P-015 - Breaking Barriers: How overcoming natural resistances in wild crop relatives reveal new insights in resistance strategies against Zymoseptoria infections

Crops are constantly threatened by fungal pathogens, making the research of plant resistance traits crucial for agriculture. Wild crop relatives serve as valuable genetic resources for identifying conserved resistance mechanisms. Fungal pathogens of the genus Zymoseptoria pose a global threat to wheat and barley, with specialized strains capable of infecting either domesticated crops or their wild relatives. We highlight wild wheat (Aegilops cylindrica) and wild barley (Hordeum murinum) as new reservoirs of resistance genes (R-genes), as they are resistant against crop-infecting strains of Z. tritici and Z. passerinii, infecting wheat and barley respectively. We observed that stomatal penetration is a critical checkpoint, where infection by incompatible isolates is aborted. Experimentally we could break this resistance barrier in the wild crop relatives by infiltrating crop-specialized Zymoseptoria spores into leaves. This leads us to hypothesize that wild wheat and barley harbor highly effective R-proteins against the crop-infecting strains of Zymoseptoria related to stomatal closure. To identify candidate R-genes, we investigated the transcriptomic response against Zymoseptoria in those wild crop relatives using transcriptome-based de novo assemblies of these non-model plants. During infection a different set of genes is activated compared to the crop relatives and leading us to the known R-gene RPP13-like as putative key regulator in both A. cylindrica and H. murinum.