Usue Pérez-López

Universidad del País Vasco / Euskal Herriko Unibertsitatea, Leioa, Basque Country, Spain

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Publications (15)28.22 Total impact

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    ABSTRACT: Differently colored lettuce (Lactuca sativa L.) cvs (green, green/red and red) were studied in order to correlate their phenolic composition with their antioxidant kinetic behavior. Electron Paramagnetic Resonance (EPR) was employed to monitor decay kinetics of 1,1-diphenyl-2-picrylhydrazyl (DPPH.) which allowed the identification of three differently-fast antioxidants. The results showed that as long as lettuce had higher red pigmentation, the hydrophilic antioxidant capacity increased together with the contents in free and conjugated phenolic acids, free and conjugated flavonoids and anthocyanins. EPR allowed the identification of slow-rate antioxidants in green and green/red cvs, intermediate-rate antioxidants in green, green/red and red cvs, and fast-rate antioxidants in green/red and red cvs. At present, we cannot attribute the different kinetic behavior to a specific antioxidant, but we can suggest that the flavonoid quercetin accounted for the majority of the intermediate-rate antioxidants whereas the anthocyanins accounted for the majority of the fast-rate antioxidants.
    Journal of agricultural and food chemistry. 11/2014;
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    ABSTRACT: The effects of elevated CO2 on the content of several nutrients in plants have been well studied, but few studies have investigated plant nutrient dynamics under future environmental conditions, which are expected to include elevated CO2 and elevated soil salt concentrations. This study investigated whether high salt and CO2 conditions, singly or in combination, might affect nutrient dynamics, and the underlying mechanisms. We measured macro- and micronutrient uptake and translocation rates, nutrient content and concentrations in whole seedlings and in each plant organ. We estimated whole-plant nutrient use efficiencies in barley subjected to 0, 80, 160, or 240 mM NaCl and grown at either 350 (ambient) or 700 (elevated) μmol mol−1 CO2. Under non-saline conditions, plants grown at elevated CO2 adjusted their root size and activity to change nutrient uptake and transport efficiency in response to the demand for a given nutrient. Under high saline conditions, salt stress reduced K, Ca, N, B, and S uptake rates and concentrations in tissues, which caused growth reduction. Nevertheless, barley had the ability to increase the selectivity of K over Na, and Ca over Na. Under combined conditions of salt stress and elevated CO2, barley seedlings were able to maintain higher uptake and translocation rates of almost all nutrients. This ability allowed the plants to adapt to higher demands under elevated CO2; they could grow more rapidly by allocating more C to root growth and by increasing active nutrient uptake and translocation. Our results indicated that salinity generally increased nutrient use efficiency under both CO2 conditions. However, we found no consistent evidence that nutrient use efficiency was affected by CO2 concentration, either under non-saline or saline conditions.
    Environmental and Experimental Botany 03/2014; 99:86–99. · 3.00 Impact Factor
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    ABSTRACT: The objective of this study was to determine the response of barley's carbon isotope composition and other physiological parameters to the interaction of salt stress and elevated CO2 levels, and the usefulness of carbon isotope discrimination (Δ13C) as indicative of the functional performance of barley (Hordeum vulgare L.). Barley plants were grown under ambient (350 μmol mol-1) and elevated (700 μmol mol-1) CO2 conditions and subjected to salt stress (0, 80, 160, and 240 mM NaCl) for 14 days. Elevated CO2 levels increased biomass production, water use efficiency and the photosynthetic rate, although this parameter was partly acclimated to elevated CO2 levels. Salt stress decreased this acclimation response because it enhanced the sink strength of the plant. Elevated CO2 significantly decreased the 13C isotopic composition (δ13C) in all plant organs; however, the ratio of δ13C between the root and the leaf was increased, indicating a higher allocation of δ13C to the below-ground parts. Conversely, salt stress increased plant δ13C, showing differences between plant organs. From the strong correlations between Δ13C and biomass production, the photosynthetic rate or water use efficiency both at ambient and elevated CO2, we concluded that Δ13C is a useful parameter for evaluating leaf and whole plant responses to salinity and can provide an integrated index of processes to understand the mechanisms underlying salt tolerance of barley both under current and future environmental CO2 conditions.
    Plant Science. 01/2014;
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    ABSTRACT: The future environment will exhibit increases in soil salt concentrations and atmospheric CO2. In general, plant growth is inhibited by salt stress and stimulated by elevated CO2. This study investigated whether elevated CO2 could improve plant growth under salt stress and the mechanisms involved. We measured functional and morphological components of growth in barley (cv. Iranis) subjected to 0, 80, 160, or 240 mM NaCl and grown at either 350 (ambient) or 700 (elevated) μmol mol−1 CO2. Under nonsaline conditions, elevated CO2 stimulated growth by increasing the relative growth rate (RGR). Maximum CO2 stimulation was observed within the first 10 days of development, before the start of the salt treatment. Afterwards, salt stress caused reductions in biomass production and RGR by decreasing the photosynthetic rate and increasing the respiration rate; this resulted in a reduced net assimilation rate (functional component). In addition, salt stress caused nutritional imbalances, which reduced the leaf expansion capacity, and changed the root-to-shoot ratio. This resulted in reductions in the specific leaf area and leaf weight ratio (morphological components). However, the functional component became more relevant with increasing salt stress. Under elevated CO2 conditions, salt stress inhibited growth less than that observed at ambient CO2. This occurred because (1) more dry biomass was synthesized for a given leaf area due to higher photosynthetic rates, and (2) greater leaf area and root biomass were maintained for photosynthesis and water and mineral uptake, respectively.
    Journal of Plant Growth Regulation 12/2013; · 2.06 Impact Factor
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    ABSTRACT: As a consequence of the increasing importance of vegetables in the human diet, there is an interest in enhancing both the productivity and quality of vegetables. A number of factors, including plant genotype and environmental growing conditions, can impact the production and quality of vegetables. The objective of this study was to determine whether elevated CO2, salinity, or high light treatments assayed individually, or salinity or high light in combination with elevated CO2, increased biomass production and antioxidant capacity in two lettuce cultivars. Elevated CO2 and its combination with salinity or high light increased biomass production in both cultivars, while high light treatment alone increased production in green-leaf lettuce but not in red-leaf lettuce. On the other hand, elevated CO2 and its combination with salinity or high light increased the antioxidant capacity of both cultivars, while high light treatment alone increased the antioxidant capacity of red-leaf lettuce, but not of green-leaf lettuce.
    Journal of plant physiology 07/2013; · 2.50 Impact Factor
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    ABSTRACT: The future environment may be altered by high concentrations of salt in the soil and elevated [CO(2)] in the atmosphere. These have opposite effects on photosynthesis. Generally, salt stress inhibits photosynthesis by stomatal and non-stomatal mechanisms; in contrast, elevated [CO(2)] stimulates photosynthesis by increasing CO(2) availability in the Rubisco carboxylating site and by reducing photorespiration. However, few studies have focused on the interactive effects of these factors on photosynthesis. To elucidate this knowledge gap, we grew the barley plant, Hordeum vulgare (cv. Iranis), with and without salt stress at either ambient or elevated atmospheric [CO(2)] (350 or 700 μmol mol(-1) CO(2), respectively). We measured growth, several photosynthetic and fluorescence parameters, and carbohydrate content. Under saline conditions, the photosynthetic rate decreased, mostly because of stomatal limitations. Increasing salinity progressively increased metabolic (photochemical and biochemical) limitation; this included an increase in non-photochemical quenching and a reduction in the PSII quantum yield. When salinity was combined with elevated CO(2), the rate of CO(2) diffusion to the carboxylating site increased, despite lower stomatal and internal conductance. The greater CO(2) availability increased the electron sink capacity, which alleviated the salt-induced metabolic limitations on the photosynthetic rate. Consequently, elevated CO(2) partially mitigated the saline effects on photosynthesis by maintaining favorable biochemistry and photochemistry in barley leaves.
    Photosynthesis Research 01/2012; 111(3):269-83. · 3.15 Impact Factor
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    ABSTRACT: Environmental and Experimental Botany j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / e n v e x p b o t a b s t r a c t The objective of this study was to determine the response of nitrogen metabolism to drought and recov-ery upon rewatering in barley (Hordeum vulgare L.) plants under ambient (350 mol mol −1) and elevated (700 mol mol −1) CO 2 conditions. Barley plants of the cv. Iranis were subjected to drought stress for 9, 13, or 16 days. The effects of drought under each CO 2 condition were analysed at the end of each drought period, and recovery was analysed 3 days after rewatering 13-day droughted plants. Soil and plant water status, protein content, maximum (NR max) and actual (NR act) nitrate reductase, glutamine synthetase (GS), and aminant (NADH-GDH) and deaminant (NAD-GDH) glutamate dehydrogenase activ-ities were analysed. Elevated CO 2 concentration led to reduced water consumption, delayed onset of drought stress, and improved plant water status. Moreover, in irrigated plants, elevated CO 2 produced marked changes in plant nitrogen metabolism. Nitrate reduction and ammonia assimilation were higher at elevated than at ambient CO 2 , which in turn yielded higher protein content. Droughted plants showed changes in water status and in foliar nitrogen metabolism. Leaf water potential (« w) and nitrogen assim-ilation rates decreased after the onset of water deprivation. NR act and NR max activity declined rapidly in response to drought. Similarly, drought decreased GS whereas NAD-GDH rose. Moreover, protein con-tent fell dramatically in parallel with decreased leaf « w . In contrast, elevated CO 2 reduced the water stress effect on both nitrate reduction and ammonia assimilation coincident with a less-steep decrease in « w . On the other hand, « w practically reached control levels after 3 days of rewatering. In parallel with the recovery of plant water status, nitrogen metabolism was also restored. Thus, both NR act and NR max activities were restored to about 75–90% of control levels when water supply was restored; the GS activity reached 80–90% of control values; and GDH activities and protein content were similar to those of control plants. The recovery was always faster and slightly higher in plants grown under elevated CO 2 conditions compared to those grown in ambient CO 2 , but midday « w dropped to similar values under both CO 2 conditions. The results suggest that elevated CO 2 improves nitrogen metabolism in droughted plants by maintaining better water status and enhanced photosynthesis performance, allowing superior nitrate reduction and ammonia assimilation. Ultimately, elevated CO 2 mitigates many of the effects of drought on nitrogen metabolism and allows more rapid recovery following water stress. (A. Robredo), usue.perez@ehu.es (U. Pérez-López), j.miranda.apodaca@gmail.com (J. Miranda-Apodaca), maite.lacuesta@ehu.es (M. Lacuesta), amaia.mena@ehu.es (A. Mena-Petite), a.munoz-rueda@ehu.es (A. M noz-Rueda).
    Environmental and Experimental Botany 02/2011; 71:399-408. · 3.00 Impact Factor
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    ABSTRACT: Future environmental conditions will include elevated concentrations of salt in the soil and an elevated concentration of CO(2) in the atmosphere. Because these environmental changes will likely affect reactive oxygen species (ROS) formation and cellular antioxidant metabolism in opposite ways, we analyzed changes in cellular H(2)O(2) and non-enzymatic antioxidant metabolite [lipoic acid (LA), ascorbate (ASA), glutathione (GSH)] content induced by salt stress (0, 80, 160 or 240 mM NaCl) under ambient (350 micromol mol(-1)) or elevated (700 micromol mol(-1)) CO(2) concentrations in two barley cultivars (Hordeum vulgare L.) that differ in sensitivity to salinity (cv. Alpha is more sensitive than cv. Iranis). Under non-salinized conditions, elevated CO(2) increased LA content, while ASA and GSH content decreased. Under salinized conditions and ambient CO(2), ASA increased, while GSH and LA decreased. At 240 mM NaCl, H(2)O(2) increased in Alpha and decreased in Iranis. When salt stress was imposed at elevated CO(2), less oxidative stress and lower increases in ASA were detected, while LA was constitutively higher. The decrease in oxidative stress could have been because of less ROS formation or to a higher constitutive LA level, which might have improved regulation of ASA and GSH reductions. Iranis had a greater capacity to synthesize ASA de novo and had higher constitutive LA content than did Alpha. Therefore, we conclude that elevated CO(2) protects barley cultivars against oxidative damage. However, the magnitude of the positive effect is cultivar specific.
    Physiologia Plantarum 02/2010; 139(3):256-68. · 3.66 Impact Factor
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    ABSTRACT: Future environmental conditions will include elevated concentrations of salt in the soils and elevated concentrations of CO(2) in the atmosphere. Soil salinization inhibits crop growth due to osmotic and ionic stress. However, plants possess salt tolerance mechanisms, such as osmotic and elastic adjustment, to maintain water status. These mechanisms, which enhance the uptake and accumulation of ions and the synthesis of compatible solutes, require substantial energy expenditure. Under elevated CO(2), the carbon and energy supplies are usually higher, which could facilitate the energetically expensive salt tolerance mechanisms. To test this hypothesis, the factors involved in osmotic and elastic adjustments in two barley cultivars (Hordeum vulgare cv. Alpha and cv. Iranis) grown under several salt concentrations and at ambient or elevated [CO(2)] were evaluated. Under ambient [CO(2)] and salt stress, both cultivars (1) decreased the volumetric elasticity modulus (epsilon) of their cell walls, and (2) adjusted osmotically by accumulating ions (Na(+) and Cl(-)) from the soil, confirming barley as an includer species. The contributions of sugars and other unidentified osmolytes also increased, while the contribution of organic acids decreased. Under elevated [CO(2)] and salt stress, epsilon decreased less and osmotic adjustment (OA) was greater than at ambient [CO(2)]. In fact, the greater OA under elevated [CO(2)] was positively correlated with the contributions of sugars and other unidentified compounds. These results indicate that barley is likely to be successful in more salinized soils due to its capacity for OA under elevated [CO(2)].
    Journal of plant physiology 09/2009; 167(1):15-22. · 2.50 Impact Factor
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    ABSTRACT: Changes in antioxidant metabolism because of the effect of salinity stress (0, 80, 160 or 240 mM NaCl) on protective enzyme activities under ambient (350 micromol mol(-1)) and elevated (700 micromol mol(-1)) CO(2) concentrations were investigated in two barley cultivars (Hordeum vulgare L., cvs Alpha and Iranis). Electrolyte leakage, peroxidation, antioxidant enzyme activities [superoxide dismutase (SOD), EC 1.15.1.1; ascorbate peroxidase (APX), EC 1.11.1.11; catalase (CAT), EC 1.11.1.6; dehydroascorbate reductase (DHAR), EC 1.8.5.1; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; glutathione reductase (GR), EC 1.6.4.2] and their isoenzymatic profiles were determined. Under salinity and ambient CO(2), upregulation of antioxidant enzymes such as SOD, APX, CAT, DHAR and GR occurred. However, this upregulation was not enough to counteract all ROS formation as both ion leakage and lipid peroxidation came into play. The higher constitutive SOD and CAT activities together with a higher contribution of Cu,Zn-SOD 1 detected in Iranis might possibly contribute and make this cultivar more salt-tolerant than Alpha. Elevated CO(2) alone had no effect on the constitutive levels of antioxidant enzymes in Iranis, whereas in Alpha it induced an increase in SOD, CAT and MDHAR together with a decrease of DHAR and GR. Under combined conditions of elevated CO(2) and salinity the oxidative damage recorded was lower, above all in Alpha, together with a lower upregulation of the antioxidant system. So it can be concluded that elevated CO(2) mitigates the oxidative stress caused by salinity, involving lower ROS generation and a better maintenance of redox homeostasis as a consequence of higher assimilation rates and lower photorespiration, being the response dependent on the cultivar analysed.
    Physiologia Plantarum 02/2009; 135(1):29-42. · 3.66 Impact Factor
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    ABSTRACT: With the changing climate, plants will be facing increasingly harsh environmental conditions marked by elevated salinity in the soils and elevated concentrations of CO2 in the atmosphere. These two factors have opposite effects on water status in plants. Therefore, our objective was to determine the interaction between these two factors and to determine whether elevated [CO2] might alleviate the adverse effects of salt stress on water status in two barley cultivars, Alpha and Iranis, by studying their relative water content and their water potential and its components, transpiration rate, hydraulic conductance, and water use efficiency. Both cultivars maintained their water status under salt stress, increasing water use efficiency and conserving a high relative water content by (1) reducing water potential via passive dehydration and active osmotic adjustment and (2) decreasing transpiration through stomatal closure and reducing hydraulic conductance. Iranis showed a greater capacity to achieve osmotic adjustment than Alpha. Under the combined conditions of salt-stress and elevated [CO2], both cultivars (1) achieved osmotic adjustment to a greater extent than at ambient [CO2], likely due to elevated rates of photosynthesis, and (2) decreased passive dehydration by stomatal closure, thereby maintaining a greater turgor potential, relative water content, and water use efficiency. Therefore, we found an interaction between salt stress and elevated [CO2] with regard to water status in plants and found that elevated [CO2] is associated with improved water status of salt-stressed barley plants.
    Environmental and Experimental Botany. 01/2009;
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    ABSTRACT: The Lower Decreases Of Pigment Content And Assimilation Rates And The Higher Rates Of Instantaneous Water Use Efficiency Observed In Plants Grown Under Salinity And Elevated Co2 Would Indicate A Better Photosynthetic CapaCity Than Their Counterparts At Ambient Co2.
    12/2007: pages 1529-1534;
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    ABSTRACT: We analysed the impact of elevated CO2 on water relations, water use efficiency and photosynthetic gas exchange in barley (Hordeum vulgare L.) under wet and drying soil conditions. Soil moisture was less depleted under elevated compared to ambient [CO2]. Elevated CO2 had no significant effect on the water relations of irrigated plants, except on whole plant hydraulic conductance, which was markedly decreased at elevated compared to ambient CO2 concentrations. The values of relative water content, water potential and osmotic potential were higher under elevated CO2 during the entire drought period. The better water status of water-limited plants grown at elevated CO2 was the result of stomatal control rather than of osmotic adjustment. Despite the low stomatal conductance produced by elevated CO2, net photosynthesis was higher under elevated than ambient CO2 concentrations. With water shortage, photosynthesis was maintained for longer at higher rates under elevated CO2. The reduction of stomatal conductance and therefore transpiration, and the enhancement of carbon assimilation by elevated CO2, increased instantaneous and whole plant water use efficiency in both irrigated and droughted plants. Thus, the metabolism of barley plants grown under elevated CO2 and moderate or mild water deficit conditions is benefited by increased photosynthesis and lower transpiration. The reduction in plant water use results in a marked increase in soil water content which delays the onset and severity of water deficit.
    Environmental and Experimental Botany. 01/2007;
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    ABSTRACT: We evaluated the combined effects of elevated CO2 and water availability on photosynthesis in barley. Soil and plant water content decreased with water stress, but less under elevated CO2 concentration (EC) compared with ambient CO2 concentration (AC). During water stress, stomatal conductance, carboxylation rate, RuBP regeneration, and the rate of triose phosphate utilisation (TPU) were decreased but less when plants grew under EC. Drought treatments caused only a slight effect on maximum photochemical efficiency (variable to maximum fluorescence ratio, Fv/Fm), whereas the actual quantum yield (ΦPS2), maximum electron transport rate (Jmax) and photochemical quenching (qP) were decreased and the non photochemical quenching (NPQ) was enhanced. Under water deficit, the allocation of electrons to CO2 assimilation was diminished by 49 % at AC and by 26 % at EC while the allocation to O2 reduction was increased by 15 % at AC and by 12 % at EC. Additional key wordsclimate change-drought-electron transport allocation- Hordeum vulgare -photochemical efficiency-quantum yield
    Biologia Plantarum 54(2):285-292. · 1.69 Impact Factor
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    ABSTRACT: Both salt stress and high carbon dioxide (CO2) levels can affect plant nitrogen (N) metabolism by acting in parallel, decreasing N metabolism; or acting in opposite directions, with salt stress decreasing N metabolism and elevated CO2 levels enhancing it. The objective of this work was to analyse the effect of salinity on N acquisition, distribution, and assimilation, the consequences of these effects on growth in barley (Hordeum vulgare L., cv. Iranis), and the possible effects on these processes provoked by elevated CO2 levels. Several steps of N metabolism were studied in H. vulgare plants exposed to 0, 80, 160, or 240 mM NaCl under ambient (350 μmol mol−1) or elevated (700 μmol mol−1) CO2. Salt stress reduced the N uptake (NUR) and translocation (NTR) rates and nitrate reductase (EC 1.7.1.1) activity, altering plant N isotope discrimination (Δ15N). Although salt stress increased glutamine synthetase (EC 6.3.1.2) activity, N and protein content, and photosynthetic nitrogen use efficiency decreased. The decrease in nitrate reductase activity was related to decreases in NUR and NTR, while Δ15N correlated with the NUR and with the nitrate reductase activity. Under mild salt stress, N metabolism was better maintained under elevated CO2 levels than under ambient CO2 levels, since NUR, NTR, photosynthetic nitrogen use efficiency, and nitrate reductase activity were less affected, yielding lower Δ15N and higher growth. In addition, growth was negatively correlated with Δ15N indicating that the Δ15N determination may allow the estimation of barley growth. As a consequence of all these results, barley plants subjected to elevated CO2 levels will likely overcome mild saline conditions because of their capacity to maintain efficiency in N metabolism.
    Environmental and Experimental Botany 87:148–158. · 3.00 Impact Factor