Effector-driven breeding for broad-spectrum disease

CS-23.6 - Potato late blight, caused by the destructive Irish famine pathogen Phytophthora infestans, is a major threat to global food security. All known late blig ht resistance genes that are identified to date belong to the NB-LRR class of immune receptors. However, virulent races of the pathogen quickly evolved to evade recognition by these intracellular cytoplasmic immune receptors. Another, yet unexploited, layer of immunity occurs at the surface of plant cells. This apoplastic immunity generally has a broader spectrum and is based on recognition of conserved proteins of pathogens. Recently we demonstrated that the receptor-like protein ELR from the wild potato Solanum microdontum mediates extracellular recognition of the elicitin domain, a molecular pat tern that is conserved in Phytophthora species. ELR mediates broad-spectrum recognition of elicitin pro teins from several Phytophthora species, including four diverse elicitins from P. infestans. Transfer of ELR to cultivated potato resulted in enhanced resistance to P. infestans. Co-immunoprecipitation studies revealed that ELR associates with the immune co-receptor BAK1/SERK3, as well as with SOBIR1/EVR. Currently we are expanding the repertoire of receptors that recognize apoplastic effectors of Phytophthora. One of our targets is the receptor of SCR74, a highly polymorphic apoplastic effector that is under diversifying selection in P. infestans. We have identified wild Solanum species that recognize SCR74, and the identification of the receptor is underway. We postulate that pyramiding diverse types of apoplastic and cytoplasmic receptors maximizes the potential of generating a broader and potentially more durable resistance to this devastating plant pathogen. infestans . We have identified wild Solanum species that recognize SCR74, and the identificati on