Localization of T-DNA Insertions in Petunia by Fluorescence in Situ Hybridization: Physical Evidence for Suppression of Recombination.
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.
Ten Hoopen
R.
R
Institute for Molecular Cell Biology, BioCentrum Amsterdam, University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands.
Robbins
T. P.
TP
Fransz
P. F.
PF
Montijn
B. M.
BM
Oud
O.
O
Gerats
AGM.
A
Nanninga
N.
N