Title: Allosyndetic recombination between a chromosome of Aegilops umbellulata and wheat chromosomes
Abstract: Allosyndetic recombination was induced between chromosome 1U of Aegilops umbellulata and wheat chromosomes by producing plants monosomic for this alien chromosome and homozygous for the mutant ph1b allele, which permits homoeologous chromosome pairing. Recombinants were selected among the progeny of such plants by observing the disruption of the Glu-1-Gpi-1-Gli-1 linkage on both the alien chromosome as well as along wheat chromosomes 1B and 1D. A frequency of 8·0 per cent recombination between the Gpi-U1 and the Gli-U1 loci was estimated when chromosomes 1U and 1B were simultaneously monosomic, whereas the rate of recombination was only 4·6 per cent when 1B was present as a disome. Some double homoeologous recombinants between the three loci Glu-1, Gpi-1 and Gli-1 were also isolated. Control populations, where homoeologous pairing was suppressed by the presence of Ph1, did not produce any allosyndetic recombinants between Gpi-1 and Gli-1.