Leaf δ15N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability

  1. Ariz, I. 1
  2. Cruz, C. 1
  3. Neves, T. 1
  4. Irigoyen, J.J. 4
  5. Garcia-Olaverri, C. 3
  6. Nogués, S. 2
  7. Aparicio-Tejo, P.M. 3
  8. Aranjuelo, I. 56
  1. 1 Universidade de Lisboa
    info

    Universidade de Lisboa

    Lisboa, Portugal

    ROR https://ror.org/01c27hj86

  2. 2 Universitat de Barcelona
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    Universitat de Barcelona

    Barcelona, España

    ROR https://ror.org/021018s57

  3. 3 Universidad Pública de Navarra
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    Universidad Pública de Navarra

    Pamplona, España

    ROR https://ror.org/02z0cah89

  4. 4 Instituto de Ciencias de la Vid y del Vino
    info

    Instituto de Ciencias de la Vid y del Vino

    Logroño, España

    ROR https://ror.org/01rm2sw78

  5. 5 Instituto de Agrobiotecnología
    info

    Instituto de Agrobiotecnología

    Aranguren, España

  6. 6 Universidad del País Vasco/Euskal Herriko Unibertsitatea
    info

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España

    ROR https://ror.org/000xsnr85

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Journal:
Frontiers in Plant Science

ISSN: 1664-462X

Year of publication: 2015

Volume: 6

Issue: AUG

Type: Article

DOI: 10.3389/FPLS.2015.00574 SCOPUS: 2-s2.0-84940185728 GOOGLE SCHOLAR

More publications in: Frontiers in Plant Science

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Abstract

The natural 15N/14N isotope composition (δ15N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ15N as an indicator of plant N status in N<inf>2</inf>-fixing plants grown under various environmental conditions, alfalfa (Medicago sativaL.) plants were subjected to distinct conditions of [CO<inf>2</inf>] (400 vs. 700 μmol mol−1), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency—WD). As expected, increased [CO<inf>2</inf>] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ15N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO<inf>2</inf>] and WD. Depletion of heavier N isotopes in plants grown under higher [CO<inf>2</inf>] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol−1 [CO<inf>2</inf>] and WD conditions. In summary, leaf δ15N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions. © 2015 Ariz, Cruz, Neves, Irigoyen, Garcia-Olaverri, Nogués, Aparicio-Tejo and Aranjuelo.