Race-specific resistance conferred by resistance genes (R-genes) is well-studied. It is assumed that R-genes encode for plant receptors that recognize pathogen effectors in order to activate highly efficient defence reactions. In absence of corresponding R-genes, pathogen effectors interact with specific host factors to suppress innate plant defence and establish effector-triggered susceptibility. Thus, suppression of plant defence is a key step for pathogens to make plants susceptible to disease; and resistance can be in principal achieved by the absence of host proteins targeted by pathogen effectors. Loss-of-function mutation(s) in the sequence-diversified family of heptahelical transmembrane proteins have proven to be effective in several plant families as the respective protein isoforms represent a conserved plant cell protein required in fungal penetration. This proposal is aimed to (1) explore susceptibility factors in Solanaceae to achieve broad-spectrum resistance to fungal diseases and (2) to enlighten an alternative strategy for resistance breeding: achieving resistance by exploration of plant genes required for susceptibility (S-genes) to pathogens. This breeding strategy will result in durable and broad-spectrum resistance.