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Understanding the role of root exudation for pathogen germination and attraction, and their application for disease control

Calum Wilson: University of Tasmania

<div>Plant roots release a substantial quantity of primary metabolites (root exudates) into the rhizosphere, the majority of which are low molecular weight organic compounds. These exudates play important roles in interactions between the plant, and other soil biota including soil-borne plant pathogens. Exudate compounds may benefit pathogens, promoting their germination, growth, survival, pathogenesis and reproduction, or may be detrimental inhibiting growth or disrupting motility. With a combined <em>in vitro </em>bioassay, light microscopy and targeted metabolomics approach using HILIC UPLC-MS analysis, we demonstrate the importance of potato root exudates for stimulating germination of resting spores of the pathogen <em>Spongospora subterranea </em>f. sp.<em> subterranea</em>. Furthermore, we show these compounds provide a chemotactic signal to attract released zoospores to the host roots enabling efficient infection. We also demonstrate application of this knowledge for novel management of soil inoculum through a ‘germinate to exterminate’ approach, and propose novel disease management approaches through disruption of pathogen chemical signalling.</div>