Functional Characterization of a Type 4 Metallothionein Gene(CsMT4) in Cucumber
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摘要
The excess amounts of heavy metals are toxic to various physiological processes in plants.Plant metallothioneins(MTs)are low molecular weight,cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions.In this study,we characterized Cs MT4,a plant type 4 MT gene identified in a complementary DNA(cDNA)library prepared from young cucumber(Cucumis sativus)fruit.Cs MT4encodes a 90 amino acid protein with a predicted molecular mass of 9.028 kD.CsMT4 contains 17 cysteine residues in three highly conserved cysteine-rich domains.In contrast to the structures of other MTs,the highly conserved amino acid pattern CxCxxxCxCxxCxC is present in the middle of CsMT4.Furthermore,CsMT4 was markedly induced in various tissues by various concentrations of Cd~(2+)and Zn~(2+)(>1.0 mmol·L~(-1)).Similar to AtMT4b function,heterologous expression of Cs MT4 in E.coli could also improved its tolerance to Cd~(2+)and led to increased uptake of Cd~(2+),and the rate of Cd~(2+)uptake was the highest in cells expressing a phytochelatin-like peptide.Our findings demonstrate that CsMT4 might be obviously induced by the metal stress in cucumber,and improves tolerance to Cd ions but not Zn ions when heterologously expressed in E.coli,and suggest that the composition and arrangement of N-terminal Cys-residues in MT4 are associated with their binding capacity and preference for different metal ions.
The excess amounts of heavy metals are toxic to various physiological processes in plants.Plant metallothioneins(MTs)are low molecular weight,cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions.In this study,we characterized Cs MT4,a plant type 4 MT gene identified in a complementary DNA(cDNA)library prepared from young cucumber(Cucumis sativus)fruit.Cs MT4encodes a 90 amino acid protein with a predicted molecular mass of 9.028 kD.CsMT4 contains 17 cysteine residues in three highly conserved cysteine-rich domains.In contrast to the structures of other MTs,the highly conserved amino acid pattern CxCxxxCxCxxCxC is present in the middle of CsMT4.Furthermore,CsMT4 was markedly induced in various tissues by various concentrations of Cd~(2+)and Zn~(2+)(>1.0 mmol·L~(-1)).Similar to AtMT4b function,heterologous expression of Cs MT4 in E.coli could also improved its tolerance to Cd~(2+)and led to increased uptake of Cd~(2+),and the rate of Cd~(2+)uptake was the highest in cells expressing a phytochelatin-like peptide.Our findings demonstrate that CsMT4 might be obviously induced by the metal stress in cucumber,and improves tolerance to Cd ions but not Zn ions when heterologously expressed in E.coli,and suggest that the composition and arrangement of N-terminal Cys-residues in MT4 are associated with their binding capacity and preference for different metal ions.
The excess amounts of heavy metals are toxic to various physiological processes in plants.Plant metallothioneins(MTs)are low molecular weight,cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions.In this study,we characterized Cs MT4,a plant type 4 MT gene identified in a complementary DNA(cDNA)library prepared from young cucumber(Cucumis sativus)fruit.Cs MT4encodes a 90 amino acid protein with a predicted molecular mass of 9.028 kD.CsMT4 contains 17 cysteine residues in three highly conserved cysteine-rich domains.In contrast to the structures of other MTs,the highly conserved amino acid pattern CxCxxxCxCxxCxC is present in the middle of CsMT4.Furthermore,CsMT4 was markedly induced in various tissues by various concentrations of Cd~(2+)and Zn~(2+)(>1.0 mmol·L~(-1)).Similar to AtMT4b function,heterologous expression of Cs MT4 in E.coli could also improved its tolerance to Cd~(2+)and led to increased uptake of Cd~(2+),and the rate of Cd~(2+)uptake was the highest in cells expressing a phytochelatin-like peptide.Our findings demonstrate that CsMT4 might be obviously induced by the metal stress in cucumber,and improves tolerance to Cd ions but not Zn ions when heterologously expressed in E.coli,and suggest that the composition and arrangement of N-terminal Cys-residues in MT4 are associated with their binding capacity and preference for different metal ions.
引文
Ahn,Y.O.,Kim,S.H.,Lee,J.,Kim,H.,Lee,H.S.,Kwak,S.S.,2012.Three Brassica rapa metallothionein genes are differentially regulated under various stress conditions.Mol Biol Rep,39:2059-2067.
Akashi,K.,Nishimura,N.,Ishida,Y.,Yokota,A.,2004.Potent hydroxyl radical-scavenging activity of drought-induced type-2 metallothionein in wild watermelon.Biochem Biophys Res Commun,323:72-78.
Brennan,R.F.,Bolland,M.D.A.,2005.Canola takes up more cadmium and phosphorus from soil than spring wheat.J Plant Nutr,28:931-948.
Capdevila,M.,Atrian,S.,2011.Metallothionein protein evolution:a miniassay.J Biol Inorg Chem,16:977-989.
Capdevila,M.,Bofill,R.,Palacios,ò.,Atrian,S.,2012.State-of-the-art of metallothioneins at the beginning of the 21st century.Coord Chem Rev,256:46-62.
Chaturvedi,A.K.,Mishra,A.,Tiwari,V.,Jha,B.,2012.Cloning and transcript analysis of type 2 metallothionein gene(SbMT-2)from extreme halophyte Salicornia brachiata and its heterologous expression in E.coli.Gene,499:280-287.
Chen,Y.,Zhi,J.,Li,X.,Zhang,H.,Liu,H.,Xu,J.,2018.Diversity in cadmium accumulation and resistance associated with various metallothionein genes(type III)in Phytolacca americana L.Int J Biol Macromol,108:704-709.
Chen,Z.,Chen,M.,Jiang,M.,2017.Hydrogen sulfide alleviates mercury toxicity by sequestering it in roots or regulating reactive oxygen species productions in rice seedlings.Plant Physiol Biochem,111:179-192.
Cobbett,C.,Goldsbrough,P.,2002.Phytochelatins and metallothioneins:roles in heavy metal detoxification and homeostasis.Annu Rev Plant Biol,53:159-182.
Cobbett,C.S.,2000.Phytochelatins and their roles in heavy metal detoxification.Plant Physiol,123:825-832.
Coyle,P.,Philcox,J.C.,Carey,L.C.,Rofe,A.M.,2002.Metallothionein the multipurpose protein.Cell Mol Life Sci,59:627-647.
Fowler,B.A.,Hildebrand,C.E.,Kojima,Y.,Webb,M.,1987.Nomenclature of metallothionein.Experientia(Suppl),52:19.
Freisinger,E.,2011.Structural features specific to plant metallothioneins.J Biol Inorg Chem,16:1035-1045.
Gautam,K.,Hemant,K.,Vaishali,P.S.,Sumita,K.,Rohit,J.,Ratna,K.,Shweta,M.,Pareek,S.L.,Ashwani,P.,2012.Clustered metallothionein genes are co-regulated in rice and ectopic expression of Os MT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging.BMC Plant Biol,12:107.
Gu,R.,Liu,X.,Zhao,W.,Yan,S.,Sun,L.,Wu,B.,Zhang,X.,2018.Functional characterization of the promoter and second intron of CUM1during flower development in cucumber(Cucumis sativus L.).Hortic Plant J,4:103-110.
Hassinen,V.H.,Tuomainen,M.,Per?niemi,S.,Schat,H.,K?renlampi,S.O.,Tervahauta,A.I.,2009.Metallothioneins 2 and 3 contribute to the metal-adapted phenotype but are not directly linked to Zn accumulation in the metal hyperaccumulator,Thlaspi caerulescens.J Exp Bot,60:187-196.
Hegelund,J.N.,Schiller,M.,Kichey,T.,Hansen,T.H.,Pedas,P.,Husted,S.,Schjoerring,J.K.,2012.Barley metallothioneins:MT3 and MT4 are localized in the grain aleurone layer and show differential zinc binding.Plant Physiol,159:1125-1137.
Hossain,Z.,Komatsu,S.,2012.Contribution of proteomic studies towards understanding plant heavy metal stress response.Front Plant Sci,3:43-48.
Huang,G.Y.,Wang,Y.S,Ying,G.G.,2011.Cadmium-inducible Bg MT2,a type 2 metallothionein gene from mangrove species(Bruguiera gymnorrhiza),its encoding protein shows metal-binding ability.JExp Mar Biol Ecol,405:128-132.
Imam,H.T.,Blindauer,C.A.,2018.Differential reactivity of closely related zinc(II)-binding metallothioneins from the plant Arabidopsis thaliana.J Biol Inorg Chem,23:137-154.
Jin,S.,Sun,D.,Wang,J.,Li,Y.,Wang,X.,Liu,S.,2014.Expression of the rgMT gene,encoding for a rice metallothionein-like protein in Saccharomyces cerevisiae and Arabidopsis thaliana.J Genet,93:709-718.
Jin,S.,Xu,C.,Li,G.,Sun,D.,Li,Y.,Wang,X.,Liu,S.,2017.Functional characterization of a type 2 metallothionein gene,Ss MT2,from alkaline-tolerant Suaeda salsa.Sci Rep,7:17914.
Kawashima,I.,Kennedy,T.D.,Chino,M.,Lane,B.G.,2010.Wheat Ec metallothionein genes.Like mammalian Zn2+metallothionein genes,wheat Zn2+metallothionein genes are conspicuously expressed during embryogenesis.Eur J Biochem,209:971-976.
Kim,Y.O.,Patel,D.H.,Lee,D.S.,Song,Y.,Bae,H.J.,2011.High cadmium-binding ability of a novel Colocasia esculenta metallothionein increases cadmium tolerance in Escherichia coli and tobacco.Biosci Biotechnol Biochem,75:1912-1920.
Kisa,D.,Ozturk,L.,Tekin,S.,2016.Gene expression analysis of metallothionein and mineral elements uptake in tomato(Solanum lycopersicum)exposed to cadmium.J Plant Res,129:989-995.
Kohler,A.,Blaudez,D.,Chalot,M.,Martin,F.,2004.Cloning and expression of multiple metallothioneins from hybrid poplar.New Phytol,164:83-93.
Ledger,S.E.,Gardner,R.C.,1994.Cloning and characterization of five cDNAs for genes differentially expressed during fruit development of kiwifruit(Actinidia deliciosa var.deliciosa).Plant Mol Biol,25:877-886.
Leszczyszyn,O.I.,White,C.R.,Blindauer,C.A.,2010.The isolated Cys2His2site in ECmetallothionein mediates metal-specific protein folding.Mol Biosyst,6:1592-1603.
Leszczyszyn,O.I.,Imam,H.T.,Blindauer,C.A.,2013.Diversity and distribution of plant metallothioneins:a review of structure,properties and functions.Metallomics,5:1146-1169.
Li,Y.,Chen,Y.Y.,Yang,S.G.,Tian,W.M.,2015.Cloning and characterization of HbMT2a,a metallothionein gene from Hevea brasiliensis Muell.Arg differently responds to abiotic stress and heavy metals.Biochem Biophys Res Commun,461:95-101.
Loebus,J.,Peroza,E.A.,Blüthgen,N.,Fox,T.,Meyer-Klaucke,W.,Zerbe,O.,Freisinger,E.,2011.Protein and metal cluster structure of the wheat metallothionein domainγ-Ec-1:the second part of the puzzle.J Biol Inorg Chem,16:683-694.
Margoshes,M.,Valiee,B.L.,1957.A cadmium protein from equine kidney cortex.J Am Chem Soc,79:4813-4814.
Mierek-Adamska,A.,D?abrowska,G.B.,Blindauer,C.A.,2018.The type4 metallothionein from Brassica napus seeds folds in a metal-dependent fashion and favours zinc over other metals.Metallomics,3.
Nezhad,R.M.,Shahpiri,A.,Mirlohi,A.,2013.Discrimination between two rice metallothionein isoforms belonging to type 1 and type 4 in metal-binding ability.Biotechnol Appl Biochem,60:275-282.
Pan,Y.,Pan,Y.,Zhai,J.,Xiong,Y.,Li,J.,Du,X.,Su,C.,Zhang,X.,2016.Cucumber metallothionein-like 2(CsMTL2)exhibits metal-binding properties.Genes,7:106.
Pilonsmits,E.A.H.,Zhu,Y.L.,Sears,T.,Terry,N.,2000.Overexpression of glutathione reductase in Brassica juncea:effects on cadmium accumulation and tolerance.Physiol Plant,110:455-460.
Ren,Y.,Liu,Y.,Chen,H.,Li,G.,Zhang,X.,Zhao,J.,2012.Type 4 metallothionein genes are involved in regulating Zn ion accumulation in late embryo and in controlling early seedling growth in Arabidopsis.Plant Cell Environ,35:770-789.
Rodríguez-Llorente,I.D.,Pérez-Palacios,P.,Doukkali,B.,Caviedes,M.A.,Pajuelo,E.,2010.Expression of the seed-specific metallothionein mt4a in plant vegetative tissues increases Cu and Zn tolerance.Plant Sci,178:327-332.
Sekhar,K.,Priyanka,B.,Reddy,V.D.,Rao,K.V.,2011.Metallothionein1(CcMT1)of pigeonpea(Cajanus cajan L.)confers enhanced tolerance to copper and cadmium in Escherichia coli and Arabidopsis thaliana.Environ Exp Bot,72:131-139.
Sereno,M.L.,Almeida,R.S.,Nishimura,D.S.,Figueira,A.,2007.Response of sugarcane to increasing concentrations of copper and cadmium and expression of metallothionein genes.J Plant Physiol,164:1499-1515.
Singlapareek,S.L.,Yadav,S.K.,Pareek,A.,Reddy,M.K.,Sopory,S.K.,2006.Transgenic tobacco overexpressing glyoxalase pathway enzymes grow and set viable seeds in zinc-spiked soils.Plant Physiol,140:613-623.
Tang,L.,Qiu,R.,Tang,Y.,Wang,S.,2014.Cadmium-zinc exchange and their binary relationship in the structure of Zn-related proteins:a mini review.Metallomics,6:1313-1323.
Tomas,M.,Pagani,M.A.,Andreo,C.S.,Capdevila,M.,Bofill,R.,Atrian,S.,2014.His-containing plant metallothioneins:comparative study of divalent metal-ion binding by plant MT3 and MT4 isoforms.J Biol Inorg Chem,19:1149-1164.
White,C.N.,Rivin,C.J.,1995.Characterization and expression of a cDNA encoding a seed-specific metallothionein in maize.Plant Physiol,108:831-832.
Yang,C.,Wang,L.,Jiang,Q.,Wang,J.,Yue,F.,Zhang,H.,Sun,Z.,Song,L.,2013.The polymorphism in the promoter region of metallothionein 1 is associated with heat tolerance of scallop Argopecten irradians.Gene,526:429-436.
Yang,M.,Zhang,F.,Wang,F.,Dong,Z.,Cao,Q.,Chen,M.,2015.Characterization of a type 1 metallothionein gene from the stresses-tolerant plant Ziziphus jujuba.Int J Mol Sci,16:16750-16762.
Yang,Z.,Wu,Y.,Li,Y.,Ling,H.Q.,Chu,C.,2009.OsMT1a,a type 1 metallothionein,plays the pivotal role in zinc homeostasis and drought tolerance in rice.Plant Mol Biol,70:219-229.
Zhou,B.,Yao,W.,Wang,S.,Wang,X.,Jiang,T.,2014.The metallothionein gene,TaMT3,from Tamarix androssowii confers Cd2+tolerance in tobacco.Int J Mol Sci,15:10398-10409.
Zhou,Y.,Chu,P.,Chen,H.,Li,Y.,Liu,J.,Ding,Y.,Tsang,E.W.T.,Jiang,L.,Wu,K.,Huang,S.,2012.Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis.Planta,235:523-537.
Akashi,K.,Nishimura,N.,Ishida,Y.,Yokota,A.,2004.Potent hydroxyl radical-scavenging activity of drought-induced type-2 metallothionein in wild watermelon.Biochem Biophys Res Commun,323:72-78.
Brennan,R.F.,Bolland,M.D.A.,2005.Canola takes up more cadmium and phosphorus from soil than spring wheat.J Plant Nutr,28:931-948.
Capdevila,M.,Atrian,S.,2011.Metallothionein protein evolution:a miniassay.J Biol Inorg Chem,16:977-989.
Capdevila,M.,Bofill,R.,Palacios,ò.,Atrian,S.,2012.State-of-the-art of metallothioneins at the beginning of the 21st century.Coord Chem Rev,256:46-62.
Chaturvedi,A.K.,Mishra,A.,Tiwari,V.,Jha,B.,2012.Cloning and transcript analysis of type 2 metallothionein gene(SbMT-2)from extreme halophyte Salicornia brachiata and its heterologous expression in E.coli.Gene,499:280-287.
Chen,Y.,Zhi,J.,Li,X.,Zhang,H.,Liu,H.,Xu,J.,2018.Diversity in cadmium accumulation and resistance associated with various metallothionein genes(type III)in Phytolacca americana L.Int J Biol Macromol,108:704-709.
Chen,Z.,Chen,M.,Jiang,M.,2017.Hydrogen sulfide alleviates mercury toxicity by sequestering it in roots or regulating reactive oxygen species productions in rice seedlings.Plant Physiol Biochem,111:179-192.
Cobbett,C.,Goldsbrough,P.,2002.Phytochelatins and metallothioneins:roles in heavy metal detoxification and homeostasis.Annu Rev Plant Biol,53:159-182.
Cobbett,C.S.,2000.Phytochelatins and their roles in heavy metal detoxification.Plant Physiol,123:825-832.
Coyle,P.,Philcox,J.C.,Carey,L.C.,Rofe,A.M.,2002.Metallothionein the multipurpose protein.Cell Mol Life Sci,59:627-647.
Fowler,B.A.,Hildebrand,C.E.,Kojima,Y.,Webb,M.,1987.Nomenclature of metallothionein.Experientia(Suppl),52:19.
Freisinger,E.,2011.Structural features specific to plant metallothioneins.J Biol Inorg Chem,16:1035-1045.
Gautam,K.,Hemant,K.,Vaishali,P.S.,Sumita,K.,Rohit,J.,Ratna,K.,Shweta,M.,Pareek,S.L.,Ashwani,P.,2012.Clustered metallothionein genes are co-regulated in rice and ectopic expression of Os MT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging.BMC Plant Biol,12:107.
Gu,R.,Liu,X.,Zhao,W.,Yan,S.,Sun,L.,Wu,B.,Zhang,X.,2018.Functional characterization of the promoter and second intron of CUM1during flower development in cucumber(Cucumis sativus L.).Hortic Plant J,4:103-110.
Hassinen,V.H.,Tuomainen,M.,Per?niemi,S.,Schat,H.,K?renlampi,S.O.,Tervahauta,A.I.,2009.Metallothioneins 2 and 3 contribute to the metal-adapted phenotype but are not directly linked to Zn accumulation in the metal hyperaccumulator,Thlaspi caerulescens.J Exp Bot,60:187-196.
Hegelund,J.N.,Schiller,M.,Kichey,T.,Hansen,T.H.,Pedas,P.,Husted,S.,Schjoerring,J.K.,2012.Barley metallothioneins:MT3 and MT4 are localized in the grain aleurone layer and show differential zinc binding.Plant Physiol,159:1125-1137.
Hossain,Z.,Komatsu,S.,2012.Contribution of proteomic studies towards understanding plant heavy metal stress response.Front Plant Sci,3:43-48.
Huang,G.Y.,Wang,Y.S,Ying,G.G.,2011.Cadmium-inducible Bg MT2,a type 2 metallothionein gene from mangrove species(Bruguiera gymnorrhiza),its encoding protein shows metal-binding ability.JExp Mar Biol Ecol,405:128-132.
Imam,H.T.,Blindauer,C.A.,2018.Differential reactivity of closely related zinc(II)-binding metallothioneins from the plant Arabidopsis thaliana.J Biol Inorg Chem,23:137-154.
Jin,S.,Sun,D.,Wang,J.,Li,Y.,Wang,X.,Liu,S.,2014.Expression of the rgMT gene,encoding for a rice metallothionein-like protein in Saccharomyces cerevisiae and Arabidopsis thaliana.J Genet,93:709-718.
Jin,S.,Xu,C.,Li,G.,Sun,D.,Li,Y.,Wang,X.,Liu,S.,2017.Functional characterization of a type 2 metallothionein gene,Ss MT2,from alkaline-tolerant Suaeda salsa.Sci Rep,7:17914.
Kawashima,I.,Kennedy,T.D.,Chino,M.,Lane,B.G.,2010.Wheat Ec metallothionein genes.Like mammalian Zn2+metallothionein genes,wheat Zn2+metallothionein genes are conspicuously expressed during embryogenesis.Eur J Biochem,209:971-976.
Kim,Y.O.,Patel,D.H.,Lee,D.S.,Song,Y.,Bae,H.J.,2011.High cadmium-binding ability of a novel Colocasia esculenta metallothionein increases cadmium tolerance in Escherichia coli and tobacco.Biosci Biotechnol Biochem,75:1912-1920.
Kisa,D.,Ozturk,L.,Tekin,S.,2016.Gene expression analysis of metallothionein and mineral elements uptake in tomato(Solanum lycopersicum)exposed to cadmium.J Plant Res,129:989-995.
Kohler,A.,Blaudez,D.,Chalot,M.,Martin,F.,2004.Cloning and expression of multiple metallothioneins from hybrid poplar.New Phytol,164:83-93.
Ledger,S.E.,Gardner,R.C.,1994.Cloning and characterization of five cDNAs for genes differentially expressed during fruit development of kiwifruit(Actinidia deliciosa var.deliciosa).Plant Mol Biol,25:877-886.
Leszczyszyn,O.I.,White,C.R.,Blindauer,C.A.,2010.The isolated Cys2His2site in ECmetallothionein mediates metal-specific protein folding.Mol Biosyst,6:1592-1603.
Leszczyszyn,O.I.,Imam,H.T.,Blindauer,C.A.,2013.Diversity and distribution of plant metallothioneins:a review of structure,properties and functions.Metallomics,5:1146-1169.
Li,Y.,Chen,Y.Y.,Yang,S.G.,Tian,W.M.,2015.Cloning and characterization of HbMT2a,a metallothionein gene from Hevea brasiliensis Muell.Arg differently responds to abiotic stress and heavy metals.Biochem Biophys Res Commun,461:95-101.
Loebus,J.,Peroza,E.A.,Blüthgen,N.,Fox,T.,Meyer-Klaucke,W.,Zerbe,O.,Freisinger,E.,2011.Protein and metal cluster structure of the wheat metallothionein domainγ-Ec-1:the second part of the puzzle.J Biol Inorg Chem,16:683-694.
Margoshes,M.,Valiee,B.L.,1957.A cadmium protein from equine kidney cortex.J Am Chem Soc,79:4813-4814.
Mierek-Adamska,A.,D?abrowska,G.B.,Blindauer,C.A.,2018.The type4 metallothionein from Brassica napus seeds folds in a metal-dependent fashion and favours zinc over other metals.Metallomics,3.
Nezhad,R.M.,Shahpiri,A.,Mirlohi,A.,2013.Discrimination between two rice metallothionein isoforms belonging to type 1 and type 4 in metal-binding ability.Biotechnol Appl Biochem,60:275-282.
Pan,Y.,Pan,Y.,Zhai,J.,Xiong,Y.,Li,J.,Du,X.,Su,C.,Zhang,X.,2016.Cucumber metallothionein-like 2(CsMTL2)exhibits metal-binding properties.Genes,7:106.
Pilonsmits,E.A.H.,Zhu,Y.L.,Sears,T.,Terry,N.,2000.Overexpression of glutathione reductase in Brassica juncea:effects on cadmium accumulation and tolerance.Physiol Plant,110:455-460.
Ren,Y.,Liu,Y.,Chen,H.,Li,G.,Zhang,X.,Zhao,J.,2012.Type 4 metallothionein genes are involved in regulating Zn ion accumulation in late embryo and in controlling early seedling growth in Arabidopsis.Plant Cell Environ,35:770-789.
Rodríguez-Llorente,I.D.,Pérez-Palacios,P.,Doukkali,B.,Caviedes,M.A.,Pajuelo,E.,2010.Expression of the seed-specific metallothionein mt4a in plant vegetative tissues increases Cu and Zn tolerance.Plant Sci,178:327-332.
Sekhar,K.,Priyanka,B.,Reddy,V.D.,Rao,K.V.,2011.Metallothionein1(CcMT1)of pigeonpea(Cajanus cajan L.)confers enhanced tolerance to copper and cadmium in Escherichia coli and Arabidopsis thaliana.Environ Exp Bot,72:131-139.
Sereno,M.L.,Almeida,R.S.,Nishimura,D.S.,Figueira,A.,2007.Response of sugarcane to increasing concentrations of copper and cadmium and expression of metallothionein genes.J Plant Physiol,164:1499-1515.
Singlapareek,S.L.,Yadav,S.K.,Pareek,A.,Reddy,M.K.,Sopory,S.K.,2006.Transgenic tobacco overexpressing glyoxalase pathway enzymes grow and set viable seeds in zinc-spiked soils.Plant Physiol,140:613-623.
Tang,L.,Qiu,R.,Tang,Y.,Wang,S.,2014.Cadmium-zinc exchange and their binary relationship in the structure of Zn-related proteins:a mini review.Metallomics,6:1313-1323.
Tomas,M.,Pagani,M.A.,Andreo,C.S.,Capdevila,M.,Bofill,R.,Atrian,S.,2014.His-containing plant metallothioneins:comparative study of divalent metal-ion binding by plant MT3 and MT4 isoforms.J Biol Inorg Chem,19:1149-1164.
White,C.N.,Rivin,C.J.,1995.Characterization and expression of a cDNA encoding a seed-specific metallothionein in maize.Plant Physiol,108:831-832.
Yang,C.,Wang,L.,Jiang,Q.,Wang,J.,Yue,F.,Zhang,H.,Sun,Z.,Song,L.,2013.The polymorphism in the promoter region of metallothionein 1 is associated with heat tolerance of scallop Argopecten irradians.Gene,526:429-436.
Yang,M.,Zhang,F.,Wang,F.,Dong,Z.,Cao,Q.,Chen,M.,2015.Characterization of a type 1 metallothionein gene from the stresses-tolerant plant Ziziphus jujuba.Int J Mol Sci,16:16750-16762.
Yang,Z.,Wu,Y.,Li,Y.,Ling,H.Q.,Chu,C.,2009.OsMT1a,a type 1 metallothionein,plays the pivotal role in zinc homeostasis and drought tolerance in rice.Plant Mol Biol,70:219-229.
Zhou,B.,Yao,W.,Wang,S.,Wang,X.,Jiang,T.,2014.The metallothionein gene,TaMT3,from Tamarix androssowii confers Cd2+tolerance in tobacco.Int J Mol Sci,15:10398-10409.
Zhou,Y.,Chu,P.,Chen,H.,Li,Y.,Liu,J.,Ding,Y.,Tsang,E.W.T.,Jiang,L.,Wu,K.,Huang,S.,2012.Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis.Planta,235:523-537.