title: Similar rye A and B chromosome organization in meristematic and differentiated interphase nuclei.
abstract: Supernumerary (B) chromosomes of rye are not required for plant development and exhibit a reduced transcription activity. These special features inspired us to analyse whether there are differences between A and B chromatin organization in interphase nuclei. Applying fluorescence in situ hybridization, we found that both rye A and B chromosomes added to hexaploid wheat showed in meristematic nuclei a string-like shape and a clear Rabl orientation. In 4C differentiated leaf nuclei, a more relaxed chromatin structure, round-shaped chromosome territories and a less pronounced Rabl configuration were found. Also, the observed random association of homologues in 2C and 4C nuclei indicated in general a similar behaviour of A and B chromosomes. Whereas in differentiated 4C nuclei A sister centromeres are separated, B sister centromeres align in nearly all nuclei. In short, despite the different transcription activity of A and B chromosomes, both types of chromosomes exhibit a similar organization in meristematic and differentiated interphase nuclei. But the deletion of a B chromosome segment responsible for non-disjunction during gametogenesis induces released sister centromeres also in some interphase nuclei of somatic tissue. Hence, the control of rye B chromosome non-disjunction is also active in sporophytic cells.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany. schubertv@ipk-gatersleben.de
authors.forename: Veit
authors.initials: V
authors.lastname: Schubert
authors.forename: Armin
authors.initials: A
authors.lastname: Meister
authors.forename: Hisashi
authors.initials: H
authors.lastname: Tsujimoto
authors.forename: Takashi Ryu
authors.initials: TR
authors.lastname: Endo
authors.forename: Andreas
authors.initials: A
authors.lastname: Houben
mesh_terms: D002454:Cell Differentiation; D002467:Cell Nucleus / Q000235:genetics*; D002842:Chromatids / Q000235:genetics; D020090:Chromosome Segregation; D032461:Chromosomes, Plant / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase / Q000235:genetics*; D018519:Meristem / Q000166:cytology / Q000235:genetics*; D008856:Microscopy, Fluorescence; D009630:Nondisjunction, Genetic; D018517:Plant Roots / Q000166:cytology / Q000235:genetics; D012434:Secale / Q000235:genetics; D014908:Triticum / Q000235:genetics