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Evolution and Regulation of the Lotus japonicus LysM Receptor Gene Family

April 2010 , Volume 23 , Number  4
Pages  510 - 521

Gitte Vestergaard Lohmann,1 Yoshikazu Shimoda,2,3 Mette Wibroe Nielsen,1 Frank Grønlund Jørgensen,4 Christina Grossmann,1 Niels Sandal,1 Kirsten Sørensen,1 Søren Thirup,1 Lene Heegaard Madsen,1 Satoshi Tabata,2 Shusei Sato,2 Jens Stougaard,1 and Simona Radutoiu1

1Centre for Carbohydrate Recognition and Signalling, MBI, University of Aarhus, Gustav Wieds Vej 10, Aarhus C, Denmark; 2Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan; 3Plant-Microbe Interaction Research Unit, National Institute of Agrobiological Sciences (NIAS), 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan; 4Bioinformatics Research Center (BiRC), University of Aarhus, C.F. Møllers Alle, Bldg. 1110, DK-8000, Aarhus C, Denmark

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Accepted 3 December 2009.

LysM receptor kinases were identified as receptors of acylated chitin (Nod factors) or chitin produced by plant-interacting microbes. Here, we present the identification and characterization of the LysM receptor kinase gene (Lys) family (17 members) in Lotus japonicus. Comprehensive phylogenetic analysis revealed a correlation between Lys gene structure and phylogeny. Further mapping coupled with sequence-based anchoring on the genome showed that the family has probably expanded by a combination of tandem and segmental duplication events. Using a sliding-window approach, we identified distinct regions in the LysM and kinase domains of recently diverged Lys genes where positive selection may have shaped ligand interaction. Interestingly, in the case of NFR5 and its closest paralog, LYS11, one of these regions coincides with the predicted Nod-factor binding groove and the suggested specificity determining area of the second LysM domain. One hypothesis for the evolutionary diversification of this receptor family in legumes is their unique capacity to decipher various structures of chitin-derived molecules produced by an extended spectrum of interacting organisms: symbiotic, associative, endophytic, and parasitic. In a detailed expression analysis, we found several Lotus Lys genes regulated not only during the symbiotic association with Mesorhizobium loti but also in response to chitin treatment.

© 2010 The American Phytopathological Society