Localization of T-DNA insertions in petunia by fluorescence in situ hybridization: physical evidence for suppression of recombination
1996
Hoopen, R ten | Robbins, T.P. | Fransz, P.F. | Montijn, B.M. | Oud, O. | Gerats, A.G.M. | Nanninga, N.
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 Fl on chromosome II. Linkage analysis had revealed that recombination around the Fl locus is suppressed in a wide cross relative to an inbred recombination assay. The localization of six Fl-linked T-DNAs and the Fl 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.
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