Nuestros investigadores

Idoia Ariz Arnedo

Publicaciones científicas más recientes (desde 2010)

Autores: Ariz, Idoia; Asensio, A. C.; Zamarreño, Ángel; et al.
ISSN 0031-9317  Vol. 148  Nº 4  2013  págs. 522 - 537
An understanding of the mechanisms underlying ammonium (NH4+) toxicity in plants requires prior knowledge of the metabolic uses for nitrogen (N) and carbon (C). We have recently shown that pea plants grown at high NH4+ concentrations suffer an energy deficiency associated with a disruption of ionic homeostasis. Furthermore, these plants are unable to adequately regulate internal NH4+ levels and the cell-charge balance associated with cation uptake. Herein we show a role for an extra-C application in the regulation of C¿N metabolism in NH4+-fed plants. Thus, pea plants (Pisum sativum) were grown at a range of NH4+ concentrations as sole N source, and two light intensities were applied to vary the C supply to the plants. Control plants grown at high NH4+ concentration triggered a toxicity response with the characteristic pattern of C-starvation conditions. This toxicity response resulted in the redistribution of N from amino acids, mostly asparagine, and lower C/N ratios. The C/N imbalance at high NH4+ concentration under control conditions induced a strong activation of root C metabolism and the upregulation of anaplerotic enzymes to provide C intermediates for the tricarboxylic acid cycle. A high light intensity partially reverted these C-starvation symptoms by providing higher C availability to the plants. The extra-C contributed to a lower C4/C5 amino acid ratio while maintaining the relative contents of some minor amino acids involved in key pathways regulating the C/N sta
Autores: Artola, E.; Cruchaga, S.; Ariz, Idoia; et al.
ISSN 0167-6903  Vol. 63  Nº 1  2011  págs. 73 - 79
The use of urea as an N fertilizer has increased to such an extent that it is now the most widely used fertilizer in the world. However, N losses as a result of ammonia volatilization lead to a decrease in its efficiency, therefore different methods have been developed over the years to reduce these losses. One of the most recent involves the use of urea combined with urease inhibitors, such as N-(n-butyl) thiophosphoric triamide (NBPT), in an attempt to delay the hydrolysis of urea in the soil. The aim of this study was to perform an in-depth analysis of the effect that NBPT use has on plant growth and N metabolism. Wheat plants were cultivated in a greenhouse experiment lasting 4 weeks and fertilized with urea and NBPT at different concentrations (0, 0.012, 0.062, 0.125%). Each treatment was replicated six times. A non-fertilized control was also cultivated. Several parameters related with N metabolism were analysed at the end of growth period. NBPT use was found to have visible effects, such as a transitory yellowing of the leaf tips, at the end of the first week of treatment. At a metabolic level, plants treated with the inhibitor were found to have more urea in their tissues and a lower amino acid content, lower glutamine synthetase activity, and lower urease and glutamine synthetase content at the end of the study period, whereas their urease activity seemed to have recovered by this stage.