Common bunt resistance gene Bt10 located on wheat chromosome 6D

Knowledge of the chromosomal location of disease resistance genes assists in their identification and classification. The determination of the chromosomal location in wheat of the common bunt (Tilletia tritici and T. laevis) resistance gene Bt10 was the goal of this study. Doubled haploid lines were developed from a cross between bunt susceptible Glenlea and bunt resistant AC Taber carrying BHO. The doubled haploid lines were inoculated with T. tritici race T19, grown in a growth room and rated for bunt near maturity. A series of 50 wheat microsatellite markers were tested on DNA of the individual lines. The population segregated 1:1 for bunt reaction with clear separation between resistant and susceptible classes. A trait related DNA polymorphism generated by gwm469 located in chromosome 6D fit a 1:1 segregation. Combined segregation of bunt resistance and the gwm469 polymorphism differed significantly from a 1:1:1:1 ratio with a preponderance of parental types confirming linkage of gwm469 with Bt10. The map distance between gwm469 and Bt10 was estimated at 19.3 cM by MAPMAKER. The microsatellite, markers wmc749, barc54 and cfd0033, located on chromosome 6D, also were significantly associated with the bunt resistance and gwm469. In total, six markers previously located to chromosome 6D were in the linkage group with the BHO common bunt resistance. The linkage of these markers with each other and Bt10 indicated that Bt10 is located on the short ann of chromosome 6D.