Chromosomal location and genetic mapping of the mismatch repair gene homologs MSH2, MSH3, and MSH6 in rye and wheat

The efficiency of homeologous recombination is influenced by mismatch repai r genes in bacteria, yeast, and mammals. To elucidate a possible role of th ese genes in homeologous pairing and cross-compatibility in plants, gene pr obes of wheat (Triticum aestivum) specific for the mismatch repair gene hom ologues MSH2, MSH3, and MSH6 were used to map them to their genomic positio ns in rye (Secale cereale). Whereas MSH2 was mapped to the short arm of chr omosome 1R, MSH3 was mapped to the long arm of chromosome 2R and MSH6 to th e long arm of chromosome 5R. Southern blots with nullisomic-tetrasomic (NT) lines of wheat indicated the presence of the sequences on the respective h omeologous group of wheat chromosomes. Additionally, an MSH6-specific homol ogue could also be detected on homoeologous group 3 of wheat. However, in t he well-known, highly homoeologous pairing wheat mutant ph1b the MSH6-speci fic sequence is not within the deleted part of chromosome 5BL, indicating t hat the pairing phenotype is not due to a loss of one of the mismatch repai r genes tested.