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Local and systemic N signaling are involved in Medicago truncatula preference for the most efficient Sinorhizobium symbiotic partners

Authors

  • Gisèle Laguerre,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Karine Heulin-Gotty,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Brigitte Brunel,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Agnieszka Klonowska,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Antoine Le Quéré,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Pascal Tillard,

    1. INRA, UMR 5004, Biochimie et Physiologie Moléculaire des Plantes, F-34000 Montpellier, France
    2. CNRS, Biochimie et Physiologie Moléculaire des Plantes, F-34000 Montpellier, France
    3. SupAgro, Biochimie et Physiologie Moléculaire des Plantes, F-34000 Montpellier, France
    4. UM2, Biochimie et Physiologie Moléculaire des Plantes, F-34000 Montpellier, France
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  • Yves Prin,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Jean-Claude Cleyet-Marel,

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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  • Marc Lepetit

    1. INRA, USC 1242, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    2. IRD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    3. CIRAD, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    4. SupAgro, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
    5. UM2, UMR 113, Symbioses Tropicales et Méditerranéennes, F-34000 Montpellier, France
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Author for correspondence:
Gisèle Laguerre
Tel: +33 4 67 59 38 62
Email: gisele.laguerre@supagro.inra.fr

Summary

  • Responses of the Medicago truncatulaSinorhizobium interaction to variation in N2-fixation of the bacterial partner were investigated.
  • Split-root systems were used to discriminate between local responses, at the site of interaction with bacteria, and systemic responses related to the whole plant N status.
  • The lack of N acquisition by a half-root system nodulated with a nonfixing rhizobium triggers a compensatory response enabling the other half-root system nodulated with N2-fixing partners to compensate the local N limitation. This response is mediated by a stimulation of nodule development (number and size) and involves a systemic signaling mechanism related to the plant N demand. In roots co-infected with poorly and highly efficient strains, partner choice for nodule formation was not modulated by the plant N status. However, the plant N demand induced preferential expansion of nodules formed with the most efficient partners when the symbiotic organs were functional. The response of nodule expansion was associated with the stimulation of symbiotic plant cell multiplication and of bacteroid differentiation.
  • A general model where local and systemic N signaling mechanisms modulate interactions between Medicago truncatula and its Sinorhizobium partners is proposed.

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