共查询到20条相似文献,搜索用时 31 毫秒
1.
Summary. Methyl-jasmonate (MeJA) has been proposed to be involved in the evocation of defense reactions, as the oxidative burst in
plants, substituting the elicitors or enhancing their effect. 48 h dark- and sterilely cultured (axenic) aeroponic sunflower
seedling roots excised and treated with different concentrations of MeJA showed a strong and quick depression of the H + efflux rate, 1.80 μM MeJA totally stopping it for approximately 90 min and then reinitiating it again at a lower rate than
controls. These results were wholly similar to those obtained with nonsterilely cultured roots and have been interpreted as
mainly based on H + consumption for O 2
•− dismutation to H 2O 2. Also K + influx was strongly depressed by MeJA, even transitorily reverting to K + efflux. These results were consistent with those associated to the oxidative burst in plants. MeJA induced massive H 2O 2 accumulation in the middle lamella and intercellular spaces of both the root cap cells and the inside tissues of the roots.
The native acidic extracellular peroxidase activity of the intact (nonexcised) seedling roots showed a sudden enhancement
(by about 52%) after 5 min of MeJA addition, maintained for approximately 15 min and then decaying again to control rates.
O 2 uptake by roots gave similar results. These and other results for additions of H 2O 2 or horseradish peroxidase, diphenylene iodonium, and sodium diethyldithiocarbamate trihydrate to the reaction mixture with
roots were all consistent with the hypothesis that MeJA induced an oxidative burst, with the generation of H 2O 2 being necessary for peroxidase activity. Results with peroxidase activity of the apoplastic fluid were in accordance with
those of the whole root. Finally, MeJA enhanced NADH oxidation and inhibited hexacyanoferrate(III) reduction by axenic roots,
and diphenylene iodonium cancelled out these effects. Redox activities by CN −- preincubated roots were also studied. All these results are consistent with the hypothesis that MeJA enhanced the NAD(P)H
oxidase of a redox chain linked to the oxidative burst, so enhancing the generation of O 2
•− and H 2O 2, O 2 uptake, and peroxidase activity by roots.
Received July 12, 2002; accepted October 2, 2002; published online May 21, 2003
RID="*" 相似文献
2.
The production of reactive oxygen species (ROS) plays important roles in the life cycle and in the stress response and defence mechanisms of plants. Various enzyme systems are involved in the formation of ROS in the apoplast, including plasmalemma NADPH oxidase and apoplastic peroxidases. The production of O 2 ·? and apoplastic peroxidase and exogenous NADH oxidation activities are all strongly dependent on the age of roots??the younger the root, the greater the activity. Apoplastic production of ROS is shown in the root by using specific histochemical probes, this ROS production is growing zone dependent. In the present study, using olive seedlings, differences were also observed between cultivars, especially in O 2 ·? production by the Verdial cultivar which was well above that of other cultivars studied. In all the cultivars, treatment of roots with methyl jasmonate (MeJA) or methyl salicylate (MeSA) increased O 2 ·? production. Similar results were observed for peroxidase activity, but not for the oxidation of exogenous NADH which was either unaffected (MeJA) or even partially inhibited (MeSA). A conclusion was that MeJA or MeSA induced apoplastic production of ROS does not use exogenous NADH. Treatment with diphenylene iodonium (DPI) reduced the formation of O 2 ·? , but affected neither peroxidase nor NADH oxidation activities. Cyanide inhibited O 2 ·? production and peroxidase and NADH oxidation activities. Treatment with MnCl 2 had a strong stimulatory effect on peroxidase and NADH oxidation activities, but much less on O 2 ·? production. Finally, azide greatly reduced all activities, but especially O 2 ·? production. Together, these results indicate a relationship between oxidative activities and the processes of root growth, and that those activities are also dependent on the cultivar, as well as an involvement of peroxidases and plasmalemma NADPH oxidase in apoplast ROS production which is sensitive to DPI, azide, and cyanide but relatively insensitive to MnCl 2, while exogenous NADH oxidation is linked to peroxidase activity. 相似文献
3.
Caffeic acid (CA), which is ubiquitously present in plants, is a potent phytotoxin affecting plant growth and physiology.
The aim of our study was to investigate whether CA-induced inhibition of adventitious root formation (ARF) in mung bean { Vigna radiata (L.) Wilczek [ Phaseolus aureus Roxb.]} involves the induction of conventional stress responses. The effect of CA (0–1000 μM) on ARF in mung bean was determined
by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H 2O 2) content, root oxidizability and changes in levels of antioxidant enzymes. Our results show that CA significantly enhanced
MDA content, indicating severe lipid peroxidation, and increased H 2O 2 accumulation and root oxidizability in the lower rooted hypocotylar region (LRHR) of mung bean, thereby inducing oxidative
stress and cellular damage. In response to CA, there was a significant upregulation in the activities of scavenging enzymes,
such as superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, catalase and glutathione reductase, in LRHRs of mung
bean. Based on these results, we conclude that CA inhibits ARF in mung bean hypocotyls by inducing ROS-generated oxidative
stress and upregulating the activities of antioxidant enzymes. 相似文献
4.
When subjected to stress, plants produce reactive oxygen species (ROS) as a part of the defense response. The oxidative response is also used to degrade organic pollutants. Hairy roots of Helianthus annuus (sunflower) are shown to oxidize oxytetracycline (OTC) through the action of the ROS released to the nutrient medium by the hairy root cultures. Methyl jasmonate (MeJA) elicits ROS formation in the hairy root cultures. The activities of the antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), and guaiacol peroxidase (GPX), are reported for hairy root cultures treated with increasing concentrations of MeJA. A bioassay using Enterococcus hirae as the test microorganism demonstrates the root-catalyzed oxidation process results in conversion of OTC into product(s) devoid of antibiotic activity. Direct evidence for putative ROS oxidation of OTC is obtained by mass spectrometry (MS) and HPLC/MS showing first quinone formation followed possibly by ring cleavage, which disrupts UV absorption and destroys antibiotic activity. 相似文献
5.
The effect of hydrogen sulfide (H 2S) donor sodium hydrosulfide (NaHS) on the heat resistance of wheat ( Triticum aestivum L.) coleoptile cells, the formation of reactive oxygen species (ROS), and the activity of the antioxidant enzymes in them was investigated. The treatment of coleoptiles with 100 µM NaHS caused transient enhancement of the generation of the superoxide anion radical (O 2 ?) and an increased hydrogen peroxide content. The activities of antioxidant enzymes—superoxide dismutase, catalase, and guaiacol peroxidase— and coleoptile resistance to damaging heat was later found to have increased. The biochemical and physiological effects of the hydrogen sulfide donor described above were inhibited by the treatment of wheat coleoptiles with the hydrogen peroxide scavenger dimethylthiourea, the NADPH oxidase inhibitor imidazole, the extracellular calcium chelator EGTA, and the phosphatidylinositol-specific phospholipase C inhibitor neomycin. A conclusion was made on the role of ROS generation, which is dependent on the activity of NADPH oxidase and calcium homeostasis, in the transduction of the H 2S signal, which induces antioxidant enzymes and the development of plant cell heat resistance. 相似文献
6.
Roots of mountain ginseng ( Panax ginseng) were exposed to various levels of oxygen (O 2) (30, 40 and 50%) for 15, 30 and 45 days in 5 L (working volume 4 L) airlift bioreactors. Ginsenoside accumulation and dry weight was enhanced up to 40% O 2; but thereafter declined ginsenoside and dry weight of the roots by increasing level of O 2. Gradual increase in H 2O 2 content and lipoxygenase activity (LOX), resulting in cellular damage and oxidative stress as indicated by increased malondialdehyde (MDA) content after 30 and 45 days at all O 2 levels was shown. Increased levels of O 2 (above ambient) resulted in increases in non-protein thiol (NP-SH) and cysteine content. Higher activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), catalase (CAT), guaiacol peroxidase (G-POD), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S transferase (GST) activities indicated that antioxidant enzymes played an important role in protecting the roots from O 2 up to 45 days, except at 50% O 2 where GR, GST and GPx decreased compared to the control. However, after 45 days, SOD activity decreased significantly compared to the control in the O 2-treated roots. This reflects the sensitivity of enzymes to O 2 toxicity. In stress related experiment, roots showed increased synthesis of ginsenosides when 25 and 50 μM H 2O 2 was applied. However, higher dose and increasing treatment inhibited ginsenoside synthesis. The results indicate that plant roots could grow and protect themselves from O 2 stress by coordinated induction of various antioxidant enzymes and metabolite contents. These results suggest that O 2 supplementation is useful for ginsenoside accumulation using 5-L bioreactors. 相似文献
7.
Methyl jasmonate (MeJA) produces an important reduction in the accumulation of proteins related to energy metabolism. The treatment of hairy roots (HR) with MeJA increased the accumulation of H 2O 2 during the first 48 h and this H 2O 2 accumulation was also observed in isolated mitochondria. Peroxidase and catalase activities decreased in the presence of MeJA, and this decrease directly correlated with the increase of H 2O 2 in HR treated with MeJA. This suggests that the H 2O 2 burst due to MeJA is the initial response to mitochondria disruption in the roots. 相似文献
8.
We investigated the interaction between heat shock protein 70 (HSP70) and abscisic acid (ABA)-induced antioxidant response
of maize to the combination of drought and heat stress. First, the increased activities of enzymes, including superoxide dismutase
(SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT), induced by drought were less than those
by heat or combined drought and heat stress, except some individual cases (e.g. CAT in leaves, GR in roots). Second, both
HSP70 synthesis and H 2O 2 production increased prominently under drought, heat or their combination stress; the increase in leaves induced by drought
and heat combination was the highest, followed by heat and by drought, while the increase in roots had not visible difference.
Third, either in leaves or roots, pretreatment with ABA inhibitor, HSP70 inhibitor and H 2O 2 scavenger, significantly arrested the stress-induced increase of antioxidant enzyme activities, and ABA inhibitor and H 2O 2 scavenger obviously suppressed HSP70 synthesis, while HSP70 inhibitor slightly heightened H 2O 2 accumulation. Finally, 100 μM ABA significantly enhanced the activities of antioxidant enzymes, HSP70 expression and H 2O 2 production under stresses in comparison with ABA-deficient mutant vp5 maize plants without pretreatment. Thus, ABA-induced H 2O 2 production enhances the HSP70 synthesis and up-regulates the activities of antioxidant enzymes, resulting in the suppression
of cellular reactive oxygen species (ROS) levels. Our results suggest that HSP70 may play a crucial role in ABA-induced antioxidant
defense of maize to drought and heat combination. 相似文献
9.
The effects of chemical and microbial elicitors such as β-aminobutyric acid (BABA), Salicylic acid (SA), and Pseudomonas fluorecens CHAO on hydrogen peroxide generation and activity of the enzymes related to its metabolism, i.e., superoxide dismutase (SOD), guaiacol peroxidase (GPOX), and catalase (CAT) were investigated in tomato roots infected with root-knot nematode ( Meloidogyne javanica). Results of this study show that treating the tomato seedlings with the above elicitors significantly reduces the nematode infection level. Among the tested elicitors, BABA has reduced the nematode galls, number of egg masses per plant and number of eggs per individual egg mass more than the others. Additionally, the amount of H 2O 2, a product of oxidative stress, SOD and GPOX specific activities were significantly increased in the elicitor treated plants in comparison to control. Our observation shows that BABA also increases the H 2O 2 accumulation and the SOD and GPOX activities more as compared with the other tested elicitors. Such increases have occurred in two phases and maximum levels of them were observed at 5 days after treatment. In contrast with the increase in SOD and GPOX activities, the CAT activity doesnot show any significant increase in treated plants as compared with the control and other tested elicitors. It can be concluded that BABA, SA, and Pseudomonas fluorescens CHAO induce oxidative stress in tomato roots through generation of reactive oxygen species (ROS) and the enzymes related to their metabolism. 相似文献
10.
The changes in the activity of some antioxidant enzymes and endogenous H 2O 2 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). H 2O 2 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 H 2O 2 level in cultured sunflower embryos. 相似文献
11.
The effects of excess copper (Cu) on the accumulation of hydrogen peroxide (H 2O 2) and antioxidant enzyme activities in roots of the Cu accumulator Elsholtzia haichowensis Sun were investigated. Copper at 100 and 300 μM significantly increased the concentrations of malondialdehyde and H 2O 2, and the activities of catalase (E.C. 1.11.1.6), ascorbate peroxidase (E.C. 1.11.1.11), guaiacol peroxidase (GPOD, E.C. 1.11.1.7)
and superoxide dismutase (SOD, E.C. 1.15.1.1). Isoenzyme pattern and inhibitor studies showed that, among SOD isoforms, only
copper–zinc superoxide dismutase (CuZn–SOD) increased. Excess Cu greatly increased the accumulation of superoxide anion (O 2
·−) and H 2O 2 in E. haichowensis roots. This study also provides the first cytochemical evidence of an accumulation of H 2O 2 in the root cell walls as a consequence of Cu treatments. Experiments with diphenyleneiodonium as an inhibitor of NADPH oxidase,
1,2-dihydroxybenzene-3,5-disulphonic acid as an O 2
·− scavenger, and N- N-diethyldithiocarbamate as an inhibitor of SOD showed that the source of H 2O 2 in the cell walls could partially be NADPH oxidase. The enzyme can use cytosolic NADPH to produce O 2
·−, which rapidly dismutates to H 2O 2 by SOD. Apoplastic GPOD and CuZn–SOD activities were induced in roots of E. haichowensis with 100 μM Cu suggesting that these two antioxidant enzymes may be responsible for H 2O 2 accumulation in the root apoplast. 相似文献
12.
The establishment of green root cultures of Stevia rebaudiana Bertoni, and the effect of elicitors such as hydrogen peroxide (H2O2) and methyl jasmonate (MeJA), is shown in the present study. Stevioside, rebaudioside A, and the isomers steviol/isosteviol were identified through DFI-ESI-IT-MSn and UPLC-TOFMS spectrometric systems, in combination with solid-phase extraction. The accumulation of steviol glycosides increased by 2.4 times (compared to the control value of 22.35 μgSG per gDW), with the addition of 250 μM H2O2. The non-enzymatic antioxidant response, which resulted from production of phenolic and flavonoid compounds, was modified based on the elicitor and the dose used. The maximum accumulation of flavonoids was induced on the third day with the addition of H2O2 (250 or 500 μM), and with MeJA (250 or 500 μM); the increase was observed on the fifth day. The enzymatic antioxidant response of the catalase and peroxidase from the roots under elicitation confirmed the stress conditions. 相似文献
13.
Despite extensive research over the past years, regeneration from protoplasts has been observed in only a limited number of
plant species. Protoplasts undergo complex metabolic modification during their isolation. The isolation of protoplasts induces
reactive oxygen species (ROS) generation in Brassica napus leaf protoplasts. The present study was conducted to provide new insight into the mechanism of ROS generation in B. napus leaf protoplasts. In vivo localization of H 2O 2 and enzymes involved in H 2O 2 generation and detoxification, molecular antioxidant-ascorbate and its redox state and lipid peroxidation were investigated
in the leaf and isolated protoplasts. Incubating leaf strips in the macerating enzyme (ME) for different duration (3, 6, and
12 h) induced accumulation of H 2O 2 and malondialdehyde (lipid peroxidation, an index of membrane damage) in protoplasts. The level of H 2O 2 was highest just after protoplast isolation and subsequently decreased during culture. Superoxide generating NADPH oxidase
(NOX)-like activity was enhanced, whereas superoxide dismutase (SOD) and ascorbate peroxidase (APX) decreased in the protoplasts
compared to leaves. Diaminobenzidine peroxidase (DAB-POD) activity was also lower in the protoplasts compared to leaves. Total
ascorbate content, ascorbate to dehydroascorbate ratio (redox state), were enhanced in the protoplasts compared to leaves.
Higher activity of NOX-like enzyme and weakening in the activity of antioxidant enzymes (SOD, APX, and DAB-POD) in protoplasts
resulted in excessive accumulation of H 2O 2 in chloroplasts of protoplasts. Chloroplastic NADPH oxidase-like activity mediated perpetual H 2O 2 generation probably induced apoptotic-like cell death of B. napus leaf protoplasts as indicated by parallel DNA laddering and decreased mitochondrial membrane potential. 相似文献
14.
The histochemical and cytochemical localization of abscisic acid (ABA)-induced H 2O 2 production in leaves of maize ( Zea mays L.) plants were examined, using 3,3-diaminobenzidine (DAB) and CeCl 3 staining, respectively, and the relationship between ABA-induced H 2O 2 production and ABA-induced subcellular activities of antioxidant enzymes was studied. H 2O 2 generated in response to ABA treatment was detected within 0.5 h in major veins of the leaves and maximized at about 2–4 h. In mesophyll and bundle sheath cells, ABA-induced H 2O 2 accumulation was observed only in apoplast, and the greatest accumulation occurred in the walls of mesophyll cells facing large intercellular spaces. Meanwhile, ABA treatment led to a significant increase in the activities of the leaf chloroplastic and cytosolic antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), and pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI), the O
2
−
scavenger Tiron and the H 2O 2 scavenger dimethylthiourea (DMTU) almost completely arrested the increase in the activities of these antioxidant enzymes. Our results indicate that the accumulation of apoplastic H 2O 2 is involved in the induction of the chloroplastic and cytosolic antioxidant enzymes. Moreover, an oxidative stress induced by paraquat (PQ), which generates O
2
−
and then H 2O 2 in chloroplasts, also up-regulated the activities of the chloroplastic and cytosolic antioxidant enzymes, and the up-regulation was blocked by the pretreatment with Tiron and DMTU. These data suggest that H 2O 2 produced at a specific cellular site could coordinate the activities of antioxidant enzymes in different subcellular compartments. 相似文献
15.
The effects of aluminum (Al) on root elongation, lipid peroxidation, hydrogen peroxide (H 2O 2) accumulation, antioxidant levels, antioxidant enzymatic activity, and lignin content in the roots of the Al-tolerant rice
variety azucena and the Al-sensitive variety IR64 were investigated. Treatment with Al induced a greater decrease in root
elongation and a greater increase in H 2O 2 and lipid peroxidation as determined by the total thiobarbituric acid-reactive substance (TBARS) level in IR64 than in azucena.
Azucena had significantly higher levels of superoxide dismutase, ascorbate peroxidase, glutathione reductase, and glutathione
peroxidase GSH POD activity compared with IR64. The concentrations of reduced glutathione (GSH) and ascorbic acid, and the
GSH/GSSG ratio (reduced vs. oxidized glutathione) were also higher in azucena than in IR64 in the presence of Al. The addition
of 1 mg/L GSH improved root elongation in both varieties and decreased H 2O 2 production under Al stress. By contrast, treatment with buthionine sulfoximine, a specific inhibitor of GSH synthesis, decreased
root elongation in azucena and stimulated H 2O 2 production in both varieties. Moreover, Al treatment significantly increased the cytoplasmic activity of peroxidase (POD)
as well as the levels of POD bound ionically and covalently to cell walls in the Al-sensitive variety. The lignin content
was also increased. Treatment with exogenous H 2O 2 also increased the lignin content and decreased root elongation in IR64. These results suggest that Al induces lignification
in the roots of Al-sensitive rice varieties, probably through an increase in H 2O 2 accumulation. 相似文献
16.
Phaseolus vulgaris cv. Korona plants were inoculated with the bacteria Pseudomonas syringae pv. phaseolicola ( Psp), necrotrophic fungus Botrytis cinerea ( Bc) or with both pathogens sequentially. The aim of the experiment was to determine how plants cope with multiple infection with pathogens having different attack strategy. Possible suppression of the non-specific infection with the necrotrophic fungus Bc by earlier Psp inoculation was examined. Concentration of reactive oxygen species (ROS), such as superoxide anion (O 2 ?) and H 2O 2 and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined 6, 12, 24 and 48 h after inoculation. The measurements were done for ROS cytosolic fraction and enzymatic cytosolic or apoplastic fraction. Infection with Psp caused significant increase in ROS levels since the beginning of experiment. Activity of the apoplastic enzymes also increased remarkably at the beginning of experiment in contrast to the cytosolic ones. Cytosolic SOD and guaiacol peroxidase (GPOD) activities achieved the maximum values 48 h after treatment. Additional forms of the examined enzymes after specific Psp infection were identified; however, they were not present after single Bc inoculation. Subsequent Bc infection resulted only in changes of H 2O 2 and SOD that occurred to be especially important during plant–pathogen interaction. Cultivar Korona of common bean is considered to be resistant to Psp and mobilises its system upon infection with these bacteria. We put forward a hypothesis that the extent of defence reaction was so great that subsequent infection did not trigger significant additional response. 相似文献
17.
We evaluated the involvement of nitric oxide (NO) in salicylic acid (SA)-induced accumulation of ginsenoside in adventitious
roots of Panax ginseng and its mediation by reactive oxygen species (ROS). Related effects of SA on components of the antioxidant system were also
sought. Adventitious roots of P. ginseng were grown in suspension culture for 3 weeks in MS medium and treated over 5 days with SA (100 μM) alone, SA in combination
with the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), or PTIO alone. Nitric oxide, the superoxide
anion (O 2·−), H 2O 2, nitrite, nonprotein thiol, and ascorbate were monitored together with ginsenoside, NADPH oxidase activity, and several antioxidant
enzymes. Salicylic acid did not inhibit root growth but induced accumulation of ginsenoside, lipid peroxidation, and generation
of NO and O 2·−. It also enhanced activities of NADPH oxidase, superoxide dismutase, catalase, and peroxidase, including ascorbate peroxidase.
These effects were suppressed by PTIO. Salicylic acid also decreased glutathione reductase activity. Inclusion of PTIO with
SA decreased the activity of glutathione reductase further. Treatment with SA plus PTIO also decreased nonprotein thiol and
ascorbate contents but caused nitrite to overaccumulate. Salicylic acid applied to adventitious roots in culture induced accumulation
of ginsenoside in an NO-dependent manner that was mediated by the associated increases in O 2·−, which gave other antioxidant responses that were dependent on NO. 相似文献
18.
The aim of this study is to investigate the effect of aluminium treatment on peroxidases activities and protein content in both soluble and cell-wall-bound fractions of sunflower leaves, stems and roots. Fourteen-day-old seedlings, grown in a nutrient solution, were exposed to a toxic amount of aluminium (500 μM AlNO 3) for 72 h. Under stress conditions, biomass production, root length and leaf expansion were significantly reduced. Also, our results showed modulations on soluble and ionically cell-wall-bound peroxidases activities. In soluble fraction, peroxidases activities were enhanced in all investigated organs. This stimulation was also observed in ionically cell-wall-bound fraction in leaves and stems. Roots showed a differential behaviour: peroxidase activity was severely reduced. Lignifying peroxidases activities assayed using coniferyl alcohol and H 2O 2 as substrates were also modulated. Significant stimulation was shown on soluble fraction in leaves, stems and roots. In ionically cell-wall-bound fraction lignifying peroxidases were enhanced only in stems but severely inhibited in roots. Also, aluminium toxicity caused significant increase on cell wall protein content in sunflower roots. 相似文献
19.
Hairy root disease is caused by infection of wounded higher plants with Agrobacterium rhizogenes. Transformation of tissues or plants with A. rhizogenes, as well as transformation with rol genes, in addition to hairy roots, may produce alterations in the plant secondary metabolism. H 2O 2 and other ROS are involved as signals in secondary metabolite production pathways and play a key role in plant defense reactions. In this work the effects of A. rhizogenes rol genes on nicotine content, antioxidant enzymes activity, H 2O 2 production, the pattern of peroxidase (POX) and superoxide dismutase (SOD) isozymes in hairy roots and regenerated Nicotiana tabacum plants were studied. The rise in SOD and POX activities in the transformed lines TRa and TRb and the resulting regenerated plants and a decreased level of H 2O 2 in them as compared with the untransformed lines indicates that rol gene expression decreases H 2O 2 level probably by increasing production of antioxidant enzymes. A decreased H 2O 2 content in TRc line, in spite of similarity of antioxidant enzyme activity as compared to normal roots, indicates that rol genes activate other mechanisms except SOD and POX enzymes for reducing H 2O 2. 相似文献
20.
Functioning of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APO), and guaiacol peroxidases
(GPO)) and low-molecular organic ROS scavengers (proline and phenolic compounds) in various organs (roots, cotyledons, stem,
and needle) of 6-week-old seedlings of pine ( Pinus sylvestris L.) developing in the chronic presence of ZnSO 4 (50, 100, and 150 μM). Pine seedlings were grown in water culture in the climate-controlled chamber at an irradiance of 37.6
W/m 2 with a 16-h photoperiod, an air temperature of 23 ± 1/15 ± 1°C (day/night), and a relative humidity of 55/70% (day/night).
Endogenous Zn content was a key factor determining SOD activity decomposing superoxide into H 2O 2 and O 2. Hydrogen peroxide produced is efficiently destroyed by CAT and also by APO and GPO. At the same time, the content of proline
increased (especially at 150 μM ZnSO 4), but the content of phenolic compounds remained unchanged. All these processes help to maintain stable intracellular levels
of O 2⊙− and H 2O 2 at elevated zinc concentrations and to prevent generation of hydroxyl radical and development of oxidative stress. 相似文献
|