Introgression of the Suppressor into Wheat.

Meiotic pairing between homoeologous chromosomes in polyploid wheat is inhibited by the locus on the long arm of chromosome 5 in the B genome. (genomes SS), the closest relative of the progenitor of the wheat B genome, is polymorphic for genetic suppression of Using this polymorphism, two major suppressor loci, and , have been mapped in is located in the distal, high-recombination region of the long arm of the chromosome 3S. Its location and tight linkage to marker makes a suitable target for introgression into wheat. Here, was introgressed into hexaploid bread wheat cv. Chinese Spring (CS) and from there into tetraploid durum wheat cv. Langdon (LDN). Sequential fluorescence hybridization and genomic hybridization showed that an segment with replaced the distal end of the long arm of chromosome 3A. In the CS genetic background, the chromosome induced homoeologous chromosome pairing in interspecific hybrids with but not in progenies from crosses involving alien disomic substitution lines. In the LDN genetic background, the chromosome induced homoeologous chromosome pairing in both interspecific hybrids and progenies from crosses involving alien disomic substitution lines. We conclude that the recombined chromosome harbors but its expression requires expression of complementary gene that is present in LDN but absent in CS. We suggest that it is unlikely that and , a paralog of located on wheat chromosomes 3A and 3B and chromosome 3D, are equivalent. The utility of for induction of recombination between homoeologous chromosomes in wheat is illustrated.