The Medicago truncatula Lysine Motif-Receptor-like Kinase Gene Family Includes NFP and New Nodule-Expressed Genes

• Published in: Plant physiology (Bethesda) 2006-09, Vol.142 (1), p.265-279
• Main Authors: Arrighi, Jean-François, Barre, Annick, Amor, Besma Ben, Bersoult, Anne, Soriano, Lidia Campos, Mirabella, Rossana, de Carvalho-Niebel, Fernanda, Journet, Etienne-Pascal, Ghérardi, Michèle, Huguet, Thierry, Geurts, René, Dénarié, Jean, Rougé, Pierre, Gough, Clare
• Format: Article
• Language: English
• Subjects: arabidopsis; Arabidopsis thaliana; Biochemistry, Molecular Biology; Biological and medical sciences; Botanics; Fundamental and applied biological sciences. Psychology; Genes; Genes. Genome; Genetics; genomic analysis; Genomics; infection; Infections; legume; Legumes; Life Sciences; lysm domains; Medicago truncatula; Microbiology and Parasitology; Molecular and cellular biology; Molecular genetics; Nodulation; nodulation factor-perception; Nodules; Oryza sativa; Plant roots; Plants; Plants genetics; protein-kinase; Proteins; Receptors; rhizobium-meliloti; Root hairs; symbiotic genes; Systems Biology, Molecular Biology, and Gene Regulation; Vegetal Biology
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.106.084657

Rhizobial Nod factors are key symbiotic signals responsible for starting the nodulation process in host legume plants. Of the six Medicago truncatula genes controlling a Nod factor signaling pathway, Nod Factor Perception (NFP) was reported as a candidate Nod factor receptor gene. Here, we provide further evidence for this by showing that NFP is a lysine motif (LysM)-receptor-like kinase (RLK). NFP was shown both to be expressed in association with infection thread development and to be involved in the infection process. Consistent with deviations from conserved kinase domain sequences, NFP did not show autophosphorylation activity, suggesting that NFP needs to associate with an active kinase or has unusual functional characteristics different from classical kinases. Identification of nine new M. truncatula LysM-RLK genes revealed a larger family than in the nonlegumes Arabidopsis (Arabidopsis thaliana) or rice (Oryza sativa) of at least 17 members that can be divided into three subfamilies. Three LysM domains could be structurally predicted for all M. truncatula LysM-RLK proteins, whereas one subfamily, which includes NFP, was characterized by deviations from conserved kinase sequences. Most of the newly identified genes were found to be expressed in roots and nodules, suggesting this class of receptors may be more extensively involved in nodulation than was previously known.