R. Izzo

Growth and mineral absorption in maize seedlings as affected by increasing NaCl concentrations

Abstract The influence of NaCl solutions of decreasing osmotic potentials (¥π = ‐0.44 and ‐0.88 MPa) on seedling growth and on the concentration of the most important macro‐ and micro‐nutrients in the shoots and roots of maize (Zea mays L., cv. Summer II) grown in Hoaglands solution in a growth chamber was studied. Salt stress was imposed on six‐day‐old seedlings for a three day period. Increasing NaCl concentrations induced a reduction in the leaf water potential and a significant decrease in the length and dry weight of the shoots, whereas these two parameters decreased in the roots only at the lowest osmotic potential. Although the absorption and accumulation of nutrients upon salt stress differed in the two treatments depending on the plant tissue and nutrient, almost all of the macronutrients decreased in the roots and shoots, showing the lowest values at ¥π = ‐0.88 MPa. Sodium and Cl increased continuously, much more in the roots than in the shoots. A different response was seen in the shoots and r...

Relation between lipoic acid and cell redox status in wheat grown in excess copper

Cell redox status and lipoic acid contents were analysed in wheat (Triticum durum Desf. cv. Creso) plants treated with 150 μM Cu to elucidate the role of the antioxidant lipoic acid against oxidative stress. In comparison with shoots, roots suffered a higher oxidative stress showing a decrease in NADPH contents and an oxidation of glutathione and ascorbate. Shoots did not evidence a clear oxidative damage since Cu was translocated in small amounts. Lipoic acid as reduced (DHLA) or oxidised (LA) form was present in both leaves and roots of wheat. Analysis of the cell sap showed that this antioxidant was present also as free form. The analyses showed that stroma contained significant amounts of free LA and that, after acidic hydrolysis, higher amounts of LA and DHLA were released. However, lipoic acid was undetectable in both thylakoids and microsomal membranes. Cu treatment did not determine changes in the contents of total LA and DHLA in roots, they being likely involved in Cu chelation. In contrast, in leaves after 48 h of treatment the metal induced an increase in DHLA, which could in part explain the reduction in the oxidised glutathione levels. In leaves free lipoic acid was more prone to be oxidised compared to the bound form, and the reduced form disappeared in both leaves and roots after Cu treatment.

Antioxidative responses of Ocimum basilicum to sodium chloride or sodium sulphate salinization.

Soils and ground water in nature are dominated by chloride and sulphate salts. There have been several studies concerning NaCl salinity, however, little is known about the Na(2)SO(4) one. The effects on antioxidative activities of chloride or sodium sulphate in terms of the same Na(+) equivalents (25 mM Na(2)SO(4) and 50 mM NaCl) were studied on 30 day-old plants of Ocimum basilicum L., variety Genovese subjected to 15 and 30 days of treatment. Growth, thiobarbituric acid reactive substances (TBARS), relative ion leakage ratio (RLR), hydrogen peroxide (H(2)O(2)), ascorbate and glutathione contents as well as the activities of ascorbate peroxidase (APX, EC 1.11.1.11); glutathione reductase (GR, EC 1.6.4.2) and peroxidases (POD, EC 1.11.1.7) were determined. In leaves, growth was more depressed by 25 mM Na(2)SO(4) than 50 mM NaCl. The higher sensitivity of basil to Na(2)SO(4) was associated with an enhanced accumulation of H(2)O(2), an inhibition of APX, GR and POD activities (with the exception of POD under the 30-day-treatment) and a lower regeneration of reduced ascorbate (AsA) and reduced glutathione (GSH). However, the changes in the antioxidant metabolism were enough to limit oxidative damage, explaining the fact that RLR and TBARS levels were unchanged under both Na(2)SO(4) and NaCl treatment. Moreover, for both salts the 30-day-treatment reduced H(2)O(2) accumulation, unchanged RLR and TBARS levels, and enhanced the levels of antioxidants and antioxidative enzymes, thus achieving an adaptation mechanism against reactive oxygen species.

Irrigation with Diluted Seawater Improves the Nutritional Value of Cherry Tomatoes

The aim of this study was to assess whether the nutritional value of cherry tomato can be improved by irrigating plants with diluted seawater (12%; EC = 10 mS/cm in comparison with a control at EC = 4 mS/cm). Berries of cherry tomato cv. Naomi were analyzed at the red-ripe stage for the contents of NADPH and NADP+ as well as for the amounts of the main antioxidants, such as ascorbic acid, lipoic acid, tocopherols, and phenolic acids. As compared to the controls, the fruits of salt-treated plants showed a higher titratable acidity and a higher concentration of reducing sugars. The fruits picked from tomato plants irrigated with diluted seawater produced berries characterized by a higher nutritional value. Following salinity, berries showed higher amounts of vitamin C, vitamin E, dihydrolipoic acid, and chlorogenic acid. It was hypothesized that protocatechuic, vanillic, caffeic, and ferulic acids were utilized to counteract the damaging effects of salinity-induced oxidative stress, allowing tomato fruits to maintain a high reduced status even following salinization.

NaCl Effects on Water Relations and Accumulation of Mineral Nutrients in Shoots, Roots and Cell Sap of Wheat Seedlings

Summary Two cvs. of Triticum durum Desf. differently sensitive to drought and to heavy metal excess (cv. Ofanto more tolerant than cv. Adamello) were exposed to 0, 50 and 100 mmol/L NaCl nutrient solutions for 9 days in a controlled environment. To investigate the effect of NaCl and to monitor possible differences in the responses of the two cvs., we determined growth parameters, leaf water relations and mineral nutrient accumulation in cell saps of the seedlings. The highest salt concentration reduced shoot growth, particularly in cv. Adamello, and shoot and root biomass production. In both cvs., water potential (Ψ W ) and osmotic potential (Ψ π ) decreased with salinity and the osmotic adjustment that occurred, due to an accumulation of Na, Cl and also K in the cell sap, maintained turgor. NaCl determined an alteration of nutrient uptake, due to an accumulation of Na + and Cl - both in shoots and roots. In particular, cv. Adamello showed higher decreases in the Ca ++ of roots and the K + of shoots and a higher increase in the Na + of shoots. Even though both cvs. seem to be able to react to the stress, the results suggest a greater sensitivity of cv. Adamello to NaCl.

Effects of water stress and salinity on sterols in Zea mays shoots

Abstract Seven-day-old seedlings of maize ( Zea mays cv. Summer II) were subjected to water and salinity stress with polyethylene glycol ( M r 4000) and sodium chloride to achieve final concentrations of 13 and 17% PEG and 0.8 and 0.16 F sodium chloride , respectively. The water potential values of stressing solutions were −0.4 and −0.8 MPa. The leaf water potential and stomatal response, as well as the dry weight and height of shoots, were compared at the two levels of stress. Leakage of ionic solutes and potassium efflux were used to assess membrane integrity. Qualitative and quantitative changes in free and total sterols were investigated. Sitosterol and stigmasterol, followed by campesterol and a small amount of cholesterol, were the major sterols present in the control and in the treated shoots. After 72 hr of stress imposition there was a reduction in free and total sterols in both treated shoots as compared with the control. In spite of the stress-induced decrease in the sterol content, the sitosterol to stigmasterol ratio and the cholesterol plus campesterol to stigmasterol plus sitosterol ratio did not show any significant difference, suggesting the relative abilities of shoots to regulate membrane permeability by maintaining their ‘more planar’ to ‘less planar’ sterol ratio.

Effects of dietary restriction on age-related changes in the phospholipid fatty acid composition of various rat tissues

Background and aims: Polyunsaturated fatty acids (PUFAs) are essential components of the cell lipid bilayer and are involved in membrane fluidify and normal functioning, but they are vulnerable to free radical attack. Given the role of oxidative stress in the aging process, age-related changes in phospholipid fatty acid (PLFA) composition in rat liver, kidney and heart were assessed in 3-, 12- and 24-month-old rats fed either ad libitum but only every other day, or daily but only 60% of the quantity normally consumed by age-matched controls. Methods: Lipids were extracted and phospholipids (PLs) were separated using the solid phase extraction technique, then transesterified and assayed by gas-liquid chromatography. Results: Saturated fatty acids (FAs) did not change significantly with age; mono- and bi-unsaturated FAs decreased in the liver and heart, and the ratio of the former to the latter increased in the liver, kidney and heart. PUFAs increased in the liver and heart. As regards individual FAs, 20:1(n-9) decreased in all organs, 14:1 and 18:1(n-7) increased in the kidney and heart, 18:1(n-9) increased in the kidney, 20:2(n-6), 18:2(n-6) and 22:5(n-3) decreased in the liver and heart, 20:3(n-6) decreased in the kidney and increased in the heart. The most abundant PUFAs, 20:4(n-6) and 22:6(n-3), either remained the same or increased with age. The N-9 family increased in the kidney, the N-7 family increased in the kidney and heart, the N-6 family decreased in all three organs, and the N-3 family increased in the liver and kidney. Dietary restriction (DR) significantly counteracted most of these changes, but changes in some FAs [20:2(n-6) in the heart] were magnified by DR and may not be age-related. Conclusions: Most age-related changes (that occurred in the rat liver, kidney and heart and were counteracted by the two different types of DR) may be involved in the mechanism of aging.

Lipid evolution during development and ripening of peach fruits

Changes in the phospholipid, glycolipid, diacyl and triacylglycerol, free fatty acid and free sterol classes were examined during the development and ripening of Prunus persica cv. Redhaven peach fruit. Total lipid and lipid class contents decreased until 100 days after full bloom (AFB). While phospholipids and glycolipids decreased in the following stages, diacyl- and triacylglycerols increased. The analysis of each lipid class showed that the predominant fatty acids were 16:0 and 18:2. The double bond index showed, in each class, a general increase during maturation. The free sterol content continuously declined during maturation with the exception of samples at 100 days AFB, which showed an increase in the free sterol to phospholipid molar ratio. The main changes observed in lipids occurred mostly between the climacteric and postclimacteric stages.

Induction of enzyme activities and antioxidant production in barley plants as a result of SO2 fumigation

Abstract Two cultivars (Arda and Plaisant) of barley (Hordeum vulgare) were exposed continuously to fumigation with low concentrations of SO2 (115, 220 and 350 μg/m3) for 34 days. The increase observed in the activities of catalase (EC 1.11.1.6.), superoxide dismutase (EC 1.15.1.1.), glutathione synthetase (EC6.3.2.3.), glutathione reductase (EC 1.6.4.2.), glutathione peroxidase (EC 1.11.1.9.) and glutathione transferase (EC 2.5.1.18.) following fumigation were higher in Arda than in Plaisant. The ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) increased significantly in Plaisant, and even more so in Arda. The antioxidant levels in lipid extracts were higher than in the control only after exposure to SO2 at the lowest concentration, while at higher concentrations no significant changes were observed. As to free radicals, only after fumigation with the highest levels of SO2 a 5% increase in free organic radicals was found in Plaisant, compared to the non-treated control. In previous studies it had been shown that Arda is more resistant to drought than Plaisant. Our data show that also in response to low SO2 concentrations Arda has a higher potential to activate anti-oxidative stress defences. These results suggest that the phenotype that proved to be more resistant to drought may have a higher ability than the sensitive one to activate antioxidative defences when exposed to SO2 at low concentrations.

Alternative Irrigation Waters: Uptake of Mineral Nutrients by Wheat Plants Responding to Sea Water Application

Abstract The growth and the uptake of mineral nutrients were investigated in seedlings of wheat cv. Ofanto grown in Hoaglands no. 2 solution, added with increasing sea water concentrations (0% for control, 10 and 20% for treatments). It was pointed out an increase of fresh and dry matter of wheat treated for 14 days with 10% sea water compared to the control, while a reduction was observed in wheat treated for 21 days and for the treatment with 20% sea water solution. Moreover, the sea water application reduced the elongation, affecting more shoots than roots. Under sea water irrigation uptake and translocation of mineral nutrients changed drastically. In particular, with growing a decrease of Cl− in shoots and an increase in roots were noted in both the treatments. The high presence of Mg++ in sea water affected considerably the plant nutritional requirement, influencing the uptake of Ca++, which was restricted for competition, and the accumulation of P and Mn, which were instead enhanced. The general trend for micronutrient acquisition was an increase in both shoots and roots, except for the iron content, which decreased at the highest level of sea water. All the results obtained suggest the possibility of using sea water for alternative irrigation, adopting adequate dilutions for tolerant plants. This prospect could therefore have a fundamental role in the economy of natural basins in numerous Mediterranean regions, where the dry weather problem has a particular importance.