Phytophthora RxLR effectors: keys to durable late blight resistance
Phytophthora produces numerous effectors, many of which are transported to the inside of the cell where they suppress defence responses and manipulate the host cell machinery. Recognition of effectors by their cognate resistance (R) proteins results in a hypersensitive response that blocks further growth of the pathogen. Breeders have introgressed late blight R genes into cultivated potato but in the field this resistance is quickly defeated. P. infestans can easily mutate its effector genes thereby avoiding recognition. Insight into the molecular interaction between effector and R protein can help in designing more rational breeding strategies. The hallmarks of oomycete effectors are an N-terminal signal peptide followed by a cell-targeting motif (RxLR), and a C terminal domain of variable length that is highly diverse and has no homology to any known protein.
MSc research projects offered within this theme are:
- Functional analysis of RxLR effector genes by in planta expression using Agrobacterium tumefaciens transient assays (ATTA) and domain swapping to determine which part of the C
- terminal domain is responsible for effector activity
- Identification of novel effector targets by yeast-2-hybrid screening
- Functional analysis of effector targets by VIGS (virus induced gene silencing)
Novel anti-Phytophthora agents: a rational strategy for target discovery
Genome mining in Phytophthora has resulted in an avalanche of information that can be exploited to search for unique features of oomycetes. In our mining expeditions focused on phospholipid modifying enzymes and G-protein signaling components, we found many genes encoding novel proteins not found in any other organism. Novel genes are intriguing. Are they key to potential anti-oomycete agents?
MSc research projects offered in this theme involve studies on two novel classes of proteins: secreted phospholipase D’s that could play a role in degradation of host membranes and transmembrane receptors named GPCR-PIPKs. Activities may include cloning, expression analysis, biochemical assays, bioinformatics, in planta expression assays, in situ localization using microscopy, mutant analysis or expression in heterologous hosts.