Controlled introgression to wheat of genes from rye chromosome arm 1RS by induction of allosyndesis : 2. Characterisation of recombinants.

Sixteen allosyndetic recombinants involving chromosome arms 1DS and 1RS derived from the wheat-rye translocation 1DL-1RS, and one 1RS recombinant derived from 1BL-1RS were characterised by cytological, biochemical and molecular methods. Analysis of isozyme markers showed that recombination had involved different breakpoints along the 1DS arm. The gene order Tri-D1 - Per-D1 - Gpi-D1 - Gli-D1 was established on chromosome 1DS, and this is consistent with the gene order known to occur on 1BS. The use of three molecular probes for loci on 1RS confirmed one of the recombinants obtained from the 1BL-1RS translocation, and two of the three recombinants obtained from the 1DL-1RS translocation. These two recombinant chromosomes appear to have approximately reciprocal structures and may prove of direct benefit to wheat breeders as they retain the stem rust resistance of the parental translocation but have recovered some of the 1D encoded proteins which are absent in 1DL-1RS lines and which are thought to affect dough quality. A 5S RNA site was discovered on chromosome arm 1DS, probably reflecting the homoeologous relationship of this chromosome with 1BS. Segregational analysis indicated that some of the homoeologous wheat-wheat exchanges probably involved more than a single allosyndetic event.