Resistance to powdery mildew in wild species of barley

Abstract

One hundred and fifty-three populations representing 24 wild Hordeum species have been screened for resistance to powdery mildew, Erysiphe graminis f. sp. hordei. All species except one are resistant to the four Scandinavian isolates tested. Histological studies have been performed during different stages of infection. In all stages, significant differences exist between all different sources of resistance. It can be concluded that a combination of mechanisms are involved in resistance reactions of wild barley species. However, the most important reactions seem to be induced by the host plants after penetration of epidermis cells. How far the development of the fungus progresses vanes with the material, but in most cases the formation of well-shaped primary haustoria and/or secondary hyphae was inhibited. In a majority of the material, resistance appears to be dominant to susceptibility.