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1.
The Relation between Accumulation of Abscisic Acid and Proline in Detached Rice Leaves 总被引:4,自引:0,他引:4
The relation between abscisic acid (ABA) and proline accumulation was investigated in detached rice (Oryza sativa L.) leaves. In darkness, proline content increased about 2-, 2,5- and 6-fold after 24, 48 and 72 h. ABA content reached maximum after 48 h. In the light, proline content remained almost unchanged until 48 h and subsequently increased slightly. ABA content in the light was lower than in darkness, but the maximum was also after 48 h. During 12-h exposure to decreased air humidity, proline content gradually increased, but ABA content increased about 25-fold after 4 h and declined thereafter. Exogenous application of ABA resulted in an increase in proline content in detached rice leaves under both light and darkness. 相似文献
2.
The effects of abscisic acid (ABA) and water stress on senescence and enzyme activities of oxygen scavenging enzymes of detached
rice leaves were compared. Exogenously applied ABA exhibited water stress-like effects by promoting senescence, by decreasing
the activities of catalase, peroxidase, ascorbate peroxidase and superoxide dismutase. It seems that the effects of water
stress on senescence and enzyme activities are possibly mediated through increased content of endogenous ABA.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Effects of Irradiance and Copper on the Activity of Ascorbate Oxidase in Detached Rice Leaves 总被引:1,自引:0,他引:1
The effects of copper on the activity of ascorbic acid oxidasc (AAO) in detached rice leaves under both light and dark conditions
and in etiolated rice seedlings were investigated. CuSO4 increased AAO activity in detached rice leaves in both light and darkness, however, the induction in darkness was higher
than in the light. In the absence of CuSO4, irradiance (40 μmol m-2 s-1) resulted in a higher activity of AAO in detached rice leaves than dark treatment. Both CuSO4 and CuCl2 increased AAO activity in detached rice leaves, indicating that AAO is activated by Cu. Sulfate salts of Mg, Mn, Zn and Fe
were ineffective in activating AAO in detached leaves. CuSO4 was also observed to increase AAO activity in the roots but not in shoots of etiolated rice seedlings.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
The effects of water stress on the contents of proline, ornithine, arginine and glutamic acid in detached rice leaves were examined. In water stressed leaves, the content of proline was elevated to a content approximately 8-, 14- and 17-fold higher than in control leaves after 4, 8 and 12 h, respectively. We also observed that omithine and arginine contents were much higher under water stress than in control leaves. However, the content of glutamic acid in water stressed leaves was higher after 4 and 8 h and lower after 12 h than that in control leaves. 相似文献
5.
Ammonium ion accumulation in detached rice leaves treated with phosphinothricin (PPT), an inhibitior of glutamine synthetase (GS), was investigated in the light and darkness. PPT treatment increased NH4
+ content and induced toxicity in rice leaves in the light but not in darkness, suggesting the importance of light in PPT-induced NH4
+ toxicity in detached rice leaves. PPT treatment in the light resulted in a decrease of activities of the cytosolic form of GS and the chloroplastic form of GS. The photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea reduced NH4
+ accumulation induced by PPT in the light. In darkness, PPT-induced NH4
+ accumulation and toxicity were observed in the presence of glucose or sucrose. 相似文献
6.
Ammonium Ion, Ethylene, and Abscisic Acid in Polyethylene Glycol-treated Rice Leaves 总被引:1,自引:0,他引:1
Polyethylene glycol (PEG)-treatment decreased chlorophyll and protein contents and increased NH4
+ content due to decreased glutamine synthetase activity in detached rice leaves. PEG-treatment also increased abscisic acid
(ABA) content and decreased ethylene production. Addition of fluridone, an inhibitor of ABA biosynthesis, reduced ABA content
in rice leaves but did not prevent chlorophyll and protein loss in rice leaves induced by PEG. Silver thiosulfate, an inhibitor
of ethylene action, was effective in preventing PEG-promoted chlorophyll and protein loss, but had no effect on PEG-induced
NH4
+ accumulation. The current results suggest that NH4
+ accumulation in rice leaves induced by PEG increases leaf sensitivity to ethylene, which in turn results in an enhancement
of chlorophyll and protein loss.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
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
8.
The effects of NaCl on putrescine (Put) content and diamine oxidase (DAO) activity in roots of rice seedlings were examined. NaCl treatment lowered the content of Put and increased the activity of DAO in roots. Our current results indicate that Cl– is not required for NaCl-induced decline in Put content and increase in DAO activity in roots. Put content in roots of rice seedlings exposed to NaCl is possibly regulated by DAO activity. 相似文献
9.
Difference in the growth response to submergence between coleoptiles and roots of rice (Oryza sativa L.) was investigated in 9-d-old rice seedlings. The coleoptile length in the submergence condition was much greater than that in aerobic condition, whereas the root length in the submergence condition was less than that in the aerobic condition. Alcohol dehydrogenase (ADH) activity in the coleoptiles in the submergence condition was much greater than that in the aerobic condition, but ADH activity in the roots in the submergence condition increased slightly. These results suggest that the preferential ADH induction in rice seedlings may contribute to the difference in the growth response between the coleoptiles and roots under low oxygen conditions. 相似文献
10.
萝卜离体子叶衰老与膜脂过氧化的关系 总被引:10,自引:0,他引:10
萝卜离体子叶在光下或暗中衰老及激素调节衰老过程中,作为叶片衰老指标的叶绿素和蛋白质含量的降低,发生在MDA含量增高之前,更早于SOD活性的下降。表明由SOD活性降低所导致的膜脂过氧化的增强,并非衰老的原初反应,而是叶片衰老到一定程度的生理变化。因此,至少在萝卜离体子叶上,不能将其衰老的启动归因于受SOD控制的膜脂过氧化作用导致的膜累积性质变。 相似文献
11.
12.
The possible role of Zn and Cr as catalytic inducers of free radicals in wheat leaves was investigated. Treatment of excess
heavy metals decreased the chlorophyll and carotenoid content in wheat leaves with the increase in time of excision. A sharp
increase in proline accumulation was marked with the increase in metal concentration. Total peroxide content and lipid peroxidation
measured as malondialdehyde content showed uniform increase under metal treatment in excised leaves. At almost all concentrations,
catalase, guaiacol peroxidase and superoxide dismutase activities decreased with a minor increase in the earlier days of excision.
Though glutathione content decreased ascorbate content showed significant increase in wheat leaves under heavy metal treatment.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Involvement of oxidative stress and role of antioxidative defense system in growing rice seedlings exposed to toxic concentrations of aluminum 总被引:6,自引:0,他引:6
When seedlings of rice (Oryza sativa L.) cultivar Pant-12 were raised in sand cultures containing 80 and 160 μM Al3+ in the medium for 5–20 days, a regular increase in Al3+ uptake with a concomitant decrease in the length of roots as well as shoots was observed. Al3+ treatment of 160 μM resulted in increased generation of superoxide anion (O2
−) and hydrogen peroxide (H2O2), elevated amount of malondialdehyde, soluble protein and oxidized glutathione and decline in the concentrations of thiols
(-SH) and ascorbic acid. Among antioxidative enzymes, activities of superoxide dismutase (SOD EC 1.15.1.1), guaiacol peroxidase
(Guaiacol POX EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), monodehydroascorbate reductase (MDHAR EC 1.6.5.4), dehydroascorbate
reductase (EC 1.8.5.1) and glutathione reductase (EC 1.6.4.2) increased significantly, whereas the activities of catalase
(EC EC 1.11.1.6) and chloroplastic APX declined in 160 μM Al3+ stressed seedlings as compared to control seedlings. The results suggest that Al3+ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX
and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al3+ toxicity. PAGE analysis confirmed the increased activity as well as appearance of new isoenzymes of APX in Al3+ stressed seedlings. Immunoblot analysis revealed that changes in the activities of APX are due to changes in the amounts
of enzyme protein. Similar findings were obtained when the experiments were repeated using another popular rice cv. Malviya-36. 相似文献
14.
Effects of four culture media on callus induction, regeneration and number of plants per unit culture were studied with mature seeds from five indica rice genotypes as explants. Based on the morphology, the calli were classified into four types as I to IV. Type I and type II are most suited to initiate suspension cultures or as target material for transformation. Number of plants regenerated per unit culture, formation of easily dissociating cell clusters and frequency of type I and type II calli were highest on NBKNB medium. Thus NBKNB medium is suitable for in vitro culture of even the hitherto recalcitrant indica genotypes. 相似文献
15.
Drought Induces Oxidative Stress and Enhances the Activities of Antioxidant Enzymes in Growing Rice Seedlings 总被引:7,自引:0,他引:7
When rice seedlings grown for 10 and 20 days were subjected to in vitro drought stress of −0.5 and −2.0 MPa for 24 h, an increase in the concentration of superoxide anion (O2.−), increased level of lipid peroxidation and a decrease in the concentration of total soluble protein and thiols was observed
in stressed seedlings compared to controls. The concentration of H2O2 as well as ascorbic acid declined with imposition of drought stress, however glutathione (GSH) concentration declined only
under severe drought stress. The activities of total superoxide dismutases (SODs) as well as ascorbate peroxidase (APX) showed
consistent increases with increasing levels of drought stress, however catalase activity declined. Mild drought stressed plants
had higher guaiacol peroxidase (GPX) and chloroplastic ascorbate peroxidase (c-APX) activity than control grown plants but
the activity declined at the higher level of drought stress. The activities of enzymes involved in regeneration of ascorbate
i.e. monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were higher
in drought stressed plants compared to controls. Results suggest that drought stress induces oxidative stress in rice plants
and that besides SOD, the enzymes of ascorbate-glutathione cycle, which have not been studied in detail earlier under stressful
conditions, appear to function as important component of antioxidative defense system under drought stress. 相似文献
16.
Summary The coleoptile of rice (Oryza sativa L. cv. Nippon-bare) emerges from the imbibed seed on day 2 after sowing and ceases its growth on day 3. In cross section, the cells near the outer epidermis turn into green between days 2 and 3, while those near the inner epidermis remain colorless. In this study, the complete process of the development in the nongreening cells in the coleoptile was examined by fluorescence and electron microscopy. Embryonic morphology on day 0 was rapidly converted into the differentiated greening or nongreening cells between days 1 and 2. Senescence in the inner, nongreening region first appeared on day 4 in the third or fourth cell layer from the inner epidermis and then spread towards both the inner and the outer epidermis, and the inner cells collapsed completely before the outer cells senesced. Cells adjacent to the inner epidermis, which senesced slowly, followed a sequence of events during development: (1) degradation of plastid DNA; (2) dispersal of nuclear chromatin, differentiation of plastids into amyloplasts, degradation of mitochondrial DNA; (3) degradation of the starch in amyloplasts; (4) disorganization of plastids; (5) condensation of the nucleus, shrinkage of mitochondria; (6) complete loss of cellular components, distortion of cell walls. In the interior cells, the early events including degeneration of plastid DNA and mitochondrial DNA occurred in parallel with those in the cells adjacent to the inner epidermis, yet rapid collapse of all the cellular components proceeded between days 3 and 5, and nuclear condensation could not be detected.Abbreviations cpDNA
chloroplast DNA
- DAPI
4,6-diamidino-2-phenylindole
- DiOC7
3,3-dihexyloxacarbocyanine
- IE
inner epidermis
- mtDNA
mitochondrial DNA
- mt-nucleoid
mitochondrial nucleoid
- OE
outer epidermis
- ptDNA
plastid DNA
- pt-nucleoid
plastid nucleoid 相似文献
17.
Activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) in heated crude extracts from seedlings of the rice cultivars
Hitomebore and IR28 was investigated in the presence of proline and betaine. Both solutes retarded the inactivation of the
enzyme extracted from the leaves of both cultivars at temperature-stress from 35 to 45 °C. At 50 °C, however, betaine was
effective in both cultivars. Stabilization of RuBPCO activity was independent of the added solute from 1 to 2 M concentration.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Jeong Ho Kim Young Min Cheon Bong -Gyu Kim Joong -Hoon Ahn 《Journal of Plant Biology》2008,51(2):97-101
The major flavonoids in rice leaves were analyzed via LC-MS/MS after their total flavonoid extracts were hydrolyzed. The most
abundant flavones were apigenin, luteolin, and tricetin. Of these, tricetin was methylated at its 3′ and 5′-hydroxyl group
to form tricin, which was probablyO-glycosylated. Both 3′-O-methylated luteolin and luteolin were found in theC-glycosylated form while apigenin wasC-glycosylated. We also cloned and characterizedOsFNS, which catalyzes the reaction from flavanone (naringenin) to flavone (apigenin). Analysis of the reaction product with recombinant
OsFNS showed that it indeed converts naringenin to apigenin. 相似文献
19.
The relationship of cellulase to detached leaf senescence of rice seedlings was investigated by examining the effect of ABA and 6-BA on changes in the level of cellulase of leaf segments during senescence. It was shown that the rise in cellulase activity increased with declining chlorophyll content, which was used as the senescence indicator during the senescence of detached rice leaves caused by ABA. The action of ABA took place only after a 48h lag period. ABA enhanced the cellulase secretion and increased the permeability of plasma membrane. A high level of cellulase activity in cell wall closely related to membrane permeability changes. The action of cellulase in the cell wall may cause depolymerization of β-1, 4-glucan in situ, thus speeding senescence. The 6-BA reverses completely or partly the increase in cellulase activity and tile permeability caused by ABA during the first two day, }) ut it antagonized hardly any of the ABA effect from the third day on, suggesting the onset of an irreversible stage in the senescence of detached rice leaves. 相似文献
20.
To determine the allelopathic potential of root exudate from early developmental stage of rice (Oryza sativa L), 6-d-old seedlings of eight cultivars were grown with 3-d-old alfalfa (Medicago sativa L.), cress (Lepidium sativum L.) or lettuce (Lactuca sativa L.) seedlings in Petri dishes under controlled condition. All rice cultivars (cv. Norin 8, Kamenoo, Nipponbare, Kinuhikari, Koshihikari, Sasanishiki, Yukihikari and Hinohikari) inhibited growth of roots, shoots and fresh mass of alfalfa, cress and lettuce seedlings. Effectiveness of cv. Koshihikari was the greatest and more than 60% inhibition was recorded in all bioassays, followed by that of cv. Norin 8 of which effectiveness was more than 40%. 相似文献