Adaptation of Medicago truncatula to nitrogen limitation is modulated via local and systemic nodule developmental responses

Authors

  • Christian Jeudy,

    1. Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses, UMR INRA 102, BP 86510, F-21065 Dijon, France
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  • Sandrine Ruffel,

    1. Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, INRA-CNRS-Sup Agro-UM2, Institut de Biologie Intégrative des Plantes, 2 Place Viala, F-34060 Montpellier, France
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  • Sandra Freixes,

    1. Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses, UMR INRA 102, BP 86510, F-21065 Dijon, France
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  • Pascal Tillard,

    1. Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, INRA-CNRS-Sup Agro-UM2, Institut de Biologie Intégrative des Plantes, 2 Place Viala, F-34060 Montpellier, France
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  • Anne Lise Santoni,

    1. Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses, UMR INRA 102, BP 86510, F-21065 Dijon, France
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  • Sylvain Morel,

    1. ENESAD, 26, Bd du docteur Petitjean, BP 87999, 21079 Dijon Cedex, France
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  • Etienne-Pascal Journet,

    1. Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR CNRS-INRA 2594/441, F-31320 Castanet-Tolosan, France
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  • Gérard Duc,

    1. Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses, UMR INRA 102, BP 86510, F-21065 Dijon, France
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  • Alain Gojon,

    1. Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, INRA-CNRS-Sup Agro-UM2, Institut de Biologie Intégrative des Plantes, 2 Place Viala, F-34060 Montpellier, France
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  • Marc Lepetit,

    1. Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, INRA-CNRS-Sup Agro-UM2, Institut de Biologie Intégrative des Plantes, 2 Place Viala, F-34060 Montpellier, France
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  • Christophe Salon

    1. Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses, UMR INRA 102, BP 86510, F-21065 Dijon, France
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Author for correspondence:
Christophe Salon
Tel: +33 (0)380 693 238
Email: salon@dijon.inra.fr

Summary

  • Adaptation of Medicago truncatula to local nitrogen (N) limitation was investigated to provide new insights into local and systemic N signaling.
  • The split-root technique allowed a characterization of the local and systemic responses of NO3 or N2-fed plants to localized N limitation. 15N and 13C labeling were used to monitor plant nutrition. Plants expressing pMtENOD11-GUS and the sunn-2 hypernodulating mutant were used to unravel mechanisms involved in these responses.
  • Unlike NO3-fed plants, N2-fixing plants lacked the ability to compensate rapidly for a localized N limitation by up-regulating the N2-fixation activity of roots supplied elsewhere with N. However they displayed a long-term response via a growth stimulation of pre-existing nodules, and the generation of new nodules, likely through a decreased abortion rate of early nodulation events. Both these responses involve systemic signaling. The latter response is abolished in the sunn mutant, but the mutation does not prevent the first response.
  • Local but also systemic regulatory mechanisms related to plant N status regulate de novo nodule development in Mt, and SUNN is required for this systemic regulation. By contrast, the stimulation of nodule growth triggered by systemic N signaling does not involve SUNN, indicating SUNN-independent signaling.

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