Identification and Functional Characterisation of Nod Factor Receptor Paralogous Genes in Lotus japonicus Vestergaard G., Radutoiu S., and Stougaard J. University of Aarhus – Denmark, firstname.lastname@example.org Until recently, the legume genes responsible for perception of rhizobial Nod factors represented an important missing link in plant-bacterial communication. This picture changed with the cloning of LysM-domain containing receptor-like kinases (LysM-RLKs) in different legume species. In Lotus japonicus, two LysM-RLKs, Nod Factor Receptor 1 (NFR1) and Nod Factor Receptor 5 (NFR5), are believed to bind Nod factor, subsequently initiating a signal cascade leading to symbiotic nodule development. Similar genes have also been identified in other plants: seven LysM-domain containing receptor-like kinases (LYKs) were found in the model legume Medicago truncatula, two of them, LYK3 and LYK4 playing a role in infection thread formation. In Arabidopsis thaliana, five LysM-RLK genes are present, but so far their function remain unknown. This study presents the identification of eight additional LysM-RLKs in Lotus japonicus. They were identified following BLAST search in the Kazusa Lotus japonicus EST database using the sequences of NFR1 and NFR5. Microsattelite markers were developed from each TAC clone containing the LysM-RLK, permitting us to locate the genes on a genetic map of Lotus japonicus. In order to get more insight into the function of these genes an inverse genetic approach using RNAi has been initiated.