Chromosomal location and genetic mapping of the mismatch repair gene homologsMSH2,MSH3, andMSH6in rye and wheat

Abstract

The efficiency of homeologous recombination is influenced by mismatch repair genes in bacteria, yeast, and mammals. To elucidate a possible role of these genes in homeologous pairing and cross-compatibility in plants, gene probes of wheat (Triticum aestivum) specific for the mismatch repair gene homologues MSH2, MSH3, and MSH6 were used to map them to their genomic positions in rye (Secale cereale). Whereas MSH2 was mapped to the short arm of chromosome 1R, MSH3 was mapped to the long arm of chromosome 2R and MSH6 to the long arm of chromosome 5R. Southern blots with nullisomic-tetrasomic (NT) lines of wheat indicated the presence of the sequences on the respective homeologous group of wheat chromosomes. Additionally, an MSH6-specific homologue could also be detected on homoeologous group 3 of wheat. However, in the well-known, highly homoeologous pairing wheat mutant ph1b the MSH6-specific sequence is not within the deleted part of chromosome 5BL, indicating that the pairing phenotype is not due to a loss of one of the mismatch repair genes tested.

A DNA mismatch repair gene links to thePh2locus in wheat

“…(GenBank accession No. AJ131669, Korzun et al 1999). The deduced amino acid sequence of the 350-bp fragment showed highest homology to MSH6.…”

“…Plants have a similar MMR system to yeast and animals. Homologues of MSH2, MSH3, and MSH6 have been found in Arabidopsis Hays 1997, 2000;Adé et al 1999), wheat (Korzun et al 1999), and maize (GenBank accession Nos. AJ238786, AF227632).…”

Meiotic genes and proteins in cereals

“…This strategy was validated through the genetic mapping of three mismatch repair gene paralogues of wheat MSH2, MSH3 and MSH6 to chromosomes 1, 2 and 5 of rye, respectively (Korzun et al, 1999). In a later study, degenerate primers for RT-PCR were designed to isolate the two closely related RecA -like genes, RAD51 and DMC1 of rye (Jenkins et al, 2005).…”

“…A mismatch repair gene ( TaMSH7 ) maps to the region deleted on chromosome 3D of the Ph2a mutant, and is also located on the short arms of chromosomes 3A and 3B (Dong et al, 2002). Mismatch repair gene MSH6 has been detected on homoeologous group 3 chromosomes (Korzun et al, 1999). Paralogues of WM5 map to the short arms of chromosomes 3A, 3B and 3D, and are proposed to have a role in meiosis and meristem development (Dong et al, 2005).…”

Strategies for the study of meiosis in rye

“…This approach has particular significance, given the relative dearth of sequence data in rye, and also the insufficient density of markers on the genetic map which at present precludes map-based cloning of meiotic genes. This approach has recently been validated in this species, for example through the mapping of wheat orthologues of the mismatch repair gene MSH to the genome of rye (Korzun et al, 1999), or more directly by the identification of an EST from anthers of rye which shows significant sequence identity to the DNA-binding HORMA domain of the ASY1 gene of A. thaliana (Chris Franklin, pers. comm.).…”