A preliminary report on the identification of SSR markers for bunt (Tilletia sp.) resistance in wheat

Common bunt and dwarf bunt, caused by Tilletia caries (DC) Tul., T. foetida (Wallr) Liro., and T. controversa, respectively, can still cause yield and quality losses, despite the availability of effective chemical treatments. Growing resistant cultivars remains the best option for economical and environmental reasons, and is the only effective alternative in organic farming. As the durability of bunt resistance has proved to be rather poor, the pyramiding of resistance genes has been envisaged as a method of extending the life of resistance genes. Molecular markers can considerably increase the efficiency of gene pyramiding, but, because incomplete expression of both susceptibility and resistance genes makes accurate phenotyping difficult, very few markers associated with bunt resistance genes have been identified to date. This is why, at the National Agricultural Research & Development Institute Fundulea-Romania, along with the breeding program for bunt resistance, research on the possible use of molecular markers for Marker Assisted Selection (MAS) was developed. Random F5 or F4 lines from crosses between a Bt11 line or a bunt resistant line derived from a Triticale/2 × wheat, and susceptible parents, were phenotyped under artificial inoculation conditions, and were genotyped using primers for several markers. Preliminary results suggest that the Bt11 gene is located on chromosome 3B, and may be associated with marker loci Xbarc180, Xwmc623, Xwmc808 and Xgwm285. The gene for bunt resistance transferred from Triticale (line F00628G34-1 - possessing a 1A/1R translocation) can make MAS possible by using 1R specific markers. Although these results are preliminary, they already prove to be useful for the diversification and pyramiding of bunt resistance genes in breeding for durability of bunt resistance.