This thesis is a preliminary study of the genetic basis for resistance to the fungal disease yellow rust caused by Piccinia striiformis Westend f.sp tritici, (Pst) in MASBASIS, a core collection of spring and winter wheat lines representing the Norwegian breeding material and important cultivars in Norwegian wheat production. Yellow rust has not been an important disease in Norway until new aggressive races of the pathogen have emerged and spread across Europe. Warrior, Warrior(-) and Kranich are some of the new races that broke the resistance present in the cultivars grown in Europe which have been sampled in Norwegian wheat fields since 2014, Warrior(-) now is the prevailing race in all of western Europe as well as in Norway. There is a need for development of cultivars with high level of durable resistance, as this is the most sustainable method of controlling yellow rust.M-P
