Analyzing wheat cultivars grown in Czech Republic for eight stem rust resistance genes

Stem rust is a disease of wheat caused by a basidiomycete Puccinia graminis f. sp. tritici ( Pgt ). Emergence of new populations of the pathogen and their spread over the world calls for growing cultivars with lasting resistance. Knowledge of resistance gene composition in local cultivars in the fields together with knowledge of global movements of pathogen races is crucial. Present study focused on using molecular markers to detect eight resistance genes in 58 wheat cultivars encompassing more than 85% of wheat-growing area of Czech Republic. Presence of genes within the cultivars was compared to disease severity in 2014–2020 field trials. Local samples of Pgt were collected and tested for their virulence profiles using differential lines and two of the accessions were then tested for virulence on the 58 wheat lines. Gene Sr38 was present most frequently (63.79%) and while cultivars with this gene showed lower infection in the non-race specific field trials, pathotypes from 2020 season were mostly virulent to it. Sr31 and Sr24 are present with 10.34% and 13.79% frequencies. The fact that none of the Pgt races collected were virulent to Sr31 and Sr24 suggests that races from the Ug99 lineage are currently not present in Czech Republic. This study showed that wheat cultivars grown in Czech Republic rely heavily on a single resistance gene that is being overcome. Two other resistance genes, while still effective, occur sporadically.