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Induced resistance to late blight depends on potato inducibility and on Phytophthora infestans effectors

Cécile Thomas: INRA UMR 1349 IGEPP (Institute of Genetics, Environment and Plant Protection)

<div>Pathogen recognition by plants<em> via</em> pathogen-associated molecular patterns leads to PAMP-triggered immunity but pathogens can modulate it <em>via </em>effectors production. Only few studies connect plant responses with parasite ecology particularly in the interaction between <em>Solanum tuberosum </em>and <em>Phytophthora infestans. </em>We hypothesize that potato induced defense triggered by PAMPs from <em>P.infestans </em>culture filtrate (CCF) could affect disease outcome and effector genes expression. Potato genotypes - Bintje, Désirée, Rosafolia - were sprayed with CCF. Detached leaflets were inoculated 48h later with 1 strain of <em>P.infestans</em>. Potato defense genes and <em>P.infestans</em> effectors expressions were assessed by qRT-PCR from 48h to 4dpi. Simultaneously, disease was evaluated by lesion area measurement and sporangia counting. Treatment with CCF increased the expression of defense genes, reduced lesion and sporangia production in Bintje and Désirée. In Rosafolia, it repressed most defense genes but it only increased sporangia number. In Bintje, after treatment and inoculation, defense genes were still induced until 3dpi but were repressed 4dpi. CCF treatment altered also the expression of pathogen effectors depending on time. Analyses are in process for the other genotypes. Our results highlight that efficiency of potato induced resistance depends on both genotype-dependent response and pathogen ecology <em>via </em>effectors expression during disease spreading.</div>