• Open Access

A Medicago truncatula NADPH oxidase is involved in symbiotic nodule functioning

Authors

  • Daniel Marino,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Emilie Andrio,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Etienne G. J. Danchin,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Elodie Oger,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Sébastien Gucciardo,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Annie Lambert,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Alain Puppo,

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author
  • Nicolas Pauly

    1. Interactions Biotiques et Santé Végétale, UMR Université de Nice-Sophia Antipolis – INRA 1301 – CNRS 6243, 400 Route des Chappes, BP 167, F-06903 Sophia Antipolis Cedex, France
    Search for more papers by this author

Author for correspondence:
Alain Puppo
Tel: + 33 4 92 38 66 31
Email: puppo@unice.fr

Summary

  • The plant plasma membrane-localized NADPH oxidases, known as respiratory burst oxidase homologues (RBOHs), appear to play crucial roles in plant growth and development. They are involved in important processes, such as root hair growth, plant defence reactions and abscisic acid signalling.
  • Using sequence similarity searches, we identified seven putative RBOH-encoding genes in the Medicago truncatula genome. A phylogenetic reconstruction showed that Rboh gene duplications occurred in legume species. We analysed the expression of these MtRboh genes in different M. truncatula tissues: one of them, MtRbohA, was significantly up-regulated in Sinorhizobium meliloti-induced symbiotic nodules.
  • MtRbohA expression appeared to be restricted to the nitrogen-fixing zone of the functional nodule. Moreover, using S. meliloti bacA and nifH mutants unable to form efficient nodules, a strong link between nodule nitrogen fixation and MtRbohA up-regulation was shown. MtRbohA expression was largely enhanced under hypoxic conditions. Specific RNA interference for MtRbohA provoked a decrease in the nodule nitrogen fixation activity and the modulation of genes encoding the microsymbiont nitrogenase.
  • These results suggest that hypoxia, prevailing in the nodule-fixing zone, may drive the stimulation of MtRbohA expression, which would, in turn, lead to the regulation of nodule functioning.

Ancillary