首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 355 毫秒
1.
Oxidative events during in vitro regeneration of sunflower   总被引:1,自引:0,他引:1  
The changes in the activity of some antioxidant enzymes and endogenous H2O2 level in zygotic sunflower embryos during organogenesis and somatic embryogenesis were monitored. Pathways of regeneration were induced on media differing with sucrose concentration 87 mmol dm−3 for shoot [shoot induction medium (SIM) medium] and 350 mmol dm−3 [embryo induction medium (EIM) medium] for somatic embryo induction. Water potential of the explants cultured on SIM increased, while the embryos maintained on EIM showed middle water deficit stress. The pattern of superoxide dismutase (SOD) isoforms was similar in organogenic and embryogenic culture; however, the intensity of MnSOD bands was higher on SIM than on EIM. Differences in catalase activity were observed: high activity on SIM predominated, whereas on EIM it was reduced. The activity of guaiacol peroxidase in the explants producing shoots and somatic embryos differed at the beginning of culture, but became comparable at the time of shoot and somatic embryo formation (day 5). H2O2 content was unchanged in organogenic culture, but on EIM it increased on day 1 followed by significant decrease. The results indicate that sugar concentration per se, or via induction of different developmental pathways influences the activity of antioxidant enzymes and also H2O2 level in cultured sunflower embryos.  相似文献   

2.
A protocol for indirect differentiation of shoots / roots from leaf callus of Asiatic hybrid lily was developed through in vitro methods. The involvement of antioxidant enzymes, like, SOD, POX and CAT, and their isoenzymes during organogenesis in the morphogenetic callus was stud ied.The activity of these enzymes was increased during early development and differentiation of callus. SOD activity increased significantly as compared to POX and CAT during root formation, while it decreased in shoot formation and the decrease was significant in POX and CAT enzymes. The results indicate that the organogenesis is a very complicated biological process involving up and down regulation of a number of antioxidant enzymes, which seem to play an important role during organogenesis of Lilium callus.  相似文献   

3.
To understand the functions of antioxidant enzymes during leaf development in sweetpotato, we investigated the activities of several antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX) and catalase (CAT). Significant increases were observed in the activities of SOD, POX and APX during the late stage of leaf development, whereas CAT activity increased during the early developmental stage. By RT-PCR analysis, various POX and APX genes showed differential expression patterns during leaf development. Four POX genes swpa3, swpa4, swpa6, swpb4 and one APX gene swAPX1 exhibited high levels of gene expression during the senescence stage of leaf development, but two POX genes, swpa1 and swpa7 were preferentially expressed at both the mature green and the late senescence stages of leaf development. These results indicate that hydrogen peroxide (H2O2)-related antioxidant enzymes are differentially regulated in the process of leaf development of sweetpotato.  相似文献   

4.
Callus was obtained from hypocotyls of Mesembryanthemum crystallinum seedlings cultured on two types of medium—germination medium (GM) and callus induction medium (CIM). Following subculture on shoot induction medium SIM1, the callus formed on CIM medium regenerated roots or somatic embryos, while that obtained on GM medium was non-regenerative. The activities of CuZn-superoxidase dismutase (SOD) were comparable in all calli, but the activities of FeSOD and MnSOD varied according to the activity of photosystem II and the regenerative potential of the tissues. Catalase (CAT) activity was related to H2O2 concentration and affected by both the culture conditions and the morphogenic potential of the calli. The possible role of CAT, SODs and H2O2 in the regeneration of M. crystallinum from callus is discussed.This work is dedicated to Prof. Dr. Hubert Ziegler on his 80th birthday.  相似文献   

5.
To verify the hypothesis that cell redox status regulates the process of microspore embryogenesis (ME), reactive oxygen species (ROS) generation and the activity of enzymatic and non-enzymatic antioxidants were analyzed in eight doubled haploid lines of triticale with significant differences in embryogenic potential. The analyses were performed in anthers excised from freshly cut tillers (control) and from low temperature (LT) pre-treated tillers (3 weeks at 4 °C) in which ME has been initiated. Significant associations between ME effectiveness and the variables studied were found. In control cultures, high superoxide dismutase (SOD) activity appeared crucial for microspore viability. On the other hand, positive though non-linear correlation between ME effectiveness and H2O2 generation, and negative correlation with catalase (CAT) activity suggest that some threshold level of H2O2 is important for successful ME initiation. LT tillers pre-treatment significantly increased H2O2 accumulation, which had a negative effect on ME effectiveness. However, even high level of H2O2 did not endanger cell viability as long as the cells exhibited high activity of ROS-decomposing enzymes (SOD, CAT and POX). The ability to sustain antioxidative enzyme activity under cold stress in the dark was another important requirement for high effectiveness of ME, allowing for the generation of the signal initiating microspore reprogramming and simultaneously protecting the cells from the toxic effects of ROS production. The role of antioxidative enzymes cannot be replaced even by high activity of non-enzymatic antioxidants. In conclusion, genetically controlled but environmentally modified cell tolerance to oxidative stress seems to play an important role in triticale ME.  相似文献   

6.
Two-month-old healthy seedlings of a true mangrove, Bruguiera parviflora, raised from propagules in normal nursery conditions were subjected to varying concentrations of NaCl for 45 d under hydroponic culture conditions to investigate the defence potentials of antioxidative enzymes against NaCl stress imposed oxidative stress. Changes in the activities of the antioxidative enzymes catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POX), glutathione reductase (GR) and superoxide dismutase (SOD) were assayed in leaves to monitor the temporal regulation. Among the oxidative stress triggered chemicals, the level of H2O2 was significantly increased while total ascorbate and total glutathione content decreased. The ratio of reduced to oxidized glutathiones, however, increased due to decreased levels of oxidized glutathione in the leaf tissue. Among the five antioxidative enzymes monitored, the APX, POX, GR and SOD specific activities were significantly enhanced at high concentration (400 mM NaCl), while the catalase activities declined, suggesting both up and downregulations of antioxidative enzymes occurred due to NaCl imposed osmotic and ionic stress. Analysis of the stress induced alterations in the isoforms of CAT, APX, POX, GR and SOD revealed differential regulations of the isoforms of these enzymes. In B. parviflora one isoform of each of Mn-SOD and Cu/Zn-SOD while three isoforms of Fe-SOD were observed by activity staining gel. Of these, only Mn-SOD and Fe-SOD2 content was preferentially elevated by NaCl treatment, whereas isoforms of Cu/Zn-SOD, Fe-SOD1 and Fe-SOD3 remained unchanged. Similarly, out of the six isoforms of POX, the POX-1,-2,-3 and -6 were enhanced due to salt stress but the levels of POX-4 and -5 remained same as in control plants suggesting preferential upregulation of selective POX isoforms. Activity staining gel revealed only one prominent band of APX and this band increased with increased salt concentration. Similarly, two isoforms of GR (GR1 and GR2) were visualized on activity staining gel and both these isoforms increased upon salt stress. In this mangrove four CAT-isoforms were identified, among which the prominent CAT-2 isoform level was maximally reduced again suggesting differential downregulation of CAT isoforms by NaCl stress. The results presented in this communication are the first report on the resolutions of isoforms APX, POX and GR out of five antioxidative enzymes studied in the leaf tissue of a true mangrove. The differential changes in the levels of the isoforms due to NaCl stress may be useful as markers for recognizing salt tolerance in mangroves. Further, detailed analysis of the isoforms of these antioxidative enzymes is required for using the various isoforms as salt stress markers. Our results indicate that the overproduction of H2O2 by NaCl treatment functions as a signal of salt stress and causes upregulation of APX, POX, GR and deactivations of CAT in B. parviflora. The concentrations of malondialdehyde, a product of lipid peroxidation and lipoxygenase activity remained unchanged in leaves treated with different concentrations of NaCl, which again suggests that the elevated levels of the antioxidant enzymes protect the plants against the activated oxygen species thus avoiding lipid peroxidation during salt stress.  相似文献   

7.
Thidiazuron [N-phenyl-N-(1, 2, 3-thidiazol-5-yl) urea, TDZ] treatment significantly improved shoot morphogenesis of Saussurea involucrata Kar. Et Kir (S. involucrata) leaf explants. The biochemical mechanisms underlying TDZ-induced shoot organogenesis were investigated by measuring endogenous plant growth hormones, H2O2, as well as the activities of superoxide dismutase (SOD) and catalase (CAT). The levels of endogenous gibberellic A3 (GA3) and zeatin (ZT) significantly increased in leaf explants subject to a 28-day treatment than the controls. However, extending exposure time to TDZ inhibited GA3 accumulation. At the same time, the SOD activity increased significantly until the 28th of TDZ treatment time and the CAT activity reduced simultaneously, which was closely linked with the significant increase in H2O2 concentrations in the explants. And there was a sharply promotion after the 35 day of culture time if the plant tissue was always in medium contained, which was in company with the cell activity decreased. We propose that a combination of increased GA3, ZT, and H2O2 concentration is the basis for the enhanced shoot morphogenesis in response to TDZ treatment. These results provide a starting point for an improved understanding of the biochemical mechanisms underlying TDZ-induced shoot organogenesis of S. involucrata.  相似文献   

8.
In the present investigation, we studied the possible potentiating effect of salicylic acid (SA) under Cd toxicity in Oryza sativa L. leaves. Cd treatments for 24 h reduced the shoot length, dry biomass and total chlorophyll content followed by high Cd accumulation in shoots. About 16 h presoaking with SA resulted in partial protection against Cd, as observed by minor changes in length, biomass and total chlorophyll. SA priming resulted in low Cd accumulation. Enhanced thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H2O2) and superoxide anion (O2 ) content were seen when Cd was applied alone, while under SA priming the extent of TBARS, H2O2 and O2 were significantly low, suggesting SA-regulated protection against oxidative stress. The antioxidant enzymes like Catalase (CAT), guaiacol peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) showed varied activities under Cd alone. CAT activity increased after Cd treatment, followed by a decline in GPX and GR activity. SOD also declined at the highest concentrations with an initial increase. Under SA-priming conditions, the efficiency of the antioxidant enzymes was significantly elevated. GPx and SOD activity showed significant increase in activity. The ascorbate activity increased after Cd treatment, followed by a decline in glutathione under SA-free condition. SA priming showed gradual increase in these non-enzymic antioxidants. Our results indicate that Cd-induced oxidative stress can be regulated by SA.  相似文献   

9.
The effects of long-term NaCl and KCl treatment on plant growth and antioxidative responses were investigated in Chenopodium album, a salt-resistant species widely distributed in semi-arid and light-saline areas of Xinjiang, China. Growth parameters [plant height, branch number, leaf morphology and chlorophyll (Chl) content], the level of oxidative stress [superoxide anion radical (O2 ), hydrogen peroxide (H2O2) and malondialdehyde (MDA) concentrations], activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POX)], the contents of non-enzymatic antioxidants [carotenoids (Car) and ascorbic acid (AsA)] and expression of selected genes were investigated. Plants were grown in the presence of 0, 50, and 300 mM NaCl or KCl for 2 months. Growth was stimulated by 50 mM NaCl or KCl, maintained stable at 300 mM NaCl, but was inhibited by 300 mM KCl. Three hundred mM NaCl did not affect O2 , H2O2, MDA, Car and AsA, but increased the activities of SOD, CAT and POX compared to the controls. RT-PCR analysis suggested that expression of some genes encoding antioxidant enzymes could be induced during long-term salt stress, which was consistent with the enzyme activities. Treatment with 300 mM KCl was associated with elevated oxidative stress, and significantly decreased Car and AsA contents. These results suggest that an efficient antioxidant machinery is important for overcoming oxidative stress induced by treatment with high NaCl concentrations in C. album. Other strategies of ion regulation may also contribute to the differential tolerance to Na and K at higher concentrations.  相似文献   

10.
Pigeonpea [Cajanus cajan (L.) Millsp.] is a waterlogging-sensitive legume crop. We studied the effect of waterlogging stress on hydrogen peroxide (H2O2) content, lipid peroxidation and antioxidant enzyme activities in two pigeonpea genotypes viz., ICPL-84023 (waterlogging resistant) and MAL-18 (waterlogging susceptible). In a pot experiment, waterlogging stress was imposed for 6 days at early vegetative stage (20 days after sowing). Waterlogging treatment significantly increased hydrogen peroxide accumulation and lipid peroxidation, which indicated the extent of oxidative injury posed by stress conditions. Enzyme activities of peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and polyphenol oxidase (PPO) increased in pigeonpea roots as a consequence of waterlogged conditions, and all the enzyme activities were significantly higher in waterlogged ICPL-84023 than in MAL-18. POX activity was the maximum immediately after imposing stress, therefore, it was suggested to be involved in early scavenging of H2O2, while rest of the enzymes (CAT, APX, SOD and PPO) were more important in late responses to waterlogging. Present study revealed that H2O2 content is directly related to lipid peroxidation leading to oxidative damage during waterlogging in pigeonpea. Higher antioxidant potential in ICPL-84023 as evidenced by enhanced POX, CAT, APX, SOD and PPO activities increased capacity for reactive oxygen species (ROS) scavenging and indicated relationship between waterlogging resistance and antioxidant defense system in pigeonpea.  相似文献   

11.
We studied the effect of water stress imposed at anthesis and pre-anthesis stages on oxidative stress and antioxidant activity in four wheat cultivars, two hexaploid Triticum aestivum cultivars, drought resistant cv. C 306 and drought susceptible cv. Hira, and two tetraploid cultivars, T. durum cv. A 9-30-1 and T. dicoccum cv. HW 24. Water stress decreased relative water content (RWC), membrane stability index (MSI), and increased H2O2 and malondialdehyde (MDA) contents as well as activity of superoxide dismutase (SOD), catalase (Cat) and peroxidase (POX) in all the genotypes at all the stages. Both the tetraploid cultivars showed higher RWC, MSI and SOD activity, and lower H2O2 and MDA contents under water stress than hexaploid ones. Cat and POX activities were highest in C 306.  相似文献   

12.
Changes in antioxidative enzymes activities during Tacitus bellus direct shoot organogenesis from leaf explants were examined. During the early stages of shoot organogenesis there was a decrease in superoxide dismutase (SOD) and an increase in catalase (CAT) activity, and later during organogenesis there was an increase in peroxidase (POD) and polyphenol oxidase (PPO) activity. Two highly regulated turning points may be distinguished regarding activities and isoforms of antioxidative enzymes: the initiation of shoot organogenesis and the shoot bud formation. Our data suggest the role of specific CAT, POD, SOD and PPO isoforms in separate processes during T. bellus direct shoot organogenesis.  相似文献   

13.
Raphidophytes (class Raphidophyceae) produce high levels of reactive oxygen species (ROS), yet little is known regarding cellular scavenging mechanisms needed for protection against these radicals. Enzymatic activities of the antioxidants superoxide dismutase (SOD) and catalase (CAT) were measured in conjunction with the production of superoxide (O2??) and hydrogen peroxide (H2O2) in batch cultures of five different raphidophytes species during early exponential, late‐exponential, and stationary growth phases. The greatest concentrations of O2?? per cell were detected during exponential growth with reduced levels in stationary phases in raphidophytes Heterosigma akashiwo (Hada) Hada ex Y. Hara et Chihara, Chattonella marina (Subrahman.) Y. Hara et Chihara, and Chattonella antiqua (Hada) Ono (strain 18). Decreasing trends from exponential to stationary phases for SOD activity and H2O2 per cell were observed in all species tested. Significant correlations between O2?? per cell and SOD activity per cell over growth phase were only observed in three raphidophytes (Heterosigma akashiwo, Chattonella marina, and Chattonella antiqua strain 18), likely due to different cellular locations of externally released O2?? radicals and intracellular SOD enzymes measured in this study. CAT activity was greatest at early exponential phase for several raphidophytes, but correlations between H2O2 per cell and CAT activity per cell were only observed for Fibrocapsa japonica Toriumi et Takano, Chattonella antiqua (strain 18), and Chattonella subsalsa Biecheler. Our results suggest that SOD and CAT play important protective roles against ROS during exponential growth of several raphidophytes, while other antioxidant pathways may play a larger role for scavenging ROS during later growth.  相似文献   

14.
15.
The aim of the research was to estimate the sensitivity of tomato tissue and spore from necrotrophic isolate of B. cinerea on H2O2. The influence of exogenic H2O2 and B. cinerea on plant tissue and on the activity of peroxidases (PO), catalase (CAT) and superoxide dismutase (SOD) in apoplastic tomato leaves fraction were investigated. It was proved that 40 mM H2O2 damaged the cells of a host, and inhibited in vitro germination of B.cinerea spores. Complete inhibition of germination was observed after the use 100 mM H2O2. In the presence of spores H2O2 was decomposed to H2O and O2. Trace activity of catalase was observed in a solution of spores used for inoculation. Necrosis which appeared on the leaves after 40 mM H2O2 treatment resembled hypersensitive response. On the leaves pretreated at this concentration the development of infection was observed. The H2O2 concentration harmful for the tissues, stimulated the PO activity measured with NADH — responsible for generation of ·O 2 , as well as with syringaldazine (S) and ferulic acid (FA), substrates characteristics of forms lignifying and strengthening the cell wall. Clear increase in CAT activity, resulting from infection and early pretreatment with H2O2 was observed in apoplast. No effect on SOD activity was observed. A hypothesis may be put forward, that germinating spores produce enzymes which allow them to decompose H2O2 generated in apoplast, so there is little likelihood that B. cinerea can be directly inhibited by reactive oxygen forms (ROS) during initial stages of infection. Necrotic lesions resembling HR generated by exogenous H2O2 as well as induction of activity of apoplastic plant enzymes, particularly PO connected with strengthening and lignification of cell wall, were not sufficient factors to inhibit fungal expansion.  相似文献   

16.
Barley seedlings were pre-treated with 1 and 5 μM H2O2 for 2 d and then supplied with water or 150 mM NaCl for 4 and 7 d. Exogenous H2O2 alone had no effect on the proline, malondialdehyde (MDA) and H2O2 contents, decreased catalase (CAT) activity and had no effect on peroxidase (POX) activity. Three new superoxide dismutase (SOD) isoenzymes appeared in the leaves as a result of 1 μM H2O2 treatment. NaCl enhanced CAT and POX activity. SOD activity and isoenzyme patterns were changed due to H2O2 pre-treatment, NaCl stress and leaf ageing. In pre-treated seedlings the rate of 14CO2 fixation was higher and MDA, H2O2 and proline contents were lower in comparison to the seedlings subjected directly to NaCl stress. Cl content in the leaves 4 and 7 d after NaCl supply increased considerably, but less in pre-treated plants. It was suggested that H2O2 metabolism is involved as a signal in the processes of barley salt tolerance.  相似文献   

17.
Evidence for the participation of reactive oxygen species (ROS) and antioxidant systems in ectomycorrhizal (ECM) establishment is lacking. In this paper, we evaluated ROS production and the activities of superoxide dismutase (SOD) and catalase (CAT) during the early contact of the ECM fungus Pisolithus tinctorius with the roots of Castanea sativa (chestnut tree). Roots were placed in contact with P. tinctorius mycelia, and ROS production was evaluated by determining the levels of H2O2 and O2 ·− during the early stages of fungal contact. Three peaks of H2O2 production were detected, the first two coinciding with O2 ·− bursts. The first H2O2 production peak coincided with an increase in SOD activity, whereas CAT activity seemed to be implicated in H2O2 scavenging. P. tinctorius growth was evaluated in the presence of P. tinctorius-elicited C. sativa crude extracts prepared during the early stages of fungal contact. Differential hyphal growth that matched the H2O2 production profile with a delay was detected. The result suggests that during the early stages of ECM establishment, H2O2 results from an inhibition of ROS-scavenging enzymes and plays a role in signalling during symbiotic establishment.  相似文献   

18.
We investigated the efficacy of Pistacia lentiscus fruit oil (PLFO) for protecting human skin from damage due to oxidative stress. PLFO contains natural antioxidants including polyphenols, sterols and tocopherols. We compared the antioxidant potential of PLFO with extra virgin olive oil (EVOO). Explants of healthy adult human skin were grown in culture with either PLFO or EVOO before adding hydrogen peroxide (H2O2). We also used cultured skin explants to investigate the effects of PLFO on lipid oxidation and depletion of endogenous antioxidant defense enzymes including glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) one day after 2 h exposure to H2O2. We found that PLFO scavenged radicals and protected skin against oxidative injury. PLFO exhibited greater antioxidant and free radical scavenging activity than EVOO. Skin explants treated with PLFO inhibited H2O2 induced MDA formation by inhibition of lipid oxidation. In addition, the oil inhibited H2O2 induced depletion of antioxidant defense enzymes including GPx, SOD and CAT. We found that treatment with PLFO repaired skin damage owing to its antioxidant properties.  相似文献   

19.
Changes in contents of reactive oxygen species (O2 and H2O2) and non-enzymatic antioxidants, activities of antioxidant enzymes and lipid peroxidation were investigated during senescence of detached cucumber cotyledons dipped in water (control) and 20 mg dm−3 triadimefon (TDM). O2 and H2O2 accumulation and lipid peroxidation were observed during senescence of cucumber cotyledons, which coincided with a drop in the contents of carotenoids (Car) and ascorbic acid (AsA), and the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), and an increase in the activity of peroxidase (POD). However, TDM could significantly inhibit the accumulation of O2 and H2O2, and lipid peroxidation by preventing the decrease of CAT, APX, Car and AsA and the increase of POD, while TDM had little effect on SOD activity during the senescence. Therefore we can draw a conclusion that TDM protects the membrane system and retards the senescence of detached cucumber cotyledons. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
The effect of silicon on the growth, boron concentrations, malondialdehyde (MDA) content, lipoxygenase (LOX) activity, proline (PRO) and H2O2 accumulation, and the activities of major antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] and non-enzymatic antioxidants (AA) of wheat grown in soil originally with toxic B concentrations were investigated. Applied of 5.0 and 10.0 mM Si to the B toxic soil significantly increased Si concentration of the wheat and counteracted the deleterious effects of B on shoot growth. The contents of PRO, H2O2, MDA, and LOX activity of wheat grown in B toxic soil were significantly reduced by Si treatments. Compared with control plants, the activities of SOD, CAT, APX and content of AA were decreased by applied Si. Based on the present work, it can be concluded that Si alleviates B toxicity of wheat by preventing oxidative membrane damage and also translocation of B from root to shoot and/or soil to plant.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号