title: Localization of T-DNA Insertions in Petunia by Fluorescence in Situ Hybridization: Physical Evidence for Suppression of Recombination.
abstract: Using fluorescence in situ hybridization (FISH) with metaphase preparations, we localized a 4-kb single-copy T-DNA sequence in a group of petunia transformants. The selected T-DNAs previously had been shown to be linked to the phenotypic marker FI on chromosome II. Linkage analysis had revealed that recombination around the FI locus is suppressed in a wide cross relative to an inbred recombination assay. The localization of six FI-linked T-DNAs and the FI locus itself, using FISH, revealed a number of aspects of recombination in petunia: (1) the central region of chromosome II showed at least a 10-fold suppression of recombination in wide crosses relative to the distal region; (2) recombination in wide hybrids over two-thirds of the chromosome was extremely low; and (3) recombination between completely homologous chromosomes in an inbred cross also was suppressed in the central region. In addition, the T-DNAs were not evenly distributed along the chromosome, suggesting a possible preference for a distal position for T-DNA integration. Implications for such a preference are discussed.
authors.affiliation: Institute for Molecular Cell Biology, BioCentrum Amsterdam, University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands.
authors.forename: R.
authors.initials: R
authors.lastname: Ten Hoopen
authors.forename: T. P.
authors.initials: TP
authors.lastname: Robbins
authors.forename: P. F.
authors.initials: PF
authors.lastname: Fransz
authors.forename: B. M.
authors.initials: BM
authors.lastname: Montijn
authors.forename: O.
authors.initials: O
authors.lastname: Oud
authors.forename: AGM.
authors.initials: A
authors.lastname: Gerats
authors.forename: N.
authors.initials: N
authors.lastname: Nanninga