Mode of action of effector proteins involved in the infection process of powdery mildew infecting barley plants.

Pathogens secrete small proteins called effectors or virulence factors which are important for the successful invasion of the host. These effectors act by compromising the host immunity. Cereal powdery mildews (Blumeria graminis) are economically important pathogens in the UK, affecting main cereal crops such as barley and wheat. Powdery mildews can only grow on “healthy and alive” cells of their targeted host. Thus they have a life style typical of obligate pathogens, which requires the ability of compromising the host resistance mechanisms for successful infection. The sequenced genome of the barley powdery mildew (Spanu et al, Science, 2010) has allowed to identifying novel Blumeria effector candidates (BECs, Bindschedler et al, MCP, 2009; Bindschedler et al, Methods, 2011). These proteins were expressed mostly in specialised cells of biotrophic fungi. Thus they are suspected to be involved in the infection process of this biotrophic pathogen. Seven candidates were biologically validated as Blumeria effector proteins. Five of these effectors are novel specific small secreted proteins, some of which only share similarities with wheat powdery mildew proteins. One of the identified Blumeria effector shares similarity to metalloproteases from other fungi.

Aim of the research
Molecular and proteomic approaches will be used to investigate the role of powdery mildew effector proteins of this plant pathogen during infection of barley by its powdery mildew Blumeria graminis f.sp. hordei.