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BahceçI, K.S. & Acar, J. (2007): Determination of guaiacol produced by Alicyclobacillus acidoterrestris in apple juice by using HPLC and spectrophotometric methods, and mathematical modeling of

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Kubis, J. (2003) Polyamines and “scavenging system”: Influence of exogenous spermidine on catalase and guaiacol peroxidase activities, and free polyamine level in Barley leaves under water deficit. Acta Physiol. Plant. 25, 337

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Hydrogen sulfide (H2S) has been recently found to be a gaseous signaling molecule in plants. In this work, we studied the role of H2S in alleviating salinity stress during wheat grain germination (Triticum aestivum L. Yangmai 158). Pretreatment with NaHS, a H2S donor, during wheat grain imbibition, could significantly attenuate the inhibitory effect of salinity stress on wheat germination. NaHS-pretreated grain showed higher amylase and esterase activities than water control. NaHS pretreatment differentially stimulated the activities of catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX), decreased the level of malondialdehyde (MDA) and reduced NaCl-induced changes in plasma membrane integrity in the radicle tips of seedlings compared with water control. We conclude that H2S plays an important role in protecting wheat grain from oxidative damage induced by salinity stress.

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The association between terrestrial plants and arbuscular mycorrhizal (AM) fungi is one of the most common and widespread mutualistic plant-fungi interaction. AM fungi are of beneficial effects on the water and nutrient uptake of plants and increase plant defense mechanisms to alleviate different stresses. The aim of this study was to determine the level of polyphenol oxidase (PPO), guaiacol peroxidase (POX) and glutathione S-transferase (GST) enzyme activities and to track the expression of glutathione S-transferase (GST) gene in plant-arbuscular mycorrhizal system under temperature- and mechanical stress conditions. Our results suggest that induced tolerance of mycorrhizal sunflower to high temperature may be attributed to the induction of GST, POX and PPO enzyme activities as well as to the elevated expression of GST. However, the degree of tolerance of the plant is significantly influenced by the age which is probably justified by the energy considerations.

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We studied oxidative stress and peroxidase activity resulting from application of excess copper in the nutrient medium on the roots of young bean seedlings. The change in H 2 O 2 content, lipid peroxidation and antioxidant enzymes activities were quantified and located. Excess of copper caused a loss of membrane integrity and the formation of hydrogen peroxide (H 2 O 2 ) as visualized in the transmission electron microscopy and measured using spectrophotometry. H 2 O 2 accumulated in the intercellular spaces and in the cell wall. The production of H 2 O 2 was accompanied by an increase in the activity of soluble and ionic GPX (guaiacol peroxidase, EC 1.11.17), CAPX (coniferyl alcohol peroxidase) and NADH oxidase.

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The effect of copper excess on growth, H 2 O 2 level and peroxidase activities were studied in maize shoots. Ten-day-old seedlings were cultured in nutrient solution that contained Cu 2+ ions at various concentrations (50 and 100 μM) for seven days. High concentrations of Cu 2+ ions caused significant decrease both in matter production and elongation of maize shoots. In addition, treatment with CuSO 4 increased levels of H 2 O 2 and induced changes in several peroxidase activities. Moreover, the disturbance of the physiological parameters was accompanied by the modulation of the peroxidase activities: GPX (Guaiacol peroxidase, EC 1.11.1.7), CAPX (Coniferyl alcohol peroxidase, EC 1.11.1.4) and APX (Ascorbate peroxidase, EC.1.11.1.11). Furthermore, this modulation becomes highly significant, especially, in the presence of 100 μM of CuSO 4 .

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Six wheat cultivars, namely PBW 343, PBW 550 (stress susceptible), PBW 621, PBW 175 (drought tolerant), C 306 and HD 2967 (heat tolerant), were used in this study to evaluate the effect of heat and drought stress on the activities of peroxidases (POXs), diamine oxidase (DAO), polyamine oxidase (PAO) and arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) in relation to contents of polyamines (PAs), lipid peroxide and lignin. High temperature (HT) elevated activities of syringaldazine peroxidase (SPX), guaiacol peroxidase (GPX) and coniferyl alcohol peroxidase (CPX) in heat tolerant cultivars while, drought stress accentuated ADC/ODC activities in drought tolerant cultivars. Both heat and drought stress enhanced activities of DAO and PAO alongwith contents of H2O2 in PBW 175 and C 306. Amongst studied POXs, SPX activity was relatively more and coincided well with lignin content under HT stress while, the levels of ADC/ODC paralleled with putrescine and spermidine contents under drought stress. Higher build up of thiobarbituric acid reactive substances in cultivars PBW 343 and PBW 550 indicated their membrane instability during both the stresses. Our results revealed that SPX mediated lignification leading to higher cell wall rigidity under heat stress and drought increased PAs involved in ROS scavenging due to presence of positive charges which can bind strongly to the negative charges in cellular components such as proteins and phospholipids and thereby stabilize the membranes under stress conditions.

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Acta Biologica Hungarica
Authors:
Fedia Rebah
,
Chayma Ouhibi
,
K. H. Alamer
,
Najoua Msilini
,
Mouhiba Ben Nasri
,
Rebecca Stevens
, and
Houneida Attia

We aimed to examine the response of three tomato introgression lines (IL925.3, IL925.5 and IL925.6) to NaCl stress. These lines originated from a cross between M82 (Solanum lycopersicum) and the wild salttolerant tomato Solanum pennellii, each line containing a different fragment of the S.pennellii genome. Salt-sensitive phenotypes related to plant growth and physiology, and the response of antioxidants, pigments and antioxidant enzymes were measured. In general, salt stress decreased the fresh weight of leaves, leaf area and leaf number and an increase of Na+ accumulation in aerial parts was observed, which caused a reduction in the absorption of K+ and Ca2+. Salt stress also induced a decrease in chlorophyll, carotenoids and lipid peroxidation (MDA) and an increase in anthocyanins and reduced ascorbate, although some differences were seen between the lines, for example for carotenoid levels. Guaiacol peroxidase, catalase and glutathione reductase activity enhanced in aerial parts of the lines, but again some differences were seen between the three lines. It is concluded that IL925.5 might be the most sensitive line to salt stress as its dry weight loss was the greatest in response to salt and this line showed the highest Na+ ion accumulation in leaves.

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In wheat, Fusarium fungus promotes the appearance of destructive disease named as Fusarium head blight (FHB) that can cause grain yield reduction and mycotoxin accumulation. The focus of this research was to verify the influence of Fusarium graminearum and F. culmorum on wheat genotypes with different susceptibility to FHB: “Super Žitarka” (susceptible), “Lucija” (moderately resistant) and “Apache” (resistant). The experiment was performed under field conditions by artificial spore inoculation of ears at the flowering stage. The effectiveness of antioxidative enzymes, hydrogen peroxide (H2O2) content and malondialdehyde (MDA) content were observed at several sampling points after Fusarium inoculation (3, 15 and 24 hours). “Lucija” responded to pathogen by increase of guaiacol peroxidase (POD) activity, high H2O2 and MDA content in the early post-inoculation times (3 and 15 hours), compared to control. “Super Žitarka” displayed inhibition of catalase (CAT) activity throughout the whole time course of the experiment. Infected plants of “Apache” showed notable decline in MDA content over time. Moreover, in “Apache” increased H2O2 accumulation was observed immediately after Fusarium exposure (3 and 15 hours), compared to 24 hours. Rapid overproduction of H2O2 under Fusarium stress marked “Apache” as FHB-resistant.

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In order to determine the toxic effect of chromium Cr(VI) on the seed germination, the root and shoot length, the root-cotyledonary leaves, the fresh and dry weight in eight-day-old seedlings Brassica oleracea L. var. acephala DC (kale) were treated with various concentrations of Cr in the growth medium. The accumulation of chromium in the tissues was determined in the cotyledons and the roots of the kale seedlings. High rate of Cr uptake was observed in the roots. But the organs could not accumulate large amount Cr. The effect of Cr on B. oleracea var. acephala was evaluated by changes in chlorophyll a, b, lipid peroxidation, proline, ascorbate, protein carbonyl groups, non-protein thiols and peroxidase activity. There were significant decreases in chlorophylls a, b content of the plants treated with Cr. Chromium treated kale seedlings had higher lipid peroxidation and the protein carbonyl groups in cotyledonary leaves than the roots. The changes refer to toxic effects of Cr. There were increases in the non-protein thiol, the total ascorbate, and proline content in the cotyledons and the roots of the seedlings grown on the media containing 0.1 and 0.15 mM Cr. The guaiacol peroxidase activity was higher in the roots of the seedlings than their cotyledons.

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