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Fuentes M.,CIPAV Roullier Group | Olaetxea M.,CIPAV Roullier Group | Baigorri R.,CIPAV Roullier Group | Zamarreno A.M.,CIPAV Roullier Group | And 6 more authors.
Journal of Geochemical Exploration | Year: 2013

The main objective of this study is to investigate the more relevant binding sites (functional groups) involved in the complexation of Fe(III) and Cu(II) by humic-based structures. To this aim we have generated a set of seven humic-based samples (MHA) by the application of a hemi-synthetic process consisting in the oxidative polymerization of different combinations of three sources of natural organic molecules: two humic acids obtained from peat and leonardite, and natural tannin extracted from the quebracho tree (Schinopsis sp.) bark. These MHA were extensively characterized by using complementary analytical techniques (13C NMR, size-exclusion chromatography, electron paramagnetic resonance, and total phenol-reductant content), and their ability to complex Fe(III) and Cu(II) was also calculated by fluorescence quenching method. The data were studied by using general correlation matrix and principal component analysis.The results obtained, taken together, indicated that in a set of humic-based structures presenting carboxylic, phenol and O-alkyl groups, and diverse aliphatic/aromatic character, the complexation of Fe(III) mainly involved specific structural arrangements including carboxylic groups distributed in aliphatic domains. However, Cu(II) complexation involved singular structural arrangements including phenols (and probably substituted phenols) and O-alkyl groups in side chains of aromatic domains. © 2013 Elsevier B.V.


Renella G.,University of Florence | Landi L.,University of Florence | Garcia Mina J.M.,CIPAV Roullier Group | Giagnoni L.,University of Florence | Nannipieri P.,University of Florence
Applied Soil Ecology | Year: 2011

Effects of indoleacetic acid (IAA) and ethylene (E) precursors on microbial biomass, respiration, and various hydrolase activities of the rhizosphere and bulk soil, were studied using a model system simulating this environment. The effects of IAA and E precursors were compared to those of glucose-C, N and S (GNS) applied at the same rate to soils. None of the treatments significantly affected respiration rates and ATP contents of soils. The IAA precursor significantly increased phosphatase, β-glycosidase, urease and protease activities of the rhizosphere layer of both soils; the E precursor significantly increased phosphodiesterase, urease and protease activities of both soils. The GNS treatment did not significantly increase any hydrolase activity. The IAA precursor also stimulated the phosphatase activity of the bulk layer of the sandy soil after 7. d of incubation, possibly due to its diffusion from the rhizosphere to the bulk soil, whereas no stimulation in the bulk soil layer was observed in either E or GNS treatments. The increased hydrolase activities in the rhizosphere upon addition of both IAA and E precursors may be due to the role of these precursors as microbial metabolic activators, and may be involved in stimulation of plant growth through other processes involving IAA and E producing root associated microorganisms. © 2010 Elsevier B.V.


Kong L.,Shandong Academy of Agricultural Sciences | Wang F.,Shandong Academy of Agricultural Sciences | Lopez-bellido L.,University of Cordoba, Spain | Garcia-mina J.M.,CIPAV Roullier Group | And 3 more authors.
Plant Biotechnology Reports | Year: 2013

Nitrogen (N) uptake is the first step in nitrate assimilation, and efficient N uptake is essential for plant growth, especially for protein biosynthesis and photosynthetic activities. In cereals, improved N uptake is closely coupled with an increase in nitrogen use efficiency (NUE) and yield improvements. Because wheat (Triticum aestivum L.) is a leading crop worldwide, a better understanding of N uptake regulation in wheat is vital to improving NUE and developing sustainable agricultural systems. However, detailed information regarding the biological mechanisms that are responsible for the more efficient uptake of ambient N by wheat is limited. This review presents recent developments in the biological mechanisms of N uptake in wheat, including plant growth regulations, fundamental roles of root systems, interactions between N species, and genetic controls. Specifically, this paper provides a number of potential strategies that can be used to increase wheat N uptake. The information provided here may guide N fertilizer management during wheat production and further elucidate the plant regulatory mechanisms that are involved in N uptake, which can thereby increase wheat NUE. © 2013 Korean Society for Plant Biotechnology and Springer Japan.


Kolodziej A.,Wroclaw University of Technology | Fuentes M.,University of Navarra | Baigorri R.,CIPAV Roullier Group | Lorenc-Grabowska E.,Wroclaw University of Technology | And 4 more authors.
Adsorption | Year: 2014

The effects of the humic acid (HA) nature and the activated carbon (AC) surface chemistry on the effectiveness of HA removal were investigated. Brown (BHA) and gray (GHA) humic acid fractions of different structure and physicochemical properties were tested in the adsorption process using mesoporous ACs. The modification of chemical structure and surface properties of AC was achieved by ammonization (AC/N) and hydrogen treatment (AC/H). Both approaches led to a decrease in the oxygen content followed by an increase in the carbon basicity, maintaining the porous texture of AC nearly unaltered. Over twice higher removal degree of BHA and GHA was observed for the modified ACs. The kinetics of adsorption of HA fractions have been discussed using the pseudo-second-order model and the intraparticle diffusion model. All ACs showed a higher adsorption capacity toward BHA compared to GHA, which is mainly attributed to the lower molecular weight of BHA. The shape of the equilibrium isotherms indicates a strong competition between water and HA molecules for adsorption sites of the carbon surface. © 2014 Springer Science+Business Media New York.


Fuentes M.,CIPAV Roullier Group | Baigorri R.,CIPAV Roullier Group | Gonzalez-Vila F.J.,Institute Recursos Naturales Y Agrobiologia | Gonzalez-Gaitano G.,University of Navarra | Garcia-Mina J.M.,CIPAV Roullier Group
Journal of Environmental Quality | Year: 2010

Flash pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used to study the structural transformations of humic fractions formed as a result of composting processes of diverse organic materials (solid wastes of wineries, solid olivemill wastes, domestic wastes, ovine manures plus straw, and mixtures of animal manures). Sodium hydroxide-extracted total humic-like extracts (THE; humic plus fulvic acids) from the composted and the initial noncomposted wastes and several reference humic and fulvic acids from soils were analyzed. These results were compared with results from previous studies using 13C-cross polarization magic angle spinning-nuclear magnetic resonance (NMR), UV-visible, and fluorescence emission spectroscopies. Alkylbenzenes and alkylphenols predominate in the pyrograms of the soil humic acids, whereas the fulvic acids showed higher contents of phenolic and polysaccharide-derived compounds. The pyrolysates of THE from the composted samples showed an increase in aromatic and nitrogenated structures and a decrease in polysaccharidederived compounds. The aromatic contents as determined by Py-GC/MS and 13C-NMR were well correlated in the reference humic substances and THE from composted materials (r = 0.99 and 0.94, respectively; P < 0.01) but not in the case of THE from noncomposted materials, probably due to an aliphatic enhancement in the pyrolysates of these samples and other secondary reactions. The content in alkylbenzenes was consistent with the variations found previously for several UV-visible and fluorescence indexes as a function of the degree of humification, suggesting their involvement in structures that are a characteristic feature of the formation and evolution of humic substances. Copyright © 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.


Garcia-Mina J.M.,CIPAV Roullier Group | Garcia-Mina J.M.,University of Navarra | Bacaicoa E.,CIPAV Roullier Group | Fuentes M.,CIPAV Roullier Group | Casanova E.,CIPAV Roullier Group
Plant Science | Year: 2013

Numerous studies have investigated the molecular and physiological-morphological mechanisms induced in plant roots in response to specific nutrient deficiencies. Both transcriptional and post-transcriptional mechanisms are involved that increase root uptake under nutrient deficiency. Root nutrient deficiency-stress root responses are mainly regulated by the nutrient status in the shoot. The signals involved in shoot to root cross-talk regulation processes for the activation of nutrient-deficiency induced root responses are not clearly elucidated. The physiological-molecular events in the leaf linked to the nutrient availability for metabolic use, are also poorly known.In this context, we focus our attention on iron plant nutrition. Some experimental evidence suggests the existence of a regulatory system concerned with the optimization of the metabolic use of iron, mainly under conditions of iron starvation. This system seems to be activated by the deficiency in iron-availability for metabolic processes in the leaf and regulates the activation of some iron-stress root responses. This regulation seems to be probably expressed by affecting the production and/or translocation of the activating signal sent from the shoot to the root under conditions of iron deficiency in the shoot. © 2012 Elsevier Ireland Ltd.


PubMed | CIPAV Roullier Group
Type: Journal Article | Journal: Journal of the science of food and agriculture | Year: 2010

In certain plant species, ammonium or urea nutrition can cause negative effects on plant development which can result in toxic symptoms. Some authors suggest that the presence of nitrate can alleviate these symptoms by increasing ammonium and urea assimilation, avoiding its accumulation. In order to study this hypothesis, wheat (Triticum aestivum L.) seedlings were grown with various nitrogen supplies containing the main nitrogen forms (ammonium, nitrate and urea). Amino acids content and the activity of the three main enzymes involved in nitrogen assimilation (nitrate reductase, glutamine synthetase and urease) were studied.The application of nitrate along with urea and/or ammonium was not associated with a time-sustained increase in the activity of glutamine synthetase and urease. Amino acid analysis revealed that nitrate induced changes in amino acid metabolism enhancing its concentration. Likewise the content of protein was also higher in nitrate-treated plants.These results suggest that the effect of nitrate is compatible with a rapid and transient increase in the activity of glutamine synthetase and urease during the first hour after the onset of treatments. Nevertheless, a possible effect of nitrate reducing ammonium accumulation through the activation of alternative metabolic pathways different from that involving glutamine synthetase cannot be ruled out. Finally, nitrate effects on amino acid concentration indicate that, whereas ammonium assimilation takes place principally in the root, urea and nitrate assimilation occurred in the shoot, under the conditions of the experiment.


Garnica M.,CIPAV Roullier Group | Houdusse F.,CIPAV Roullier Group | Zamarreno A.M.,CIPAV Roullier Group | Garcia-Mina J.M.,CIPAV Roullier Group | Garcia-Mina J.M.,University of Navarra
Journal of the Science of Food and Agriculture | Year: 2010

BACKGROUND: In certain plant species, ammonium or urea nutrition can cause negative effects on plant development which can result in toxic symptoms. Some authors suggest that the presence of nitrate can alleviate these symptoms by increasing ammonium and urea assimilation, avoiding its accumulation. In order to study this hypothesis, wheat (Triticum aestivum L.) seedlings were grown with various nitrogen supplies containing the main nitrogen forms (ammonium, nitrate and urea). Amino acids content and the activity of the three main enzymes involved in nitrogen assimilation (nitrate reductase, glutamine synthetase and urease) were studied. RESULTS: The application of nitrate along with urea and/or ammonium was not associated with a time-sustained increase in the activity of glutamine synthetase and urease. Amino acid analysis revealed that nitrate induced changes in amino acid metabolism enhancing its concentration. Likewise the content of protein was also higher in nitrate-treated plants. CONCLUSION: These results suggest that the effect of nitrate is compatible with a rapid and transient increase in the activity of glutamine synthetase and urease during the first hour after the onset of treatments. Nevertheless, a possible effect of nitrate reducing ammonium accumulation through the activation of alternative metabolic pathways different from that involving glutamine synthetase cannot be ruled out.Finally,nitrate effects on aminoacid concentration in dicate that,where as ammonium assimilation takes place principally in the root, urea and nitrate assimilation occurred in the shoot, under the conditions of the experiment. © 2009 Society of Chemical Industry.


Garnica M.,CIPAV Roullier Group | Houdusse F.,CIPAV Roullier Group | Zamarreno A.M.,CIPAV Roullier Group | Garcia-Mina J.M.,CIPAV Roullier Group | Garcia-Mina J.M.,University of Navarra
Journal of Plant Physiology | Year: 2010

Ammonium can result in toxicity symptoms in many plants when supplied as a sole nitrogen source. Nitrate reduces the negative effects caused by ammonium and promotes plant growth. In order to explore the mechanism responsible of this beneficial effect, we investigated whether nitrate application causes significant changes in the indoleacetic acid (IAA)- and cytokinin-plant distribution and abscisic acid (ABA) accumulation in wheat (Triticum aestivum L.) plants grown with ammonium. Two different doses of nitrate were supplied to ammonium-fed plants (100μM and 5. mM), to determine whether the effects of nitrate require significant doses (nutritional character), or can be promoted by very low doses (signal effect).The results showed that the presence of NO 3 - was associated with clear increases in the active forms of cytokinins (zeatine (Z), trans-zeatine riboside (tZR), isopentenyl adenosine (IPR)) and reduction of the levels of the lower active forms (cis-zeatine riboside (cZR)), independently of the dose applied. Likewise, the presence of nitrate also enhanced IAA shoot content, which correlated with higher cytokinin levels and a tendency toward lower ABA concentration. This study presents further evidence that the possible signal effect of NO 3 - involved in its beneficial effect on the growth of wheat plants fed with NH 4 + could be mediated by a coordinated action of the levels of cytokinins, IAA and ABA in the shoot. © 2010 Elsevier GmbH.

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