Peroxidase Activity In Roots Research Articles

Root exudates of wheat are involved in suppression of Fusarium wilt in watermelon in watermelon-wheat companion cropping

Fusarium wilt disease in watermelon is widespread and responsible for serious economic losses. Petri dish experiments were performed to assess the effect of root exudates of 10 wheat varieties on mycelium growth of Fusarium oxysporum f. sp. niveum (Fon). The results showed that D123 wheat root exudates significantly inhibited mycelial growth of Fon. Pot experiments were performed to investigate the responses of Fusarium wilt in watermelon to companion cropping with D123 wheat. The results showed that watermelon seedlings suffered less Fusarium wilt in a companion system as compared to a monoculture system. Compared with monoculture, companion cropping with D123 wheat decreased malondialdehyde content and guaiacol peroxidase activities in watermelon roots after inoculation with Fon, and companion cropping with D123 wheat increased the polyphenol oxidase activities before Fon inoculation and 15 days after Fon inoculation. Companion cropping with D123 wheat slightly increased β-1, 3-glucanase and chitinase activities in watermelon roots compared with monoculture. Companion cropping with D123 wheat decreased phenylalanine ammonia-lyase activities in watermelon roots at 5 days after Fon inoculation and increased phenylalanine ammonia-lyase activity at 15 days after Fon inoculation compared with monoculture. The jasmonic acid and shikimate–phenylpropanoid–lignin biosynthetic genes were induced during the early stage of Fon infection in companion cropping compared to monoculture. It is suggested that companion cropping with D123 wheat alleviated Fusarium wilt in watermelon by inhibiting the mycelial growth of Fon and by inducing physiological changes and gene expression to protect the watermelon from injury.

Upregulation of antioxidant enzymes by exogenous gallic acid contributes to the amelioration in Oryza sativa roots exposed to salt and osmotic stress.

The aim of this study is to elucidate the influence of the exogenous application of gallic acid (GLA) in alleviating the detrimental effects of salinity (NaCl), osmotic stress (polyethylene glycol; PEG), and their combination in Oryza sativa L. roots. To produce same osmotic potential (-0.5 MPa), 3-week-old rice seedlings were treated with 120 mM NaCl and/or 20 % PEG6000 with/without GLA (0.75 and 1.5 mM) treatments for 72 h. Both alone and combination of stresses decreased growth (RGR) and osmotic potential (Ψ Π). Moreover, stress caused a significant increase in proline (Pro) and hydrogen peroxide (H2O2) contents. Also, Pokkali and IR-28 had higher H2O2-scavenging enzyme activities including catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities in NaCl-treated roots. Only CAT activity was induced in both cultivars with PEG. Therefore, the enhanced levels of lipid peroxidation (thiobarbituric acid reactive substances (TBARS)) were more pronounced under PEG than NaCl. However, GLA significantly mitigated NaCl and/or PEG-induced stress injury. Under salinity, TBARS was lesser in GLA-applied rice that was associated with greater activities of superoxide dismutase (SOD), peroxidase (POX), and APX. GLA in the presence of PEG improved the activities of CAT and POX. According to these findings, GLA alleviated the damaging effects of NaCl and/or PEG (especially under NaCl) by improving the antioxidative system in rice. This is the first study elucidating the effects of GLA on tolerance to salinity, osmotic stress, and their combination in plants.

Pengimbasan Ketahanan Tanaman Pisang Terhadap Penyakit Darah (Ralstonia solanacearum Phylotipe IV) MengGunakan Bakteri Endofit

Induced resistance of banana against blood disease (Ralstonia solanacearum Phylotipe IV) using endophytic bacteria. Endophytic bacteria play a role to control plant pathogenic bacteria indirectly by inducing the plant to increase production of the metabolites in activating the plant resistance. This study aimed to determine the ability of endophytic bacteria to induce resistance in banana plants against blood disease. Indicators of induced resistance of banana plant were analyzed through the existence of defense enzyme activities (peroxidase and polyphenol oxidase) and the amount of salicylic acid on banana roots. The results showed that endophytic bacteria isolates EAL15, EKK10, EKK20 and EKK22 suppressed the incidence of blood disease in Cavendish banana by 70-85%. Increased activity of peroxidase and polyphenol oxidase in roots of banana plants were higher in plants treated with endophytic bacteria compared to untreated plants. Salicylic acid content in banana plants treated with isolates EAL15, EKK10 and EKK20 was higher than that of EKK22 isolates and control plants.

EFFECT OF METABOLIC PRODUCTS OF STREPTOMYCES RECIFENSIS VAR. LYTICUS ON THE VEGETABLES SPROUTS GROWTH

Purpose. To study the effect of the preparation P3X of strain Streptomyces recifensis var. lyticus 2435 and supernatant cultural liquid (SCL) of strain Streptomyces recifensis var. lyticus 2R -15 on the vegetables sprouts growth and compare with the action of plant growth regulators emistym and heteroauxin. Methods. Biometric and biochemical changes of sprouts of squashes, cucumbers, tomatoes, radishes for the actions of microbial preparations and plant growth regulators were investigated. Changing of germination energy of seeds, roots length, proteinase, peroxidase, poliphenoloxidase activity was studied. Results. It was shown that the action of SCL and P3X was the most effective for accelerate the growth of sprouts of squashes, cucumbers, tomatoes, radishes. These preparations stimulated germination energy and length of roots on 8–30% and 5–20%. Emistym stimulated only the length of roots on 10–40% and did not affect positively to germination energy of seeds. It was found that heteroauxin inhibited biometric indicators on 12–50%. Stimulation of proteinase activity of seeds was effectively carried by emistim (stimulation in 1.5–5.0 times) and SCL (1.3–2.9 times); peroxidase activity of roots – emistim (1.3–3.5 times) and SCL (1.4–3.0 times); polyphenoloxidase activity of leaves – SCL (1.3–4.0 times) and emistym (1.2–3.8 times). Conclusions. Study of microbial preparations and plant growth regulators of sprouts of vegetables showed that positive change of biometric parameters and enzymatic activities that occur in sprouts is a response to the action of biotic factors and it depends on the a type of preparation and a type of vegetable. Stimulation of biometric and biochemical parameters which was observed for the sprouts after action of preparations SCL, P3X and emistym may be used to accelerate growth of plants.

Growth, Yield, and Metabolic Responses of Temperature-stressed Tomato to Grafting onto Rootstocks Differing in Cold Tolerance

Tomato (Solanum lycopersicum cv. Kommeet) plants were either self-grafted, grafted onto the cold-sensitive cultivar Moneymaker or onto LA 1777, a cold-tolerant accession of Solanum habrochaites. Plants were grown at three different temperatures (T): optimal (19.4 °C), intermediate (17 °C), or low (14.6 °C). Grafting tomato ‘Kommeet’ onto LA 1777 increased shoot growth at intermediate and optimal T and root growth at low or intermediate T in comparison with self-grafting or grafting onto ‘Moneymaker’. Reducing T significantly suppressed fruit yield as a result of reduced fruit number per plant without any interaction with grafting treatments. Grafting ‘Kommeet’ onto LA 1777 remarkably restricted fresh and dry fruit mass in comparison with self-grafting of ‘Kommeet’ as a result of a reduction in the fruit number per plant while not influencing flower number per plant and mean fruit mass, regardless of T regime. Negative effect of LA 1777 on fruit setting points to impairment of pollen fertility indicating signals originating from the root. At low and intermediate T, plants grafted onto LA 1777 were capable of increasing soluble carbohydrates, total amino acids, and guaiacol peroxidase activity in roots to higher levels than those grafted onto S. lycopersicum rootstocks while maintaining a significantly lower malondialdehyde content. These differences point to a much weaker oxidative stress in roots of plants grafted onto S. habrochaitis than those grafted onto S. lycopersicum rootstocks when exposed to low and intermediate T. Furthermore, plants grafted onto LA 1777 exhibited significantly higher levels of soluble carbohydrates, total amino acids, and guaiacol peroxidase activity in leaves and fruit and superoxide dismutase in fruit at low and intermediate T, which indicates that LA 1777 improved the level of antioxidant compounds in tomato shoots, thereby enhancing its adaptation to lower T than optimal.

Evaluating the plant growth promoting ability of thermotolerant bacteria and cyanobacteria and their interactions with seed spice crops

The potential of eight thermotolerant bacteria (seven Bacillus spp. and one actinobacterium Kocuria sp.) and two cyanobacteria (Anabaena laxa and Calothrix elenkinii) as plant growth promoting (PGP) agents was evaluated with seed spices – coriander, cumin and fennel, under controlled conditions in potting mix fortified with microbial cultures. Amendment with Anabaena brought about 25% enhanced germination in cumin over control, while Calothrix enhanced root/shoot length significantly in all the three crops, especially fennel. Fortification with microbes led to 30–50% increase in shoot/root length, which was reflected as two–three fold enhancement in the vigour index of the plants. Among the bacterial strains, T4 (Bacillus pumilus) was most promising in terms of PGP traits in fennel and cumin crop. Plant dry weight and peroxidase activity of shoots and roots were enhanced by 5–10-folds in all the microbe inoculated treatments, with highest values in Calothrix treated coriander seedlings. β-1,3 endoglucanase activity showed twofold enhancement in shoots from Anabaena inoculated coriander seedlings. The fungicidal activity of the root extracts from the bacteria treated treatments of coriander seedlings against Macrophomina phaseolina was highest, while root extracts of fennel seedlings were able to show largest zones of inhibition against Fusarium moniliforme. This study highlighted the promise of fortification with both heterotrophic and photosynthetic microbes in plant growth promotion, and their significant role in enhancing and eliciting peroxidase/endoglucanase enzyme and fungicidal activity of plant extracts of seed spices.

Effects of Low Temperature Stress on Resistance Indices of Sympodial Bamboo Seedlings

An indoor low temperature experiment was conducted to study the variations of membrane permeability, malondialdehyde, soluble protein and soluble sugar contents, superoxide dismutase (SOD) and peroxidase (POD) activities and membrane lipid fatty acid content in leaves and roots of sympodial bamboo seedlings (Dendrocalamus latiflorus)under different levels of cold stress. Results showed that after low temperature pretreatment (8 °C) for 15 days, the soluble protein, soluble sugar contents and POD activities in leaves as well as soluble sugar contents and POD activities in roots were increased obviously. After cold-hardening (-2 °C) for 72 h, the soluble protein, soluble sugar contents and SOD, POD activities in leaves and SOD, POD activities and ratio of membrane lipid unsaturated fatty acid in roots with pretreatment were obviously higher than those without pretreatment. Membrane permeability in leaves with pretreatment was obviously lower than that without pretreatment. But the level of membrane lipid peroxidation in leaves with pretreatment was significantly greater than that before cold-hardening. While the level of membrane permeability and lipid peroxidation in roots with pretreatment had no significant change after cold-hardening. Overall, leaves had higher soluble protein, soluble sugar contents and POD activities to avoid low temperature injuries while roots had higher SOD, POD activities and unsaturated fatty acid to avoid membrane lipid peroxidation and membrane injuries.

Early responses of Avicennia marina (Forsk.) Vierh. to intertidal elevation and light level

Combined effects of intertidal elevation and light level on two-month-old seedlings of Avicennia marina were studied at Zengying, Xiamen of China. Leaf number, area and thickness were promoted by decreasing elevation or elevating light level. Stem height differed little between light levels but was significantly stimulated by moderate waterlogging. Expansion of stem basal diameter was promoted by high light level but not affected by elevation. Total biomass showed highest at the middle elevation and was promoted by high light level. Seedlings in the gaps generally had higher root weight ratio (RWR) and stem weight ratio (SWR) but lower leaf weight ratio (LWR) than those under the canopy. Leaf pigment contents in the gaps were significantly stimulated by low elevations, while a reverse tendency occurred under the canopy. Both roots and leaves increased superoxide dismutase (SOD) and peroxidase (POD) activities to defend prolonged waterlogging. High light level resulted in high SOD and POD activities in roots but not in leaves. Malonaldehyde (MDA) contents changed little between light levels but were significantly promoted by prolonged waterlogging. These growth and physiological responses suggested that A. marina seedlings had strong tolerance to prolonged waterlogging but not to canopy shade.

Efeito de inibidores da peroxidase sobre a conservação de raízes de mandioca in natura

A alta perecibilidade da mandioca (Manihot esculenta, Crantz) in natura faz com que o consumo seja feito dentro de um período curto após a colheita. A principal causa de perda se deve à deterioração fisiológica, atribuída à atividade da enzima peroxidase (E.C.1.11.1.7). Este trabalho objetivou avaliar o efeito combinado de diferentes inibidores da peroxidase nas concentrações de 1, 5 e 10 mM em raízes da variedade Cacau Amarela. As raízes foram tratadas por uma hora em soluções com ácido ascórbico, bissulfito de sódio, sódio, Na2-EDTA, L-cisteína e SDS, e armazenadas a 25 °C por seis dias. A cada dois dias, foram realizadas análises visuais e retiradas amostras para posterior avaliação da peroxidase. Todos os tratamentos foram eficientes em aumentar a vida de prateleira das raízes de mandioca in natura em até quatro dias. O tratamento com ácido ascórbico e bissulfito de sódio a 10 mM e L-cisteína a 5 mM foram eficientes em aumentar a vida de prateleira em até seis dias. No segundo dia de armazenamento, houve redução na atividade da peroxidase em relação ao controle, em todas as concentrações dos inibidores aplicados.

Enzymatic and non-enzymatic antioxidant responses of alfalfa leaves and roots under different salinity levels

The effect of increasing NaCl concentrations on biomass, hydrogen peroxide (H2O2), ascorbic acid (ASC), proline and total thiol, and the activity of some antioxidant enzymes in alfalfa (Medicago sativa L. cv. Gara-Yonjeh) were investigated. The dry weights of roots and shoots with increasing NaCl concentrations decreased progressively, and the strongest toxicity was detected at NaCl treatment of 200 mM. Superoxide dismutase (SOD) activity in the leaves increased gradually up to NaCl concentrations of 100, while the higher concentration of NaCl reduced SOD activity in both leaves and roots. The maximum levels of ascorbate peroxidase (APX) activity were increased at 150 mM and 100 mM NaCl in leaves and roots of Gara-Yonjeh, respectively. Peroxidase (POD) activity in roots of Gara-Yonjeh increased (82% at 200 mM) by salinity, while it decreased (43% at 200 mM) in leaves. In contrast, catalase (CAT) activity increased (84% at 200 mM) in leaves, and decreased (57% at 200 mM) in the roots of Gara-Yonjeh. Electrophoresis analysis suggested that different patterns in SOD, CAT and POD isoenzymes depend on NaCl concentrations, and the staining intensities of these isoforms are supported the results obtained from the spectrophotometric determinations. In POD and CAT, activity of isoform III was detected at all concentrations, by a "low-high-low" pattern, with the maximum activity at 50 mM of NaCl. Results imply that the function of antioxidant systems in higher NaCl concentration is responsible for the salt tolerance observed in Gara-Yonjeh.

Arsenate (As V) in water: Quantitative sensitivity relationships among biomarker, ecotoxicity and genotoxicity endpoints

It is useful to test ecotoxicity and genotoxicity endpoints in the environmental impact assessment. Here, we compare and discuss ecotoxicity and genotoxicity effects in organisms in response to exposure to arsenate (As V) in solution. Eco(geno)toxicity responses in Aliivibrio fischeri, Lytechinus variegatus, Daphnia magna, Skeletonema costatum and Vicia faba were analyzed by assessing different endpoints: biomass growth, peroxidase activity, mitotic index, micronucleus frequency, and lethality in accordance with the international protocols. Quantitative sensitivity relationships (QSR) between these endpoints were established in order to rank endpoint sensitivity. The results for the QSR values based on the lowest observed effect concentration (LOEC) ratios varied from 2 (for ratio of root peroxidase activity to leaf peroxidase activity) to 2286 (for ratio of higher plant biomass growth to root peroxidase activity). The QSR values allowed the following sensitivity ranking to be established: higher plant enzymatic activity>daphnids≈echinoderms>bacteria≈algae>higher plant biomass growth. The LOEC values for the mitotic index and micronucleus frequency (LOEC=0.25mgAsL−1) were similar to the lowest LOEC values observed in aquatic organisms. This approach to the QSR of different endpoints could form the basis for monitoring and predicting early effects of pollutants before they give rise to significant changes in natural community structures.

Effect of Cadmium Stress on the Growth, Antioxidative Enzymes and Lipid Peroxidation in Two Kenaf (Hibiscus cannabinus L.) Plant Seedlings

The effects of cadmium stress on the growth, antioxidative enzymes and lipid peroxidation in two kenaf plants, Fuhong 991 and ZM412, were analysed under control (0.5-strength Hoagland's nutrient solution) or five levels of cadmium stress (0.5-strength Hoagland's nutrient solution containing different concentrations of Cd2+). The leaves and roots of control and cadmium-stressed plants were harvested after 3 wk. At the same Cd concentration, the Cd tolerance index of Fuhong 991 was higher than that of ZM412, indicating that Fuhong 991 may be more tolerant to Cd than ZM412. The superoxide dismutase (SOD), catalase activity (CAT) and peroxidase (POD) activities fluctuated in the leaves of the Cd-stressed plants compared to the control, whereas the glutathione reductase activity (GR) was much larger than the control for Fuhong 991, ensuring that sufficient quantities of GSH were available to respond to the cadmium stress. In comparison to the control, the dynamic tendency of the SOD, CAT and POD activities in roots of the Cd-stressed plants all increased and then declined, but the POD activity of Fuhong 991 remained nearly unchanged at all of the stress levels. The increase in the enzyme activities demonstrated that Fuhong 991 was more tolerant to cadmium than ZM 412. The lipid peroxidation was enhanced only in the leaves of Cd-stressed ZM 412. These findings indicated that antioxidative activities may play important roles in Cd-stressed Fuhong 991 and ZM 412 and that the leaf and root cell membranes of Fuhong 991 have a greater stability than those of ZM 412. For pollution monitoring purposes, the GR activity in the roots and leaves may serve as a biomarker of Cd for Fuhong 991, whereas lipid peroxidation may serve as biomarker for ZM 412.

Hydrogen peroxide pretreatment of roots enhanced oxidative stress response of tomato under cold stress

In the view of physiological role of H2O2, we investigated whether exogenous H2O2 application would affect short-term cold response of tomato and induce acclimation. Pretreatments were performed by immersing roots into 1 mM H2O2 solution for 1 h when transferring seedlings from seedling substrate to soil (acclimated group). Cold stress (3 °C for 16 h) caused significant reduction in relative water content (RWC) of control and non-acclimated (distilled water treated) groups when compared with unstressed plants. H2O2 promoted maintenance of relatively higher RWC under stress. Anthocyanin level in leaves of acclimated plants under cold stress was significantly higher than that of unstressed control and non-acclimated plants. Malondialdehyde (MDA) levels demonstrated low temperature induced oxidative damage to control and non-acclimated plants. MDA remained around unstressed conditions in acclimated plants, which demonstrate that H2O2 acclimation protected tissues against cold induced lipid peroxidation. H2O2 acclimation caused proline accumulation in roots under cold stress. Ascorbate peroxidase (APX) activity in roots of cold stressed and unstressed H2O2 acclimated plants increased when compared with control and non-acclimated plants, with highest increase in roots of acclimated plants under cold stress. CAT levels in roots of acclimated plants also increased, whereas levels remained unchanged in unstressed plants. Endogenous H2O2 levels significantly increased in roots of control and non-acclimated plants under cold stress. On the other hand, H2O2 content in roots of acclimated plants was significantly lower than control and non-acclimated plants under cold stress. The results presented here demonstrated that H2O2 significantly enhanced oxidative stress response by elevating the antioxidant status of tomato.

Involvement of Antioxidative Defense System in Rice Seedlings Exposed to Aluminum Toxicity and Phosphorus Deficiency

Plants growing in acid soils may suffer both phosphorus (P) deficiency and aluminum (Al) toxicity. Hydroponic experiments were undertaken to assess the single and combination effects of Al toxicity and low P stress on seedling growth, chlorophyll and proline contents, antioxidative response and lipid peroxidation of two rice genotypes (Yongyou 8 and Xiushui 132) differing in Al tolerance. Al toxicity and P deficiency both inhibited rice seedling growth. The development of toxic symptoms was characterized by reduced chlorophyll content, increased proline and malondialdehyde contents in both roots and leaves, and increased peroxidase and superoxide dismutase activities in roots, but decreased in leaves. The stress condition induced more severe growth inhibition and oxidative stress in Yongyou 8, and Xiushui 132 showed higher tolerance to both Al toxicity and P deficiency. P deficiency aggravated Al toxicity to plant growth and induced more severe lipid peroxidation.

Growth, proline accumulation and peroxidase activity in maize seedlings under osmotic stress

The influence of osmotic stress induced by polyethylene glycol (PEG) on plant growth, proline content and activities of soluble peroxidases was studied on 12 maize inbred lines at seedling stage. Reduction of plant growth, fresh weight and length of roots and shoots occurred in all of the studied genotypes and was followed by increase in free proline content of shoots and especially in roots of the majority of genotypes. Correlation analysis of changes in root proline content with growth parameters revealed direct positive correlation. Changes in root peroxidase activities ranged from approximately 40 % reduction to 20 % stimulation, depending on the genotype. It was shown that genotypes with higher proline changes under drought treatment exhibited lower peroxidase activities. In addition, genotypes with less pronounced root growth reduction under stress conditions exhibited increased peroxidase activities, as well as lower proline content. In the field experiments, grain yield was positively correlated with root proline content and negatively with root length changes in drought-treated seedlings grown in laboratory conditions.

Effect of Aluminium Toxicity on Growth Responses and Antioxidant Activities In Gmelina Arborea Roxb. Inoculated with am Fungi

Arbuscular mycorrhizal fungi alleviating the adverse Aluminium effects on growth and antioxidant activity was tested in Gmelina plants. Under greenhouse and aluminium stress condition, the mycorrhizal Gmelina plants showed good growth as compared to non mycorrhizal Gmelina plants. Mycorrhizal colonization in Gmelina was found not to be significantly influenced by aluminium concentrations. Results also indicate that symbiotic association was successfully established between Glomus intraradices and Gmelina plants and mycorrhizal colonization consequently increased the biomass of Gmelina. The root proline accumulation was found to increase in mycorrhizal Gmelina plants for osmotic adjustment of stress tissues under first and second level of Aluminium stress. It was observed that Mycorrhizal colonization increased the shoot root Peroxidase and Superoxide dismutase activities in mycorrhizal Gmelina under second level of Aluminium stress. Mycorrhizal fungi play a major role in phytostabilization by secreting one of the glycoprotein, i.e., Glomalin, which stabilizes the Aluminium in soil as well as in the roots of Gmelina plants.

Comparison of antioxidant responses to cadmium and lead in Bruguiera gymnorrhiza seedlings

Seedlings of mangrove plant Bruguiera gymnorrhiza cultured in sand with Hoagland’s nutrient solution were treated with 1 to 30 mM Cd(NO3)2 or Pb(NO3)2 for 2 months. In all Cd/Pb treatments, the malondialdehyde content increased while the chlorophyll content declined. Peroxidase (POD) and superoxide dismutase (SOD) activities in roots increased at moderate Cd/Pb concentrations (1–10 mM), whereas decreased at higher concentrations (20–30 mM). Catalase (CAT) activity in roots was inhibited by 1–10 mM Cd but enhanced by 1–10 mM Pb. The activities of POD, SOD and CAT in leaves were less affected by Cd and Pb than in roots. A new SOD and three CAT isoenzymes were induced by Pb. In contrast, no additional SOD and CAT isoenzymes were induced by Cd.

EFFECT OF TREATMENT WITH TRICHODERMA SPP ON THE LEVEL OF PEROXIDASE, POLYPHENOLOXIDAES AND CHITINASE IN COWPEA PLANTS VIGNA UNGUICULATA EFFECTED BY ROOT-KNOT NEMATODAS MELOIDOYGNE JAVANICA

Two isolates of biocontrol agent Trichoderma spp involved a mutant isolate Trichoderma harzianum Thk20 and Trichoderma viride were used in this study Results revealed the ability of two isolates in inducing systemic disease resistance in cowpea plants against root knot nematode Meloidogyne javanica throughout increasing the activity of peroxidase, polyphenoloxidas and chitinase enzymes in cowpea roots. Isolates Thk20 caused highest activity of peroxidase 1.83 unit/g f.w. and polyphenoloxidase 5.58 unit / g f.w comparing with other treatments, at the same time this isolate did not differ significantly with the other isolate and the treatment (M. javanica + T. viride) where enzyme activity were 5.12 and 5.21 unit / g f.w respectively . The treatment (M. javanica + Thk20) caused the highest activity of chitinase enzyme in cowpea roots with 10.74 unit / g f.w followed by (M. javanica +T. viride), Thk20 and T. viride in which enzyme activity was 7.45, 5.34 and 5.23 unit / g f.w respectively.

Comparison of antioxidant responses to cadmium and lead in B ruguiera gymnorrhiza seedlings

Seedlings of mangrove plant Bruguiera gymnorrhiza cultured in sand with Hoagland's nutrient solution were treated with 1 to 30 mM Cd(NO3)2 or Pb(NO3)2 for 2 months. In all Cd/Pb treatments, the malondialdehyde content increased while the chlorophyll content declined. Peroxidase (POD) and superoxide dismutase (SOD) activities in roots increased at moderate Cd/Pb concentrations (1-10 mM), whereas decreased at higher concentrations (20-30 mM). Catalase (CAT) activity in roots was inhibited by 1-10 mM Cd but enhanced by 1-10 mM Pb. The activities of POD, SOD and CAT in leaves were less affected by Cd and Pb than in roots. A new SOD and three CAT isoenzymes were induced by Pb. In contrast, no additional SOD and CAT isoenzymes were induced by Cd.

Peroxidase activity in roots of arracacha affected by pH and temperature

In this paper, roots of arracacha (Arracacia xanthorrhyza Bancroft) were stored at 5ºC to induce chilling injury symptoms and stress-related peroxidase activity. Later, peroxidase kinetic activity was determined in different pH and temperature conditions. For this, soluble crude extract was sequentially saturated with ammonium sulfate, obtaining a semi-purified enzyme solution used for the analysis. Activity of peroxidase induced by the chilling at 5oC was determined from pH 2.5 to 9.0 and at temperature ranging from 10 to 80oC. The peroxidase had higher activity when the reaction occurred between pH 5.5 and 6.0 and at temperature of 30oC. Complete inactivation of the activity was observed in pH 2.5 after 60 minutes of pre-incubation or at 60oC for 10 minutes or alternatively at 70oC after 5 minutes of pre-incubation. The enzyme is more susceptible to inactivation in acid than alkaline pHs or alternatively using heat treatment.