Plant and microbial proteins contributing to beneficial and detrimental root colonisation by filamentous microbes
S. SCHORNACK (1), C. Quan (1), T. Rey (1), M. Bonhomme (2), C. Jacquet (2), A. Chatterjee (1), J. Toulotte (1) (1) University of Cambridge, Sainsbury Laboratory, United Kingdom; (2) LRSV, University Paul Sabatier, France

Plant roots form a symbiosis with arbuscular mycorrhiza fungi (AM fungi) but are also target tissues for filamentous pathogens. Both, pathogenic and symbiotic interactions follow structurally similar colonisation processes. It is thus reasonable to assume that a number of processes involved in colonisation are shared between both types of interactions and that both types of interactions utilise microbial effectors to target similar processes. By comparatively studying interactions of plants with the filamentous pathogen Phytophthora palmivora and beneficial Rhizophagus irregularis AM fungi we aim to identify common mechanisms underlying their colonisation. Using genome-wide association studies (GWAS) coupled to reverse genetics we uncovered a Medicago truncatula GRAS-type transcription factor contributing to colonisation by symbiotic AM fungi as well as pathogenic P. palmivora. By applying a pathogen effector prediction pipeline we identified a family of Rhizophagus irregularis effector candidates with functional similarity to filamentous pathogen effectors. When expressed constitutively in Nicotiana benthamiana roots, a member of this effector family significantly enhances the extent of mycorrhization. Currently, we are pursuing the identification of host target proteins. These results demonstrate the presence of common principles underlying the interactions of plants with phylogenetically unrelated fungal symbionts and filamentous pathogens. In the future, we hope to utilise our findings to establish quantitative broad-spectrum resistance against filamentous root pathogens with similar lifestyle.

Abstract Number: C7-3, P1-12
Session Type: Concurrent