P-182 - Unveiling a new pathosystem: Dissecting Aphanomyces euteiches resistance in Aeschynomene evenia

Aphanomyces euteiches, a major legume pathogen in Europe and North America, lacks effective chemical control, making genetic resistance the best strategy. The model legume Medicago truncatula, a natural A. euteiches host, has been extensively studied for resistance mechanisms. Genetic analyses identified prAe1, a key quantitative resistance locus conferring resistance to multiple strains, mapped by GWAS to a locus containing genes for a kinase, a CNL immune receptor, and a Myb transcription factor. To expand our understanding of legume immunity, we established a novel Aeschynomene evenia-A. euteiches pathosystem, identifying symbiotic genes involved in immunity. Surprisingly, we also found that the bryophyte Marchantia polymorpha is a host of A. euteiches. Leveraging its genetic traits, we explored resistance conservation between bryophytes and angiosperms. Overexpressing M. truncatula resistance genes in both Mt and Mp revealed enhanced resistance. This study pioneers bryophytes as models for plant immunity and validates candidate resistance genes from legumes. Additionally, the Aeschynomene-Aphanomyces pathosystem offers new insights into NF-independent symbiosis. Ultimately, these findings could benefit Pisum sativum (pea), the primary crop targeted by A. euteiches.