Extensive infections of crop plants by plant pathogens have repeatedly resulted in catastrophic harvest failures causing major economic and social problems worldwide. Successful plant defence against pathogens is based on early microbe recognition and fast activation of downstream immune signalling (e.g. phosphorylations, production of reactive oxygen species, transcriptomic reprogramming). Plant surface pattern-recognition receptors (PRRs) act as initial detectors that can recognise microbial-associated molecular patterns (MAMPs) to induce the basal resistance response called MAMP-triggered immunity (MTI). Despite the increasing number of PRRs discovered in the past 20 years, for most of them, it has not been determined whether they are indeed true receptors, especially for receptor-like proteins (RLPs) lacking kinase activity that function in complex with receptor-like kinases (RLKs) to regulate defence response. A well-described and accessible model of the plant-microbe relationship is represented by the interaction between Solanaceae plants and proteinaceous MAMPs, called elicitins, secreted by oomycetes. These include many economically significant crop pathogens, like Phytophthora infestans, causing late blight disease, but also other oomycetes, such Phytophthora cryptogea, that trigger defence against pathogenic microbes in tobacco. Thus, understanding of the mechanisms taking place in the recognition of oomycetal MAMPs could lead to new methods providing a durable resistance. In this context, we focus on the characterisation of structural regions necessary for the interaction of elicitins with the newly characterized ELicitin Receptor (ELR), and on the signalling events following MAMP perception by receptor RLP-RLK complex (namely ELR-SOBIR1) at the plasma membrane.