The present invention relates to the finding that an until now orphan protein named receptor-like protein 1 (RLP1) in plants mediates an immune response to bacterial infections. Specifically, the invention relates to RLP1, now named receptor of enigmatic microbe-associated molecular pattern (MAMP) of Xanthomonas (REMAX), in Arabidopsis thaliana. REMAX was found to recognise the presence of Xanthomonas and to initiate an immune signalling that eventually yields into a typical plant immune responses to bacterial infections. Furthermore, the invention relates to chimeric pattern recognition receptors (PRRs) composed of the extracellular domain of REMAX, which is the recognition site for sensing infection, and c-terminal portions of PRRs of other plant species. Also provided is a method to modulate the immune response of a plant to a bacterial infection by either increasing or decreasing the expression of REMAX or REMAX-like proteins, or the inventive chimeric PRRs in plants. Finally, the invention provides methods for the identification and purification of new microbe-associated molecular patterns in plants using REMAX or REMAX-like proteins and/or the novel chimeric PRRs of the present invention.
