Crop genomic related with heavy metal toxicity
菜豆多聚泛肽基因在重金属胁迫下的表达_英文_
菜豆多聚泛肽基因在重金属胁迫下的表达_英文_ () 植物学报 1999 , 41 10:1052,1057Acta B ota nica Si nicaΞ菜豆多聚泛肽基因在重金属胁迫下的表达柴团耀张玉秀( )中国科学技术大学研究生院生物部北京 100039( ) 摘要差别筛选 HgCl胁迫的菜豆 Phaseolus vulgaris L . 幼苗叶片 cDNA 库 , 分离出两个重金属胁迫相应基因 2 ( ) PvS R5 和 PvS R51 Phaseolus vulgaris stress- related gene片段。
cDNA 和氨基酸序列分析表明 PvS R5 和 PvS R51 分别编码一种多聚泛肽。
Northern blot 分析表明多聚泛肽是组成性表达蛋白 ,主要在根中表达 ,叶片和茎中表达较少 ; Hg 、Cd 、Cu 和 Zn 等重金属、高温和水杨酸能强烈地刺激其在叶片中的表达 ,而受伤几乎没有影响。
推测多聚泛肽在抵抗重金属胁迫和提高植物的抗逆性方面有重要作用。
关键词重金属 ,多聚泛肽 ,菜豆Expression Analysis of Polyubiquitin Genes from BeanΞ in Response to Heavy MetalsCHAI Tuan- Yao ZHANG Yu- Xiu( )Department of Biology , Graduate School of University of Science and Technology of China , The Chinese Academy of Sciences , Beijing 100039( Abstract Using differential screening of a leaf cDNA library prepared from a bean cultivar Phaseolus vul2) garis L . cv. Saxaexposed to HgCl, the authors have isolated and characterized two heavy metal- regulated 2( ) cDNA fragments , designated as PvS R5 and PvS R51 Phaseolus vulgaris stress- related gene. The sequencesof the cDNA inserts and homological analysis showed that both PvS R5 and PvS R51 encode a polyubiquitin re2spectively. The polyubiquitin genes were constitutively expressed in roots but weakly expressed in stems andleaves. Northern blot analysis revealed a low level of transcripts of polyubiquitin in unstressed bean leaves , butthe gene expression was strongly stimulated by heavy metals , elevated temperature and salicylic acid , whereaswounding had almost no effect . These suggested that polyubiquitin might play important roles in resistance toheavy metals and various environmental stresses.Key words Heavy metals ,Polyubiquitin , Phaseolus vulgarisUbiquitin is a 76 amino acid protein highly con2 mal protein , the ubiquitin- dependent pathway controls the served in all eukaryotes. The ubiquitins are encoded by levels of many key cell regulators , i . e . phytochrome andcyclin. So it plays major roles in various biological pro2 two different gene families , polyubiquitin genes and ubiq2 1 ,2 ) ( uitinextension protein genes UbEP . Polyubiquitin cesses, including DNArepair , transcription , signaltransduction , the cell cycle control , apoptosis and stress genes contain several direct repeats of the ubiquitin codingunit . UbEP genes contain a single ubiquitin coding unit responses. The expression of polyubiquitin genes can be 3 ,4 fused in frame to the coding region for a small protein as2 enhanced by HgClin maize and tobacco , we report 2sociated with ribosomes. Ubiquitin monomer in the cyto2 here the identification and characterization of polyubiqui2 plasm can be covalently attached to other proteins via a tin cDNA from bean and gene expression in response toheavy metals. Furthermore , the mechanism of plant resis2 multistep enzymatic process. The linkage occurs at specif2tance to heavy metals is discussed. ic lysine residues of the acceptor protein with formation ofan isopeptide bond between the carboxyl group of the C- 1 Materials and Methods εterminal glycine of ubiquitin and- NHgroup s of the ly2 2 sine side- chains of the target protein. The conjugation of 111Plant materials and stress conditions ubiquitin to protein may alter their stability or serve as a ( ) Bean Phaseolus vulgaris L . cv. Saxaseeds were recognition signal for proteolysis by the 26 S proteo2 surface- sterilized with a 2 . 5 % calcium hypochloride solu2 1 some .In addition to removing the denatured or abnor2 tion for 10 min , rinsed several times with distilled water() Ξ Supported by the“863”Grant for Youth and the NationalNatural Science Foundation of China No . 39870078. Received : 1999- 01- 14 Revised : 1999- 05- 16and then imbibed in sterile water for 16 h. Germination signal with the control probe . The two clones were sub2 ?after which the young plants were trans2 occurred at 22 ( ) cloned into pBluescript KS + plasmid vector and se2 ferred onto a liquid culture medium containing KNO2 3 quenced by the dideoxy method.( ) mmol/ L , Ca NO2 . 5 mmol/ L , MgSO1 mmol/ L , 3 2 4 113Northern blot analysisKHPO1 mmol/ L and Fe 2 . 8 mg/ L , Mn 0 . 55 mg/ L , 2 4 RNA samples were prepared and analyzed according 6 Zn 0 . 65 mg/ L , Cu 0 . 06 mg/L , B 0 . 32 mg/ L , Mo 0 . to standard protocols, by electrophoresis on 1 . 2 % a2 02 mg/ L . Plants were grown in a growth chamber with a garose-formaldehyde gels , transferring onto Hybond N photoperiod of 16 h at 22 ? during the day and 18 ? membranes , and hybridizing for 24 hin the presence of 6 during the night and a photosynthetic photon flux density ( ×SSC 1 ×SSC : NaCl 0 . 15 mol/ L , CHNaO0 . 15 6 537 32 - 2 - 1 ) μmol/ L- 50 % formamide at 42 ? to P- cDNA probes. When the two primary leaves of 150 mol m? s? .Hybridization was followed by three washes for 15 min were well expanded , plants were stressed by adding one ofeach at 42 ?in 2 ×SSC. Finally , the membrane was ex2the following metals : HgCl, CdCl, CuSOor ZnSOat a 2 2 4 4μposed to X- ray film for autoradiography at - 80 ?.final concentration of 100mol/ L . For other experiments() plants were grown in plots in soilunder the same light- 2 Results dark and temperature conditions. Various types of abiotic PvSR51 encode a polyubiquitin re2 2 . 1 PvSR5 and stress were applied asfollows : leaves were sprayed with a spectively ( ) 0 . 2 % W/ VHgClor CdCl, or 10 mmol/ L salicylic 2 2 analysis showed that PvS R5 clone con2 Sequence ( ) acid SA solution. For heat- shock treatment , plants ( ) tained a 790 bp insert Fig. 1A. Northern blot revealed were placed at42 ? for 4 h , while wounding was per2 7 that PvS R5 mRNA has a size of 1 200 nucleotides, in2 formed by dusting the leaves with celite and gentle rub2 dicating that the cDNA was not full- length. PvS R5 cDNA bing. Leaf tissue was harvested at various time points after contains more than two repeats of ubiquitin coding unit stress treatment . and lacks the 5′end coding sequence , leucine which is 2 bean cD NA li12 Construction and screening of a 1unique non- ubquitin residue at the end of the last ubiqui2 brary tin repeat . Total RNA extraction was done using the phenol/ PvS R51 cDNA is also partial fragment that lacks the 5 chloroform/ isoamylalcohol technique. Polyadenylated 5′coding region.It encodes more than four ubiquitin re2mRNAs were obtained by chromatographing total RNA peats , the terminal repeat contains another additional ( ) twice on oligo- dTcellulose as described by Sambrook ( )amino acid , phenylalanine Fig. 1B. Repeats of 228 nu2 6 et al . Double- stranded cDNA was synthesized from cleotides encoding ubiquitin monomers were aligned below polyadenylated RNA isolated from bean plantsharvested 6 the first complete one taken as an arbitrary reference . Ho2 h after spraying with mercuric choloride solution using the mologies were found to range between 80 % to 90 %. Pharmacia Biotech kit . The cDNA library was constructed There are no homologies in the3′untranslated region be2 λin the bacteriophagegt 10 cloning vector . tween PvS R5 and PvS R51 genes. Therefore , PvS R51 en2 The cDNA clones were placed at a density of about codes a polyubiquitin that isdifferent from PvS R5 . ( ) 1 000 plaques/ dish diameter 9 cm. Duplicate sets of 2 . 2 Expression of PvSR5 gene in various tissues of nitrocellulose filters containing recombinant phage plaques young bean plants 32 were screened with [ P - labelled cDNA probes , pre2 PvS R5 gene is highly expressed in root but weakly pared of using polyadenylated RNAs extracted from mer2 ( ) expressed in stems and leaf tissue Fig. 2. The same curic chloride- treated or untreated bean leaves. Differen2 ( pattern was observed on PvS R51 gene results not tial screening permitted the isolation of clones that were ) shown, demonstrating that polyubiquitin genes are con2 only expressed in mercury- treated plants or that were ex2 stitutively expressed in different tissues. pressed at higher levels in stressed plants than in control PvS R5 gene expres2 Effect of heavy metals on 2 . 3 plants. Both types of clones were considered to be heavy- sion in primary leaves( metal stress- related. 32 positive clones Phaseolus vul2 Theexpression of polyubiquitin gene was studied in ) garis stress- related gene , PvS R were isolated by screen2 response to several metal stresses. More than one hy2 ing of the cDNA library , in which PvS R5 and PvS R51 bridization signals are observed in Fig. 3 , as PvS R5 clones gave a strong hybridization signal with the cDNA probe contains partialubiquitin coding sequence that is probe obtained from mercury- treated plants and a weak植物学报 1054 41 卷() ()Fig. 1 Nucleotide sequence and deduced amino acid sequence of PvS R5 cDNA Aand PvS R51 cDNA B A. The initiation amino acid of the ubiquitin repeats is boxed , asterisk indicates the stop codon. GenBank access number for PvS R5 is U77940. B. The stop codon is indicated by an asterisk and the putative polyadenylation signal is underlined.Nucleotide sequences of the ubiq2 uitin repeats are aligned. Identical nucleotides are indicated by dots. Amino acid sequences are given in the one- letter code below the last u2 biquitin repeat . GenBank access number for PvS R51 is U77939.levels in the leaves , but with a different kinetics of induc2tion from that obtained with sprayed leaves. When mer2curic chloride was absorbed by the roots , PvS R5 mRNAstarted to accumulate at 9 h after the onset of treatment ,( ) reached a maximum at 48 h and then declined Fig. 3C.The transcript level continued to increase from 9 h afterthe onset of treatment until a maximum was reached 48 h( ) later when cadmium was absorbed by the roots Fig. 3D. Root- absorbed copper also stimulated the PvS R5 expres2 Fig. 2 PvS R5 gene expression in various tissues of Phaseolus vul2 garis seedlings sion , the transcripts reached a maximum after 24 h , ( μ) Total RNAs 10 g/ laneextracted from the various tissues of 12( ) whereas zinc had alittle effect Fig. 3 E , F. day-old plants were separated on formaldehyde- agarose gels , trans2 2 . 4 PvSR5 gene regulation by otherf orms of a biotic ferred onto membranes and hybridized with PvS R5 cDNA. R. Root ;S. Stem ; L . Primary leaves. stress Spraying with SA resulted in a large increase in tran2 highly homologous to the other ubiquitin gene . As shown script levels , reached a maximum at 3 h and then de2 in Fig.3A and 3B , the amounts of PvS R5 transcripts in2 ) ( ) (clined Fig. 4A. High temperature 42 ?also stimu2 creased rapidly , reached a maximum at3 h and then de2 ( ) lated strongly PvS R5 gene expression Fig. 4B, PvSR5 creased gradually when the leaves were sprayed with mer2 ( mRNA reached a maximum at 1 h during the stress 4 curic chloride or cadmium chloride solution. When the ) h, and then decreased after plants were returned to nor2 mercuric chloride or cadmium chloride was added to the mal temperature condition. Wounding had almost no effect liquid culture medium instead of being sprayed onto the ( ) PvS R5 gene expression Fig. 4C. on plants , PvS R5 mRNA also accumulated above the basalFig. 3 Northern blots analysis showing the levels of PvS R5 mRNA in bean leaves treated with various metals () () The time course of accumulation of PvS R5 transcripts after the seedlings were treated byvaporization of HgClAand CdClB, or by root- 2 2 ( ) () ( ) ( ) absorption of HgClC, CdClD, CuSOE, and ZnSOF. 2 2 4 4encode a polyubiquitin respectively. Both PvS R5 and 3 Discussion PvS R51 cDNA are incomplete at their 5′end probablySequence analysis showed that PvS R5 and PvS R51 because of inverted repeats in coding regions of ubiquitin genes contained more than two repeats of the ubiquitin mRNAs forming snap back loop structures which are self- 4 coding unit . The additional amino acid residues of both primed during cDNA synthesis. PvS R5 mRNA prefer2 genes encoded are different , PvS R5 terminates at entially accumulated in the root of bean seedling indicat2 leucine , whereas the phenylalanine is found at the C- ter2 ing that polyubiquitin gene has tissue- specific expression. minal of PvS R5 , suggesting that PvS R5 and PvS R51植物学报 1056 41 卷stimulate the expression of PvS R5 , but Cu and Zn had a( ) little effect Fig. 3, demonstrating that Hg and Cd ions are more toxic than Cu and Zn to living cell .PvS R5 gene responds not only to heavy metals , butalso to other stresses such as elevated temperature , 13 12 and virus infection, indicating that the ubiqui2 UVtin pathway has important roles in eliminating the damagedproteins induced by various stresses and maintaining thecell structure and function. Transgenic rice experimentsshowed that polyubiquitin gene expression was limited tothe region exposed to heat stress and/ or wounding , oraround the necrotic lesion induced by pathogen infection , 14 but rather not regulated systemically. This implied thatpolyubiquitins have key roles in the processes of the localdefence reaction. SA is a natural signal in the inductionof defense responses , which accumulates upon ozone or 15 Fig. 4 Northern blot analysis showing the time course of PvS R5 UV treatment , as well as pathogen attack. Exogenous accumulation in bean leaves under various abiotic stresses SA can positively regulate the gene expression of PvS R5 , The arrow on panel B indicates the transfer of the stressed plants to leading to the conclusion that SA might be involved in the normal growth conditions and the time points behind the arrows the duration of recovery. A. Salicylic acid ; B. Heat stress ; C. pathway of polyubiquitin mRNA synthesis in response to Wounding. 16 stresses. Chen et al . proposed that systemically ac2quired resistance signaling is mediated by an accumulation PvS R5 transcripts was detected in un2 A low level ofof HO, because SA specifically binds to catalase and ( ) stressed bean leaves Fig. 3, but the gene expression was 22 2 + 2 + inhibits its activity , leading to an elevation of HOlevel . ( 22 strongly stimulated by heavy metals Hg, Cdand 2 + Furthermore , HOinduces expression of defense- related 22 ) Cu. The datum is consistent with the responses of genes. A rapid and transient release of active oxygen polyubiquitin genes to mercuric stress in maize and tobac2 9 3 ,4 () species AOScan be induced by heavy metals, UV , , suggesting that polyubiquitin may playan impor2 co 16 17 pathogen infection, SA and heat stress. These re2tant role in resistance to heavy metals. Heavy metal ions sults suggest that PvS R5 gene expression was possibly in2 can bind to protein sulfhydryl group s , leading to deficien2volved in the regulation of AOS in response to stresses , cy of essential ions and destruction of the enzyme struc2 8 ,9 and there may be a common signal transduction pathway ture . Other toxicity mode is oxidative damage by free 9 ,10for various stresses in the regulation of PvS R5 gene ex2 radicals generated by metal redox cycling . Eventual2 pression. ly , the two processes result in accumulating huge amount of denatured and damaged proteins by metals in the cell .References In eukaryotes , an important selective proteolysis pathway for the elimination of abnormal proteins that are generated Belknap W R , Garbarino J E. The role of ubiquitin in plant 1 senescence and stress responses. Trends Plant Sci , 1996 , 1 : under normal or stress conditions is ATP- dependent and 2 331,335 mediated by ubiquitin system. The ubiquitin monomers generated by UbEP genes act as a molecular“chaperone” Tanaka K. Proteasones : Structure and biology. J Biochem , 21998 , 123 : 195,204in facilitating ribosome assembly. In contrast , the polyu2 Didierjean L , Frendo P , Nasser W , Geneviève G , Marivet J , 3 biquitin genes would provide monomers for general utiliza2 Burkard G. Heavy metal- responsive genes in maize : Identifi2 1 ,2 tion inubiquitin- mediated processes in cell. In cation and comparison of theirexpression upon various forms of yeast , the expressions ofpolyubiquitin and ubiquitin- con2 abiotic stress. Planta , 1996 , 199 : 1,8jugating enzyme genes are activated in response to cadmi2 4 Genschik P , Parmentier Y , Durr A , Marbach J , Criqui M C.um exposure and the mutants deficient in specific ubiqui2 Ubiquitin genes are differentially expressed in protoplast- de2rived cultures of Nicotiana sylvestris and in response to varioustin- conjugating enzymes are hypersensitive to cadmium , stresses. Plant Mol Biol , 1992 , 20 : 897,910 proposed that cadmium resistance is meditated partially by 11 Ragueh F , Lescure N , Roby D , Marco Y. Gene expression in 5 ubiquitin pathway. PvS R5 mRNA levels are increased Nicotiana tabacum in response to compatible and incompatible upon treatment with metals , implying that enormous ubiq2 isolates of Pseudomonas solanacearum . Physiol Mol Plant uitin monomers are required for degrading the abnormal Pathol , 1989 , 35 : 23,33 proteins produced by metals. Hg and Cd can strongly 6 Sambrook J , Fritsch E F , Maniatis T. Molecular Cloning : A() ()Laboratory Manual . 2nd ed. New York : Cold Spring Harbor 生物物理学报,1998 , 14 : 767,771 in Chinese() ( ) 13 Zhang Y- X张玉秀, Chai T- Y柴团耀. Effects of alfalfa Laboratory Press , 1989.) ( ) ( 7 柴团耀 , Zhang Y- X 张玉秀 , Burkard G. Chai T- Y mosaic virus infection on the expression of stress- responsiveHeavy metal- responsive genes in bean : cloning of cDNAs and ()genes in bean. Acta Hort Sin 园艺学报,1998 , 25 : 399,(()gene expression analysis. Acta Phytophysiol Sin 植物生理学 401 in Chinese ) ()14 Takimoto I , Christensen A H , Quail P H , Uchimiya H , Toki 报, 1998 , 24 : 399,404 in ChineseS. Non- systemic expression of a stress- responsive maize polyu2 8 Van Assche F , Clijsters H. Effects of metal on enzyme activity in plants. Plant Cell Environ , 1990 , 13 : 195,206 () biquitin gene Ubi-1in transgenic rice plants. Plant Mol Bi2 ( ) ( ) Zhang Y- X 张玉秀 , Chai T- Y 柴团耀 , Burkard G. ol , 1994 , 26 : 1007,1012 9 (Heavymetal tolerance mechanisms in plants. Acta B ot Sin 植 Ec Key- Kaltenbach H , Kiefer E , Grosskopf E , Ernst D , San2 15 ) ()物学报, 1999 , 41 : 453,457 in Chinese dermann H. Differential transcript induction of parsley patho2 González A , Steffen K L , Lynch J P. Light and excess man2genesis- related proteins and of a small heat shockprotein by o2 10 ganese implications for oxidative stress in common bean. Plant zone and heat shock. Plant Mol Biol , 1997 , 33 : 343,350 Physiol , 1998 , 118 : 493,50816 Chen Z , Silva H , Klessig D F. Active oxygen species in the J ungmann J , Reins H A , Schobert C , J entsch S. Resistance to 11 induction of plant systemic acquired resistance by salicylic cadmium mediated by ubiquitin- dependent proteolysis. N a2 acid. Science , 1993 , 262 : 1883,1886 ture , 1993 , 361 : 369,371 17Dat J F , Lopez- Delgado H , Foyer C H , Scott I M. Parallel () () (Chai T- Y柴团耀, Zhang Y- X张玉秀, Zhang Z- D 张正 changes in HOand catalaseduring thermotolerance induced 12 22 ) 东. Effects of elevated ultraviolet radiation on the stress- re2 by salicylic acid or heat acclimation in mustard seedlings. sponsive gene expression of bean seedling. Acta Biophys Sin Plant Physiol , 1998 , 116 : 1351,1357。
利用作物生长模型和时序信号甄别水稻镉胁迫
第37卷第4期农业工程学报 V ol.37 No.42021年2月Transactions of the Chinese Society of Agricultural Engineering Feb. 2021 249 利用作物生长模型和时序信号甄别水稻镉胁迫孔丽，刘美玲※，刘湘南，邹信裕（中国地质大学（北京）信息工程学院，北京 100083）摘要：在自然农田生态系统中，农作物的生长通常受到各类环境胁迫（如重金属胁迫、病虫害、水分、营养）的影响，如何区分重金属胁迫与其他胁迫有待进一步研究。
该研究选取了湖南省株洲为试验区，收集2017—2019年的Sentinel-2卫星影像数据，结合野外实测数据，开展水稻重金属镉（Cd）胁迫识别研究。
首先，利用作物生长模型World Food Studies （WOFOST）同化时序遥感数据获取每年的叶面积指数（Leaf Area Index，LAI）时间序列曲线；然后运用集合经验模态分解（Ensemble Empirical Mode Decomposition，EEMD）方法对LAI时间序列进行多尺度分解，得到不同的时序信号分量（Intrinsic Mode Function，IMF）；最后使用动态时间规整（Dynamic Time Warping，DTW）方法计算受胁迫水稻分解后的时间序列与健康水稻分解后的时间序列之间的DTW距离，即归一化胁迫指数。
结果表明：归一化胁迫指数是水稻重金属胁迫敏感的参数，与土壤重金属含量的相关系数为0.851，水稻受到的胁迫程度越高，归一化胁迫指数值越大，反之越低；在试验区中，水稻重度重金属胁迫的分布面积比例相对较低，且主要集中在西部、东北部以及偏东南地区。
融合集合经验模态分解和动态时间规整方法能有效地甄别并定量分析水稻重金属胁迫状况，从而为作物重金属污染胁迫监测提供重要参考。
关键词：遥感；模型；重金属；镉胁迫；时序信号分解；WOFOSTdoi：10.11975/j.issn.1002-6819.2021.04.030中图分类号：S127 文献标志码：A 文章编号：1002-6819(2021)-04-0249-08孔丽，刘美玲，刘湘南，等. 利用作物生长模型和时序信号甄别水稻镉胁迫[J]. 农业工程学报，2021，37(4)：249-256.doi：10.11975/j.issn.1002-6819.2021.04.030 Kong Li, Liu Meiling, Liu Xiangnan, et al. Identifying heavy metal (Cd) stress in rice using time-series signals and crop growth model[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(4): 249-256. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2021.04.030 0 引 言随着经济的不断发展，工业化不断推进，土壤重金属污染成为当今世界面临的重大生态环境问题之一[1]。
印度芥菜_BrassicajunceaL__重金属耐性机理研究进展
中国生态农业学报 2011年1月 第19卷 第1期Chinese Journal of Eco-Agriculture, Jan. 2011, 19(1): 226−234* 国家高技术研究发展计划(863计划)项目(2007AA021404, 2006AA10Z407)和转基因生物新品种培育科技重大专项(2009ZX08009-130B) 资助** 通讯作者: 柴团耀(1960~), 男, 教授, 博士, 主要研究方向为植物抗逆分子生物学。
E-mail: tychai@ 孙涛(1979~), 男, 博士研究生, 研究方向为植物基因表达调控。
E-mail: suntao07b@DOI: 10.3724/SP.J.1011.2011.00226印度芥菜(Brassica juncea L .)重金属耐性机理研究进展*孙 涛1 张玉秀2 柴团耀1**(1. 中国科学院研究生院生命科学学院 北京 100049; 2. 中国矿业大学(北京)化学与环境工程学院 北京 100083)摘 要 印度芥菜可富集/忍耐Cd 、Zn 等多种重金属, 是研究植物修复技术的一种模式植物。
高浓度的重金属离子会改变植物的基因表达、细胞形态、细胞结构, 最终使植物生长受抑, 甚至死亡。
印度芥菜高效的抗氧化系统、损伤修复系统以及对重金属的螯合、区域化可部分解除重金属的毒性, 缓解重金属离子的毒害作用。
利用基因工程技术在印度芥菜中导入重金属耐性及运输相关基因可大幅度提高其重金属富集能力, 在重金属污染修复方面具有广阔的应用前景。
关键词 印度芥菜 重金属胁迫 超富集植物 植物修复技术 抗氧化系统 中图分类号: X53 文献标识码: A 文章编号: 1671-3990(2011)01-0226-09Research progress on tolerance of Indian mustard (Brassica juncea L .)to heavy metalSUN Tao 1, ZHANG Yu-Xiu 2, CHAI Tuan-Yao 1(1. College of Life Science, Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 2. School of Chemicaland Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China)Abstract Much research has been conducted on the mechanism of phytoremediation of heavy metal pollution by Indian mustard. Indian mustard plants typically have high heavy metal (e.g. Zn and Cd) accumulation capacity. Changes had been noted in plant gene expression, cell morphology and cell structure under high heavy metal concentration, which eventually resulted in growth inhibition and even death. In Indian mustard, high efficient antioxidant system, injury-repairing system and chelation, compartmentalization for heavy metals could detoxicate the toxicity of heavy metals and alleviate the injury induced by heavy metals. Transgenic Indian mus-tard with tolerance or transport genes improved heavy metal accumulation ability. This implied that Indian mustard had a great poten-tial for phytoremediation of heavy metal contaminated soils.Key words Indian mustard, Heavy metal stress, Hyperaccumulator, Phytoremediation, Antioxidant system (Received May 1, 2010; accepted Aug. 13, 2010)植物对非生物胁迫所具有的耐性可使其适应一些极端苛刻的环境, 土壤重金属污染就是植物所必须面临的一种非生物胁迫[1]。
英语资讯：农业废弃物变成黄金
Reporter: China produces more than 800 million tonnes of crop straw and stover every year.In the past, most of this biomass had been burnt in open fires resulting in heavy air pollution.Although scientists and engineers have found other profitable uses for these tonnes of agricultural waste, like generating bio-fuel or using them as building materials, many farmers are still unaware of how to make money with it.The International Green Economy Association, a Beijing-based NGO, is taking action to tackle the problem.Deng Jihai is the Secretary-General of the association."Our research findings show that those regions that have a high rate of crop straw utilization actually have very low-levels of efficiency, and this has slowed down the rate of GDP growth. Hence, the biggest most important focus of our action plan is to make this industry more profitable, making organic waste processing a key sector of the green economy."It is estimated that if China could reduce crop straw burning by 200 million tons each year, it would lead to a drop of carbon dioxide emissions by about 214 million tons. A large scale reduction in straw burning activities could also reduce the possibility of fire hazards, further saving an estimated 100 billion yuan.On the other hand, if crop straw can be processed and used in the manufacturing of biodiesel, organic fertilizer, bio-feed and even used to as a building material instead of wood, this could help to increase a farmer's income by 1800 to 2400 yuan per acre of cropland.The International Green Economy Association is determined to assist farmers to convert their agricultural waste into clean bio products.Deng Jihai explains:"This year, we'll accelerate to develop the industry of comprehensive utilization of crop straw. This project aims not only to tackle the soil erosion and air pollution issues, including smog, as a result of crop straw burning, but develop it into a new industry instead of mere utilization."A conference on the industrial development of crop straw resources' will be held in Ulanhot in Inner Mongolia in mid-June. It will bring together high-tech enterprises and agricultural scientists from China and abroad to come up with effective ways to turn agricultural waste recycling into a thriving industry.For China Drive, I'm Xu Fei.更多英语学习方法：外贸英语学习/study-trade.html。
超富集植物吸收富集重金属的生理和分子生物学机制
超富集植物吸收富集重金属的生理和分子生物学机制3李文学 陈同斌33(中国科学院地理科学与资源研究所环境修复室,北京100101)【摘要】 与普通植物相比,超富集植物在地上部富集大量重金属离子的情况下可以正常生长,其富集重金属的机理已经成为当前植物逆境生理研究的热点领域.尤其是近两年,随着分子生物学等现代技术手段的引入,关于重金属离子富集机理的研究取得了一定进展.通过与酵母突变株功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA ;也从分子水平上研究了谷胱甘肽、植物螯合素、金属硫蛋白、有机酸或氨基酸等含巯基物质与重金属富集之间的可能关系.本文从植物生理和分子生物学角度简要评述超富集植物对重金属元素的吸收、富集、螯合及区室化的机制.关键词 超富集植物 重金属 生理学机制 分子生物学机制文章编号 1001-9332(2003)04-0627-05 中图分类号 X171.5 文献标识码 APhysiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccu 2mu altors.L I Wenxue ,CHEN Tongbin (L aboratory of Environmental Remediation ,Institute of Geographical Sciences and N atural Resources Research ,Chinese Academy of Sciences ,Beijing 100101,China ).2Chin.J.A p 2pl.Ecol .,2003,14(4):627～631.In comparison with normal plants ,hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil ,without suffering from detrimental effects.With the help of molecular tech 2nologies ,the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress.A number of trace element trans porters have been cloned by functional complementation with yeast mutants defective in metal absorption.The relations between glutathione ,phytochelatins metallothioneins ,organic acids and heavy metals have been studied by molecular technologies.This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.K ey w ords Hyperaccumulator ,Heavy metal ,Physiological mechanisms ,Molecular biological mechanisms.3国家自然科学基金项目(40071075)、中国科学院知识创新工程重点方向项目(K Z CX 22401202)和王宽诚博士后工作奖励基金资助.33通讯联系人.E 2mail :chentb @ 2002-07-05收稿,2002-11-28接受.1 引 言土壤重金属污染是一个重要的环境问题,传统的治理主要采用物理或化学方法,费用高,对大面积的污染效果差;与传统措施相比,植物修复技术以成本低、操作简单等优点而倍受青睐.广义上的植物修复是指利用植物去除土壤、水体或空气中重金属、有机污染物等污染物的技术,包含植物萃取(Phytoextraction )、根际过滤(Rhizofiltration )、植物挥发(Phytovolatilization )、植物固定(Phytostabilization )等技术,现在通常提到的植物修复主要是指植物萃取[32].超富集植物(Hyperaccumulator )是植物修复的基础,国际上已发现400多种超富集植物,国内对于超富集植物的研究相对较晚,研究较为系统的当属As 、Zn 等重金属的超富集植物[2,3,33].与普通植物相比,重金属离子进入超富集植物体内同样经过吸收/转运、富集/转化/矿化等生理生化过程,而且许多重金属离子进入植物体内的离子通道与必需营养元素相同,这就决定了超富集植物必然具有独特的生理代谢过程.关于这些过程的研究已经成为新的研究热点.本文对有关超富集植物吸收和富集重金属离子的生理及分子机制研究进行评述.2 重金属离子吸收的分子生物学机制 遏蓝菜属(Thlaspi L.)植物具有非常强的富集Zn 的能力,能够在地上部富集高达3%(干重)的Zn ,同时植物正常生长,没有表现出任何中毒症状,它已经成为研究重金属富集机理的模式植物之一.但无论是超富集植物或是普通植物,金属离子进入植物体内的第一步是根系吸收,也就是说吸收过程很可能是超富集植物富集重金属离子的第一个限速步骤.T.caerulescens 与T.arvense 同属于遏蓝菜属,T.caerulescens 能够富集Zn 而T.arvense 则不具此能力,通过比较它们对Zn 2+的吸收动力学发现:两者Km 值差异不大,但T.caerulescens 的Vmax 要比T.arvense 高3.5倍[21],表明T.caerulescens 富集Zn 2+的能力并非是与Zn 2+有更高的亲和力,而很可能是因为锌离子的流入量加大所致,也就是说在T.caerulescens 根系细胞膜上分布有更多的锌离子转应用生态学报 2003年4月 第14卷 第4期 CHIN ESE JOURNAL OF APPL IED ECOLO GY ,Apr.2003,14(4)∶627～631运蛋白.近年来随着分子生物学等现代技术手段的引入,人们对金属离子如何进入细胞有了新的认识.通过对酵母突变株进行功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA,其中研究最多的是ZIP基因家族(ZRT,IRT-like Protein).ZIP基因家族分布非常广泛,在真菌、动物、植物等真核细胞中均发现了ZIP基因家族成员.ZIP基因编码的蛋白一般具有8个跨膜区,C2端和N2端的氨基酸均位于细胞膜外.此家族包含至少25个成员,z rt1、z rt2(zinc2regulated transporter)和irt1(iron2regulated transporter)是最早克隆到的ZIP基因.z rt1、z rt2均由酵母中获得,与Zn的吸收密切相关[36,37];irt1编码的蛋白主要位于拟南芥的根系,体内缺Fe时可诱导irt1表达[8].另一类与金属离子吸收有关的蛋白是Nramp基因家族(Natural resistance associated macrophage proteins).Nramp基因家族编码的蛋白一般具有12个跨膜区,这与ZIP基因家族明显不同.Nramp最初在哺乳动物中发现,植物中的研究主要集中于水稻(Oryz a sativa)和拟南芥(A rabidopsis).O2 ryz a sativa和A rabidopsis的Nramp基因家族分为2类,Os2 Nramp1、OsNramp3和AtNramp5属于一类,OsNramp2、At2 Nramp1、AtNramp2、AtNramp3与AtNramp4属于另一类. Nramp基因家族在植物中的功能现在仍不清楚,AtNramp3和AtNramp4能够维持A rabidopsis体内铁离子的平衡[29].此外,AtNramp3很可能与Ca2+的吸收有关,破坏AtNramp3基因可增加植物对Cd的耐性,过量表达则导致植物对Ca2+的超敏感性.对于超富集植物而言,Zn的吸收过程研究相对较清楚.通过与酵母突变株进行功能互补,Pence等[24]在具有富Zn 能力的T.caerulescen中克隆到z nt1.z nt1编码Zn2+转运蛋白,属ZIP基因家族,缺Zn和Zn供应充足条件下均可以在根系和叶片中高量表达,表明其可能是组成型表达;对于不具有富Zn能力的T.arvense而言,z nt1主要在缺Zn件下表达,供Zn时,表达明显受到抑制.这种表达方式的不同很可能是造成Thlaspi富Zn能力差异的主要原因之一.Assun2 cao等[1]的研究结果也表明Zn转运蛋白基因T.caerulescen 的表达量要远高于T.arvense.从Pence等[24]、Assuncao等[1]与Lasat等[21]的实验结果可以发现根系Zn转运蛋白基因的表达量与Thlaspi富集Zn的能力正相关,初步验证了吸收过程是超富集植物富集重金属离子的首个限速步骤的假设.但是目前还不能肯定转运蛋白是否在超富集植物吸收重金属方面起到决定性作用.譬如说,尽管z nt1、z nt2在T. caerulescen的表达量要远高于T.arvense,但是它们在具有不同富集能力T.caerulescen中的表达量几乎相同[1],即T.caerulescen富集能力的差异与吸收并无太大的相关性.造成此现象的原因很可能在于:(1)一般来说,转运蛋白由一个基因家族控制,而现在得到的克隆还不足以代表整个家族,许多未知的基因可能起到更为重要的作用,如在T. caerulescen就又克隆到z at基因,它与Zn2+的区室化(Se2questration)密切相关,但是此基因与ZIP基因家族明显不同,仅含有6个跨膜区[34];(2)对已知转运蛋白的性质研究还不清楚,金属离子转运蛋白对底物专一性不强,造成多种吸收途径同时对一种金属离子发挥作用,所以在进行具体的分子生物学研究时,必须清楚那些转运蛋白对该金属离子起作用;(3)现在转运蛋白的研究主要集中于根系,叶片中转运蛋白的研究相对较少,但是对超富集植物而言,重金属离子在地上部的含量要远远高于根系,即叶片中的转运蛋白很可能起到更为主要的作用.3 木质部运输 在木质部存在大量的有机酸和氨基酸,它们能够与金属离子结合,这种复合物是重金属离子在木质部中运输的主要形式.譬如在木质部,Fe主要是以柠檬酸铁的形式存在,Zn 主要是与柠檬酸或苹果酸结合,而Cu随着植物不同可与天冬酰胺酸、谷氨酸、组氨酸或烟碱结合,当然也有许多是以离子形态存在的,如Ca、Mg、Mn.在超富集植物中研究较多的为组氨酸.Kramer等[19]发现,组氨酸与A lyssum montanum 富集Ni的能力密切相关,当植物地上部Ni含量高时,木质部中组氨酸含量也较高,外源组氨酸的加入也能显著促进Ni装载入木质部,从而提高Ni向地上部的运输.然而,最近的研究表明,组氨酸反应很可能并不是Ni超富集植物的普遍机理.Persans等[25]在研究Ni的超累积植物Thlaspi geosingense时并没有发现His反应,同时他们克隆了控制His 合成的关键酶基因thg1、thb1、thd1,其表达量并没有随着Ni用量的增加而升高. 重金属由根系进入木质部至少需要3个过程:进入根细胞,由根细胞运输到中柱,装载到木质部.在内皮层由于凯氏带的存在,使得共质体运输在重金属进入木质部的过程中起到主导作用.在共质体运输中起关键作用的是膜转运蛋白,然而直到现在还没有在木质部中克隆到与重金属离子运输相关的基因,这方面的研究,尤其是在研究超富集植物时应该引起充分的重视.与普通植物相比,超富集植物能够高效、迅速地把重金属离子由根系运输到地上部,而通过凯氏带是重金属离子进入木质部主要屏障之一,探明此过程,将有利于提高植物修复的效果.4 对金属离子的解毒机制411 谷胱甘肽(GSH) 许多金属离子是植物必需的微量养分,它们参与植物体内众多的生理代谢过程.但如果含量过高,尤其是具有氧化还原活性的金属,会对植物产生毒害作用,这种毒害作用很可能是由于自由基的形成造成的.GSH含巯基,具有很强的氧化还原特性,可有效地清除活性氧等自由基,因此GSH在植物抗逆境胁迫中起重要作用.GSH为三肽,结构通式为γ2 G lu2Cys2G ly,合成主要通过两步依赖于A TP的反应完成,γ2 EC合成酶和GSH合成酶是其中的关键酶.γ2EC合成酶由gsh1编码,GSH合成酶由gsh2编码,gsh1与gsh2在拟南芥826应 用 生 态 学 报 14卷基因组中均以单拷贝的形式存在. 正常条件下,GSH的合成依赖于半胱氨酸的活性,同时存在明显的反馈抑制现象,表明由γ2EC合成酶催化的反应是整个合成的限速步骤.重金属胁迫条件下,重金属离子激活植物螯合素的合成,消除了GSH的反馈抑制作用,由GSH 合成酶催化的反应也成为限速步骤,此时如果加强gsh2的表达,则既可增加植物螯合素的合成又能避免GSH的耗竭,从而缓解重金属胁迫.Zhu等[38,39]的实验结果验证了此假设.他把大肠杆菌的gsh1与gsh2分别转入到印度芥菜(B rassica juncea),发现印度芥菜对Cd2+的耐性与富集能力均有明显增加,且耐性和富集能力还与gsh2的表达正相关.然而,Foyer等[10]把gsh2转入白杨树(Populus)后,白杨树抗氧化胁迫的能力(光抑制)并没有增加;G oldsbrough等[13]的结果也表明gsh2转入野生型的拟南芥后并不能增加其对Cd的抗性.由此可见,如何通过基因工程改造GSH,以增加植物对重金属的耐性和富集能力还有待于进一步研究.412 植物螯合素(PCs) 植物螯合素(PCs,=cadystins in S.pombe)由植物体内一系列低分子量、能够结合金属离子的多肽组成,其结构通式为(γ2G lu2Cys)n2G ly(图1),一般来讲,n为2～5,最高可达11[5].现已发现多种PC的同功异构体,主要是C端的G ly 被β2Ala、Ser取代形成.原来认为植物螯合素仅存在于植物中,但是随着研究的深入,陆续在线虫、蚯蚓等克隆到PC合成酶的类似基因. PCs不能由基因直接编码,必须在PCs合成酶的催化下完成[14].PC合成酶为四聚体,分子量95000道尔顿,等电点在p H4.8附近,最适反应温度和p H分别为35o℃、7.9[14].然而,由克隆到的编码PCs的全长cDNA推测的结果与此不符,推测结果表明PCs不是多聚体,分子量为42000～70000道尔顿,这种偏差很可能由于在Grill等提纯的酶中PCs并不是主要成分造成的.不同重金属离子诱导PCs合成的能力有很大差别[15],一般为Cd2+>Pb2+>Zn2+>Sb3+>Ag+> Hg2+>As5+>Cu+>Sn2+>Au3+>Bi3+;不同重金属离子诱导PC合成酶活性的能力与诱导PCs合成的能力稍有不同[35]:Cd2+>Ag+>Pb2+>Cu+>Hg2+>Zn2+>Sn2+> Au3+>As5->In3+>Tl3+>G e4+>Bi3+>G a3+.关于PCs 功能研究得相对清楚的是PCs与Cd之间的关系(图2).现图1 植物螯合素的化学结构示意图Fig.1Chemical structure of phytochelatin.已明确PCs在植物解Cd毒中起到重要作用,PCs2Cd复合物是Cd由细胞质进入液泡的主要形式.正是由于PCs在重金属离子区室化中所起的重要作用,近年来PCs已成为植物抗重金属胁迫的研究热点之一. 目前PCs的分子生物学研究基本集中于普通植物或耐性植物,而有关超富集植物的研究相对较少.Schmoger等[28]在用As处理过的蛇根木(Rauvolf ia serpentina)悬浮细胞及拟南芥幼苗中发现了PCs,Hartley2Whitaker等[17]在绒毛草(Holcus lanatus)上也证实了上述现象.但这些植物多属于耐性植物.Ebbs等[7]的实验表明,无论是否具有富集能力, Thlaspi用Cd处理后都会有大量PCs的合成,但是T.ar2 vense中PCs的总量要高于T.caerulescens,说明PCs与植物富Cd能力之间并无太大的关系.由于PCs在超富集植物中的研究还很少,所以PCs在超富集植物是否起到重要作用还有待于深入研究. Cobbett、Rea和等3个研究小组于1999年分别在拟南芥、小麦、酵母中克隆到了编码PC合成酶的全长cDNA.其中,通过对拟南芥cad1突变株(含有与野生型相似的GSH含量,但不含PC)定位克隆获得At PCS1[16],小麦耐Cd基因At PCS1与TaPCS1主要是通过与酵母突变株功能互补得到[4,30].对PC合成酶相应的全长cDNA对齐比较发现其保守区位于N端,同一性高达40%.长时间Cd2+处理cad1突变株也没有发现PCs的合成,表明PCs的合成可能是由单基因控制[18].但随着拟南芥基因组测序的完成,发现了与At PCS1高度同源的At PCS2基因[16],其功能尚不清楚,但与At PCS1相比,其表达量非常低.但植物在长期的进化历程中把At PCS2作为功能基因保留下来,尽管其在正常条件下表达量很低,可以想象在某些器官或环境下,At PCS2基因的表达肯定会起到重要作用.图2 以Cd为例说明谷胱甘肽、植物螯合素在抗重金属胁迫中的作用(+表示增加基因表达或酶活性,-表示减少基因表达或酶活性, HM T1表示位于液泡膜上的PC2Cd转运蛋白),参见Cobbert[5]并作修改Fig.2Function of GSH and PC in the metal tolerance of plants under metal stress(+and2indicate positive and negative regulation of enzyme activities or gene expression,respectively;HM T1is a vacuolar meme2 brane transporter of PC2Cd complex;revised from the figure of Cob2 bert[5]).413 金属硫蛋白(M T) 金属硫蛋白(Metallothioneins)是自然界中普遍存在的一种低分子量、富含半胱氨酸的蛋白质.它与PCs的本质区别在于M T由基因直接编码,而PCs在PCs合成酶的催化下完成.与PCs一样,金属硫蛋白能够通过巯基与金属离子结合,从而降低重金属离子的毒性,它对于Zn2+和Cu2+的解毒效9264期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 果尤为明显[23]. 植物中首先鉴定的M T是Ec蛋白,它由小麦成熟胚芽中分离得到.在植物中已发现大约50种M T,根据半胱氨酸残基的排列方式,可以将其分为Ⅰ型、Ⅱ型、Ⅲ型和V型,大多属于Ⅰ型和Ⅱ型.Ⅰ型中的半胱氨酸残基仅有Cys2Xaa2 Cys一种排列方式;Ⅱ型中的半胱氨酸残基有两种排列方式,分别为Cys2Cys、Cys2Xaa2Xaa2Cys.编码I型M T的cDNA 在根系的表达水平较高,编码Ⅱ型M T的cDNA主要在叶片表达. 金属硫蛋白极易水解,尤其植物中的金属硫蛋白氨基酸链比较长,极易在半胱氨酸区水解,同时金属硫蛋白在有氧的条件下非常不稳定,所以难以获得相应蛋白质的资料,目前仅对小麦Ec蛋白及拟南芥M T1、M T2编码的蛋白进行了纯化,这就限制了对M T类似基因功能的研究.Murphy 等[22]证实Cu2+诱导拟南芥M T2表达,而且表达强度与不同基因型抗Cu胁迫的能力密切相关;Nathalie等[13]的研究结果也证实Cu的耐性植物Silene v ulgaris耐Cu胁迫的特性与M T2b的表达紧密联系.王剑虹等[31]在重金属耐性植物紫羊茅草(Festuca rebra)中克隆到mc M T1的全长cD2 NA,此基因编码70个氨基酸,含有12个Cys残基,在N端和C端分别含有3个Cys2Xaa2Cys结构,将此基因转入到酵母M T基因缺失突变株中发现,mc M T1的表达增加了酵母细胞对Cu、Cd和Pb的抗性.在拟南芥和蚕豆中,M T主要在毛状体中表达[9,12],而Cd等许多有毒重金属离子也在毛状体中累积[27],暗示M T和重金属累积有某种联系.414 细胞壁的固持与区室化作用 植物细胞壁残基对阳离子有高亲和力,可以影响重金属离子向细胞内扩散速率,从而影响金属离子的吸收.比较黄花茅(A nthox anthum odoratum)悬浮细胞和原生质体固Pb 能力发现,Pb浓度对从耐Pb细胞克隆分离的悬浮细胞无太大影响,而原生质体的死亡率上升,相应地,从Pb敏感细胞克隆分离的悬浮细胞和原生质体对Pb极其敏感,表明细胞壁在A nthox anthum odoratum抗Pb胁迫中起到重要作用[26].需要明确的是,细胞壁对金属的固定作用不是一个普遍的抗金属毒害的机制,例如抗Zn毒和Zn敏感型菜豆的细胞壁物质表现出相似的亲和力,同时细胞壁有一定的金属容量,而超富集植物能够在地上部富集大量的重金属离子,暗示细胞壁不可能在超富集植物中起到重要作用.最近的研究表明,区室化作用与超富集植物富集重金属离子的能力密切相关.就Thlaspi而言,具有富集能力的T.geosingense液泡中Ni的含量要比不具有富集能力的T.arvense高1倍[20]; Frey等[11]也证实Zn在T.caerulescens中主要分布于表皮细胞液泡中.但区室化作用是否为超富集植物富集重金属离子的一个普遍机理还需对新发现的超富集植物进一步研究才能确定.5 研究展望 关于超富集植物富集重金属离子的研究虽然取得了一定进展,但至今对其分子和生理机制仍不是很清楚,研究人员的看法也存在明显的分歧.在把超富集植物用于实践的过程中,首先要研究清楚对超富集植物富集的生理基础,譬如重金属离子如何进入根细胞,在木质部如何被运输,在叶片中如何分布;其次要注意不同生理过程的联系,就吸收而言,它其实是根系吸收与体内再分配的有机结合,所以在利用基因工程方法增加重金属离子吸收量时,不仅要考虑到增加根系的吸收位点,提高转运蛋白底物的专一性,同时要注意细胞器,尤其是液泡膜上与重金属离子区室化相关膜蛋白的表达,只有这样,才会达到比较好的效果;最后要强调的是学科交叉与渗透,Dhankher等[6]将细菌中的砷酸盐还原酶ArsC 基因和γ2谷氨酰半胱氨酸合成酶(γ2ECS)在拟南芥的叶子中表达,这样运输到地上部的砷酸盐在砷酸盐还原酶的作用下转化成亚砷酸盐,γ2ECS表达可增加一些连接重金属(如亚砷酸盐)并解除其毒性的化合物,将这些复合物限制在叶子中,从而使植物能够积累并忍耐不断增加的As含量.参考文献1 Assuncao A G L,Martins PDC,Polter SD,et al.2001.Elevated expression of metal transporter genes in three accessions of the met2 al hyperaccumulator Thlaspi caerulescens Plant Cell Envi ron,24: 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encodes the low affinity zinc transporter in S accaromyces cerevisiae.J Biol Chem,271: 23203～2321038 Zhu Y L,Pilon2Smits EAH,Jouanin L.1999.Overexpression of glutathione synthetase in Indian mustard enhances cadmium accu2 mulation and tolerance.Plant Physiol,119:73～7939 Zhu Y L,Pilon2Smits EAH,Tarun AS,et al.1999.Cadmium tol2 erance and accumulation in Indian mustard is enhanced by overex2 pressingγ2glutamylcysteine synthetase.Plant Physiol,121:1169～1177作者简介 李文学,男,1973年生,博士后.主要从事植物营养遗传与重金属污染生态学研究,在国内外发表论文8篇. E2mail:liwx@1364期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 。
Heavy Metal Pollution and Ecological Risk Assessme
Heavy Metal Pollution and Ecological Risk Assessment of Cultivated Land Soil in the Farming Areas of Coastal China: A Case Study of Donghai County, Jiangsu Province 作者：Ligang LYU Xiaorui WANG Xueyan SUI Zhenyu LIU Yong YUAN Chen LIN来源：《农业生物技术（英文版）》2018年第06期Abstract;Classical statistics ， Inverse Distance Weighted and Hakasnson potential ecological index were used to study the distribution characteristics of 8 kinds of heavy metals （Cr ， Ni ， Cu ，Zn， As， Cd， Pb and Hg） as well as their potential ecological risks in the topsoil （0-20 cm） of cultivated land in Donghai County， a typical agricultural area along the Southeast Coast of China. The results showed that the average content of heavy metals in the cultivated soil of Donghai County was not over the risk screening values set in the Environmental Quality Standard for Soils. However， it was worth noting that in some of the sampling points， the content of Cr exceeded the risk screening value， and the standard exceeding points accounted for 24.74% of the total. In addition， the average content of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and values for Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province. The heavy metals were at the medium integrated potential ecological risk level， and the potential ecological risk indices were high in the east and low in the west， and distributed in interlaced island shape. The potential ecological risk indices of the plains in the east were higher than those of the central gentle slope area and the western hillock area. The potential ecological risk was at a high level in Niushan Town which was situated the county center and in some regions with high urbanization levels.Key words;Heavy metal contamination; Cultivated land; Ecological risk assessment; Farming area; Donghai CountyThe accumulation of heavy metals in cultivated land not only reduces the yield and quality of crops[1-2]， but also seriously threatens the safety of ecosystems and humans. Anthropogenic sources are the main source of heavy metal pollution in soil， mainly including fertilization， animal wastes and biosolids application， sewage irrigation， atmospheric deposition and so on[3-5]. Industrial development and urbanization have increased the accumulation of heavy metals in the soil， resulting in heavy metal pollution in the soil， and the pollution area has expanded year by year[6-8]. The National Soil Pollution Survey Bulletin， jointly issued by the Ministry of Land and Resources and the Ministry of Environmental Protection of the Peoples Republic of China on April 17， 2014，shows that the overall state of soil environment in China is not promising， soil pollution is serious in some regions and the cultivated soil environment quality is very low， where the exceeding standard rates of 8 kinds of heavy metals （Cd， Hg， As， Cu， Pb， Cr， Zn and Ni） are 7.0%，1.6%，2.7%， 2.1%， 1.5%， 1.1%， 0.9%， 4.8%， respectively. Moreover， 19.4% of the investigated sites in cultivated land exceed the maximum allowable heavy metal contents， and the proportions of slight， light， medium and heavy pollution are 13.7%， 2.8%， 1.8% and 1.1%，respectively. Therefore， it is the basis for agricultural ecological security to strengthen the investigation and evaluation of heavy metal pollution in cultivated land[9].The eastern coastal areas of China are dominated by plains， with good quality of cultivated land， flat and deep topsoil， and high levels of agricultural intensification. These areas have high level of urbanization and industrialization， thereby causing serious risk of agricultural land pollution. Therefore， in this paper， the distribution characteristics of soil heavy metals （Cr， Ni， Cu，Zn， As， Cd， Pb and Hg） in the topsoil （0-20 cm） of cultivated land were investigated with Donghai County， a typical agricultural county along the eastern coast of China， as an example，and the potential ecological risks were evaluated using the soil heavy metal accumulation index，with the aim to provide scientific bases and guidance for soil environmental quality assessment and land use planning in agricultural areas along the eastern coast of China.Materials and MethodsStudy areaLocated in the northeastern part of Jiangsu Province，China with the coordinates of 34°11′-34°44′N，118°23′-119°10′E， Donghai County borders the Yellow Sea on the east. With a humid monsoon climate， Donghai has an average annual temperature of 13.7 ℃ and an average precipitation of 912.3 mm. The county has 11 towns， 6 townships， 2 street offices， 2 stateowned farms， and 1 provincial farm. The total land area of the county is 200 981.02 hm;2， in which there is 155 642.97 hm;2 of agricultural land， accounting for 77.44% of the total land area; 36 770.72 hm;2 of construction land， accounting for 18.30% of the total land area; 8 583.33 hm;2 of unused land， accounting for 4.26% of the total land area. Among the agricultural land， the cultivated land area is 122 482.29 hm;2， accounting for 60.95% of the total land area. The soil of cultivated land is dominated by brown soil and Shajiang black soil， accounting for 46.38% and 39.52% of the cultivated land area of the county， respectively. Donghai County has a large ratio of agricultural land and is rich in cultivated land resources， making it suitable for planting rice， wheat， corn and other crops. It also has a long history of agriculture production， and longterm intensive cultivation has greatly improved the land limitation factors， so the land productivity is relatively high.Sample collection and analysisFrom the end of March to the beginning of April 2018， a total of 92 sampling points were set up in Donghai County. Considering the landform types and administrative divisions， 4-6 sampling points were arranged in each township. In order to avoid the influence of the surrounding environment， the sampling points were selected from the continuous cultivated land areas， which were located in the center of the cultivated land away from the rivers with the polygon area of greater than 6.67 hm;2 and a distance over 50 m from the roads and ditches （Fig.1）. The soil samples were collected using the 5spot method from the topsoil （0-20 cm） of each sampling point. For each sampling point， soil samples were collected from 5 spots on a diagonal of 10 m， and then the soil samples from the 5 spots were fully mixed. Then， 1 kg of soil was taken by the quartering method，which was then brought back to the laboratory in a plastic bag. In the meantime， the basic information of the sampling point was recorded， including the latitude and longitude， farming method， slope， and aspect. After removing the plant roots and rocks， the collected soil samples were airdried in the laboratory， and then the samples were ground and crushed， and screened through a 100mesh nylon sieve for determination of heavy metals in the soil. The contents of the 8 kinds of heavy metals， Cr， Ni， Cu， Zn， As， Cd， Pb and Hg， were determined accordingto the methods provided in the Guidance on Longterm Soil Monitoring in Natural Ecosystem （GB/T 32740-2016）.Data AnalysisThe classical statistical parameters such as mean， maximum， minimum， standard deviation and coefficient of variation were used to describe the overall characteristics of heavy metals in cultivated land in the study area. Among them， the standard deviation was the average distance of each data deviating from the average， which could reflect the dispersion degree of soil heavy metal data. The coefficient of variation （CV） could reflect the spatial variability of soil heavy metals，and CV≤10% indicated weak variability， CV of 10%-100% indicated moderate variability， and CV≥100% was intensity variability[10]. Classic statistical analysis was performed using PASW Statistics 18.0， and relevant statistical maps were drawn using SigmaPlot 12.5. The spatial distribution of heavy metals in soil was obtained by using the inverse distance weighted interpolation of ArcGIS 10.6.The potential ecological risks of heavy metals in soil were evaluated using the potential ecological risk index （PERI） proposed by Hakanson in 1980[11]. The calculation formula was as follows：C;if=Ci/Bi（1）E;ir=T;ir×C;if（2）RI=∑mi=1E;ir（3）Where， Ci is a measured concentration of metal i in the soil sample; Bi is the background value of same metal i in the soil， and in this study， the background values （total amount） of soil elements in Jiangsu Province were taken as the reference values[12]， namely， Cr of 75.6 mg/kg，Ni of 32.8 mg/kg， Cu of 23.4 mg/kg， Zn of 64.8 mg/kg， As of 9.4 mg/kg， Cd of 0.085 mg/kg，Pb of 22 mg/kg， and Hg of 0.025 ng/g）; T;ri is the toxicresponse factor of metal i according to the toxicity of heavy metals and the response of the environment， respectively Cr of 2， Ni of 5 ， Cu of 5， Zn of 1， As of 10， Cd of 30， Pb of 30 and Hg of 40[13]; C;if is the single contamination factor; E;ir is the monomial ecological risk factor of metal I; RI is potential ecological risk index，which characterizes the potential ecological risk degree of heavy metals in soil. The single contamination factor index and potential ecological risk index of Cr， Ni， Cu， Zn， As， Cd，Pb and Hg are classified according to the relevant literature[14-15].Results and AnalysisMean heavy metal content in topsoil of cultivated landThe statistical characteristics of heavy metal content in the topsoil soil of cultivated land in Donghai County were shown in Table 1. On the whole， the average contents of various heavy metals in cultivated land did not exceed the risk screening values set in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land， but it is worth noting that in some of the sampling points， the contents of Cr， Ni， Cu and Cd exceeded the risk screening values，especially Cr had the most standard exceeding points， which reached 20， accounting for 24.74% of the total， while the standard exceeding points for Ni and Cu were 3， and 1 for Cd. The overstandard content of Cr may be caused by metal smelting， openair waste incineration， livestock wastes， and farmland irrigation[16-17]. At the same time， the average contents of heavy metals of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and the average contents of Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province. In addition， the coefficients of variation of heavy metals at each sampling point were between 26.13% and 72.13%， which indicated moderate variability， and the variation from high to low was in the order of Hg > Ni > Cu > Cr > As > Pb > Cd > Zn. Among them， Hg had the largest coefficient of variation， indicating that it was most affected by exogenous factors.Distribution of heavy metals content in topsoil of cultivated landThe spatial distribution of various heavy metals in the topsoil of cultivated land in Donghai County was shown in Fig.2. The spatial distribution characteristics of the 8 kinds of heavy metals were significantly different. Specifically， the content of Cr was between 62.37 and 279.09 mg/kg，which was obviously higher in the western hilly area， and the high values were found in Linian Township and Shuangdian Town. The content of Ni was between 16.99 and 153.56 mg/kg， which was higher in the eastern plain area than the central gentle slope area， and the highest content was found at the junction of Linian Township and Shuangzuokou Township. The content of Cu was between 11.21 and 56.47 mg/kg， and the highest content was located in Taolin Town and Shilianghe Town. The content of Zn was between 33.93 and 99.55 mg/kg， which was higher in the east and lower in the middle and west， and highest value was found in Pingming Town and Zhangwan Town. The content of As was between 5.33 and 27.06 mg/kg， and the distribution characteristics were consistent with the spatial trend of elevation， showing a trend of low in the west and high in the east. The content of Cd was between 0.083 and 0.35 mg/kg， and the highest content was located in Taolin Town. The content of Pb was between 19.64 and 78.78 mg/kg， and the areas with relatively higher content were mainly distributed in Taolin Town in the west and Niushan Town and Baitabu Town in the central part. The content of Hg was between 7.90 and 159.33 ng/g， and the content of Hg in the eastern plain was higher， mainly concentrated in Pingming Town and Shilianghe Town.Assessment of potential ecological risk of heavy metalsThe average single contamination factors （Ci） of the 8 kinds of heavy metals in cultivated land in Donghai County were calculated from the soil background values of Jiangsu Province as Cd of 1.89 > Cr of 1.65 > Pb of 1.53 > As of 1.19 > Hg of 1.14 > Ni of 1.12 > Cu of 0.97 > Zn of 0.88.According to PERI classification[14-15]， the heavy metals such as Cd， Cr， As， Hg and Ni in cultivated land were in the moderate pollution levels （1-3）， and Cu and Zn were in the light pollution levels （<1）.The average monomial ecological risk factor （E;ri） of the soil heavy metals showed that the ecological risk factors of As （11.88）， Ni （5.58）， Cu （4.83）， Cr （3.30） and Zn（0.88） were all smaller than 30， indicating light potential risk， the ecological risk factors of Cd （56.69）， Pb （45.87） and Hg （45.69） were in the range of 30-60， indicating that the potential ecological risk was moderate， but it was worth noting that the ecological risk factor of Cd was close to the upper limit of the moderate risk span.The potential ecological risk index （RI） of heavy metals in the surface of cultivated land in Donghai County was between 107.39% and 383.76%， and the regional average was 174.73，indicating that the overall potential ecological risk level of heavy metals was moderate （110-220）in Donghai County. The spatial distribution of potential ecological risk index showed a gradual increasing trend from west to east. The potential ecological risk index of the plain area in the east was higher than that in the central gentle slope area and the western hill area. The reasons may be related to soil type， arable land elevation， proximity to urban areas， and agricultural production levels （use of agricultural inputs such as chemical fertilizers， pesticides， organic fertilizers， and sludge）[18-20]. In addition， the ecological risks were high in the regions with high urbanization levels like Niushan Town， Taolin Town， Baitabu Town， Pingming Town， Shilianghe Town and Shilianghe Town， which were in the highlevel risk area.Conclusion（1） The average content of heavy metals in the cultivated soil of Donghai County was not over the risk screening values set in the Environmental Quality Standard for Soils. However， it was worth noting that in some of the sampling points， the content of Cr exceeded the risk screening value， and the standard exceeding points accounted for 24.74% of the total. In addition， the average content of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and values for Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province.（2） The heavy metals were at the medium integrated potential ecological risk level， and the potential ecological risk indices were high in the east and low in the west， and distributed in interlaced island shape. The potential ecological risk indices of the plains in the east were higher than those of the central gentle slope area and the western hillock area. The potential ecological risk was at a high level in Niushan Town which was situated the county center and in some regions with high urbanization levels.References[1] CHEN HM， ZHENG CR， TU C， et al. Heavy Metal Pollution in Soils in China： Status and Countermeasures[J]. Ambio， 1999， 28（2）：130-134.[2] RAGHUNATH R， TRIPATHI RM， KUMAR AV， et al. Assessment of Pb， Cd，Cu， and Zn exposures of 6 to 10yearold children in Mumbai[J]. Environmental Research， 1999，80（3）：215.[3] JIAO WT， CHEN WP， CHANG AC， et al. Environmental risks of trace elements associated with longterm phosphate fertilizers applications： a review[J]. Environmental Pollution，2012， 168（1）：44-53.[4] SINGH J， LEE BK. Reduction of environmental availability and ecological risk of heavy metals in automobile shredder residues[J]. Ecological Engineering， 2015， 81： 76-81.[5] LIU JL， WU H， FENG JX， et al. Heavy metal contamination and ecological risk assessments in the sediments and zoobenthos of selected mangrove ecosystems， South China[J]. Catena， 2014， 119： 136-142.[6] YANG Y， JIN Q， FANG JM， et al. Spatial distribution， ecological risk assessment，and potential sources of heavy metal（loid）s in surface sediments from the Huai River within the Bengbu section， China[J]. Environmental Science and Pollution Research， 2017， 24（12）：11360-11370.[7] ISLAM MS， AHMED MK， RAKNUZZAMAN M， et al. Heavy metals in the industrial sludge and their ecological risk： A case study for a developing country[J]. Journal of Geochemical Exploration， 2017， 172： 41-49.[8] KE X， GUI S， HUANG H， et al. Ecological risk assessment and source identification for heavy metals in surface sediment from the Liaohe River protected area， China[J]. Chemosphere，2017， 175： 473-481.[9] TIAN K， HUANG B， XING Z， et al. Geochemical baseline establishment and ecological risk evaluation of heavy metals in greenhouse soils from Dongtai， China[J]. Ecological indicators， 2017， 72： 510-520.[10] WANG HM， XIE YZ， WANG K. Spatial heterogeneity of soil moisture in different artificial grasslands with finer scales[J]. Acta Agrestia Sinica， 2013， 21（6）：1052-1058.[11] HAKANSON L. An ecological risk index for aquatic pollution control： a sedimentological approach[J]. Water Research， 1980， 14（8）：975-1001.[12] GB 15618—1995 Environmental Quality Standard for Soil. Beijing： Standards Press of China，1997.[13] XU ZQ， NI SJ， TAO XG， et al. Calculation of Heavy Metals Toxicity Coefficient in the Evaluation of Potential Ecological Risk Index[J].Environmental Science & Technology， 2008，31（2）：112-115.[14] LI QL， WU Q， GAO JB， et al. Distribution of heavy metals in topsoils affected by land use patterns at a small watershed scale： a case study in the Bantou Reservoir watershed in Xiamen，China[J]. Acta Ecologica Sinica，2015，35（16）： 5486-5494.[15] JU TN， WU X， SHI HD， et al. Heavy metal pollution and Ecological Risk assessment of arable land soil in Haigou small watershed[J]. Journal of Environmental Engineering Technology，2018， 8（5）： 556-562.[16] LU SJ， WANG YY， TENG YG， et al. Heavy metal pollution and ecological risk assessment of the paddy soils near a zinclead mining area in Hunan[J]. Environmental monitoring and assessment， 2015， 187（10）： 627.[17] BAI JH， CUI BS， CHEN B， et al. Spatial distribution and ecological risk assessment of heavy metals in surface sediments from a typical plateau lake wetland， China[J]. Ecological Modelling， 2011， 222（2）： 301-306.[18] SUN H， DU Y， SONG YB， et al. Distribution and Evaluation of Contamination of Heavy Metals in Selected Farmland Soils in Donghai County of Jiangsu Province[J]. Journal of AgroEnvironment Science， 2006.[19] BARKETT MO， AKUN E. Heavy metal contents of contaminated soils and ecological risk assessment in abandoned copper mine harbor in Yedidalga， Northern Cyprus[J]. Environmental Earth Sciences， 2018， 77（10）： 378.[20] DING XG， YE SY， YUAN HM， et al. Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area， Bohai Sea， China[J]. 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甘薯及其野生近缘种的基因组测序研究进展
第３８卷第２期２０２０年５月江苏师范大学学报（自然科学版）ＪｏｕｒｎａｌｏｆＪｉａｎｇｓｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ（ＮａｔｕｒａｌＳｃｉｅｎｃｅＥｄｉｔｉｏｎ）Ｖｏｌ．３８，Ｎｏ．２Ｍａｙ，２０２０ 收稿日期：２０２０ ０３ ２０基金项目：江苏省自然科学基金项目（ＢＫ２０１９０９９６），江苏师范大学博士学位教师科研支持项目（１８ＸＬＲＸ０３３），江苏高校优势学科建设工程资助项目（ＰＡＰＤ），现代农业产业技术体系建设专项资金（ＣＡＲＳ １０ Ｂ３）作者简介：勾晓婉，女，讲师，博士，主要从事植物细胞遗传学与基因组学研究．通信作者：李宗芸，女，教授，博士生导师，主要从事植物遗传学研究，Ｅ ｍａｉｌ：ｚｏｎｇｙｕｎｌｉ＠ｊｓｎｕ．ｅｄｕ．ｃｎ．文章编号：２０９５ ４２９８（２０２０）０２ ００５２ ０３甘薯及其野生近缘种的基因组测序研究进展勾晓婉，侯文倩，平艳飞，韩永华，李宗芸（江苏师范大学生命科学学院，江苏徐州２２１１１６）摘要：甘薯作为重要的粮食与经济作物，拥有复杂且庞大的基因组，因此，其基因组测序、拼接等相关研究一直进展缓慢．综述了近年来栽培甘薯及其野生近缘种相关的基因组测序研究进展，为有效利用基因组学分析手段对甘薯进行遗传育种、性状改良等方面的研究提供参考．关键词：番薯属；甘薯；野生近缘种；基因组测序中图分类号：Ｑ３，Ｓ５３１ 文献标识码：Ａ 犱狅犻：１０．３９６９／ｊ．ｉｓｓｎ．２０９５ ４２９８．２０２０．０２．０１１犚犲狊犲犪狉犮犺犪犱狏犪狀犮犲犻狀犵犲狀狅犿犻犮狊犲狇狌狀犮犻狀犵狅犳狊狑犲犲狋狆狅狋犪狋狅犪狀犱犻狋狊狑犻犾犱狉犲犾犪狋犻狏犲狊ＧｏｕＸｉａｏｗａｎ，ＨｏｕＷｅｎｑｉａｎ，ＰｉｎｇＹａｎｆｅｉ，ＨａｎＹｏｎｇｈｕａ，ＬｉＺｏｎｇｙｕｎ（ＳｃｈｏｏｌｏｆＬｉｆｅＳｃｉｅｎｃｅ，ＪｉａｎｇｓｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ，Ｘｕｚｈｏｕ２２１１１６，Ｊｉａｎｇｓｕ，Ｃｈｉｎａ）犃犫狊狋狉犪犮狋：Ｓｗｅｅｔｐｏｔａｔｏｉｓａｎｉｍｐｏｒｔａｎｔｆｏｏｄａｎｄｃａｓｈｃｒｏｐ，ｉｔｈａｓａｈｕｇｅａｎｄｃｏｍｐｌｅｘｇｅｎｏｍｅ．Ｔｈｅｒｅｆｏｒｅ，ｉｔｓｇｅｎｏｍ ｉｃｓｅｑｕｅｎｃｉｎｇ，ｓｐｌｉｃｉｎｇａｎｄｏｔｈｅｒｒｅｌａｔｅｄｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｐｒｏｇｒｅｓｓｉｎｇｓｌｏｗｌｙ．Ｉｎｔｈｉｓｐａｐｅｒ，ｔｈｅａｄｖａｎｃｅｉｎｇｅｎｏｍｉｃｓｅｑｕｅｎｃｉｎｇｏｆｃｕｌｔｉｖａｔｅｄｓｗｅｅｔｐｏｔａｔｏａｎｄｉｔｓｗｉｌｄｒｅｌａｔｉｖｅｓｐｅｃｉｅｓａｒｅｒｅｖｉｅｗｅｄ，ｉｔｃａｎｂｅｐｒｏｖｉｄｅｄａｒｅｆｅｒｅｎｃｅｆｏｒｔｈｅｒｅｓｅａｒｃｈｏｎｇｅｎｅｔｉｃｂｒｅｅｄｉｎｇａｎｄｃｈａｒａｃｔｅｒｉｍｐｒｏｖｅｍｅｎｔｏｆｓｗｅｅｔｐｏｔａｔｏｂｙｕｓｉｎｇｇｅｎｏｍｉｃａｎａｌｙｓｉｓ．犓犲狔狑狅狉犱狊：犐狆狅犿狅犲犪；ｓｗｅｅｔｐｏｔａｔｏ；ｗｉｌｄｒｅｌａｔｉｖｅｓｏｆｓｗｅｅｔｐｏｔａｔｏ；ｇｅｎｏｍｉｃｓｅｑｕｅｎｃｉｎｇ 基因组学是由美国遗传学家ＴｈｏｍａｓＨ．Ｒｏｄ ｅｒｉｃｋ于１９８６年提出，用于研究生物基因组的结构与功能的一门新兴学科［１］．基因组测序技术也在近４０年得到飞速发展，从１９７７年以Ｓａｎｇｅｒ发明的“双脱氧链终止法”［２］和Ｍａｘａｍ Ｇｉｌｂｅｒｔ的“化学降解法”［３］为标志的第１代测序技术的兴起，到Ｒｏｃｈｅ、Ｉｌｌｕｍｉｎａ和ＡＢＩ３大测序公司引领的第２代测序，再到现今的纳米孔单分子３代测序等［４］，实现了基因组测序水平从低通量到高通量、高成本向低成本的转变，同时也大大提升了ＤＮＡ测序的精确度，为各物种的基因组测序提供了技术支持．甘薯［犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．］，又称番薯、红薯、地瓜、山芋等，属于旋花科（Ｃｏｎｖｏｌｖｕｌａｃｅａｅ）番薯属（犐狆狅犿狅犲犪）植物，是重要的粮食、经济和能源作物．甘薯块根中富含多种营养物质，如花青素、类胡萝卜素、多种维生素、膳食纤维以及钙、铁、硒等矿物质［５］．除食用价值外，甘薯还可用于制作淀粉、酒精、天然色素等，茎叶可制作饲料．另外，甘薯起源于美洲大陆的热带和亚热带地区［６］，其生存环境决定了它具有耐高温、抗旱等优良性状［７］，为在全世界范围的种植奠定了基础．栽培甘薯是六倍体物种（２狀＝６狓＝９０），基因组庞大，且具有无性繁殖、自交不亲和的特性，使得甘薯的遗传组成等基础研究进展缓慢，落后于其他主要作物．然而，随着高通量测序和生物信息学技术的迅猛发展，甘薯基因组学和生物信息学的研究工作如火如荼，进展迅速［８－１０］．本文梳理了甘薯及其近缘野生种的基因组测序发展历程，为更好地利用日趋精细的基因组图谱信息，理清甘薯组的起源进化关系，挖掘抗病虫害等重要基因，以及甘薯育种及品质改良提供理论基础．１ 甘薯野生近缘种基因组研究进展在测序过程中，因多倍体植物部分同源染色体间的序列相似性，序列拼接成为难点．因此，科学家常优先完成二倍体祖先物种的测序以作为多倍体物种的参考基因组．番薯属的研究策略亦是如此．２０１０年，日本学者利用二倍体三浅裂野牵牛（犐狆狅犿狅犲犪狋狉犻犳犻犱犪２狀＝２狓＝３０）的０４３１ １与Ｍｘ２３ ４品系杂交获得的Ｆ１群体构建扩增片段长度多态性（ＡＦＬＰ）连锁图谱．其中，０４３１ １品系获得了１７个连锁群，Ｍｘ２３ ４品系获得了１５个连锁群［１１］，此连锁图谱被认为是构建甘薯参考基因组的第１步骤．至２０１５年，此课题组对前述２个犐．狋狉犻犳犻犱犪品系进行从头合成全基因组测序［１２］，自交系Ｍｘ２３Ｈｍ（由Ｍｘ２３ ４自交至Ｓ１１代）成功装配５１３Ｍｂ的基因组，推测包含６２４０７个基因；高度杂合系０４３１ １成功装配７１２Ｍｂ的基因组，约包含１０９４４９个基因．数据对比发现，两组材料之间存在着大量的单核苷酸多态性（ＳＮＰ）和拷贝数变异［１２］．这些基因组数据为犐．狋狉犻犳犻犱犪及番薯属其他物种的研究奠定了基础．２０１６年，日本科学家利用２代与３代测序相结合的手段，破解了牵牛花（犐狆狅犿狅犲犪狀犻犾，２狀＝２狓＝３０）的基因组图谱［１３］，共拼接出大小为７５０Ｍｂ的基因组，预测其包含４３７８３个基因，ｃｏｎｔｉｇＮ５０长度为１．８７Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度为２．８８Ｍｂ，覆盖总基因组的９８％，并将所有的ｓｃａｆｆｏｌｄ都挂载到了１５条假定染色体上．利用组装好的基因组检测Ｔｐｎ１家族的转座子，发现它是牵牛花突变的主要诱变剂，并且与矮杆基因犆犗犖犜犚犃犆犜犈犇作用相关［１３］．牵牛花的基因组序列为番薯属第１个装配到染色体水平上的基因组草图．２０１８年，由美国、中国、澳大利亚、秘鲁、肯尼亚、乌干达６个国家的１６支科研团队通力合作，共同绘制出犐．狋狉犻犳犻犱犪和犐．狋狉犻犾狅犫犪２个甘薯二倍体野生种的高质量基因组图谱，为六倍体甘薯改良提供了参考［１４］．装配出的犐．狋狉犻犳犻犱犪基因组大小为４６２Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度约１．２Ｍｂ，包含约３２３０１个蛋白编码基因；犐．狋狉犻犾狅犫犪基因组大小为４５７．８Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度约６．９Ｍｂ，包含约３１４２３个蛋白编码基因．通过基因组序列的系统发生关系对比，证明犐．狋狉犻犳犻犱犪与栽培甘薯的亲缘关系更近［１４］．２０１９年，霍恺森等利用流式细胞术和２代测序技术，对马鞍藤（犐狆狅犿狅犲犪狆犲狊 犮犪狆狉犪犲）全基因组大小进行了测定和评估．流式细胞术估测马鞍藤的基因组大小为（１０１２．７０４±１７．３７）Ｍｂ，测序数据拼接草图估测基因组大小为１０４１．６５Ｍｂ，且重复序列占比高达７４．５２％［１５］，此结果为马鞍藤基因组的深度测序和耐盐基因在栽培甘薯中的应用打下了基础．同年，同一课题组对甘薯近缘野生种犐．犾犻狋狋狅狉犪犾犻狊也进行了全基因组评估分析，数据经过滤拼接之后，预估其基因组大小为６７６．２７Ｍｂ，重复序列比例达６０．９８％．此研究首次报道犐．犾犻狋狋狅狉犪犾犻狊基因组特征信息，为进一步全基因组深度测序提供了参考［１６］．２ 栽培甘薯基因组研究进展早在１９９４年，Ｏｚｉａｓ Ａｋｉｎｓ等利用流式细胞术对番薯属２４个物种的５３个品系进行ＤＮＡ含量评估，证明该属物种的倍性水平与ＤＮＡ含量显著相关，且测定栽培甘薯基因组的ＤＮＡ含量为４．８～５．３ｐｇ／２Ｃ［１７］．２０１８年，Ｓｒｉｓｕｗａｎ等重新分析番薯属物种的ＤＮＡ含量，与前人报道略有不同，１０个六倍体栽培甘薯样本的ＤＮＡ含量平均为３．１２～３．２９ｐｇ／２Ｃ．另外，通过扫描电镜对花粉粒的尺寸分析也证明花粉粒的大小会随着倍性增加而增大［１８］．２００３年，Ｋｒｉｅｇｎｅｒ等利用ＡＦＬＰ技术对Ｔａｎ ｚａｎｉａ和Ｂｉｋｉｌａｍａｌｉｙａ２个甘薯品种进行遗传连锁图绘制，结合分子标记，获得连锁图谱长度分别为３６５５．６ｃＭ和３０１１．５ｃＭ［１９］．２０１６年，Ｓｉ等第１次构建了甘薯的ＢＡＣ（ｂａｃｔｅｒｉａｌａｒｔｉｆｉｃｉａｌｃｈｒｏｍｏｓｏｍｅ）文库，此文库包含２４０３８４个克隆，平均插入长度为１０１ｋｂ，文库数据量是甘薯全基因组大小的７．９～１０．８倍．从文库中随机选择８３１０个克隆进行双端测序，产生１１５４２条高质量ＢＥＳｓ（ＢＡＣ ｅｎｄｓｅｑｕｅｎｃｅｓ）序列，累计测序长度达７５９５２６１ｂｐ．对ＢＥＳｓ序列分析显示，１２．１７％为甘薯基因组内已知的重复序列，１８．３１％为其特有的重复ＤＮＡ，仅有１０．００％预测为蛋白编码区［２０］．ＢＡＣ文库为后续高分辨率的基因组组装提供了强大支援．２０１７年，中德科学家合作，对栽培甘薯“泰中６号”进行测序，利用Ｉｌｌｕｍｉｎａ测序平台，采用单倍型分析手段，成功绘制了六倍体甘薯的基因组精细图谱［２１］，其总基因组大小约为４．４Ｇｂ，单套染色体大小约为８３６Ｍｂ，ｓｃａｆｆｏｌｄＮ５０约为２０１ｋｂ．以犐．狀犻犾的基因组序列作为参考，通过共线性分析，将约７５．７％的改良版单倍型拼接区段数据锚定到１５条假定染色体上．另外，通过构建同源染色体的系统发生树，推测现今栽培甘薯形成过程经历２次全基因组加倍事件：第１次加倍事件发生在约８０万年前，形成了甘薯的四倍体祖先；第２次加倍事件发生在约５０万年前，二倍体祖先与四倍体祖先经过杂交和多倍化，成为六倍体甘薯（Ｂ１Ｂ１Ｂ２Ｂ２Ｂ２Ｂ２）［２１］．２０１９年，Ｄｉｎｇ等［２２］采用２、３代测序技术相结合的方法，对栽培品种徐薯１８和野生近缘种犐．狋狉犻犳犻犱犪进行多个植物组织（如幼嫩叶片、成熟叶片、芽、茎、纤维根等）的全长转录组测序，结果显示，２组材料中的开放阅读框数目高达１０４５１０和９４１７４个，长链非编码ＲＮＡ有４１７和５３１条，同时还伴随高频率的可变剪接时间的发生．这项研究提供的甘薯及其野生种的全长转录本资源，促进了甘薯的结构、功能和比较基３５第２期勾晓婉，等：甘薯及其野生近缘种的基因组测序研究进展 因组学的发展．２０２０年，Ｆｅｎｇ等［２３］利用ＲＡＤ ｓｅｑ技术分析８１个甘薯品系，评估甘薯的遗传结构多样性．通过＞１２８Ｇｂ的大数据，共鉴定５５６２２个限制性位点标签，包含９０７０１０个ＳＮＰ．利用全基因组ＳＮＰ分型数据，基于遗传相似性，将８１个品系分为５大类，这种分类方式有助于育种专家寻找适合用于杂交的品系，以提高待育品种的品质或抗性．另外，通过对此数据分析，还建立了一套ＳＳＲ标记系统，为育种过程提供更加丰富的辅助标记［２３］．３ 展望随着测序技术的不断升级优化以及生物信息学分析手段的迅猛发展，越来越多的物种基因组被破译．尽管甘薯基因组十分复杂，但参考序列也在循序更新，不断完善，为以后的精细基因功能研究奠定了基础．通过不同品种甘薯的基因组比较，以及对野生物种基因组资源的开发，可以获取到相关重要农艺性状的基因或位点信息，从而实现分子、序列水平的定点育种改良．另外，甘薯起源问题也一直困扰着科学家们，现有望利用ＤＮＡ水平的数据比对，理清甘薯的起源与进化过程．现今甘薯种植面临多种病虫害的侵蚀，如根腐病、蔓割病、黑斑病、茎线虫病等，以及生长环境的恶劣影响，例如土地的盐碱化、高温天气延长、干旱地区扩张等，大大降低了甘薯的产量．甘薯基因组信息的完善，可以使科学家从更精细的层面去探寻抗性基因，实现存优去劣，使甘薯自身具有较高的抵抗不利环境的能力，从而减少外界药物或肥料的施加，提高生产安全性，减轻土地负担，实现良性发展．参考文献：［１］ 李伟，印莉萍．基因组学相关概念及其研究进展［Ｊ］．生物学通报，２０００，３５（１１）：１．［２］ ＳａｎｇｅｒＦ，ＮｉｃｋｌｅｎＳ，ＣｏｕｌｓｏｎＡＲ．ＤＮＡｓｅｑｕｅｎｃｉｎｇｗｉｔｈｃｈａｉｎ ｔｅｒｍｉｎａｔｉｎｇｉｎｈｉｂｉｔｏｒｓ［Ｊ］．ＰＮＡＳ，１９７７，７４（１２）：５４６３．［３］ ＭａｘａｍＡＭ，ＧｉｌｂｅｒｔＷ．ＡｎｅｗｍｅｔｈｏｄｆｏｒｓｅｑｕｅｎｃｉｎｇＤＮＡ［Ｊ］．ＰＮＡＳ，１９７７，７４（２）：５６０．［４］ 孙海汐，王秀杰．ＤＮＡ测序技术发展及其展望［Ｊ］．科研信息化技术与应用，２００９（３）：１９．［５］ 张立明，王庆美，王荫墀．甘薯的主要营养成分和保健作用［Ｊ］．杂粮作物，２００３，２３（３）：１６２．［６］ 小林仁，邓纯宝．甘薯的起源与分化Ⅰ．甘薯的原产地和品种分化［Ｊ］．国外农学杂粮作物，１９８３（１）：４３．［７］ ＭａｂｈａｕｄｈｉＴ，ＭｏｄｉＡＴ，ＭｏｔｓａＮＭ．Ｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊Ｌ．）ａｓａｄｒｏｕｇｈｔｔｏｌｅｒａｎｔａｎｄｆｏｏｄｓｅｃｕｒｉｔｙｃｒｏｐ［Ｊ］．ＳＡｆｒＪＳｃｉ，２０１５，１１１（１１／１２）：１．［８］ ＩｓｏｂｅＳ，ＳｈｉｒａｓａｗａＫ，ＨｉｒａｋａｗａＨ．Ｃｈａｌｌｅｎｇｅｓｔｏｇｅ ｎｏｍｅｓｅｑｕｅｎｃｅｄｉｓｓｅｃｔｉｏｎｉｎｓｗｅｅｔｐｏｔａｔｏ［Ｊ］．ＢｒｅｅｄＳｃｉ，２０１７，６７（１）：３５．［９］ 杨俊，范维娟，王红霞，等．番薯属植物基因组测序最新进展［Ｊ］．植物生理学报，２０１７，５３（５）：７６８．［１０］ ＩｓｏｂｅＳ，ＳｈｉｒａｓａｗａＫ，ＨｉｒａｋａｗａＨ．Ｃｕｒｒｅｎｔｓｔａｔｕｓｉｎｗｈｏｌｅｇｅｎｏｍｅｓｅｑｕｅｎｃｉｎｇａｎｄａｎａｌｙｓｉｓｏｆ犐狆狅犿狅犲犪ｓｐｐ．［Ｊ］．ＰｌａｎｔＣｅｌｌＲｅｐ，２０１９，３８（１１）：１３６５．［１１］ ＮａｋａｙａｍａＨ，ＴａｎａｋａＭ，ＴａｋａｈａｔａＹ．ＡｎＡＦＬＰ ｂａｓｅｄｇｅｎｅｔｉｃｌｉｎｋａｇｅｍａｐｏｆ犐狆狅犿狅犲犪狋狉犻犳犻犱犪（Ｈ．Ｂ．Ｋ．）Ｇ．Ｄｏｎ．，ａｄｉｐｌｏｉｄｒｅｌａｔｉｖｅｏｆｓｗｅｅｔｐｏｔａｔｏ，犐．犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．［Ｊ］．ＴｒｏｐＡｇｒｉｃＤｅｖ，２０１０，５４（１）：９．［１２］ ＨｉｒａｋａｗａＨ，ＯｋａｄａＹ，ＴａｂｕｃｈｉＨ，ｅｔａｌ．Ｓｕｒｖｅｙｏｆｇｅ ｎｏｍｅｓｅｑｕｅｎｃｅｓｉｎａｗｉｌｄｓｗｅｅｔｐｏｔａｔｏ，犐狆狅犿狅犲犪狋狉犻犳犻犱犪（Ｈ．Ｂ．Ｋ．）Ｇ．Ｄｏｎ［Ｊ］．ＤＮＡＲｅｓ，２０１５，２２（２）：１７１．［１３］ ＨｏｓｈｉｎｏＡ，ＪａｙａｋｕｍａｒＶ，ＮｉｔａｓａｋａＥ，ｅｔａｌ．ＧｅｎｏｍｅｓｅｑｕｅｎｃｅａｎｄａｎａｌｙｓｉｓｏｆｔｈｅＪａｐａｎｅｓｅｍｏｒｎｉｎｇｇｌｏｒｙ犐狆狅犿狅犲犪狀犻犾［Ｊ］．ＮａｔＣｏｍｍ，２０１６，７（１）：１３２９５．［１４］ ＷｕＳ，ＬａｕＫＨ，ＣａｏＱＨ，ｅｔａｌ．Ｇｅｎｏｍｅｓｅｑｕｅｎｃｅｓｏｆｔｗｏｄｉｐｌｏｉｄｗｉｌｄｒｅｌａｔｉｖｅｓｏｆｃｕｌｔｉｖａｔｅｄｓｗｅｅｔｐｏｔａｔｏｒｅｖｅａｌｔａｒｇｅｔｓｆｏｒｇｅｎｅｔｉｃｉｍｐｒｏｖｅｍｅｎｔ［Ｊ］．ＮａｔＣｏｍｍ，２０１８，９（１）：４５８０．［１５］ 霍恺森，赵冬兰，陈艳丽，等．甘薯属耐盐植物马鞍藤基因组大小及特征分析［Ｊ］．植物遗传资源学报，２０１９，２０（３）：７２８．［１６］ 霍恺森，曹清河，王珧，等．甘薯近缘野生种犐狆狅犿狅犲犪犾犻狋狋狅狉犪犾犻狊全基因组Ｓｕｒｖｅｙ分析［Ｊ］．热带作物学报，２０１９，４０（１０）：２００１．［１７］ Ｏｚｉａｓ ＡｋｉｎｓＰ，ＪａｒｒｅｔＲＬ．ＮｕｃｌｅａｒＤＮＡｃｏｎｔｅｎｔａｎｄｐｌｏｉｄｙｌｅｖｅｌｓｉｎｔｈｅｇｅｎｕｓ犐狆狅犿狅犲犪［Ｊ］．ＪＡｍＳｏｃｆｏｒＨｏｒｔＳｃｉ，１９９４，１１９（１）：１１０．［１８］ ＳｒｉｓｕｗａｎＳ，ＳｉｈａｃｈａｋｒＤ，ＭａｒｔｉｎＪ，ｅｔａｌ．ＣｈａｎｇｅｉｎＮｕｃｌｅａｒＤＮＡｃｏｎｔｅｎｔａｎｄｐｏｌｌｅｎｓｉｚｅｗｉｔｈｐｏｌｙｐｌｏｉｄｉｓａｔｉｏｎｉｎｔｈｅｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊，Ｃｏｎｖｏｌｖｕｌａｃｅａｅ）ｃｏｍｐｌｅｘ［Ｊ］．ＰｌａｎｔＢｉｏｌ，２０１９，２１（２）：２３７．［１９］ ＫｒｉｅｇｎｅｒＡ，ＣｅｒｖａｎｔｅｓＪ，ＢｕｒｇＫ，ｅｔａｌ．Ａｇｅｎｅｔｉｃｌｉｎｋａｇｅｍａｐｏｆｓｗｅｅｔｐｏｔａｔｏ［犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．］ｂａｓｅｄｏｎＡＦＬＰｍａｒｋｅｒｓ［Ｊ］．ＭｏｌＢｒｅｅｄ，２００３，１１（３）：１６９．［２０］ ＳｉＺＺ，ＤｕＢ，ＨｕｏＪＸ，ｅｔａｌ．Ａｇｅｎｏｍｅ ｗｉｄｅＢＡＣ ｅｎｄｓｅｑｕｅｎｃｅｓｕｒｖｅｙｐｒｏｖｉｄｅｓｆｉｒｓｔｉｎｓｉｇｈｔｓｉｎｔｏｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．）ｇｅｎｏｍｅｃｏｍｐｏｓｉｔｉｏｎ［Ｊ］．ＢＭＣＧｅｎｏｍｉｃｓ，２０１６，１７（１）：９４５．［２１］ ＹａｎｇＪ，ＭｏｅｉｎｚａｄｅｈＭＨ，ＫｕｈｌＨ，ｅｔａｌ．Ｈａｐｌｏｔｙｐｅ ｒｅ ｓｏｌｖｅｄｓｗｅｅｔｐｏｔａｔｏｇｅｎｏｍｅｔｒａｃｅｓｂａｃｋｉｔｓｈｅｘａｐｌｏｉｄｉｚａｔｉｏｎｈｉｓｔｏｒｙ［Ｊ］．ＮａｔＰｌａｎｔｓ，２０１７，３（９）：６９６．［２２］ ＤｉｎｇＮ，ＣｕｉＨ，ＭｉａｏＹ，ｅｔａｌ．Ｓｉｎｇｌｅ ｍｏｌｅｃｕｌｅｒｅａｌ ｔｉｍｅｓｅｑｕｅｎｃｉｎｇｉｄｅｎｔｉｆｉｅｓｍａｓｓｉｖｅｆｕｌｌ ｌｅｎｇｔｈｃＤＮＡｓａｎｄａｌｔｅｒｎａｔｉｖｅ ｓｐｌｉｃｉｎｇｅｖｅｎｔｓｔｈａｔｆａｃｉｌｉｔａｔｅｃｏｍｐａｒａｔｉｖｅａｎｄｆｕｎｃｔｉｏｎａｌｇｅｎｏｍｉｃｓｓｔｕｄｙｉｎｔｈｅｈｅｘａｐｌｏｉｄｃｒｏｐｓｗｅｅｔｐｏｔａｔｏ［Ｊ］．ＰｅｅｒＪ，２０１９（７）：ｅ７９３３．［２３］ ＦｅｎｇＪＹ，ＺｈａｏＳ，ＬｉＭ，ｅｔａｌ．Ｇｅｎｏｍｅ ｗｉｄｅｇｅｎｅｔｉｃｄｉｖｅｒｓｉｔｙｄｅｔｅｃｔｉｏｎａｎｄｐｏｐｕｌａｔｉｏｎｓｔｒｕｃｔｕｒｅａｎａｌｙｓｉｓｉｎｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊）ｕｓｉｎｇＲＡＤ ｓｅｑ［Ｊ］．Ｇｅｎｏｍｉｃｓ，２０２０，１１２（２）：１９７８．［责任编辑：史成娣］４５ 江苏师范大学学报（自然科学版）第３８卷 。
北方湖库沉积物重金属区域特征及生态风险评价
中国环境科学 2020,40(11)：4927~4935 China Environmental Science 北方湖库沉积物重金属区域特征及生态风险评价李捷1,2,3,宋鹏2,李慧1,2,程云轩1,焦立新1,3*,李国栋1(1.中国环境科学研究院,湖泊水污染治理与生态修复技术国家工程实验室,北京 100012；2.河南科技大学农学院,河南洛阳 471000；3.中国环境科学研究院,国家环境保护饮用水水源地保护重点实验室,国家环境保护湖泊污染控制重点实验室,北京 100012)摘要：以白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖沉积作为研究对象,通过对北方六湖库沉积物中Cu、Zn、Pb、Cr、Ni等重金属元素进行分析,并与国内外其他水域重金属污染情况进行多因素比较,探讨了六湖库主要重金属污染源的差异性,区域分布特征以及与国内外其他水域污染的相似性和区别.结果表明,六湖库沉积物重金属污染处于中等偏下水平.六湖库之间主要重金属污染源存在差别.沉积物重金属含量未出现明显上升的趋势.其中Zn、Pb存在富集现象,但Pb含量与历史数据相比出现下降,Zn的含量与其他地区相比整体偏高.大伙房水库沉积物重金属污染较重,Cu、Zn、Pb、Cr、Ni含量平均值分别为56.28,142.3,17.44,97.9,44.44mg/kg.小兴凯湖沉积物重金属含量最低,Cu、Zn、Pb、Cr、Ni含量平均值分别为2.41,63.90,13.37,56.36,26.09mg/kg.六湖库综合风险评价结果为大伙房水库>于桥水库>白洋淀>衡水湖>松花湖>小兴凯湖,重金属整体潜在生态风险指数为低.关键词：湖库；沉积物；重金属；空间分布特征；生态风险；北方中图分类号：X131 文献标识码：A 文章编号：1000-6923(2020)11-4927-09Heavy metal regional characteristics and potential ecological risk assessment of lakes and reservoirs in North China. LI Jie1,2,3, SONG Peng2, LI Hui1,2, CHENG Yun-xuan1, JIAO Li-xin1,3*, LI Guo-dong1 (1.National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences, Beijing 100012, China；2.College of Agriculture, Henan University of Science and Technology, Luoyang 471000, China；3.State Environmental P rotection Key Laboratory for Lake P ollution Control, State Environmental P rotection Key Laboratory of Drinking Water Source P rotection, Chinese Research Academy of Environmental Sciences, Beijing 100012, China). China Environmental Science, 2020,40(11)：4927~4935Abstract：The sediments of Baiyangdian Lake, Hengshui Lake, Yuqiao Reservoir, Songhua Lake, Dahuofang Reservoir and Xiaoxingkai Lake were selected as research objects. The contents of heavy metal elements including Cu, Zn, Pb, Cr and Ni in the sediments of the six lakes and reservoirs were determined with descriptive statistical analysis combined with multi-factor comparison of heavy metal pollution in other waters at home and abroad. The significant differences between the major sources of heavy metal pollution in the six lakes and reservoirs, the accumulation of heavy metals in the sediments and the similarities and differences with other waters at home and abroad were discussed. Heavy metal pollution in the sediments of Baiyangdian Lake, Hengshui Lake, Yuqiao Reservoir, Songhua Lake, Dahuofang Reservoir and Xiaoxingkai Lake was at a moderate to low level. There were differences in the main pollution sources between the six lakes. The heavy metal content of the sediment did not show a clear upward trend. Sediment heavy metal (Zn, Pb) are enriched in the six lakes, But the Pb content decreased compared with historical data, and the zinc content is generally higher than other regions. Dahuofang Reservoir sediments had the most heavy metal pollution. The average values of Cu, Zn, P b, Cr and Ni were 56.28mg/kg, 142.3mg/kg, 17.44mg/kg, 97.9mg/kg, 44.44mg/kg respectively. Xiaoxingkai Lake has the lowest heavy metal content. The average values of Cu, Zn, Pb, Cr and Ni are 2.41mg/kg, 63.90mg/kg, 13.37mg/kg, 56.36mg/kg, 26.09mg/kg respectively. Comprehensive risk assessment of the six lakes and reservoirs, Dahuofang Reservoir> Yuqiao Reservoir> Baiyangdian Lake> Hengshui Lake> Songhua Lake> Xiaoxingkai Lake. The overall potential ecological risk index of heavy metals is low.Key words：lake and reservoir；sediment；heavy metal；spatial distribution；ecological risk；Northern China湖泊在水源供给、渔业养殖、水运、小气候调节、物种多样性保护等多个方面都具有着不可替代的作用[1].重金属元素是一种典型的具有强烈积累性和持久污染能力的污染物[2].在进入水体后一部分与水中的各类物质相结合沉积于水底,伴随着环收稿日期：2020-03-17基金项目：国家科技基础性工作专项(2015FY110900-005)* 责任作者, 副研究员,****************.cn4928 中国环境科学 40卷境因素的改变逐渐释放,对水体造成持续的污染[3-4].目前以白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖等为代表的淡水湖库,随着供给侧结构性改革持续深化,城市人口的不断集中,造成污水排放量逐年递增,湖泊水资源的过度开发利用[5],北方水资源日趋紧张、水环境有恶化现象出现.其相关水质情况及水生态研究就显得很有必要,崔志丹等[6]研究发现,松花湖沉积物中PAHs污染程度较低.高秋生等[7]研究发现,白洋淀沉积物重金属Cd污染极为严重,应立刻采取修复措施.王乃珊等[8]认为,衡水湖沉积物重金属Hg存在富集现象,这与人类活动有密不可分的关系.目前已有研究多为针对单个湖泊的沉积物重金属研究,主要集中于水质的监测、水污染的治理等方面[6-9],缺乏横向的对比与北方多湖库的系统分析.所以,采用更科学的统计技术,系统的研究我国北方地区湖泊水资源的规律,不但可以为当地水质监测和水资源利用提供参考,也能为国家制定水资源相关政策提供数据支撑.本研究通过对北方六湖库沉积物中重金属含量特征分析,运用优劣解距离多指标综合评价模型和潜在生态风险指数法对数据进行整理,并探讨重金属分布特征与生态风险,结合各湖库差异对北方地区做出综合评价,以期为北方地区水体污染防控和湖库生态环境的保护提供科学依据.1材料与方法1.1 采样点设置与样品采集表1北方六湖库水环境基本特征Table 1 Water environment characteristics of six northernlakes and reservoirs水体沉积物采样湖库水温(℃) pH值COD(mg/L)粒径(µm)有机质(%)电导率(µS/cm)白洋淀 23.2 7.94 6.21 62.3 14.6 348.9 衡水湖 18.9 8.13 4.34 54.4 10.9 159.7 于桥水库 20.1 8.02 5.49 20.4 12.9 234.1 大伙房水库 12.6 7.49 5.89 34.9 12.7 364.2 松花湖 13.5 7.49 3.59 45.2 9.4 197.5 小兴凯湖 7.8 7.79 3.01 39.8 8.7 201.9 2018年8~12月分别对白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖进行采样,根据湖泊大小、河流入湖位置和湖库水环境情况(表1),在保证湖面全覆盖的基础上设置采样位置:白洋淀采样点15个、衡水湖采样点10个、于桥水库采样点9个、松花湖采样点29个(个别点位经、纬度缺失)、大伙房水库采样点10个、小兴凯湖采样点15个.泥样采集:每个采样点用抓斗式采泥器采集0~10cm沉积物样品500g,每个采集点采集3个平行样品,混合后为1个沉积物样品,置于密封袋中[10].所用样品采集后立刻密封并低温保存,上岸后立即将所采样品送回实验室进行指标测量.1.2 样品前处理与分析沉积物样品经过冷冻干燥,剔除动、植物残体等杂质,经研钵研磨后过100目筛,使用天平准确称取风干沉积物样品(0.5000±0.0010)g,放置于消解管中,加3mL氢氟酸和4mL王水均匀混合后120℃消解4h,再加入2mL王水、2mL高氯酸均匀混合后120℃消解4h,然后开盖在160℃进行赶酸,至颜色清亮,呈胶状固体为佳,拿出前补加2mL硝酸、10mL纯水,充分溶解后定容至50mL.完成前处理后,样品重金属含量使用电感耦合等离子体质谱仪(安捷伦ICP-MS 7500CX)进行测定.样品处理检测过程中,使用试剂纯度均为GR,所有器皿均使用35%硝酸浸泡24h后,用去离子水清洗并干燥.每批次样品均设置CK与标准样GBW07301a(GSD-1a),以保证前处理和数据的准确性.数据使用Excel、SPSS和Origin等软件进行分析.1.3统计分析方法本研究采用优劣解距离多指标综合评价模型和潜在生态风险指数法对北方六湖库的重金属污染情况进行分析,做出风险评价的同时对北方六湖库重金属污染的差异性、与国内外其他水体的异同点进行综合对比分析.优劣解距离多指标综合评价模型[11-12]也叫做逼近于理想解的技术,是系统工程中有限方案多目标决策分析的经典决策模型,该模型具有数据结果直观、数据稳定性高、精度高等特点,适用于多变量多因素的情况,目前已在医疗、经济、农业等领域中得到广泛认可.在采用优劣解距离多指标综合评价模型对各湖库重金属情况进行分析时,首先要建立n湖泊,m 种重金属的原始矩阵,用以消除不同指标不同量纲及其数量级的差异对评价结果的影响.该矩阵的最11期 李 捷等：北方湖库沉积物重金属区域特征及生态风险评价 4929优评价方案及最劣评价方案即为对所有数据进行评价的最低和最高标准. ()ij m n χ×=X (1) 原始矩阵经归一化处理:min max min /ij ij y =χχχχ−− (2) 在得到归一化处理的矩阵后,根据归一化矩阵,得到矩阵向量的最佳评价方案A +和最劣评价方案A -.由归一化矩阵计算出最佳评价方案A +和最劣评价方案A -分别为(0,0,0,0,0)和(1,1,1,1,1).然后根据各点位的归一化数据计算出其与最佳评价方案和最劣评价方案的距离D i +和D i -.即:+iD =i D −=(4)最后根据计算得出各指标与最佳评价方案A +的接近程度,即为对其的综合评价./()i C D D D −−+=+ (5)表2 重金属潜在生态风险指数等级划分Table 2 Classification of potential ecological risk index ofheavy metalsi r E 污染等级 RI 污染等级 <40 低 <150 轻度生态危害40~80 中 150~300 中等的生态危害80~160 较重 300~600 强的生态危害160~320 重 ≥320严重≥600很强的生态危害表3 土壤重金属背景值及毒性系数Table 3 Background value of soil heavy metal and toxicitycoefficient参数 Cu Zn Pb Cr Ni 土壤背景值 22.6 74.2 26 61 26.9 毒性系数51522潜在生态风险指数法[13]:该方法为瑞典的Hakanson 最先提出,其原理是通过对污染元素的含量、种类、毒性和水体对这种元素的敏感程度等因素进行指标量化,然后根据重金属潜在生态风险指数等级划分(表2)对重金属的潜在风险进行评级.计算公式:RI immii rri i=1i=1n C =E =T C ∑∑ (6)式中:E r i 是所测元素的潜在生态风险参照值;RI 是沉积物所测多元素的潜在生态风险参照值;C n i 为所测元素的实测值;C i 为所测元素的参照值,参照采用全国土壤背景值中的重金属背景值;T r i 为重金属的毒性系数,见表3.2 结果与讨论2.1 沉积物重金属分布特征如图1所示,北方六湖库沉积物重金属中Cu 含量为1.01~85.17mg/kg,均优于GB 15618-2018《土壤环境质量 农用地土壤污染风险管控标准(试行)》[14]Ⅰ类污染风险标准;Zn 含量为33.68~ 208.80mg/kg,除松花湖与大伙房水库个别点位接近或略高于Ⅰ类污染风险标准,属于Ⅱ类污染风险管制标准范围,其余均优于Ⅰ类污染风险标准;Pb 含量为1.14~87.91mg/kg,均优于Ⅰ类污染风险标准;Cr 含量为14.35~141.81mg/kg,优于Ⅰ类污染风险标准;Ni 含量为9.49~59.87mg/kg,优于Ⅰ类污染风险标准.对照全国土壤背景值[15]对沉积物中的重金属含量进行评价可发现,六湖库中大伙房水库沉积物重金属Cu 、Zn 、Pb 、Cr 、Ni 含量均高于土壤背景值,沉积物重金属Cu 、Zn 、Cr 、Ni 分别为56.28,142.3, 97.9,44.44mg/kg.其中Cu 含量最高,达到土壤背景值的2.49倍;小兴凯湖各项重金属指标均低于背景值,且Zn 含量为六湖最低,为63.9mg/kg;于桥水库Pb 含量最高,为59.84mg/kg.本研究结果与王祖伟等研究基本保持一致[3,16-20],六湖在重金属元素含量分布上存在显著差异,其中小兴凯湖沉积物重金属污染程度最低,大伙房水库重金属污染程度最高,且大伙房水库各重金属元素与土壤背景值存在明显差异,可见大伙房水库受到外来污染与自身扰动等因素的影响较大.通过整理国内外各水体沉积物重金属含量情况(表4).对比博斯腾湖、羊卓雍错、青海湖、昆仲错[21-23]等我国西北部湖库,北方六湖库沉积物Cu 含量除污染较重的大伙房水库(56.28mg/kg),高于西部湖库,其余含量相当;沉积物Zn 含量北方六湖库均高于西部;沉积物Pb 含量白洋淀、衡水湖、于桥水库高于西部地区,最高达到59.84mg/kg;沉积物Cr 含量除大伙房水库外,含量相当;Ni 含量北部地区与西部地区各湖库均在土壤背景值上下浮动.沉积物重金4930 中国环境科学 40卷属整体含量与西部湖库沉积物相比基本持平,略高于西部地区.图1 北方六湖库沉积物各重金属分布特征Fig.1 Distribution of heavy metals in sediments of six northern lakes and reservoirs 同巢湖、太湖、洞庭湖等[24-26]长江中下游湖库相比,北方六湖库的沉积物Cu、Zn含量略高于长江中下游湖库;而Pb、Cr、Ni的含量除了污染较为严重的大伙房水库外,其余均低于长江中下游湖库.沉积物重金属整体含量低于长江中下游湖库.同滇池、泸沽湖、百花湖、洱海等[27-30]西南部湖库相比,北方六湖库沉积物重金属整体含量水平较低,污染相比滇池较轻.同泸沽湖等湖体污染水平相当.北方六湖库整体重金属含量水平与国内其他湖库相比处于中等偏低水平,与美国、英国、墨西哥[31-33]等国家湖库相比沉积物重金属含量处于较低水平.同中部的南四湖相比,松花湖、小兴凯湖沉积物重金属含量低于南四湖;大伙房水库高于南四湖;其余3湖库相差不大;重金属整体含量同南四湖持平.但经济相对发达的珠江口相比重金属含量则明显高于北方六湖库.湖库沉积物重金属污染情况大致可分为基本无污染、轻微污染、重污染3种.白洋淀等北方六湖库都属于基本无污染范畴,整体水质保持良好,只有个别点位出现重金属元素超标情况;珠江口等属于轻微污染状态,Zn含量超标,其余处于污染较低水平;滇池、美国Narragansett湾则属于典型的重污染范畴,滇池沉积物中Zn、Pb、Cr为轻度污染,Cu为中度污染状态,整体多元素超标,水质较差.综上所述,与我国西南部、长江中下游、西北部、中部、南部等其他地区对比,北方六湖库沉积物重金属Zn的含量相对其他重金属较高,这可能与我国北11期李捷等：北方湖库沉积物重金属区域特征及生态风险评价 4931 部地区的土壤背景值有一定关系,且可能与北部地区电泳电镀等企业分布较多有关[23].与美国、英国、墨西哥等国外水域相比,沉积物重金属Zn、Pb含量明显高于背景值,有富集现象存在.不同湖库沉积物重金属的分布也具有显著的区域性,不同地区主要污染源存在明显差别,且存在人类频繁活动地区湖库沉积物重金属含量高于人类活动较少地区,工业密集区湖库沉积物重金属含量要明显高于工业非密集区,这表明除了土壤背景值导致的区域性差别外,人为扰动也是导致北方六湖库沉积物重金属含量存在差别的主要因素.表4北方六湖库沉积物重金属及国内外其他水体沉积物重金属含量Table 4 Heavy metal content in sediments of six northernlakes and reservoirs and heavy metal content in otherwaters at home and abroad湖库Cu(mg/kg)Zn(mg/kg)Pb(mg/kg)Cr(mg/kg)Ni(mg/kg)来源白洋淀28.83 91.19 45.26 48.53 25.51本研究衡水湖25.86 74.30 43.94 56.45 23.59本研究于桥水库37.86 74.97 59.84 61.13 30.28本研究大伙房水库56.28 142.30 17.44 97.90 44.44本研究松花湖 2.24 110.56 10.41 52.66 24.28本研究小兴凯湖 2.41 63.90 13.37 56.36 26.09本研究博斯腾湖17.17 40.20 13.21 34.14 18.10[21]羊卓雍错31.47 62.53 21.72 67.39 35.28[22]青海湖16.60 26.70 24.84 31.80 11.62[23]昆仲错32.5 64.7 17.25 102.3 95.2[22]滇池83.63 205.64 65.68 125.73 42.50[27]泸沽湖59.15 11.55 39.69 [30]百花湖22.4 58.3 20.0 29.1 [29]洱海110.5 167.3 60 130 80 [28]巢湖19.07 54.82 21.93 57.33 22.04[23]太湖26.03 61.33 25.72 85.74 38.85[24]洞庭湖10.20 63..99 44.55 79.34 [25]南四湖38.90 59.60 19.10 54.50 [23]珠江口71.47 196.84 56.64 100.79 [26]美国Narragansett湾190 250 140 155 [31]英国Thames河61 219 179 59 [32]墨西哥La Piedad河40.90 115.00 59.50 [33] 2.2沉积物重金属污染综合评价优劣解距离法主要优势在于对多个目标湖库归一化(表5)处理后,能够精准的对这些目标湖体的沉积物重金属含量情况进行量化,从而达到对多个目标横向对比分析的目的.采用优劣解距离法对六湖库的405个重金属含量数据进行整体的归一化处理,处理后对单一湖库数据建立底泥重金属的空间分布特征(图2),能够发现各湖库在沉积物重金属的空间分布特征上存在明显差异.表5北方六湖库沉积物重金属归一化指标Table 5 Normalized index of heavy metals in sediments of six lakes and reservoirs in North China湖库 Cu Zn Pb Cr Ni 白洋淀0.492 0.348 0.705 0.000 0.092 衡水湖0.437 0.133 0.678 0.160 0.000 于桥水库0.659 0.141 1.000 0.255 0.321 大伙房水库 1.000 1.000 0.142 1.000 1.000 松花湖0.000 0.595 0.000 0.084 0.033 小兴凯湖0.003 0.000 0.060 0.159 0.120 白洋淀沉积物重金属污染在空间分布上呈现西部采样点污染整体高于东部采样点,污染偏高的采样点主要分布在上游入湖口附近,可见其污染主要来源为外源污染,对比白洋淀历史文献数据,沉积物中重金属Cu、Ni、Cr含量保持相对稳定,Zn 和Pb在2008年前后达到最高,含量远超土壤背景值,之后出现了下降趋势,这与高秋生等[16]的研究一致,这种趋势可能与当地企业的迭代以及近几年白洋淀多次补水有直接关系.衡水湖作为衡水市和冀州市的水源地,为周边提供居民生活和工农业用水,其是“南水北调”的储水枢纽,主要水源来自黄河引流,湖体被分为东西两湖,且两湖常年有渔民捕鱼,旅游业发达,沉积物重金属污染空间分布上南部采样点污染高于北部采样点,且西部冀州小湖湖体采样点污染高于东部主湖体采样点,这可能是因为衡水湖的补水闸口在北部,补充进来的黄河水对底泥产生冲刷.对比张曼胤等[18]研究的衡水湖历史文献数据,发现沉积物重金属Cu、Cr波动较小,基本与土壤背景值持平,但重金属Zn上升趋势较为明显,且上升趋势较为一致,这可能与衡水湖捕鱼业发达,含Pb石油在周边排放较大有直接关系.于桥水库是拥有灌溉、蓄水、发电等功能的综合性大型水库,该水库目前是天津市的主要生活用水水源地.其沉积物重金属污染空间分布上为西部采样点污染高于中东部采样点,推测其主要原因为西部临近蓟州,有生产活动污水排入其中,且其上游河流有矿产企业分布,外源污染较多.对比侯迎迎等[34]研究的于桥水库历史文献数据,沉积物中除重金属Cu含量(37.86mg/kg)略有升高,达到背景4932 中国环境科学 40卷值的2.3倍外,其余重金属含量均呈现下降趋势.这可能与于桥水库上游黎河、沙河、淋河沿途的工厂污染排放治理有关.大伙房水库沉积物重金属污染西北部采样点最高,其主要原因是其上游浑河有红透山铜矿等矿产企业,且该企业是开采冶炼一体的综合性企业,已运营80多年,是大伙房水库的主要污染源头.对比罗燕等[17]研究大伙房水库的历史文献数据,发现沉积物中重金属Cu、Zn、Cr未发生明显变化,重金属Pb则从36.96mg/kg降至17.44mg/kg,下降近1倍.松花湖重金属污染在空间分布上5、22、25号点位污染较为严重,最高点位风险系数达到0.727,推测5号点位位于漂河镇附近,人类活动密集,且处于河湖道转弯处,重金属易产生淤积,22、25号点位湖道相对封闭,自净能力差,有景区分布是其主要污染原因.对比张颖等[12]的研究能够发现重金属Pb的含量也发生了明显的降低.小兴凯湖沉积物重金属风险为六湖库最低,空间分布上表现为东西采样点低,中部采样点高的趋势,2号点位白鱼滩附近污染相对较高,风险系数达到0.693,推测其主要原因是白鱼滩附近渔业活动造成的人为扰动,提高了其沉积物重金属含量.在与历史数据的对比中发现,北方六湖库整体保持了良好的水质,未出现沉积物重金含量明显上升的现象,且除小兴凯湖外其余5湖库的Pb含量均出现了下降,这种整体的趋势很可能与北方地区对有色金属冶炼等高污染企业重点治理、车辆限行减排、以及实施湖库休养生息等政策有直接关系.对六湖库重金属数据的污染差异性进行多重比较的横向综合评价,评价结果见表6.C i的值越小说明受污染程度越小;反之,受污染程度越大.根据C i 值对六湖库进行等次排序可发现,大伙房水库的C i 值最高(0.672),小兴凯湖的C i值最低(0.082),松花湖次之(0.214),衡水湖(0.383)、白洋淀(0.459)、于桥水库(0.499)分别位于3、4、5位置,这表明六湖库中大伙房水库污染程度相对最高,小兴凯湖最低,白洋淀、衡水湖、于桥水库差异性不显著.11期李捷等：北方湖库沉积物重金属区域特征及生态风险评价 4933图2 各湖库沉积物重金属采样点及综合评价指数Fig.2 Distribution of heavy metal sampling points in sediments of lakes and reservoirs and Comprehensive Evaluation Index表6北方六大湖库沉积物重金属综合评价Table 6 Comprehensive evaluation of heavy metals insediments of six northern lakes and reservoirs湖库D-D+C i等次白洋淀 1.367 1.611 0.459 4衡水湖 1.074 1.727 0.383 3于桥水库 1.413 1.421 0.499 5大伙房水库 2.061 1.005 0.672 6松花湖 0.602 2.216 0.214 2小兴凯湖 0.208 2.315 0.082 1在水环境的保护治理中,沉积物重金属污染带来的负面效应大,持续时间长,恢复难度高,会对当地整个生态环境带来巨大的破坏.重金属污染物进入水体后经过一系列迁移转化,参与和干扰各种环境化学过程和物质循环,最终以一种或多种形态长期存留在环境中,造成永久性的潜在危害.在对比历史数据及综合评价结果后发现,北方六湖库沉积物重金属污染程度并没有完全与经济发展水平保持一致,推测其原因,各湖库的主要定位和使用方式有区别,周围人文地理环境条件不同及当地对水体的监管治理力度有区别导致.但目前缺少水体上游及周边工业排放、农用化肥和渔业养殖等数据,因此北方六湖库之间重金属污染存在明显差异的原因还需要进一步探讨.2.3沉积物重金属潜在生态风险评价优劣解距离法主要优势在于对多个目标湖库归一化处理后污染程度的横向对比分析,主要侧重空间上的评价,但该方法并未考虑其对生物的毒害程度.潜在生态风险指数法是根据重金属元素特性,通过沉积学原理综合多元素协同作用、毒性水平和物种敏感性等条件对湖库沉积物的重金属含量情况进行评价的一种算法.如表7所示,从E r i可以看出,六湖库中于桥水库、大伙房水库潜在生态风险参数最高,其中Cu对大伙房水库的生态风险贡献最大达到12.45,Cu、Pb对于桥水库的生态风险贡献最大分别为8.38和11.51,松花湖与小兴凯湖的潜在生态风险指数最低,除松花湖和小兴凯湖的其余4湖库均存在Cu、Pb生态风险贡献偏大的情况,且Pb在白洋淀、衡水湖、于桥水库的含量均超过土壤背景值的2倍以上,这表明Cu、Pb两种重金属已在湖泊沉积物中发生富集,后期产生污染的风险较大,在湖库水体中,一般水生动植物生长发育的整个周期都在水内,因此在湖库被污染的情况下很容易在其体内积累大量的重金属元素,通过食物链转移到人体.因此应加强对这两种重金属元素入湖的监控.潜在生态风险评价法所得结论与综合评价法互相印证,所得结论保持一致.六湖库5项沉积物重金属潜在风险参数目前均处于污染等级低的档位,重金属潜在生态风险较低,但在北方工业发展逐步提速的今天也应当警惕重金属污染的可能性,提前做好各类预防措施.表7北方六湖库沉积物重金属潜在生态风险参数E r i、RITable 7 Potential ecological risk coefficient and index ofheavy metals in sediments of six northern lakes andreservoirs E r i、RIE r i湖库Cu Zn Pb Cr NiRI白洋淀 6.38 1.23 8.7 1.59 1.9 21.62衡水湖 5.72 1 8.45 1.85 1.75 20.37于桥水库8.38 1.01 11.51 2 2.25 26.69大伙房水库12.45 1.92 3.35 3.21 3.3 25.66松花湖 0.49 1.49 2 1.73 1.81 8.6小兴凯湖0.53 0.86 2.57 1.85 1.94 8.784934 中国环境科学 40卷3 结论3.1目前六湖库沉积物重金属含量并未出现明显上升的趋势,水环境保持较好.其中大伙房水库沉积物重金属污染最重.除小兴凯湖外其余5湖库的Pb 含量出现下降趋势.这表面明外源减少,Pb重新释放入水体,沉积物重金属Pb含量降低.3.2北方六湖库之间主要重金属污染源存在明显区别,人类频繁活动地区沉积物重金属含量高于人类活动较少地区,工业密集区湖库沉积物重金属含量高于工业非密集区,但没有呈现出随经济水平的提高重金属污染越来越重的趋势.这除了土壤背景值导致的区域性差别外,人为扰动因素也是导致北方六湖库沉积物重金属含量存在差别的主要因素.3.3对比国内外其他湖库沉积物重金属含量北方六湖库沉积物重金属含量较低,污染处于中等偏下水平,潜在生态风险污染等级均为低,沉积物重金属Zn的含量与其他地区相比存在含量偏高的情况. 3.4Cu和Pb为白洋淀、衡水湖、于桥水库、大伙房水库的潜在生态风险的主要贡献元素,污染风险相对较高.沉积物重金属生态风险和污染程度从高到低依次为大伙房水库、于桥水库、白洋淀、衡水湖、松花湖、小兴凯湖.参考文献：[1] 金相灿,王圣瑞,席海燕.湖泊生态安全及其评估方法框架 [J]. 环境科学研究, 2012,25(4):357-362.Jin X C, Wang S R, Xi H Y. 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• protect the from metal stress;
• provides essential resources for hybridization breeding and
transgenic breeding.
catalyzing the catabolism of heme to yield biliverdin IXa, carbon monoxide (CO) and iron.
Reference Hua Li, Ming Jiang, Li Ling Che. (2012) BjHO-1 is involved in the detoxification of heavy metal in India mustard (Brassica juncea). Biometals. DOI: 10.1007/s10534-012-9588-9
Discussion
• The study revealed a novel effect of plant genotypes on communication between plants and rhizosphere bacteria, and offer a new way to consider for phytoremediation of heavy metal-contaminated soil.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results
• genotypes diversify the components of organic acid.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results • Multiple stress-responsive elements were detected in a 1099 bp promoter sequence upstream of BjHO-1 being cloned by genome walking approach. • The expression of BjHO-1::GUS was significantly induced by Zn, Cd, Hg, and Pb. revealed that transcripts of transformants were significantly increased in seedlings
魏铭
Introduction
•
•
Plant-microbe interactions play a important role in the phytoremediation
of heavy metal-contaminated soil. Two genotypes of the Silene vulgaris, which have shown tolerance to Cr, were tested.
Results • Testing with histochemical staining of H2O2 in leaves, the wild type leaves treated with Hg were stained extensively, whereas those transformed with BjHO-1 displayed relatively light staining for H2O2.
Introduction
• • Heavy Metal-resistant Gene BjHO-1
BjHO-1 has been proved involved in the detoxification of India mustard (Brassica juncea).
Previously, Heme oxygenase-1 (HO-1) is a stress-responsive gene coding for an enzyme
Hg-induced oxidative stress. This work also provides a new example for design of transgenic plants that do not accumulate or minimizing accumulation of toxic trace metals growing on heavy metalcontaminated soils.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results
• the community structure of bacterium around root were influenced significantly by genotypes and less by Cr contamination.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Reference Hua Li, Ming Jiang, Li Ling Che. (2012) BjHO-1 is involved in the detoxification of heavy metal in India mustard (Brassica juncea). Biometals. DOI: 10.1007/s10534-012-9588-9
Results • The transcript abundance varied considerably in cotyledon, hypocotyl, leaf and root respectively.
Results • Treatments with Hg resulted in a time-dependent and progressively increasing expression of BjHO-1, while the expression of BjHO-1 was extremely low under normal condition.
Results • The biomass in shoots and roots are also significantly increased comparing with wild type under Hg stress.
Results • The accumulation of Hg in transformants was significantly less than wild type.
Thanks.
魏铭 13生物技术(英) 2013332860049
Discussion
The results of research above suggest that the heavy metal-inducible gene, HO-1 provides plant
resistance to Hg toxicity by improving plant dry mass, reducing Hg accumulation, and attenuating
Results
• genoptypes significantly impact the metal uptake in shoots and roots.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.