Host-pathogen interaction: Identification of pea signals that trigger Aphanomyces euteiches.

Aphanomyces root rot is a destructive disease in pea and lentil production worldwide causing over $20 million in economic loss annually in the Canadian prairies. Aphanomyces euteiches is a soil-borne oomycete that produces asexual (zoospores) and sexual (oospores) spores. In the close vicinity of pea roots, oospores germinate via sensing of chemical signals and produce biflagellate zoospores. Host signals attract the motile zoospores towards the pea root surface. Zoospores, once in contact with pea roots, encyst, germinate and penetrate the host root cells. The main goal of this research is to identify the host signals that elicit pathogen activation by triggering oospore germination and zoospore chemotaxis. The time points of zoospore adhering to and encysted on the root surface, germination, and penetration into the pea root were monitored using scanning electron microscopy. Metabolomics on infected and control pea roots was performed at the same time as zoospore germination and penetration. The exploitation of host signals that trigger oospores and attract zoospores can lead to novel and innovative disease management strategies.