Microbial life manifests itself in complex communities such as the ones attached to plant surfaces. They consist of beneficial mutualists and epiphytes as well as of potential pathogens. Plants express surface receptors that recognize them according to their microbe-associated molecular patterns (MAMPs). MAMP-stimulated plant responses have been studied for a long time. Recently a number of reports have provided a deeper understanding on how perception of MAMPs contributes to basal resistance at both layers of pre-invasive and post-invasive immunity. Comparative profiling of gene expression revealed a large overlap of plant responses towards different MAMPs or plant-microbe interactions, indicating common signaling components.