Effect of copper on antioxidant enzyme activities and mineral nutrition of white lupin plants grown in nutrient solution

We analyzed the effect of different copper (Cu) concentrations (0.10, 0.15, 0.20 and 0.35 mM) and time (1 day to 9 days) on several growth and biochemical parameters of roots and shoots of white lupin plants (Lupinus albus cv Estoril) grown in nutrient solution. A significant decrease in leaf fresh weight and leaf area was detected. Copper accumulated in the roots, and an impairment of nutrient translocation was only observed after six days at the highest Cu concentrations applied. A transient increase in the activity of polyphenoloxidase (EC 1.10.3.1) enforces a role for lignification as a defense strategy under enhanced Cu levels. The activities of several antioxidative enzymes were enhanced after Cu application. Our results indicate that Lupinus albus cv ‘Estoril’ is a rather resistant plant that can cope with moderate concentrations of copper, mostly by controlling up to a certain point, the uptake of excessive amounts of this meta

Characterization of plant antioxidative system in response to abiotic stresses: a focus on heavy metal toxicity

During their life span, plants can be subjected to a number of abiotic stresses, like drought, temperature (both high and low), radiation, salinity, soil pH, heavy metals, lack of essential nutrients, air pollutants, etc. When affected by one, or a combination of abiotic stresses, a response is induced by changes in the plant metabolism, growth and general development. Reactive Oxygen Species (ROS) are a natural consequence of the aerobic metabolism, and plants have mechanisms to deal with them in normal conditions, controlling the formation and removal rates. Under stress conditions, cell homeostasis is disrupted and ROS production can increase a lot putting a heavy burden on the those antioxidative mechanisms, some of which are activated in order to eliminate the excess ROS (Mittler et al., 2004). Trace element contamination cause abiotic stress in plants and it can affect crop production and quality. Certain metals, like copper, are essential for plants, but at high concentrations (depending on plant species) can be considered toxic. Other elements like cadmium and arsenic (a metalloid), while not essential elements for plants, are widespread pollutants that are present in nature due to both natural and manmade activities. Plants have developed different strategies to cope with these stresses. Some use an avoidance strategy to reduce trace element assimilation while others use internal defence mechanisms to cope with the increasing levels of the toxic species. Phytotoxic amounts of trace elements are known to affect several physiological processes and can cause oxidative stress. Plants have developed several trace element defence mechanisms, that allow them to grow despite the presence of variable concentrations of trace elements, but the threshold concentrations as well as the different response mechanisms strongly depend on plant species and on the type of metal. Metal toxicity can cause a redox imbalance and induce the increase of ROS concentration, activating the antioxidant defence mechanisms of plants (Sharma & Dietz, 2009). These mechanisms are very dependent on the metal and the plant but usually include the involvement of the ascorbate-glutathione cycle enzymes which is a major antioxidative defence mechanism, and of other antioxidant enzymes like catalase, peroxidases, and superoxide dismutase. Other non-enzymatic substances with reported antioxidant properties can also be involved in plant defence mechanisms, like ascorbate, glutathione, alkaloids, phenolic compounds, non-proteic amino-acids and carotenoid

Effect of Cd, Cr, Cu, Mn, Ni, Pb and Zn on seed germination and seedling growth of two lettuce cultivars (Lactuca sativa L.)

In this study, the effect of different concentrations of Cd, Cr, Cu, Mn, Ni, Pb and Zn on seed germination and seedling growth at an early stage of two lettuce cultivars (one with green and the other with red leaves) was evaluated. The inhibitory effects of these metals on germination rate, viable seedlings, shoot and root biomass, root length, seedling vigor and root tolerance index was determined. Globally, a decrease was observed in these variables with increasing concentrations of the metals. The present results indicate that seedling growth was more sensitive than germination. Lactuca sativa seeds were usually tolerant for all metals during the germination process and this probably occurred due to barrier effect of seed coat that prevented the metals to come in contact with the developing embryo. The inhibitory effects of these metals on seedling growth varied. In general, the presence of low Ni and Cr concentrations stimulated the growth of green leaf lettuce seedlings. Low concentrations of Zn promoted the growth of red-leaf lettuce which is less tolerant to Cd. In this study it was verified that Lactuca sativa seedlings can survive in contaminated media, however, it was more sensitive to Cd and Cu and tolerant to Mn.info:eu-repo/semantics/acceptedVersio

Physiological responses of Lupinus luteus to different copper concentrations

Yellow lupin (Lupinus luteus L.) plants were grown in hydroponic solution for 15 d under different copper concentrations (0.1, 0.5, 1.0, 10, 25 and 50 μM). With increasing Cu concentration total biomass was not affected, leaf area slightly decreased, while chlorophyll content decreased considerably. Cu content increased significantly both in roots and in leaves, but the contents of other ions were only slightly affected at the highest Cu concentration (Mn content decreased both in roots and in leaves, P content decreased only in leaves and Zn content increased in roots). Superoxide dismutase (SOD) activity increased up to day 7 after copper application. Peroxidase (GPOD) and polyphenol oxidase (PPO) activities also increased, while catalase (CAT) activity remained constan

Influence of enzymes and technology on virgin olive oil composition

This work aims at presenting the state-of-the-art about the influence of the activity of olive endogenous enzymes, as well as of the application of adjuvants in olive oil technology, discussing their influence on the composition of virgin olive oil, especially in phenols and volatile compoundsinfo:eu-repo/semantics/publishedVersio

Comparison between a traditional (horse manure) and a non-conventional (cork powder) organic residue in the uptake of potentially toxic elements by lettuce in contaminated soils

The use of natural organic correctives is a current agricultural practice that may have advantages for the production of plants in contaminated soils. Cork powder is a natural sub-product of the cork industry that has several potential benefits compared to more commonly used soil amendments. In this work, an evaluation was performed of the use of cork powder (a non-conventional organic residue) and horsemanure (traditionally used in agriculture) to control the availability of potentially toxic elements in artificially contaminated soils. Four concentrations were used for each element: Cr (100 to 800 mg kg-1), Ni (37.5 to 300mg kg-1), Zn (150 to 1200mg kg-1), Cd (1.5 to 12mg kg-1) and Pb (150 to 1200mg kg-1). The accumulation of these elements in lettuce plants grown in pots under controlled conditions was evaluated. With the exception of Cd, no significant differences were detected in the absorption of the different elements by lettuce plants at the studied amounts of correctives applied (1% for cork powder and 0.5% for horse manure). Cadmium was the element that accumulated most in lettuce. Cork powder was shown to be less effective than horse manure in controlling the bioavailability of these elements in the soil. Further tests with chemically modified cork products could improve its efficiencyinfo:eu-repo/semantics/publishedVersio

The effect of calcium dips combined with mild heating of whole kiwifruit for fruit slices quality maintenance

The effect of moderate heat treatment combined with calcium dips on the quality of minimally processed kiwifruit was studied. Whole fruits were treated for 25 min at 45 C by dipping in deionised water or CaCl2 solutions (1%, 2% and 3% (w/v)) and cooled to 4 C. Twenty-four hours later fruits were peeled, sanitized, cut into slices and packed. The firmness of kiwifruit slices’ was subsequently evaluated during 8 days of storage. Calcium content, pectinmethylesterase activity and heat shock proteins accumulation were also investigated. Heat treatment conducted in water induced a firming effect and avoid softening of fruit slices while calcium dips had a marginal effect on this parameter. A calcium loss was observed due to dip treatment, but this effect was minimized when treatment was conducted in 3% CaCl2 solution. The firming effect provided is due to the activation of pectinmethylesterase and the presence of calcium in treatment solution reduces or inhibits enzyme activation. Under the tested conditions, no heat shock proteins de novo synthesis was detecte

Co-processed olive oils with Thymus mastichina L. - New product optimization

Olive co-processing consists of the addition of ingredients either in the mill or in the malaxator. This technique allows selecting the type of olives, the ingredients with the greatest flavoring and bioactive potential, and the technological extraction conditions. A new product—a gourmet flavored oil—was developed by co-processing olives with Thymus mastichina L. The trials were performed using overripe fruits with low aroma potential (cv. ‘Galega Vulgar’; ripening index 6.4). Experimental conditions were dictated by a central composite rotatable design (CCRD) as a function of thyme (0.4-4.6%, w/w) and water (8.3-19.7%, w/w) contents used in malaxation. A flavored oil was also obtained by adding 2.5% thyme during milling, followed by 14% water addition in the malaxator (central point conditions of CCRD). The chemical characterization of the raw materials, as well as the analysis of the flavored and unflavored oils, were performed (chemical quality criteria, sensory analysis, major fatty acid composition, and phenolic compounds). Considering chemical quality criteria, the flavored oils have the characteristics of “Virgin Olive Oil” (VOO), but they cannot have this classification due to legislation issues. Flavored oils obtained under optimized co-processing conditions (thyme concentrations > 3.5-4.0% and water contents varying from 14 to 18%) presented higher phenolic contents and biologic value than the non-flavored VOO. In flavored oils, thyme flavor was detected with high intensity, while the defect of “wet wood”, perceived in VOO, was not detected. The flavored oil, obtained by T. mastichina addition in the mill, showed higher oxidative stability (19.03 h) than the VOO and the co-processed oil with thyme addition in the malaxator (14.07 h), even after six-month storage in the dark (16.6 vs. 10.3 h)info:eu-repo/semantics/publishedVersio

Optimization of olive oil extraction of Cobrançosa olives by means of processing aids

Modelling and optimization of the operation conditions of olive oil extraction were performed, using surface response methodology, following a central rotation composite matrix, as a function of the contents of enzymes (Endozym Olea AS; 0.04- 0.24%) and natural microtalc (FC8-AW; 0.12-0.68%) added at the beginning of the thermobeating step. Yield was evaluated by the extractability index and by the residual pomace fat content. The obtained results showed that the extraction yield depends on the amount of talc used but does not depend on the amount of enzyme added, within the tested range. Also, the presence of these processing aids did not affect either quality parameters or the content of green pigments in the obtained olive oils

Characterization of aroma compounds in Portuguese extra virgin olive oils from Galega vulgar and Cobrançosa cultivars using GC-O and GC-x-GC-ToFMS

Aroma compounds of virgin olive oils extracted from two olive cultivars – Galega Vulgar and Cobrançosa – grown in Beira Baixa region in central Portugalwere investigated. Gas chromatography–olfactometry (GC–O) was carried out to select the important odorants for subsequent comprehensive gas chromatography/time of flightmass spectrometry (GC × GC–ToFMS) analysis. By GC–O fifteen odorants were identified. For the quantification of volatile compounds, headspace solid phasemicroextraction (SPME) techniquewas optimized. Under optimized conditions, 22 volatile compounds were quantified in all samples. Trans-2-hexenal was the most abundant compound. A discriminant analysis (DA) was used to discriminate among olive oil samples obtained from olives of the two cultivars with different harvest time/ripening stages. Concerning the harvesting time and cultivar, nine volatiles showed to have discriminant power among samples, namely heptanal, trans-2-hexenal, 1-octen-1-ol, nonanal, 2,3-butanedione, ethyl-2-methylbutyrate, hexanal, cis-3-hexenylacetate and 3-methylbuthylacetat