Combined phosphate and nitrogen limitation generates a nutrient stress transcriptome favorable for arbuscular mycorrhizal symbiosis in Medicago truncatula

Authors

  • Laurent Bonneau,

    1. UMR 1347 Agroécologie INRA/Université de Bourgogne/Agrosup, Pôle Interactions Plantes-Microorganismes ERL CNRS 6300, Dijon Cedex, France
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  • Stéphanie Huguet,

    1. Unité de Recherche en Génomique Végétale (URGV), UMR INRA 1165 – Université d'Evry Val d'Essonne – ERL CNRS 8196, Evry Cedex, France
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  • Daniel Wipf,

    1. UMR 1347 Agroécologie INRA/Université de Bourgogne/Agrosup, Pôle Interactions Plantes-Microorganismes ERL CNRS 6300, Dijon Cedex, France
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  • Nicolas Pauly,

    1. Institut Sophia Agrobiotech, UMR INRA 1355 CNRS 7254, Université de Nice-Sophia Antipolis, Sophia Antipolis Cedex, France
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  • Hoai-Nam Truong

    Corresponding author
    • UMR 1347 Agroécologie INRA/Université de Bourgogne/Agrosup, Pôle Interactions Plantes-Microorganismes ERL CNRS 6300, Dijon Cedex, France
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Author for correspondence:

Hoai-Nam Truong

Tel: +33 3 80 69 31 91

Email: hntruong@dijon.inra.fr

Summary

  • Arbuscular mycorrhizal (AM) symbiosis is stimulated by phosphorus (P) limitation and contributes to P and nitrogen (N) acquisition. However, the effects of combined P and N limitation on AM formation are largely unknown.
  • Medicago truncatula plants were cultivated in the presence or absence of Rhizophagus irregularis (formerly Glomus intraradices) in P-limited (LP), N-limited (LN) or combined P- and N-limited (LPN) conditions, and compared with plants grown in sufficient P and N.
  • The highest AM formation was observed in LPN, linked to systemic signaling by the plant nutrient status. Plant free phosphate concentrations were higher in LPN than in LP, as a result of cross-talk between P and N. Transcriptome analyses suggest that LPN induces the activation of NADPH oxidases in roots, concomitant with an altered profile of plant defense genes and a coordinate increase in the expression of genes involved in the methylerythritol phosphate and isoprenoid-derived pathways, including strigolactone synthesis genes.
  • Taken together, these results suggest that low P and N fertilization systemically induces a physiological state of plants favorable for AM symbiosis despite their higher P status. Our findings highlight the importance of the plant nutrient status in controlling plant–fungus interaction.

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