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A receptor kinase gene regulating symbiotic nodule development

Naturevolume 417pages962966 (2002) | Download Citation



Leguminous plants are able to establish a nitrogen-fixing symbiosis with soil bacteria generally known as rhizobia. Metabolites exuded by the plant root activate the production of a rhizobial signal molecule, the Nod factor, which is essential for symbiotic nodule development1,2. This lipo-chitooligosaccharide signal is active at femtomolar concentrations, and its structure is correlated with host specificity of symbiosis3, suggesting the involvement of a cognate perception system in the plant host. Here we describe the cloning of a gene from Medicago sativa that is essential for Nod-factor perception in alfalfa, and by genetic analogy, in the related legumes Medicago truncatula and Pisum sativum. The identified ‘nodulation receptor kinase’, NORK, is predicted to function in the Nod-factor perception/transduction system (the NORK system) that initiates a signal cascade leading to nodulation. The family of ‘NORK extracellular-sequence-like’ (NSL) genes is broadly distributed in the plant kingdom, although their biological function has not been previously ascribed. We suggest that during the evolution of symbiosis an ancestral NSL system was co-opted for transduction of an external ligand, the rhizobial Nod factor, leading to development of the symbiotic root nodule.

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We thank D. Cook for comments, suggestions and help in finalizing the manuscript, A. Kondorosi for critical reading of the manuscript, A. Perhald for help in transformation experiments, and P. Kiss, S. Jenei, K. Lehoczky, Z. Liptay, P. Somkúti and A. Lengyel for technical assistance. This work was supported by the BRC, Szeged, Hungary, the Bástyai-Holczer Foundation, the Hungarian Academy of Sciences, the Hungarian Scientific Research Fund, the Hungarian National Committee for Technical Development, the Szechenyi Fund of the Hungarian Ministry of Education, the EuDicotMap and the Medicago projects of the European Union.

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  1. Institute of Genetics, Biological Research Center of the Hungarian Academy of Sciences, H-6701, PO Box 521, Szeged, Hungary

    • Gabriella Endre
    • , Attila Kereszt
    • , Zoltán Kevei
    • , Sorina Mihacea
    • , Péter Kaló
    •  & György B. Kiss


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The authors declare that they have no competing financial interests.

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Correspondence to György B. Kiss.

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