Mapping a Resistance Gene to f. sp. in the Bread Wheat Cultivar 'Matlabas'.

f. sp. race TTKSF+ was collected from the South African wheat cultivar 'Matlabas' in 2010. F and F populations derived from a Matlabas × Line 37-07 cross segregated for a single resistance gene to race TTKSF that is avirulent to Matlabas. In screening genomic DNA bulks of susceptible or resistant F plants with simple sequence repeat (SSR) markers, three chromosome arm 2BS markers and one multilocus marker amplified alleles present only in the resistant bulks and Matlabas. Additional 2B-specific SSR markers, incorporating markers spanning regions containing , , , and , were screened in the parental lines and mapped in the F population. Linkage and QTL mapping showed that the gene is located between in the centromeric region and on the long arm of chromosome 2B. When 2B-specific SNP markers were mapped, the area of interest was delimited to a 15.3 cM region on chromosome arm 2BL, with and as flanking loci. Matlabas, Webster, and related lines all produced a similar, low infection type to race TTKSF, but were susceptible to race TTKSF+. Phenotypic data and allelic studies suggested that stem rust resistance in Matlabas was derived from an source.