Phytoremediation is a cost-effective and environment-friendly strategy for decontaminating heavy-metal-contaminated soil.However, the practical use of phytoremediation is constrained by the low biomass of plants and l...Phytoremediation is a cost-effective and environment-friendly strategy for decontaminating heavy-metal-contaminated soil.However, the practical use of phytoremediation is constrained by the low biomass of plants and low bioavailability of heavy metals in soil.A pot experiment was conducted to investigate the effects of the metal chelator ethylenediaminetetraacetic acid(EDTA) and EDTA in combination with plant growth-promoting rhizobacteria(Burkholderia sp.D54 or Burkholderia sp.D416) on the growth and metal uptake of the hyperaccumulator Sedum alfredii Hance.According to the results, EDTA application decreased shoot and root biomass by 50% and 43%, respectively.The soil respiration and Cd,Pb, Zn uptake were depressed, while the photosynthetic rate, glutathione and phytochelatin(PC) contents were increased by EDTA application.Interestingly, Burkholderia sp.D54 and Burkholderia sp.D416 inoculation significantly relieved the inhibitory effects of EDTA on plant growth and soil respiration.Compared with the control, EDTA + D416 treatment increased the Cd concentration in shoots and decreased the Pb concentration in shoots and roots, but did not change the Zn concentration in S.alfredii plants.Furthermore,EDTA, EDTA + D54 and EDTA + D416 application increased the cysteine and PC contents in S.alfredii(p < 0.05);among all tested PCs, the most abundant species was PC2, and compared with the control, the PC2 content was increased by 371.0%, 1158.6% and 815.6%,respectively.These results will provide some insights into the practical use of EDTA and PGPR in the phytoremediation of heavy-metal-contaminated soil by S.alfredii.展开更多
Phytochelatins （PCs） play an important role in heavy metal resistance and accumulation. To reduce the accumulation of cadmium （Cd） in rice seeds, the expression of phytochelatin synthase （PCS） gene OsPCS1 was su...Phytochelatins （PCs） play an important role in heavy metal resistance and accumulation. To reduce the accumulation of cadmium （Cd） in rice seeds, the expression of phytochelatin synthase （PCS） gene OsPCS1 was suppressed by RNA interference （RNAi）. A hairpin construct of a PCS fragment was designed in the pRNAi-OsPCS1 under the control of ZMM1, a seed-specific promoter from maize. The construct was introduced into rice （japonica） through Agrobacterium tumefaciens. The RNAi rice plantlets were selected and cultivated in pots exposured to 10 mg/kg Cd. The transcriptional level of OsPCS1 declined in seeds of some RNAi rice compared to the wild type. As a result Cd accumulation was reduced by about half in the seeds of RNAi rice. As expected, no apparent difference of growth appeared between RNAi and wild-type plants. The results suggest that this new approach can be used to control heavy metal accumulation in crops.展开更多
Bermudagrass （Cynodon dactylon L. cv. Goldensun） is highly resistant to and accumulates large amounts of cadmium （Cd）. A phytochelatin synthase （PCS） cDNA （CdPCS1） was isolated from this grass by rapid amplifi...Bermudagrass （Cynodon dactylon L. cv. Goldensun） is highly resistant to and accumulates large amounts of cadmium （Cd）. A phytochelatin synthase （PCS） cDNA （CdPCS1） was isolated from this grass by rapid amplification of cDNA ends. The putative CdPCS1 protein shared a high homology with PCS from other plants, with 79% homology at the N-terminal and 47% homology at the C-terminah However, 16 Cys residues were found at the C-terminal of CdPCS1, and among these residues, three positions were different from other PCS proteins. Semiquantitative reverse transcription-polymerase chain reaction analysis showed that Cd stress induced CdPCS1 expression in both roots and leaves in Bermudagrass. We verified that CdPCS1 plays an important role in Cd tolerance in yeast cells by expressing the gene in ABDE1, a Cdsensitive mutant. CdPCS1 was then introduced into tobacco plants. The phytochelatin level in some transgenic tobacco lines increased 3.88-fold more than in wild type plants and Cd accumulation in these transgenic plants was enhanced 3.21-fold accordingly. The results suggested that CdPCS1 could be used as a gene element for phytoremediation in the future.展开更多
Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots...Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins (PCs), and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.展开更多
基金supported by the National Natural Science Foundation of China (Nos.41977274, 41807123)the Shaanxi Province Key Research & Development Plan (No.2018ZDXMSF-022)the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.18JK0100).
文摘Phytoremediation is a cost-effective and environment-friendly strategy for decontaminating heavy-metal-contaminated soil.However, the practical use of phytoremediation is constrained by the low biomass of plants and low bioavailability of heavy metals in soil.A pot experiment was conducted to investigate the effects of the metal chelator ethylenediaminetetraacetic acid(EDTA) and EDTA in combination with plant growth-promoting rhizobacteria(Burkholderia sp.D54 or Burkholderia sp.D416) on the growth and metal uptake of the hyperaccumulator Sedum alfredii Hance.According to the results, EDTA application decreased shoot and root biomass by 50% and 43%, respectively.The soil respiration and Cd,Pb, Zn uptake were depressed, while the photosynthetic rate, glutathione and phytochelatin(PC) contents were increased by EDTA application.Interestingly, Burkholderia sp.D54 and Burkholderia sp.D416 inoculation significantly relieved the inhibitory effects of EDTA on plant growth and soil respiration.Compared with the control, EDTA + D416 treatment increased the Cd concentration in shoots and decreased the Pb concentration in shoots and roots, but did not change the Zn concentration in S.alfredii plants.Furthermore,EDTA, EDTA + D54 and EDTA + D416 application increased the cysteine and PC contents in S.alfredii(p < 0.05);among all tested PCs, the most abundant species was PC2, and compared with the control, the PC2 content was increased by 371.0%, 1158.6% and 815.6%,respectively.These results will provide some insights into the practical use of EDTA and PGPR in the phytoremediation of heavy-metal-contaminated soil by S.alfredii.
基金Supported by the National Program of Research and Development of Transgenic Plants of China （JY03A2001） and the National Natural Science Foundation of China （30570138 and 30370127）.The authors thank Professors Kang Chong and Zheng Meng of the Institute of Botany, the Chinese Academy of Sciences, for kindly providing the vectors of pTCK303 and pKZMM1.
文摘Phytochelatins （PCs） play an important role in heavy metal resistance and accumulation. To reduce the accumulation of cadmium （Cd） in rice seeds, the expression of phytochelatin synthase （PCS） gene OsPCS1 was suppressed by RNA interference （RNAi）. A hairpin construct of a PCS fragment was designed in the pRNAi-OsPCS1 under the control of ZMM1, a seed-specific promoter from maize. The construct was introduced into rice （japonica） through Agrobacterium tumefaciens. The RNAi rice plantlets were selected and cultivated in pots exposured to 10 mg/kg Cd. The transcriptional level of OsPCS1 declined in seeds of some RNAi rice compared to the wild type. As a result Cd accumulation was reduced by about half in the seeds of RNAi rice. As expected, no apparent difference of growth appeared between RNAi and wild-type plants. The results suggest that this new approach can be used to control heavy metal accumulation in crops.
基金Supported by the Special Project of Transgenic Plants Research (JY03A2001)
文摘Bermudagrass （Cynodon dactylon L. cv. Goldensun） is highly resistant to and accumulates large amounts of cadmium （Cd）. A phytochelatin synthase （PCS） cDNA （CdPCS1） was isolated from this grass by rapid amplification of cDNA ends. The putative CdPCS1 protein shared a high homology with PCS from other plants, with 79% homology at the N-terminal and 47% homology at the C-terminah However, 16 Cys residues were found at the C-terminal of CdPCS1, and among these residues, three positions were different from other PCS proteins. Semiquantitative reverse transcription-polymerase chain reaction analysis showed that Cd stress induced CdPCS1 expression in both roots and leaves in Bermudagrass. We verified that CdPCS1 plays an important role in Cd tolerance in yeast cells by expressing the gene in ABDE1, a Cdsensitive mutant. CdPCS1 was then introduced into tobacco plants. The phytochelatin level in some transgenic tobacco lines increased 3.88-fold more than in wild type plants and Cd accumulation in these transgenic plants was enhanced 3.21-fold accordingly. The results suggested that CdPCS1 could be used as a gene element for phytoremediation in the future.
基金the National Natural Science Foundation of China (Grant Nos. 20535020, 20475046 and 20775062)the National "863" Hi-Tech Project of China (Grant No. 2006AA06Z404)the National Basic Research Program of China (Grant No. 2003CD415001)
文摘Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins (PCs), and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.
