Relocation of Sr48 to Chromosome 2D Using an Alternative Mapping Population and Development of a Closely Linked Marker Using Diverse Molecular Technologies.

The Ug99-effective stem rust resistance gene was mapped to chromosome 2A based on its repulsion linkage with in an Arina/Forno recombinant inbred line (RIL) population. Attempts to identify markers closely linked to using available genomic resources were futile. This study used an Arina/Cezanne F RIL population to identify markers closely linked with . Using the Arina/Cezanne DArTseq map, was mapped on the short arm of chromosome 2D and it co-segregated with 12 markers. These DArTseq marker sequences were used for BlastN search to identify corresponding wheat chromosome survey sequence (CSS) contigs, and PCR-based markers were developed. Two simple sequence repeat (SSR) markers, and , and two Kompetitive Allele-Specific PCR (KASP) markers were derived from the contig 2DS_5324961 that mapped distal to . Molecular cytogenetic analysis using sequential fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH) identified a terminal translocation of chromosome 2A in chromosome 2DL of Forno. This translocation would have led to the formation of a quadrivalent involving chromosomes 2A and 2D in the Arina/Forno population, which would have exhibited pseudo-linkage between and in chromosome 2AL. Polymorphism of the closet marker among a set of 178 wheat genotypes suggested that this marker can be used for marker-assisted selection of .