BLUMERIA EFFECTORS · FUNCTIONAL ANALYSIS OF THE BLUMERIA HAUSTORIA - BARLEY INTERACTOME

Blumeria graminis f. sp hordei is an economically important pathogen of cereals that causes barley powdery mildew. This obligate biotrophic pathogen is able to penetrate the cell wall barrier and develop a highly complex intracellular structure -the “haustorium”. This structure has long been known to actively take up nutrients, but it is now also believed to control host perception and defence, enabling the invading pathogen to survive, avoid and suppress rejection responses. How this is achieved is unknown, but current thinking postulates that this control is mediated by protein effectors secreted by the pathogen into the host cells. In this proposal I aim at discovering details of the molecular mechanisms by which B. graminis establishes control of the host barley cell through the action of the haustorium and effectors. To do this, I will define a panel of genes that encode candidate effectors proteins based on current data available and on new proteogenomic data generated at Dr. Spanu’s laboratory (Imperial College London, UK) in collaboration with the University of Reading (UK). These candidates will be cloned in vectors for functional analysis and expression as recombinant proteins. Effector proteins that alter infection levels will be identified by in vivo assays developed and used successfully by Dr. Wise’s group at USDA (USA). These effectors will be used to ‘’fish’’ host proteins they bind to and interact with, which will define candidate effectors targets. Evidence of interactions will be sough both, in the plant cells themselves and in extracts from infected plants. I will use the same approach to identify barley or Blumeria proteins which interact with Bln-1, the recently discovered modulator of susceptibility in Blumeria/barley interactions. Understanding of the molecular mechanisms underlying disease in the cereal mildew has the potential of aiding future developments in disease resistance and management.