Résumé
Plant pathogen genomes co-evolve with their host genomes to overcome the plantresistance mechanisms through generation of a variety of isolates. The causal agent of rice blast,Magnaporthe oryzae, the major Rice pathogen, is responsible of economically significant crop losses.During the infection stage the fungus secretes small proteins acting as virulent factors, calledeffectors, some of them being translocated inside host cells. Among them, avirulent effectors arerecognized by the plantimmune system through cytoplasmic receptor proteins that activates“effector triggered immunity” mediating the resistance answer. Here, we solved the NMR structuresof two such effectors of M.oryzae: AVR-Pia and AVR1-CO39. Structurally, they share a commonthree-dimensional architecture, also found in M. oryzae AVR-Piz-t effector and Pyrenophora triticirepens toxin ToxB, pathogenic for wheat. Sequence comparison search of fungi protein databasesbased in the 3D structures and sequence alignments, revealed new possible members of this sub-class of plant pathogen effectors.