Emerging Blumeria graminis f. sp. hordei pathotypes reveal ‘Psaknon’ resistance in European barley varieties

Abstract

SUMMARYBarley (Hordeum vulgare L.) is one of the most important cereal crops in the world and powdery mildew caused by the airborne fungus Blumeria graminis f. sp. hordei is a worldwide disease that causes frequent epidemics in Central and Northwestern Europe. Psaknon was one of first varieties in which powdery mildew resistance (Mlp1) was found, but no commercial variety with this resistance and no pathotype with the corresponding virulence have been recorded. In 2014, four isolates collected in the Czech Republic and virulent to Mlp1 were tested on 25 varieties and were also virulent to seven other resistances, including Venezia. These isolates revealed the presence of Mlp1 in six commercial spring and winter barley varieties from Southeastern and Central Europe and in six German winter barley candidate lines for registration in Czech variety trials. Based on the combined results of virulence and resistance, it was concluded that Vp1 is becoming a major factor contributing to increased virulence complexity and pathotype diversity in Central Europe. In breeding, employment of the non-specific resistance Mlo for spring barley and accumulation of quantitative resistance genes for winter barley can still be recommended in addition to exploiting a non-host resistance from an alternative source such as that present in Hordeum bulbosum.