A unique race of the wheat stem rust pathogen with virulence on <i>Sr31</i> identified in Spain and reaction of wheat and durum cultivars to this race

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a re-emerging disease, posing threat to wheat production. In Spain, rust has been rarely detected since the 1970s, but infection was observed in fields 2018. We analysed six samples collected Rota, Cádiz province and one from Monteagudo del Castillo, Teruel province. All Rota were typed as race TKTTF, whereas sample field adjacent barberry bushes, TKHBK. This unique significant virulence combination that includes Sr31, Sr33, Sr53 Sr59, avirulent Rusty, durum line developed for universal susceptibility pathogen. TKHBK first outside Ug99 group with Sr31 known Sr59. Genotyping studies indicate does not belong or TKTTF groups constitutes previously unknown lineage. Two hundred bread cultivars breeding lines Spain evaluated against TKHBK, additional races. Resistance all races evaluated. Molecular markers confirmed presence of Sr7a, Sr24, Sr38 Sr57 wheat, Sr13 wheat. The re-emergence occurrence virulences underscore need continue surveying monitoring this disease.