Research Summary

Official webpage at the Université de Sherbrooke

The Moffett lab is interested in understanding the molecular basis of pathogen defense afforded by plant disease resistance (R) genes. Plant genomes contain hundreds of R genes that encode NB-LRR proteins, so named because they possess nucleotide-binding and leucine-rich repeat domains. NB-LRR proteins are highly variable both within and between species, and confer resistance to viruses, bacteria, fungi, oomycetes, nematodes and insects.

Our main experimental model is the potato Rx gene, which confers resistance to potato virus X (PVX) and functions in tobacco. The latter affords a number of technical advantages as a model plant, including ease of protein expression and virus induced gene silencing (VIGS).

Our goals are to understand the molecular basis by which closely related NB-LRR proteins are able to recognize different pathogens and how this recognition is subsequently translated into the initiation of defense responses. To do so, we are studying the protein-protein interactions that take place within the Rx protein as well as between Rx and other cellular proteins. We have recently identified a protein, RanGAP2 that interacts with the Rx protein. RanGAP2 appears to be involved in the recognition process of Rx as well as another NB-LRR protein, Gpa2, which is highly similar to Rx but confers resistance to the potato pale cyst nematode.

We have recently started a project whose goal is to apply our knowledge of NB-LRR protein function to the engineering of crop plants that are resistant to the late blight pathogen Phytophthora capsici.

Additional projects include the identification of the downstream components required for an effective Rx-mediated anti-viral response and defining how NB-LRR proteins cause viruses to be targeted by this response. To study these questions we use various biochemical, genetic, molecular and cell biology methodologies.