Figure 1. Mechanistic model of the NLR-mediated NHR.

(A) NLRs evolved to recognize adapted pathogen effectors also recognize conserved homologous effectors of non-adapted pathogen. A, A′, B, and B′ indicate different strains (or species) of pathogen. (B) Effectors of distantly related non-adapted pathogens targeting similar host targets of adapted pathogens could be recognized by surveillance system of nonhost plants. (C) While non-adapted pathogens recognized by nonhost plants NLRs, non-adapted pathogens cannot efficiently suppress nonhost defense machineries, because of lack of adaptation. (D) Transfer of nonhost NLRs into susceptible host plants could be promising strategy for conferring durable resistance.