Philipp.Schulz@julius-kuehn.de

Wheat stem rust is a critical disease that is currently spreading into new areas within Europe, while at the same time developing new virulence around the globe. Control of the disease relies either on pesticides or on varietal resistance, the later unfortunately being under high pressure from newly developing rust races. Currently marketed varieties are largely unprotected even against non-Ug99 related races.

However, introgression of new resistant sources, usually from secondary or even tertiary gene pool is a timely and laborious task. The success of such process also strongly depends on the race(s) used for selection, which may not necessarily represent the current native race situations in target regions.

To identify direct usable sources, we screened 263 European elite lines in a 4-year (2019-2022), two locations trial under natural and artificial infection conditions with natural present isolates in southern and central Europe. Additionally, we used different molecular markers and seedling resistance based gene postulations finally to deliver validated directly usable resistances in elite material.

Noteworthy, only 10 out of the 263 tested varieties displayed a high and durable level of resistance across the four years and both locations. The multiple level analysis of those clearly show that Sr24 and Sr31 are the major resistance drivers in European cultivars, with some support on field level by Sr38. Our study provides a directly usable source to fortify European elite cultivars against the currently present Pgt isolates.