Calcium ion promotes successful penetration of powdery mildew fungi into barley cells

摘要

To determine whether Ca2+ promotes powdery mildew penetration, Ca2+-treated barley coleoptiles were inoculated with conidia of pathogenic and nonpathogenic fungi. Penetration efficiency of the pathogenic powdery mildew Blumeria graminis was enhanced by Ca2+ treatment, but that of the necrotrophic pathogen Helminthosporium sp. remained unaffected. Similarly, when actin-dependent penetration resistance is suppressed with cytochalasin A, Ca2+ treatment specifically enhanced penetration of the nonpathogenic powdery mildew Erysiphe pisi but not that of other nonpathogens. Calmodulin inhibitors suppressed the promotive effect of Ca2+ on B. graminis penetration. These results suggest that barley powdery mildew specifically requires Ca2+ and calmodulin for penetration.