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1.
Cysteine serves as a precursor for the synthesis of various sulfur-containing metabolites, and the cysteine synthase (CS)
gene plays a central role in the sulfur cycle in nature. In the present study, rcs1, a cytosolic CS gene of rice, was introduced into the genome of tobacco (Nicotiana tabacum). The tolerance of wild-type tobacco plants as well as of the resulting transgenic tobacco plants overexpressing the rcs1 gene to toxic levels of ozone (O3, 0.15 μ mol−1) was measured after various lengths of exposure. Leaf lesions in plants exposed for 2 weeks to O3 were more prevalent in the leaves of the wild-type plants than in those of the transgenic tobacco plants. Transgenic tobacco
plants showed a higher growth rate and a higher chlorophyll content than the wild-type plants. Cysteine synthase activity
and cysteine and glutathione contents were higher in transgenic plants than in wild-type plants irrespective of the length
of the O3 treatment. Our results indicate that the CS gene plays a role in the protection of the plant against toxic O3 gas, probably through the mechanism of an over-accumulation of such sulfur-rich antioxidants as cysteine and glutathione. 相似文献
2.
Thalli of epiphytic lichen Hypogymnia physodes (L.) Nyl. and terricolous Cladonia furcata (Huds.) Schrad., collected from an area with background arsenic concentrations, were exposed to 0, 0.1, 1 and 10 μg mL−1 arsenate (As(V)) solutions for 24 h. After exposure they were kept in the metabolically active state for 0, 24 and 48 h in
a growth chamber. In the freeze dried samples glutathione (GSH), glutathione disulphide (GSSG), cysteine (Cys) and cystine
were analysed and induction of phytochelatin (PC) synthesis measured by reversed-phase high-performance liquid chromatography
in combination with fluorescence detection or UV spectrometry. Total arsenic content in thalli was measured by instrumental
neutron activation analysis (INAA). In H. physodes, which contained higher amounts of arsenic compared to C. furcata, total glutathione content significantly decreased in samples exposed to 10 μg mL−1 As(V), whereas in C. furcata a significant increase was observed. In both species PC synthesis was induced in thalli exposed to 10 μg mL−1. 相似文献
3.
Herbaceous Echinochloa crusgalli var. frumentacea is highly resistant to a wide range of heavy metal concentrations. However, its detoxification mechanism has not been reported
yet. We exposed plants to 100 μM CdCl2 for 7 days then examined cadmium accumulation and its subcellular distribution in binding to ligands. Cd concentration increased
over the exposure period to a saturation point at day 5 when its level reached 1,732.41 μg g−1 dry weight, an amount about 820 times greater than that found in the control. In the roots, most Cd was distributed in the
insoluble fraction, perhaps because of an absorption mechanism at the root surface. Our profile for distribution revealed
two Cd-binding ligand peaks: a high molecular weight of 60 kDa and a 2.5-kDa Cd-binding ligand. The latter increased with
time and had a typical phytochelatin (PC) amino acid composition of predominantly cysteine, glutamate, and glycine (16.5%,
16.6%, and 11.9%, respectively). The ratio of glutamate/cysteine/glycine was 1.4:1.4:1.0, which is similar to that for other
typical PCs. 相似文献
4.
Phytochelatins (PCs) are heavy metal binding peptides that play an important role in sequestration and detoxification of heavy
metals in plants. In this study, our goal was to develop transgenic plants with increased tolerance for and accumulation of
heavy metals from soil by expressing an Arabidopsis
thaliana
AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A 35S promoter fused to a FLAG–tagged AtPCS1 cDNA was expressed in Indian mustard, and transgenic lines, designated pc lines, were evaluated for tolerance to and accumulation
of Cd and Zn. Transgenic plants with moderate AtPCS1 expression levels showed significantly higher tolerance to Cd and Zn
stress, but accumulated significantly less Cd and Zn than wild type plants in both shoot and root tissues. However, transgenic
plants with highest expression of the transgene did not exhibit enhanced Cd and Zn tolerance. Shoots of Cd-treated pc plants
had significantly higher levels of phytochelatins and thiols than wild-type plants. Significantly lower concentrations of
gluthatione in Cd-treated shoot and root tissues of transgenic plants were observed. Moderate expression levels of phytochelatin
synthase improved the ability of Indian mustard to tolerate certain levels of heavy metals, but at the same time did not increase
the accumulation potential for Cd and Zn. 相似文献
5.
Barbi Tommaso Drake Pascal M. W. Drever Matthew van Dolleweerd Craig J. Porter Andrew R. Ma Julian K-C. 《Transgenic research》2011,20(3):701-707
In this paper we describe the engineering and regeneration of transgenic tobacco plants expressing a recombinant plasma membrane-retained
antibody specific to microcystin-LR (MC-LR), the environmental toxin pollutant produced by cyanobacteria. The antibody was
created by a genetic fusion of the antigen binding regions of the microcystin-specific single chain antibody, 3A8, with the
constant regions from the murine IgG1κ, Guy’s 13, including a membrane retention sequence at the C-terminal end of the antibody
heavy chain. The antibody produced in the leaves was shown to be functional by binding to MC-LR in an ELISA with antibody
yields in transgenic plant leaves reaching a maximum of 1.2 μg g−1 leaf f.wt (0.005% total soluble protein). Antibody-MC-LR complexes formed in leaves after addition of MC-LR to hydroponic
medium around the roots of transgenic plant cultures. 相似文献
6.
Phytochelatins (PCs) are post-translationally synthesized thiol reactive peptides that play important roles in detoxification
of heavy metal and metalloids in plants and other living organisms. The overall goal of this study is to develop transgenic
plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by expressing an Arabidopsis
thaliana
AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A FLAG-tagged AtPCS1 gDNA, under its native promoter, is expressed in Indian mustard, and transgenic pcs lines have been compared with wild-type
plants for tolerance to and accumulation of cadmium (Cd) and arsenic (As). Compared to wild type plants, transgenic plants
exhibit significantly higher tolerance to Cd and As. Shoots of Cd-treated pcs plants have significantly higher concentrations
of PCs and thiols than those of wild-type plants. Shoots of wild-type plants accumulated significantly more Cd than those
of transgenic plants, while accumulation of As in transgenic plants was similar to that in wild type plants. Although phytochelatin
synthase improves the ability of Indian mustard to tolerate higher levels of the heavy metal Cd and the metalloid As, it does
not increase the accumulation potential of these metals in the above ground tissues of Indian mustard plants. 相似文献
7.
Shukla D Kesari R Mishra S Dwivedi S Tripathi RD Nath P Trivedi PK 《Plant cell reports》2012,31(9):1687-1699
Phytochelatin synthase (PCS), the key enzyme involved in heavy metal detoxification and accumulation has been used from various sources to develop transgenic plants for the purpose of phytoremediation. However, some of the earlier studies provided contradictory results. Most of the PCS genes were isolated from plants that are not potential metal accumulators. In this study, we have isolated PCS gene from Ceratophyllum demersum cv. L. (CdPCS1), a submerged rootless aquatic macrophyte, which is considered as potential accumulator of heavy metals. The CdPCS1 cDNA of 1,757?bp encodes a polypeptide of 501 amino acid residues and differs from other known PCS with respect to the presence of a number of cysteine residues known for their interaction with heavy metals. Complementation of cad1-3 mutant of Arabidopsis deficient in PC (phytochelatin) biosynthesis by CdPCS1 suggests its role in the synthesis of PCs. Transgenic tobacco plants expressing CdPCS1 showed several-fold increased PC content and precursor non-protein thiols with enhanced accumulation of cadmium (Cd) and arsenic (As) without significant decrease in plant growth. We conclude that CdPCS1 encodes functional PCS and may be part of metal detoxification mechanism of the heavy metal accumulating plant C. demersum. KEY MESSAGE: Heterologous expression of PCS gene from C. demersum complements Arabidopsis cad1-3 mutant and leads to enhanced accumulation of Cd and As in transgenic tobacco. 相似文献
8.
Genetic engineering of the biosynthesis of glycinebetaine enhances thermotolerance of photosystem II in tobacco plants 总被引:1,自引:0,他引:1
Genetically engineered tobacco (Nicotiana tabacum L.) with the ability to accumulate glycinebetaine was established. The wild type and transgenic plants were exposed to heat
treatment (25–50°C) for 4 h in the dark and under growth light intensity (300 μmol m−2 s−1). The analyses of oxygen-evolving activity and chlorophyll fluorescence demonstrated that photosystem II (PSII) in transgenic
plants showed higher thermotolerance than in wild type plants in particular when heat stress was performed in the light, suggesting
that the accumulation of glycinebetaine leads to increased tolerance to heat-enhanced photoinhibition. This increased tolerance
was associated with an improvement on thermostability of the oxygen-evolving complex and the reaction center of PSII. The
enhanced tolerance was caused by acceleration of the repair of PSII from heat-enhanced photoinhibition. Under heat stress,
there was a significant accumulation of H2O2, O2− and catalytic Fe in wild type plants but this accumulation was much less in transgenic plants. Heat stress significantly
decreased the activities of catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate
reductase in wild type plants whereas the activities of these enzymes either decreased much less or maintained or even increased
in transgenic plants. In addition, heat stress increased the activity of superoxide dismutase in wild type plants but this
increase was much greater in transgenic plants. Furthermore, transgenic plants also showed higher content of ascorbate and
reduced glutathione than that of wild type plants under heat stress. The results suggest that the increased thermotolerance
induced by accumulation of glycinebetaine in vivo was associated with the enhancement of the repair of PSII from heat-enhanced
photo inhibition, which might be due to less accumulation of reactive oxygen species in transgenic plants. 相似文献
9.
Akhilesh Kumar Amrita Chakraborty Srijani Ghanta Sharmila Chattopadhyay 《Plant Cell, Tissue and Organ Culture》2009,96(2):117-126
Morphologically identical transgenic mint (Mentha arvensis L.) with bacterial glutathione synthetase gene has been developed. Transformed plants were obtained by co-cultivation of
leaf disks with Agrobacterium tumefaciens strain LBA 4404 harbouring a binary vector pCAMBIA-CpGS that carried E. coli glutathione synthetase (GS), β-glucuronidase as reporter gene and nptII as selective marker gene for kanamycin resistance. Using a constitutive double CaMV 35S promoter and an rbcS transit peptide, we successfully addressed CpGS to the chloroplasts through pJIT 117 vector. Preculture and the presence of AS in the co-cultivation medium played a significant
role in enhancing transformation frequency. The highest transformation frequency was achieved with MS selection medium supplemented
with 25% coconut water, 1.12 mg l−1 BAP, 0.2 mg l−1 NAA, 50 mg l−1 kanamycin and 125 mg l−1 cefotaxime. Robust rooting of regenerated shoots was obtained in half-strength liquid MS medium containing 0.2 mg l−1 NAA and 50 mg l−1 kanamycin. The presence and expression of transgenes in transgenics (T0) was evidenced by GUS histoenzymatic assay, PCR and RT-PCR analysis of nptII and the gene of interest, i.e., GS of putative transgenic leaves. Chromosomal integration of GS gene was confirmed by Southern blot analysis. Transgenic plants were successfully acclimatized in the greenhouse. An overall
transformation frequency of 15% was achieved in approximately 3 months of time period. These results are discussed in relation
to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications.
Akhilesh Kumar and Amrita Chakraborty contributed equally. 相似文献
10.
This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides,
fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial
isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL−1 against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The
strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose),
400 and 600 μg kg−1 soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg−1 soil of pyriproxyfen. Fipronil at 600 μg kg−1 soils and pyriproxyfen at 3,900 μg kg−1 soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram
plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants
grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed
soils. 相似文献
11.
Thiol metabolism play significant role during cadmium detoxification by Ceratophyllum demersum L. 总被引:1,自引:0,他引:1
Seema Mishra R.D. Tripathi Sudhakar Srivastava Sanjay Dwivedi Prabodh Kumar Trivedi O.P. Dhankher A. Khare 《Bioresource technology》2009,100(7):2155-2161
In the present study, the level of thiols and activity of related enzymes were investigated in coontail (Ceratophyllum demersum L.) plants to analyze their role in combating the stress caused upon exposure to cadmium (Cd; 0–10 μM) for a duration up to 7 d. Plants showed the maximum accumulation of 1293 μg Cd g?1 dw after 7 d at 10 μM. Significant increases in the level of total non-protein thiols (NP-SH) including phytochelatins (PCs) as well as upstream metabolites of the PC biosynthetic pathway, cysteine and glutathione (GSH) were observed. In addition, significant increases in the activities of cysteine synthase (CS), glutathione-S-transferase (GST), glutathione reductase (GR), as well as in vitro activation of phytochelatin synthase (PCS), were noticed in response to Cd. In conclusion, under Cd stress, plants adapted to a new metabolic equilibrium of thiols through coordinated synthesis and consumption to combat Cd toxicity and to accumulate it. 相似文献
12.
Zornitsa Katerova Sergei Ivanov Sergio Mapelli Vera Alexieva 《Acta Physiologiae Plantarum》2009,31(1):111-117
Pea (Pisum sativum L.) seedlings were exposed to low, moderate, and high regimes of ultraviolet-B (UV-B) (ld-B 4.4, md-B 13.3, and hd-B 26.5 kJ m−2 day−1), or ultraviolet-C (UV-C) (ld-C 0.1, md-C 0.3, and hd-C 0.6 kJ m−2 day−1) radiations. Concentrations of total phenols, free proline, and low-molecular thiol groups were determined in the last formed
(young) and older leaves after irradiation for 7, 10 or 14 consecutive days. Shoot length and weight did not change markedly
after 14 days of ld-B and ld-C, but reduced substantially after moderate and high regimes of both UV-B and UV-C. Proline decreased
upon high doses of irradiation, while in ld-B treated plants, by contrast, an increase was observed. The reduction in total
phenols and thiols was stronger after hd-B than after hd-C irradiations, although an induction was found in ld-B treated plants.
In contrast to ld-B, ld-C regime led mainly to reductions or insignificant changes in proline, phenols, and thiols. Therefore,
the stress-protection mechanisms are different between low UV-B and UV-C irradiation regimes in regard to proline, phenols,
and thiols. 相似文献
13.
A new bacterial strain producing succinic acid was enriched from bovine rumen content. It is facultatively anaerobic, belongs
to the family Pasteurellaceae and has similarity to the genus Mannheimia. In batch cultivations with D-glucose or sucrose the strain produced up to 5.8 g succinic acid l−1 with a productivity and a yield of up to 1.5 g l−1 h−1 and 0.6 g g−1, respectively. With crude glycerol up to 8.4 g l−1, 0.9 g l−1 h−1 and 1.2 g g−1 were obtained.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Wawrzynski A Kopera E Wawrzynska A Kaminska J Bal W Sirko A 《Journal of experimental botany》2006,57(10):2173-2182
Transgenic tobacco (Nicotiana tabacum cv. LA Burley 21) lines expressing three genes encoding enzymes thought to be critical for the efficient production of phytochelatins, (i) serine acetyltransferase (EC 2.3.1.30) involved in the production of O-acetylserine, the cysteine precursor, (ii) gamma-glutamylcysteine synthetase (EC 6.3.2.2) involved in the production of gamma-glutamylcysteine, the precursor of glutathione, and (iii) phytochelatin synthase (EC 2.3.2.15), were obtained and analysed for non-protein thiol content and cadmium accumulation. After a 3 week exposure to 15 microM CdCl2, plants expressing transgenes (either separately or in combination) had increased cadmium concentration in roots but not in shoots compared with the wild type. Nearly all transgenic lines analysed had more non-protein thiols than the wild type. The greatest effects (about 8-fold elevation of thiols) were found in one of the lines simultaneously expressing the three transgenes. Despite the fact that a multi-transgene strategy described in this work resulted in a strong increase in the levels of several classes of non-protein thiols in transgenic plants, other factors appeared to restrict cadmium accumulation in shoots. 相似文献
15.
16.
Overexpression of Glutathione Synthetase in Indian Mustard
Enhances Cadmium Accumulation and Tolerance 总被引:22,自引:0,他引:22
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Yong Liang Zhu Elizabeth A.H. Pilon-Smits Lise Jouanin Norman Terry 《Plant physiology》1999,119(1):73-80
An important pathway by which plants detoxify heavy metals is through sequestration with heavy-metal-binding peptides called phytochelatins or their precursor, glutathione. To identify limiting factors for heavy-metal accumulation and tolerance, and to develop transgenic plants with an increased capacity to accumulate and/or tolerate heavy metals, the Escherichia coli gshII gene encoding glutathione synthetase (GS) was overexpressed in the cytosol of Indian mustard (Brassica juncea). The transgenic GS plants accumulated significantly more Cd than the wild type: shoot Cd concentrations were up to 25% higher and total Cd accumulation per shoot was up to 3-fold higher. Moreover, the GS plants showed enhanced tolerance to Cd at both the seedling and mature-plant stages. Cd accumulation and tolerance were correlated with the gshII expression level. Cd-treated GS plants had higher concentrations of glutathione, phytochelatin, thiol, S, and Ca than wild-type plants. We conclude that in the presence of Cd, the GS enzyme is rate limiting for the biosynthesis of glutathione and phytochelatins, and that overexpression of GS offers a promising strategy for the production of plants with superior heavy-metal phytoremediation capacity. 相似文献
17.
Rios-Barrera D Vega-Segura A Thibert V Rodríguez-Zavala JS Torres-Marquez ME 《Archives of microbiology》2009,191(1):47-54
Living organisms are subject to stress, and among these stressors, heavy metals exposure triggers accumulation of sulfur metabolites.
Among these metabolites, glutathione and phytochelatins are found in several organisms, such as Euglena gracilis. Pre-exposing E. gracilis to low concentrations of Hg2+ generates a population with resistance to even 0.2 mM Cd2+, and this resistance relies partly on phytochelatins. p38 MAPK is stimulated by stress and is involved in apoptotic as well
as survival mechanisms. In this study, we explored its participation in heavy metal-induced stress and its possible role in
sulfur metabolite accumulation. We found that about 51% of the E. gracilis pretreated with Hg2+ becomes resistant to Cd2+ and proliferates despite the presence of this metal. The accumulation of the sulfur metabolites γ-glu-cys, glutathione and
phytochelatin 2 displayed cyclic patterns that were disturbed by a challenge with Cd2+. We observed a p38 MAPK-like activity that was stimulated by acute or chronic heavy metal exposure, and its inhibition by
SB203580 slightly diminished the accumulation of sulfur compounds. p38 MAPK inhibition also affected basal levels of glutathione
in either pretreated or control cells. Thus, it appears that p38 MAPK mediates redox stress component of the signal pathway
induced by heavy metals. 相似文献
18.
Donghua Liu Ping Xue Qingmin Meng Jing Zou Jiegang Gu Wusheng Jiang 《Plant cell reports》2009,28(4):695-702
The effects of lead and copper on the arrangement of microtubule (MT) cytoskeleton in root tip cells of Allium sativum L. were investigated. Batch cultures of garlic were carried out under defined conditions in the presence 10−4 M Pb/Cu of various duration treatments. With tubulin immunolabelling and transmission electron microscopy (TEM), we found
four different types of MT structures depending on the cell cycle stage: the interphase array, preprophase band, mitotic spindle
and phragmoplast were typical for the control cells. Pb/Cu affected the mechanisms controlling the organization of MT cytoskeleton,
and induces the following aberrations in interphase and mitotic cells. (1) Pb/Cu induced the formation of atypical MT arrays
in the cortical cytoplasm of the interphase cells, consisting of skewed, wavy MT bundles, MT fragments and ring-like tubulin
aggregations. (2) Pb/Cu disordered the chromosome movements carried out by the mitotic spindle. The outcome was chromosome
aberrations, for example, chromosome bridges and chromosome stickiness, as well as inhibition of cells from entering mitosis.
(3) Depending on the time of exposure, MTs disintegrated into shorter fragments or they completely disappeared, indicating
MT depolymerization. (4) Different metals had different effects on MT organization. MTs were more sensitive to the pressure
of Cu ions than Pb. Moreover, TEM observations showed that the MTs were relatively short and in some places wavy when exposed
to 10−4 M Pb/Cu solutions for 1–2 h. In many sections MTs were no longer visible with increasing duration of treatment (>4 h). Based
on these results, we suggested that MT cytoskeleton is primarily responsible for Pb/Cu-associated toxicity and tolerance in
plants. 相似文献
19.
Yu Ding Jin-Lai Miao Quan-Fu Wang Zhou Zheng Guang-You Li Ji-Chang Jian Zao-He Wu 《Polar Biology》2007,31(1):23-30
A psychrophilic glutathione reductase from Antarctic ice microalgae Chlamydomonas sp. Strain ICE-L was purified by ammonium sulfate fractionation and three steps of chromatography. The yield was up to 25.1%
of total glutathione reductase in the crude enzyme extract. The glutathione reductase activity was characterized by the spectrophotometric
method under different conditions. Purified glutathione reductase was separated by SDS-PAGE, which furnished a homogeneous
band. The native molecular mass of the enzyme was 115 kDa. Apparent Km values for NADPH and NADH (both at 0.5 mmol L−1 oxidized glutathione) were 22.3 and 83.8 μmol L−1, respectively. It was optimally active at pH 7.5, and it was stable from pH 5 to 9. Its optimum temperature was 25°C, with
activity at 0°C 23.5% of the maximum. Its optimum ion strength and optimum Mg2+ were 50–90 and 7.5 mmol L−1, respectively. Ca2+, Mg2+, and cysteine substantially increased the activity of the enzyme but chelating agents, heavy metals (Cd2+, Pb2+, Cu2+, Zn2+, etc.), NADPH, and ADP had significant inhibitory effects. This glutathione reductase can be used to study the adaptation
and mechanism of catalysis of psychrophilic enzymes, and it has a high potential as an environmental biochemical indicator
under extreme conditions. 相似文献
20.
Metallothionein (MT) has two domains, α and β domain. α domain preferred to bind Cd2+and Hg2+. Mouse metallothionein mutant αα has been constructed and expressed in E.coli, which has the same stability as the nature one but has stronger affinity to heavy metals. To testify the result in vivo, αα mutant gene was cloned into plant expression vector pE3 under the CaMV 35S promoter. A transgenic tobacco was obtained by using leaf discs of tobacco (Nicotiana tabacum L. cv. NC89) to Agrobacterium-mediated ααgene transfer. Southern blotting analysis indicated that the αα mutant gene was indeed integrated into the tobacco genome; Western blot indicated that the αα mutant gene was expressed in transgenic tobacco. It was also demonstrated that the transgenic tobacco with αα mutant gene have a little higher tolerance to heavy metals than that with natural MT gene. Moreover, the transgenic tobacco can accumulate more Cd2+ in its roots than natural, so that, it can decrease the concentration of Cd2+ in its leaves. 相似文献