A New Map Location of Gene for Resistance to Septoria Tritici Blotch in Wheat.

Septoria tritici blotch (STB), caused by (synonym: ; asexual stage: ), is an important disease of wheat worldwide. Management of the disease usually is by host resistance or fungicides. However, has developed insensitivity to most commonly applied fungicides so there is a continuing need for well-characterized sources of host resistance to accelerate the development of improved wheat cultivars. Gene has been a useful source of major resistance, but its mapping location has not been well characterized. Based on linkage to a single marker, a previous study assigned to a location on the short arm of chromosome 6D. However, the results from the present study show that this reported location is incorrect. Instead, linkage analysis revealed that is located on the short arm of wheat chromosome 7A, completely linked to microsatellite (SSR) locus and flanked by loci (12.4 cM distal) and (2.1 cM proximal). Linkage between and was validated in BCF progeny of other crosses, and analyses of the flanking markers with deletion stocks showed that the gene is located on 7AS between fraction lengths 0.73 and 0.83. This revised location of is different from those for other STB resistance genes previously mapped in hexaploid wheat but is approximately 20 cM proximal to an STB resistance gene mapped on the short arm of chromosome 7A in . The markers described in this study are useful for accelerating the deployment of in wheat breeding programs.