Providing carbon skeletons to sustain amide synthesis in roots underlines the suitability of Brachypodium distachyon for the study of ammonium stress in cereals
Plants mainly acquire N from the soil in the form of nitrate (NO3-) or ammonium (NH4+). Ammonium-based nutrition is gaining interest because it helps to avoid the environmental pollution associated with nitrate fertilization. However, in general, plants prefer NO3- and indeed, when growing only with...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universidad del País Vasco |
| Repositorio: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/40529 |
| Acceso en línea: | http://hdl.handle.net/10810/40529 |
| Access Level: | acceso abierto |
| Palabra clave: | ammonium assimilation Asn carbon metabolism Gln monocots nitrate nitrogen metabolism root TCA cycle glutamine-synthetase phosphoenolpyruvate carboxylase arabidopsis-thaliana gene-expression plant nitrogen use efficiency crucial role tolerance toxicity metabolism |
| Sumario: | Plants mainly acquire N from the soil in the form of nitrate (NO3-) or ammonium (NH4+). Ammonium-based nutrition is gaining interest because it helps to avoid the environmental pollution associated with nitrate fertilization. However, in general, plants prefer NO3- and indeed, when growing only with NH4+ they can encounter so-called ammonium stress. Since Brachypodium distachyon is a useful model species for the study of monocot physiology and genetics, we chose it to characterize performance under ammonium nutrition. Brachypodium distachyon Bd21 plants were grown hydroponically in 1 or 2.5 mM NO3- or NH4+. Nitrogen and carbon metabolism associated with NH4+ assimilation was evaluated in terms of tissue contents of NO3-, NH4+, K, Mg, Ca, amino acids and organic acids together with tricarboxylic acid (TCA) cycle and NH4+-assimilating enzyme activities and RNA transcript levels. The roots behaved as a physiological barrier preventing NH4+ translocation to aerial parts, as indicated by a sizeable accumulation of NH4+, Asn and Gln in the roots. A continuing high NH4+ assimilation rate was made possible by a tuning of the TCA cycle and its associated anaplerotic pathways to match 2-oxoglutarate and oxaloacetate demand for Gln and Asn synthesis. These results show B. distachyon to be a highly suitable tool for the study of the physiological, molecular and genetic basis of ammonium nutrition in cereals. |
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