title: Comparative analysis of crossover exchanges and chiasmata in Allium cepa x fistulosum after genomic in situ hybridization (GISH).
abstract: Genomic in situ hybridization (GISH) successfully differentiated homoeologous genomes in the inter-specific hybrid Allium cepa x fistulosum, thus allowing the detection of reciprocal crossover events as label exchanges in separating anaphase I chromosomes. Three of the eight chromosome pairs were positively identified by fluorescence in situ hybridization (FISH) to rDNA sequences. There was a general similarity of the GISH-based label exchange frequencies and metaphase I chiasma frequencies, but with a 20% deficit of chiasmata. Reasons for this apparent deficit are discussed. The locations of chiasmata and label exchanges are in broad agreement.
authors.affiliation: School of Biological Sciences, The University of Birmingham, Edgbaston, UK.
authors.forename: M
authors.initials: M
authors.lastname: Stevenson
authors.forename: S J
authors.initials: SJ
authors.lastname: Armstrong
authors.forename: B V
authors.initials: BV
authors.lastname: Ford-Lloyd
authors.forename: G H
authors.initials: GH
authors.lastname: Jones
mesh_terms: D000490:Allium / Q000235:genetics* / Q000648:ultrastructure; D000705:Anaphase; D003434:Crossing Over, Genetic; D006822:Hybrid Cells; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D008540:Meiosis; D008677:Metaphase