We are broadly interested in plant-microbe interactions. However, we focus on powdery mildew diseases caused by fungi in the Erysiphaceae; primarily the Arabidopsis powdery mildew disease caused by Golovinomyces cichoracearum and the barley powdery mildew disease caused by Blumeria graminis f. sp. hordei. Some of the questions of interest in the lab are what are the mechanisms of disease resistance deployed by plants against this group of pathogens and what plant processes support optimal disease development by these obligate biotrophic pathogens. In addressing the first question, we have studied “non-host” resistance exhibited by Arabidopsis against the barley powdery mildew and the role of the plant cell wall in restricting powdery mildew host range.  With the advent of whole genome sequencing of powdery mildews, opportunities to study pathogen determinants of disease development open up. Initially, we will characterize powdery mildew effectors required for successful disease development and the host targets of these effectors.  All these approaches provide complementary strategies for manipulating disease resistance in plants to standard Resistance gene-based methods.  

Plants perceive multiple elicitors in natural infections

Plant and animal hosts are thought to “identify” and respond defensively to two signals generated during pathogen attack – one is a MAMP or conserved microbe molecular (such as bacterial flagellin or fungal chitin) and the second a “pattern of pathogenesis” (such as microbe effectors injected into host cells; host cell wall damage due to microbe hydrolytic enzymes).

Powdery mildew effectors

Microbe effector proteins have been well studied in bacteria but are relatively unexplored in fungi such as the powdery mildews.

Powdery mildew resistant mutants have altered cell walls

J. Vogel isolated a series of powdery mildew resistant mutants (pmr1 – pmr6) and a series of suppressor mutants of pmr5 (p5s1 – p5s10).

Powdery mildew genome sequencing, a collaboration with Mary Wildermuth

Even though powdery mildews as a group are among the most economically important diseases of plants, with over 900 species infecting more than 6000 plant species, relatively little is known about these pathogens.