期刊
PLANT SCIENCE
卷 241, 期 -, 页码 32-44出版社
ELSEVIER IRELAND LTD
DOI: 10.1016/j.plantsci.2015.09.021
关键词
Ammonium tolerance; Elevated CO2; Nitrate nutrition; Nitrogen assimilation; Solanum lycopersicum L.; TCA cycle
资金
- Basque Government [BFI-2010-365, IT526-10]
- Spanish Government [AGL 2012-37815-C05-02]
- University of the Basque Country [EHUA14/14]
- EU Marie Curie Actions People Program [334019]
Ammonium (NH4+) toxicity typically occurs in plants exposed to high environmental NH4+ concentration. NH4+ assimilating capacity may act as a biochemical mechanism avoiding its toxic accumulation but requires a fine tuning between nitrogen assimilating enzymes and carbon anaplerotic routes. In this work, we hypothesized that extra C supply, exposing tomato plants cv. Agora Hybrid F1 to elevated atmospheric CO2, could improve photosynthetic process and thus ameliorate NH4+ assimilation and tolerance. Plants were grown under nitrate (NO3-) or NH4+ as N source (5-15 mM), under two atmospheric CO2 levels, 400 and 800 ppm. Growth and gas exchange parameters, N-15 isotopic signature, C and N metabolites and enzymatic activities were determined. Plants under 7.5 mM N equally grew independently of the N source, while higher ammonium supply resulted toxic for growth. However, specific stomatal closure occurred in 7.5 mM NH4+-fed plants under elevated CO2 improving water use efficiency (WUE) but compromising plant N status. Elevated CO2 annulled the induction of TCA anaplerotic enzymes observed at non-toxic NH4+ nutrition under ambient CO2. Finally, CO2 enrichment benefited tomato growth under both nutritions, and although it did not alleviate tomato NH4+ tolerance it did differentially regulate plant metabolism in N-source and -dose dependent manner. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
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