title: FISH mapping and molecular organization of the major repetitive sequences of tomato.
abstract: This paper presents a bird's-eye view of the major repeats and chromatin types of tomato. Using fluorescence in-situ hybridization (FISH) with Cot-1, Cot-10 and Cot-100 DNA as probes we mapped repetitive sequences of different complexity on pachytene complements. Cot-100 was found to cover all heterochromatin regions, and could be used to identify repeat-rich clones in BAC filter hybridization. Next we established the chromosomal locations of the tandem and dispersed repeats with respect to euchromatin, nucleolar organizer regions (NORs), heterochromatin, and centromeres. The tomato genomic repeats TGRII and TGRIII appeared to be major components of the pericentromeres, whereas the newly discovered TGRIV repeat was found mainly in the structural centromeres. The highly methylated NOR of chromosome 2 is rich in [GACA](4), a microsatellite that also forms part of the pericentromeres, together with [GA](8), [GATA](4) and Ty1-copia. Based on the morphology of pachytene chromosomes and the distribution of repeats studied so far, we now propose six different chromatin classes for tomato: (1) euchromatin, (2) chromomeres, (3) distal heterochromatin and interstitial heterochromatic knobs, (4) pericentromere heterochromatin, (5) functional centromere heterochromatin and (6) nucleolar organizer region.
authors.affiliation: Wageningen University, Laboratory of Genetics, 6703 BD, Wageningen, The Netherlands.
authors.forename: Song-Bin
authors.initials: SB
authors.lastname: Chang
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Yang
authors.forename: Erwin
authors.initials: E
authors.lastname: Datema
authors.forename: Joke
authors.initials: J
authors.lastname: van Vugt
authors.forename: Ben
authors.initials: B
authors.lastname: Vosman
authors.forename: Anja
authors.initials: A
authors.lastname: Kuipers
authors.forename: Marie
authors.initials: M
authors.lastname: Meznikova
authors.forename: Dóra
authors.initials: D
authors.lastname: Szinay
authors.forename: René Klein
authors.initials: RK
authors.lastname: Lankhorst
authors.forename: Evert
authors.initials: E
authors.lastname: Jacobsen
authors.forename: Hans
authors.initials: H
authors.lastname: de Jong
mesh_terms: D002874:Chromosome Mapping / Q000379:methods*; D018744:DNA, Plant / Q000235:genetics*; D018745:Genome, Plant; D006570:Heterochromatin; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D018551:Solanum lycopersicum / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D006570:Heterochromatin