Nucleus / Q000502:physiology* / Q000648:ultrastructure; D002843:Chromatin / Q000378:metabolism; D003562:Cytidine / Q000031:analogs & derivatives* / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D019175:DNA Methylation; D007150:Immunohistochemistry; D018519:Meristem / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D027861:Prunus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D013997:Time Factors; D015026:Zeatin / Q000378:metabolism
chemical_list: D002843:Chromatin; D003583:Cytokinins; D003562:Cytidine; D015026:Zeatin; C016568:5-methylcytidine