The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity.Since phytochelatins can effectively chelate heavy metals,it was hypothesized that S.salsa possessed a phyt...The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity.Since phytochelatins can effectively chelate heavy metals,it was hypothesized that S.salsa possessed a phytochelatin synthase(PCS) gene.In the present study,the cDNA of PCS was obtained from S.salsa(designated as SsPCS) using homologous cloning and the rapid amplification of cDNA ends(RACE).A sequence analysis revealed that SsPCS consisted of 1 916 bp nucleotides,encoding a polypeptide of 492 amino acids with one phytochelatin domain and one phytochelatin C domain.A similarity analysis suggested that SsPCS shared up to a 58.6%identity with other PCS proteins and clustered with PCS proteins from eudicots.There was a new kind of metal ion sensor motif in its C-terminal domain.The SsPCS transcript was more highly expressed in elongated and fibered roots and stems(P<0.05) than in leaves.Lead and mercury exposure significantly enhanced the mRNA expression of SsPCS(P<0.05).To the best of our knowledge,SsPCS is the second PCS gene cloned from a halophyte,and it might contain a different metal sensing capability than the first PCS from Thellungiella halophila.This study provided a new view of halophyte PCS genes in heavy metal tolerance.展开更多
利用RT-PCR扩增拟南芥螫合肽合成酶(AtPCS1)基因全序列.进一步构建AtPCS1的植物表达载体pB I 121-AtPCS1,转化农杆菌EHA105;然后用转化的农杆菌EHA105以叶盘法侵染苜蓿甘农一号叶片,在50mg/L Kan的筛选压下,经过约80～100d的筛选,获得5...利用RT-PCR扩增拟南芥螫合肽合成酶(AtPCS1)基因全序列.进一步构建AtPCS1的植物表达载体pB I 121-AtPCS1,转化农杆菌EHA105;然后用转化的农杆菌EHA105以叶盘法侵染苜蓿甘农一号叶片,在50mg/L Kan的筛选压下,经过约80～100d的筛选,获得57棵再生苗.随机取其中9棵再生苗进行PCR检测,其中6棵为阳性.初步鉴定表明AtPCS1基因已整合到苜蓿基因组中.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
Under heavy metal stress,higher plants initiate a set of defense responses,among which biosynthesis of phytochelatins (PCs) is important. PCs are rich in cystein and biosynthesized by phytochelatin synthase. The chemi...Under heavy metal stress,higher plants initiate a set of defense responses,among which biosynthesis of phytochelatins (PCs) is important. PCs are rich in cystein and biosynthesized by phytochelatin synthase. The chemical structure of PCs and their ability to form complexes with a large range of metal ions is clear. Up to now,these peptides are known to play an important role in both endogenous metal ion homeostasis and heavy metal ion detoxification. The mechanism of cadmium tolerance is illustrated in detail. A model of this mechanism suggested that the detoxification process of cadmium include such steps as PCs induction,transport of cadmium into the tonoplast,formation of the HMW-Cd-PCs complexes and sequestration in vacuole. At the same time,PCs also have other functions,such as detoxification of arsenic,protecting enzyme from metal ion inhibition and supplying metal ion as a cofactor to the enzyme potentially. However,a lot of questions about its biological function remain to be answered. In 1999,three independent labs isolated the genes encoding the PCs synthase. This breakthrough of plant heavy metal tolerance research gave us a chance to further study the heavy metal tolerance mechanism. All the results from the reserch of PCs have a great application potential in phytoremidation. Fig 1,Ref展开更多
基金Supported by the 100 Talents Program of the Chinese Academy of Sciencesthe Key Technology R&D Program of Shandong Province(No.2012GGA06032)
文摘The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity.Since phytochelatins can effectively chelate heavy metals,it was hypothesized that S.salsa possessed a phytochelatin synthase(PCS) gene.In the present study,the cDNA of PCS was obtained from S.salsa(designated as SsPCS) using homologous cloning and the rapid amplification of cDNA ends(RACE).A sequence analysis revealed that SsPCS consisted of 1 916 bp nucleotides,encoding a polypeptide of 492 amino acids with one phytochelatin domain and one phytochelatin C domain.A similarity analysis suggested that SsPCS shared up to a 58.6%identity with other PCS proteins and clustered with PCS proteins from eudicots.There was a new kind of metal ion sensor motif in its C-terminal domain.The SsPCS transcript was more highly expressed in elongated and fibered roots and stems(P<0.05) than in leaves.Lead and mercury exposure significantly enhanced the mRNA expression of SsPCS(P<0.05).To the best of our knowledge,SsPCS is the second PCS gene cloned from a halophyte,and it might contain a different metal sensing capability than the first PCS from Thellungiella halophila.This study provided a new view of halophyte PCS genes in heavy metal tolerance.
文摘利用RT-PCR扩增拟南芥螫合肽合成酶(AtPCS1)基因全序列.进一步构建AtPCS1的植物表达载体pB I 121-AtPCS1,转化农杆菌EHA105;然后用转化的农杆菌EHA105以叶盘法侵染苜蓿甘农一号叶片,在50mg/L Kan的筛选压下,经过约80～100d的筛选,获得57棵再生苗.随机取其中9棵再生苗进行PCR检测,其中6棵为阳性.初步鉴定表明AtPCS1基因已整合到苜蓿基因组中.
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Supported by the National Natural Science Foundation (30170086,30370127),the Special Project of Transgenic Research (JY03A2001)and Hi_-tech R & D Program of China (2001AA645010-5)
文摘Under heavy metal stress,higher plants initiate a set of defense responses,among which biosynthesis of phytochelatins (PCs) is important. PCs are rich in cystein and biosynthesized by phytochelatin synthase. The chemical structure of PCs and their ability to form complexes with a large range of metal ions is clear. Up to now,these peptides are known to play an important role in both endogenous metal ion homeostasis and heavy metal ion detoxification. The mechanism of cadmium tolerance is illustrated in detail. A model of this mechanism suggested that the detoxification process of cadmium include such steps as PCs induction,transport of cadmium into the tonoplast,formation of the HMW-Cd-PCs complexes and sequestration in vacuole. At the same time,PCs also have other functions,such as detoxification of arsenic,protecting enzyme from metal ion inhibition and supplying metal ion as a cofactor to the enzyme potentially. However,a lot of questions about its biological function remain to be answered. In 1999,three independent labs isolated the genes encoding the PCs synthase. This breakthrough of plant heavy metal tolerance research gave us a chance to further study the heavy metal tolerance mechanism. All the results from the reserch of PCs have a great application potential in phytoremidation. Fig 1,Ref
