Publications by authors named "Verónica Mora"

20 Publications

  • Page 1 of 1

The Singular Molecular Conformation of Humic Acids in Solution Influences Their Ability to Enhance Root Hydraulic Conductivity and Plant Growth.

Molecules 2020 Dec 22;26(1). Epub 2020 Dec 22.

Department of Environmental Biology, BIOMA Institut, Sciences School, University of Navarra, 31007 Pamplona, Spain.

Some studies have reported that the capacity of humic substances to improve plant growth is dependent on their ability to increase root hydraulic conductivity. It was proposed that this effect is directly related to the structural conformation in solution of these substances. To study this hypothesis, the effects on root hydraulic conductivity and growth of cucumber plants of a sedimentary humic acid and two polymers-polyacrylic acid and polyethylene glycol-presenting a molecular conformation in water solution different from that of the humic acid have been studied. The results show that whereas the humic acid caused an increase in root hydraulic conductivity and plant growth, both the polyacrylic acid and the polyethylene glycol did not modify plant growth and caused a decrease in root hydraulic conductivity. These results can be explained by the different molecular conformation in water solution of the three molecular systems. The relationships between these biological effects and the molecular conformation of the three molecular systems in water solution are discussed.
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http://dx.doi.org/10.3390/molecules26010003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7792592PMC
December 2020

What Do We Know About the Publications Related with Azospirillum? A Metadata Analysis.

Microb Ecol 2021 Jan 21;81(1):278-281. Epub 2020 Jul 21.

Laboratorio de Fisiología Vegetal y de la Interacción Planta-microorganismo, Instituto de Investigaciones en Agrobiotecnología (INIAB-CONICET), Universidad Nacional de Río Cuarto, Córdoba, Argentina.

Azospirillum is one of the most successful plant growth-promoting bacteria (PGPB) genera and it is considered a study model for plant-bacteria interactions. Because of that, a wide broad of topics has been boarded and discussed in a significant number of publications in the last four decades. Using the Scopus® database, we conducted a bibliographic search in order to analyze the number and type of publications, the authors responsible of these contributions, and the origin of the researchers, as well as the keywords and journals selected by the authors, among other related characteristics, with the aim to understand some less addressed details about the work done with Azospirillum worldwide since its discovery in 1925. Despite that the largest numbers of publications about this bacterium were obtained between the 1970 and 1980s, there is still a linear increase tendency in the number of published works. Understanding the mechanisms involved in the ability of these bacteria to promote growth in a wide broad of plant species under both laboratory and field conditions has been a preferential target for these published articles. This tendency could be considered a cause or consequence of the current increase in the number of commercial products formulated with Azospirillum around the world and a catalyzer for the increase of published articles along time.
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http://dx.doi.org/10.1007/s00248-020-01559-wDOI Listing
January 2021

Correction to: Evaluation of growth and motility in non-photosynthetic Azospirillum brasilense exposed to red, blue, and white light.

Arch Microbiol 2020 10;202(8):2343

Laboratorio de Fisiología Vegetal y de la Interacción Planta-microorganismo, Universidad Nacional de Río Cuarto, Ruta 36, Km 601, Río Cuarto, Córdoba, Argentina.

In the original article, last name and first names of all the authors are inverted. The correct names should appears as "Romina Molina, Gastón López, Belén Rodríguez, Susana Rosas, Verónica Mora, Fabricio Cassán".
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http://dx.doi.org/10.1007/s00203-020-01952-6DOI Listing
October 2020

Median rhomboid glossitis associated with candida infection in a woman treated with ixekizumab.

Eur J Dermatol 2020 Apr 16. Epub 2020 Apr 16.

Department of Dermatology of Hospital Universitari Germans Trias i Pujol. Carretera del Canyet s/n, 08916, Badalona, Spain.

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http://dx.doi.org/10.1684/ejd.2020.3724DOI Listing
April 2020

Co-treatment of an oily sludge and aged contaminated soil: permanganate oxidation followed by bioremediation.

J Environ Manage 2020 May 31;261:110169. Epub 2020 Jan 31.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, INIFTA (UNLP; CCT-La Plata, CONICET), La Plata, Argentina.

The bioremediation of an oily sludge (321 ± 30 mg of polycyclic aromatic hydrocarbons/kg and 13420 ± 1300 mg of aliphatic hydrocarbons/kg) by mixture with contaminated soil (23 ± 2 mg of polycyclic aromatic hydrocarbons/kg and 98 ± 10 mg of aliphatic hydrocarbons/kg) was studied. Furthermore, the effect of oxidative pretreatments (persulfate and permanganate) on the performance of the global process was examined. The treatments reached contamination levels lower than the original residues, indicating the presence of synergic processes between a highly contaminated sludge and soil with a selected hydrocarbon-degrading community. Pretreatment with permanganate significantly improved biodegradation, possibly due to the increase in bioavailability and biodegradability of petroleum hydrocarbons. Two months of incubation was enough to reach the complete elimination of polycyclic aromatic hydrocarbons and 92% elimination of aliphatic hydrocarbons. Monitoring using five parameters (concentration of total petroleum hydrocarbons, total cultivable heterotrophic bacteria count, lipase and dehydrogenase activities, and polycyclic aromatic hydrocarbon-degrading bacteria count) as an approach for a preliminary scanning of the effectiveness of a treatment is proposed based on principal components analysis.
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http://dx.doi.org/10.1016/j.jenvman.2020.110169DOI Listing
May 2020

Evaluation of growth and motility in non-photosynthetic Azospirillum brasilense exposed to red, blue, and white light.

Arch Microbiol 2020 Jul 20;202(5):1193-1201. Epub 2020 Feb 20.

Laboratorio de Fisiología Vegetal y de la Interacción Planta-microorganismo, Universidad Nacional de Río Cuarto, Ruta 36, Km 601, Río Cuarto, Córdoba, Argentina.

Azospirillum brasilense is a non-photosynthetic rhizobacterium that promotes the growth of plants. In this work, we evaluated the effects of different light qualities on the growth, viability, and motility in combination to other culture conditions such as temperature or composition of the culture medium. Exponential cultures of A. brasilense Az39 were inoculated by drop-plate method on nutritionally rich (LB) or chemically defined (MMAB) media in the presence or absence of Congo Red indicator (CR) and exposed continuously to white light (WL), blue light (BL), and red light (RL), or maintained in dark conditions (control). The exposure to BL or WL inhibited growth, mostly in LB medium at 36 °C. By contrast, the exposure to RL showed a similar behavior to the control. Swimming motility was inhibited by exposure to WL and BL, while exposure to RL caused only a slight reduction. The effects of WL and BL on plant growth-promoting rhizobacteria should be considered in the future as deleterious factors that could be manipulated to improve the functionality of foliar inoculants, as well as the bacterial effects on the leaf after inoculation.
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http://dx.doi.org/10.1007/s00203-020-01829-8DOI Listing
July 2020

Root ABA and H-ATPase are key players in the root and shoot growth-promoting action of humic acids.

Plant Direct 2019 Oct 10;3(10):e00175. Epub 2019 Oct 10.

Department of Environmental Biology (Biological and Agricultural Chemistry Group (BACh) CMI-Roullier Group Faculty of Sciences University of Navarra Pamplona Spain.

Although the ability of humic (HA) and fulvic acids (FA) to improve plant growth has been demonstrated, knowledge about the mechanisms responsible for the direct effects of HA and FA on the promotion of plant growth is scarce and fragmentary. Our study investigated the causal role of both root PM H-ATPase activity and ABA in the SHA-promoting action on both root and shoot growth. The involvement of these processes in the regulation of shoot cytokinin concentration and activity was also studied. Our aim was to integrate such plant responses for providing new insights  to the current model on the mode of action of HA for promoting root and shoot growth. Experiments employing specific inhibitors and using L. plants show that both the root PM H-ATPase activity and root ABA play a crucial role in the root growth-promoting action of SHA. With regard to the HA-promoting effects on shoot growth, two pathways of events triggered by the interaction of SHA with plant roots are essential for the increase in root PM H-ATPase activity-which also mediates an increase in cytokinin concentration and action in the shoot-and the ABA-mediated increase in hydraulic conductivity (Lp).
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http://dx.doi.org/10.1002/pld3.175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785783PMC
October 2019

[Development of sequence characterized amplified region markers for identification of Azospirillum brasilense Az39].

Rev Argent Microbiol 2020 Jan - Mar;52(1):50-60. Epub 2019 Jun 11.

Laboratorio de Fisiología Vegetal y de la Interacción Planta-Microorganismo, Departamento de Ciencias Naturales, FCEFQyN, Universidad Nacional de Río Cuarto. Electronic address:

Azospirillum brasilense Az39 has been used since more than 30 years by several companies in South America for biofertilizers production. This strain may promote plants growth and development, as well as the ability of inoculated plants to tolerate environmental stresses, which determines an increase in the productivity under field conditions. At present, there are no protocols in Argentina to confirm the identity of Az39 in commercial products; however, such biofertilizers are formulated almost exclusively with this strain. Therefore, the objective of this paper was to develop a molecular methodology that allows the accurate identification of A. brasilense Az39. Using the complete genome sequence and several bioinformatics tools, fragments of DNA present only in the Az39 genome were recognized. A set of PCR primers to amplify these sequences were designed, and the specific products were observed only in the strain of our interest. The sensitivity of the methodology was evaluated, where the strain could be detected up to a titer of 10 CFU/ml (4.5 ng/μl ADN) or 10 CFU/ml (0.88 ng/μl DNA) or in a minimal concentration of 0.098 ng/μl DNA, depending on the DNA extraction methodology used. Primers were tested against direct samples of commercial inoculants and cultures, in both cases there were specifics products, both in direct samples and in confirmatory tests from isolated colonies from those products. The procedure presented in this paper allows the accurate identification of A. brasilense Az39 in pure cultures, mixtures of microorganisms, and commercial biofertilizers.
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http://dx.doi.org/10.1016/j.ram.2019.02.004DOI Listing
January 2021

Regulation of IAA Biosynthesis in Azospirillum brasilense Under Environmental Stress Conditions.

Curr Microbiol 2018 Oct 6;75(10):1408-1418. Epub 2018 Jul 6.

Universidad Nacional de Río Cuarto, Ruta 36, Km 601, Río Cuarto, Córdoba, Argentina.

Indole-3-acetic acid (IAA) is one of the most important molecules produced by Azospirillum sp., given that it affects plant growth and development. Azospirillum brasilense strains Sp245 and Az39 (pFAJ64) were pre-incubated in MMAB medium plus 100 mg/mL L-tryptophan and treated with or exposed to the following (a) abiotic and (b) biotic stress effectors: (a) 100 mM NaCl or NaSO 4.0% (w/v) PEG 0.5 mM HO 0.1 mM abscisic acid, 0.1 mM 1-aminocyclopropane 1-carboxylic acid, 45 °C or daylight, and (b) 4.0% (v/v) filtered supernatant of Pseudomonas savastanoi (Ps) or Fusarium oxysporum (Fo), 0.1 mM salicylic acid (SA), 0.1 mM methyl jasmonic acid (MeJA), and 0.01% (w/v) chitosan (CH). After 30 and 120 min of incubation, biomass production, cell viability, IAA concentration (µg/mL), and ipdC gene expression were measured. Our results show that IAA production increases with daylight or in the presence of PEG, ABA, SA, CH, and Fo. On the contrary, exposure to 45 °C or treatment with HO NaCl, NaSO ACC, MeJA, and Ps decrease IAA biosynthesis. In this report, growth and IAA biosynthesis in A. brasilense under biotic and abiotic stress conditions are discussed from the point of view of their role in bacterial lifestyle and their potential application as bioproducts.
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http://dx.doi.org/10.1007/s00284-018-1537-6DOI Listing
October 2018

Shoot iron status and auxin are involved in iron deficiency-induced phytosiderophores release in wheat.

BMC Plant Biol 2018 Jun 4;18(1):105. Epub 2018 Jun 4.

Department of Environmental Biology (BACh Group), School of Sciences, University of Navarra, Pamplona, Navarra, Spain.

Background: The release of phytosiderephores (PS) to the rhizosphere is the main root response to iron (Fe) deficiency in graminaceous plants. We have investigated the role of the Fe status in the shoot as well as of the signaling pathways controlled by three relevant phytoregulators - indolacetic acid (IAA), ethylene and nitric oxide (NO) - in the regulation of this root response in Fe-starved wheat plants. To this end, the PS accumulation in the nutrient solution and the root expression of the genes encoding the nicotianamine aminotransferase (TaNAAT) and ferritin (TaFER) have been evaluated in plants subjected to different treatments.

Results: The application of Fe to leaves of Fe-deficient plants prevented the increase in both PS root release and TaNAAT gene expression thus showing the relevant role of the shoot to root communication in the regulation of PS root release and some steps of PS biosynthesis. Experiments with specific hormone inhibitors showed that while ethylene and NO did not positively regulate Fe-deficiency induced PS root release, auxin plays an essential role in the regulation of this process. Moreover, the application of IAA to Fe-sufficient plants promoted both PS root release and TaNAAT gene expression thus indicating that auxin might be involved in the shoot to root signaling network regulating Fe-deficiency root responses in wheat.

Conclusions: These results therefore indicate that PS root release in Fe-deficient wheat plants is directly modulated by the shoot Fe status through signaling pathways involving, among other possible effectors, auxin.
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http://dx.doi.org/10.1186/s12870-018-1324-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5987636PMC
June 2018

Efficiency of surfactant-enhanced bioremediation of aged polycyclic aromatic hydrocarbon-contaminated soil: Link with bioavailability and the dynamics of the bacterial community.

Sci Total Environ 2018 Sep 5;634:224-234. Epub 2018 Apr 5.

Centro de Investigación y Desarrollo en Fermentaciones Industriales, CINDEFI (UNLP; CCT-La Plata, CONICET), La Plata, Argentina; Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, La Plata, Argentina. Electronic address:

Shifts in the bacterial-community dynamics, bioavailability, and biodegradation of polycyclic aromatic hydrocarbons (PAHs) of chronically contaminated soil were analyzed in Triton X-100-treated microcosms at the critical micelle concentration (T-CMC) and at two sub-CMC doses. Only the sub-CMC-dose microcosms reached sorbed-PAH concentrations significantly lower than the control: 166±32 and 135±4mgkg dry soil versus 266±51mgkg; consequently an increase in high- and low-molecular-weight PAHs biodegradation was observed. After 63days of incubation pyrosequencing data evidenced differences in diversity and composition between the surfactant-modified microcosms and the control, with those with sub-CMC doses containing a predominance of the orders Sphingomonadales, Acidobacteriales, and Gemmatimonadales (groups of known PAHs-degrading capability). The T-CMC microcosm exhibited a lower richness and diversity index with a marked predominance of the order Xanthomonadales, mainly represented by the Stenotrophomonas genus, a PAHs- and Triton X-100-degrading bacterium. In the T-CMC microcosm, whereas the initial surface tension was 35mNm, after 63days of incubation an increase up to 40mNm was registered. The previous observation and the gas-chromatography data indicated that the surfactant may have been degraded at the CMC by a highly selective bacterial community with a consequent negative impact on PAHs biodegradation. This work obtained strong evidence for the involvement of physicochemical and biologic influences determining the different behaviors of the studied microcosms. The results reported here contribute significantly to an optimization of, surfactant-enhanced bioremediation strategies for chronically contaminated soil since the application of doses below the CMC would reduce the overall costs.
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http://dx.doi.org/10.1016/j.scitotenv.2018.03.303DOI Listing
September 2018

Strategies for oxidation of PAHs in aged contaminated soil by batch reactors.

Ecotoxicol Environ Saf 2018 Apr 5;151:76-82. Epub 2018 Jan 5.

Centro de Investigación y Desarrollo en Fermentaciones Industriales, CINDEFI (UNLP; CCT-La Plata, CONICET), La Plata, Argentina. Electronic address:

Polycyclic aromatic hydrocarbons (PAH) are neutral, nonpolar and hydrophobic molecules that tend to sorb onto soil organic matter. Chemical oxidation is a good choice to avoid the limitations of bioremediation. To evaluate the efficiency of different types of oxidation (permanganate, hydrogen peroxide, and persulfate) and activation (heat, alkaline, and iron), batch reactors were prepared. The soil was contaminated with phenanthrene and pyrene (1200 ± 200 and 2800 ± 100mg per kg of dry soil, respectively) and aged for fifteen months. Treatments were prepared with 10g of contaminated dry soil and 20ml of water and incubated at room temperature for 7 days. Analyses of phenanthrene and pyrene concentrations, soil pH and electric conductivity were performed. Counts of heterotrophic cultivable bacteria on R2A medium and PAH-degraders were carried out after 7 days of treatment. The persulfate treatment at room temperature, without the addition of activators, achieved better results than treatments with the same doses of permanganate or hydrogen peroxide. All the strategies to improve persulfate treatments yielded higher degradation of pyrene than the biological control, as expected from the structural description of this compound by Clar's model. The thermal activation of persulfate (65°C for 6h) led to the degradation of more than 90% of both PAHs after 7 days of treatment.
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http://dx.doi.org/10.1016/j.ecoenv.2017.12.067DOI Listing
April 2018

Involvement of Hormone- and ROS-Signaling Pathways in the Beneficial Action of Humic Substances on Plants Growing under Normal and Stressing Conditions.

Biomed Res Int 2016 5;2016:3747501. Epub 2016 Jun 5.

Department of Environmental Biology, Agricultural Chemistry and Biology Group-CMI Roullier, Faculty of Sciences, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain.

The importance of soil humus in soil fertility has been well established many years ago. However, the knowledge about the whole mechanisms by which humic molecules in the rhizosphere improve plant growth remains partial and rather fragmentary. In this review we discuss the relationships between two main signaling pathway families that are affected by humic substances within the plant: one directly related to hormonal action and the other related to reactive oxygen species (ROS). In this sense, our aims are to try the integration of all these events in a more comprehensive model and underline some points in the model that remain unclear and deserve further research.
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http://dx.doi.org/10.1155/2016/3747501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913021PMC
March 2017

Root-Shoot Signaling crosstalk involved in the shoot growth promoting action of rhizospheric humic acids.

Plant Signal Behav 2016 ;11(4):e1161878

a Department of Environmental Biology , Agricultural Chemistry and Biology Group-CMI Roullier, Faculty of Sciences, University of Navarra.

Numerous studies have shown the ability of humic substances to improve plant development. This action is normally reflected in an enhancement of crop yields and quality. However, the mechanisms responsible for this action of humic substances remain rather unknown. Our studies have shown that the shoot promoting action of sedimentary humic acids is dependent of its ability to increase root hydraulic conductivity through signaling pathways related to ABA, which in turn is affected in roots by humic acids in an IAA-NO dependent way. Furthermore, these studies also indicate that the primary action of humic acids in roots might also be physical, resulting from a transient mild stress caused by humic acids associated with a fouling-cleaning cycle of wall cell pores. Finally the role of alternative signal molecules, such as ROS, and corresponding signaling pathways are also discussed and modeled in the context of the above-mentioned framework.
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http://dx.doi.org/10.1080/15592324.2016.1161878DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4883868PMC
December 2016

Abscisic Acid Regulation of Root Hydraulic Conductivity and Aquaporin Gene Expression Is Crucial to the Plant Shoot Growth Enhancement Caused by Rhizosphere Humic Acids.

Plant Physiol 2015 Dec 8;169(4):2587-96. Epub 2015 Oct 8.

Department of Environmental Biology (Agricultural Chemistry and Biology Group), Faculty of Sciences, University of Navarra, 31080 Pamplona, Spain (M.O., V.M., E.B., M.G., M.F., E.C., A.M.Z., R.B., J.M.G.-M.); andAntenna Group, Electrical and Electronic Engineering Department, Public University of Navarra, 31006 Pamplona, Spain (J.C.I., D.E., I.E., R.G.)

The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discussed in detail. Experiments using cucumber (Cucumis sativus) plants show that the shoot growth enhancement caused by a structurally well-characterized humic acid with sedimentary origin is functionally associated with significant increases in abscisic acid (ABA) root concentration and root hydraulic conductivity. Complementary experiments involving a blocking agent of cell wall pores and water root transport (polyethylenglycol) show that increases in root hydraulic conductivity are essential in the shoot growth-promoting action of the model humic acid. Further experiments involving an inhibitor of ABA biosynthesis in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic conductivity and shoot growth depended on ABA signaling pathways. These experiments also show that a significant increase in the gene expression of the main root plasma membrane aquaporins is associated with the increase of root hydraulic conductivity caused by the model humic acid. Finally, experimental data suggest that all of these actions of model humic acid on root functionality, which are linked to its beneficial action on plant shoot growth, are likely related to the conformational structure of humic acid in solution and its interaction with the cell wall at the root surface.
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http://dx.doi.org/10.1104/pp.15.00596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4677878PMC
December 2015

Remediation of phenanthrene-contaminated soil by simultaneous persulfate chemical oxidation and biodegradation processes.

Environ Sci Pollut Res Int 2014 Jun 6;21(12):7548-56. Epub 2014 Mar 6.

Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), Facultad de Ciencias Exactas-UNLP, CCT-La Plata, CONICET, La Plata, 1900, Argentina.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds with carcinogenic and/or mutagenic potential. To address the limitations of individual remediation techniques and to achieve better PAH removal efficiencies, the combination of chemical and biological treatments can be used. The degradation of phenanthrene (chosen as a model of PAH) by persulfate in freshly contaminated soil microcosms was studied to assess its impact on the biodegradation process and on soil properties. Soil microcosms contaminated with 140 mg/kgDRY SOIL of phenanthrene were treated with different persulfate (PS) concentrations 0.86-41.7 g/kgDRY SOIL and incubated for 28 days. Analyses of phenanthrene and persulfate concentrations and soil pH were performed. Cultivable heterotrophic bacterial count was carried out after 28 days of treatment. Genetic diversity analysis of the soil microcosm bacterial community was performed by PCR amplification of bacterial 16S rDNA fragments followed by denaturing gradient gel electrophoresis (DGGE). The addition of PS in low concentrations could be an interesting biostimulatory strategy that managed to shorten the lag phase of the phenanthrene biological elimination, without negative effects on the physicochemical and biological soil properties, improving the remediation treatment.
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http://dx.doi.org/10.1007/s11356-014-2687-0DOI Listing
June 2014

Phenol depletion by thermally activated peroxydisulfate at 70°C.

Chemosphere 2011 Aug 23;84(9):1270-5. Epub 2011 May 23.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata, Argentina.

The ability of thermal activated peroxydisulfate (PS) of mineralizing phenol at 70°C from contaminated waters is investigated. Phenol in concentrations of 10(-4) to 5×10(-4)M is quantitatively depleted by 5×10(-3) to 10(-2)M activated PS in 15 min of reaction. However, mineralization of the organic carbon is not observed. Instead, an insoluble phenol polymer-type product is formed. A reaction mechanism including the formation of phenoxyl radicals and validated by computer simulations is proposed. High molecular weight phenolic products are formed by phenoxyl radical H-abstraction reactions. This is not the case for the room temperature degradation of phenol by sulfate radicals where sulfate addition to the aromatic ring mainly leads to the generation of hydroxycyclohexadienyl radicals leading to hydroxybenzenes and oxidized open chain products. Therefore, a change in the reaction mechanism is observed with increasing temperature, and thermal activation of PS at 70°C does not lead to the mineralization of phenol. Thus PS activation at 70°C may be considered a potential method to reduce the load of phenol in polluted waters by polymerization.
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http://dx.doi.org/10.1016/j.chemosphere.2011.04.062DOI Listing
August 2011

Auxin: a major player in the shoot-to-root regulation of root Fe-stress physiological responses to Fe deficiency in cucumber plants.

Plant Physiol Biochem 2011 May 26;49(5):545-56. Epub 2011 Feb 26.

CIPAV TimacAGRO International-Roullier Group, Polígono Arazuri-Orcoyen, c/C n° 32, 31160 Orcoyen, Navarra, Spain.

The aim of this study was to investigate the effects of IAA and ABA in the shoot-to-root regulation of the expression of the main Fe-stress physiological root responses in cucumber plants subjected to shoot Fe functional deficiency. Changes in the expression of the genes CsFRO1, CsIRT1, CsHA1 and CsHA2 (coding for Fe(III)-chelate reductase (FCR), the Fe(II) transporter and H+-ATPase, respectively) and in the enzyme activity of FCR and the acidification capacity were measured. We studied first the ability of exogenous applications of IAA and ABA to induce these Fe-stress root responses in plants grown in Fe-sufficient conditions. The results showed that IAA was able to activate these responses at the transcriptional and functional levels, whereas the results with ABA were less conclusive. Thereafter, we explored the role of IAA in plants with or without shoot Fe functional deficiency in the presence of two types of IAA inhibitors, affecting either IAA polar transport (TIBA) or IAA functionality (PCIB). The results showed that IAA is involved in the regulation at the transcriptional and functional levels of both Fe root acquisition (FCR, Fe(II) transport) and rhizosphere acidification (H+-ATPase), although through different, and probably complementary, mechanisms. These results suggest that IAA is involved in the shoot-to-root regulation of the expression of Fe-stress physiological root responses.
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http://dx.doi.org/10.1016/j.plaphy.2011.02.018DOI Listing
May 2011

Action of humic acid on promotion of cucumber shoot growth involves nitrate-related changes associated with the root-to-shoot distribution of cytokinins, polyamines and mineral nutrients.

J Plant Physiol 2010 May 24;167(8):633-42. Epub 2010 Feb 24.

Department of Chemistry and Soil Chemistry, Faculty of Sciences, University of Navarra, P.O. Box 273, 31080 Pamplona (Navarra), Spain.

Numerous studies have reported the ability of humic substances to increase shoot growth in different plant species cultivated under diverse growth conditions. However, the mechanism responsible for this effect of humic substances is poorly understood. It is possible that the shoot promoting effect of humic substances involves a primary effect on root H(+)-ATPase activity and nitrate root-shoot distribution that, in turn, causes changes in the root-shoot distribution of certain cytokinins, polyamines and abscisic acid, thus affecting shoot growth. We investigated this hypothesis in the present study. The results showed that the root application of a purified humic acid causes a significant increase in shoot growth that is associated with an enhancement in root H(+)-ATPase activity, an increase in nitrate shoot concentration, and a decrease in roots. These effects were associated with significant increases in the shoot concentration of several cytokinins and polyamines (principally putrescine), concomitant with decreases in roots. Likewise, these changes in the root-shoot distribution of diverse active cytokinins correlated well to significant changes in the root-shoot distribution of several mineral nutrients. These results, taken together, indicate that the beneficial effects of humic substances on shoot development in cucumber could be directly associated with nitrate-related effects on the shoot concentration of several active cytokinins and polyamines (principally putrescine).
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http://dx.doi.org/10.1016/j.jplph.2009.11.018DOI Listing
May 2010

Thermally activated peroxydisulfate in the presence of additives: a clean method for the degradation of pollutants.

Chemosphere 2009 Jun 13;75(10):1405-9. Epub 2009 Mar 13.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET. C.C. 16, Suc. 4, (1900) La Plata, Argentina.

The kinetics and mechanism of the thermal activation of peroxydisulfate, in the temperature range from 60 to 80 degrees C, was investigated in the presence and absence of sodium formate as an additive to turn the oxidizing capacity of the reaction mixture into a reductive one. Trichloroacetic acid, TCA, whose degradation by a reductive mechanism is well reported in the literature, was used as a probe. The chemistry of thermally activated peroxydisulfate is described by a reaction scheme involving free radical generation. The proposed mechanism is evaluated by a computer simulation of the concentration profiles obtained under different experimental conditions. In the presence of formate, SO(4)(-) radicals yield CO(2)(-), which are the main species available for degrading TCA. Under the latter conditions, TCA is more efficiently depleted than in the absence of formate, but otherwise identical conditions of temperature and [S(2)O(8)(2-)]. We therefore conclude that activated peroxydisulfate in the presence of formate as an additive is a convenient method for the mineralization of substrates that are refractory to oxidation, such as perchlorinated hydrocarbons and TCA. This method has the advantage that leaves no toxic residues.
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http://dx.doi.org/10.1016/j.chemosphere.2009.02.038DOI Listing
June 2009
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