Identification of rice varieties with high tolerance or sensitivity to lead and characterization of the mechanism of tolerance

Pb inhibits plant growth. To study Pb tolerance in rice (Oryza sativa), we screened 229 varieties for Pb tolerance or sensitivity. Three-day-old seedlings were treated for 12 d with 20 microM Pb solution. Based on the dry weight of the root, three Pb-tolerant (var CH-55, var KH-2J, var Kumnung) and three Pb-sensitive (var Aixueru, var C-9491, var Milyang23) rice varieties were selected. The root biomasses of the tolerant varieties were approximately 10-fold higher than those of the sensitive ones. The greatest morphological difference between the two groups was in the growth of the adventitious roots, as tolerant lines were able to develop adventitious roots after 6 d of Pb treatment, whereas sensitive ones did not develop any even after 15 d. The growth of adventitious roots in the tolerant varieties was dependent on a mechanism, whereby Pb was altered to a form that cannot be taken up by the tissue, because (a) the solution in which the tolerant varieties of rice had grown still contained Pb but nevertheless did not affect the root growth of new rice seedlings, and (b) the adventitious roots of tolerant seedlings developed in Pb solution contained little Pb. The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties, whereas the opposite was observed for the sensitive ones. Oxalate added to the growth solution ameliorated the inhibition of root growth by Pb. These results suggest that compounds such as oxalate secreted from the root may reduce the bio-availability of Pb, and that this may constitute an important Pb tolerance mechanism in the tolerant rice varieties studied here.     

野皂荚对NaCl胁迫的生理响应及耐盐性

以盆栽野皂荚2年生实生苗为材料,设置土壤NaCl含量分别为0.053%（CK）、0.15%、0.3%、0.45%和0.6%的盐胁迫处理,研究不同浓度盐处理对苗木生长、细胞膜透性、细胞保护酶活性以及Na⁺和K⁺分布格局的影响,探讨了其耐盐阈值和机理.结果表明：随着NaCl浓度增加,苗木生长量逐渐降低,盐害指数逐渐升高;野皂荚可忍耐的土壤含盐量为0.42%.随着NaCl浓度增加,叶片相对电导率、氧自由基产生速率和丙二醛(MDA)含量均逐渐增大;超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性呈先上升后下降的变化趋势,在土壤含盐量0.3%或0.45%时达到峰值;高盐胁迫下,SOD、POD和CAT活性的增强可及时清除盐胁迫产生的氧自由基,进而缓解或避免膜脂过氧化作用对组织细胞的伤害.盐胁迫下根、茎、叶的Na⁺含量均逐渐增大,且呈现根>叶>茎的分布格局;K⁺含量和K⁺/Na⁺呈下降趋势,呈现叶>根>茎的分布格局;K⁺-Na⁺选择性运输系数(S_K⁺·Na⁺)随着土壤含盐量的增加逐渐升高,且叶S_K⁺·Na⁺高于茎S_K⁺·Na⁺.野皂荚耐盐机制是根系拒盐和叶片耐盐;盐胁迫下,根系Na⁺累积能力增强可控制Na⁺向地上运输以避免盐害发生,叶片K⁺选择性吸收和累积能力的显著提高可忍耐和补偿Na⁺对组织的伤害.     

Increase of glutathione in mine population of Sedum alfredii: a Zn hyperaccumulator and Pb accumulator

Phytochelatins (PCs) have been induced in a large range of plant species, but their role in heavy metal tolerance is unclear. Sedum alfredii is a new zinc (Zn) hyperaccumulator and lead (Pb) accumulator found in an old Pb/Zn mine in the Zhejiang Province of China. Until now, the mechanisms of its hyperaccumulation/accumulation and tolerance were poorly understood. The aim of this work was to investigate whether PCs were differentially produced in mine populations of S. alfredii compared with a non-mine control of the same species. The results showed that plants from the mine site were more tolerant to increasing Zn and Pb concentrations than those from the control site. No PCs and cysteine (Cys) were detected by pre-column derivatization with HPLC fluorescence in any tissues of two populations at any treatment, which in turn indicated they were not responsible for Zn and Pb tolerance in the mine population. Instead, Zn and Pb treatments resulted in the increase of glutathione (GSH) for both populations in a tissue-dependent manner. Significant increases were observed in leaf, stem and root tissues of plants grown on the mine site. The results suggest that GSH, rather man PCs, may be involved in Zn and Pb transport, hyperaccumulation/accumulation and tolerance in mine population of S. alfredii.     

古老铅锌矿区生态型东南景天对锌耐性及超积累特性的研究

 植物长期生长在重金属污染的生境中,逐渐进化成不同的生态型。通过调查中国东南部古老Pb/zn矿和非矿山生境中的植物种群,发现生长在古老Pb／Zn矿的东南景天(Sedum alfredii Hance)是一种新的Zn超积累植物。在自然和控制条件下,古老Pb／Zn矿生态型比非矿山生态型植株的茎粗、叶片大、植株高。在矿山土壤Zn有效含量为105.5～325.4mg·kg-1时,矿山生态型东南景天植株地上部Zn含量为4134～5000mg·kg-1;当营养液中Zn浓度为1223.6μmol时,其Zn含量高达2％。在相同Zn浓度下,矿山生态型地上部Zn含量比非矿山生态型高30倍左右。两种生态型体内Zn分布也不同,古老铅锌矿山生态型的不同器官中Zn含量以茎>叶片>根系,而非矿山生态型则以根系>茎>叶片。古老铅锌矿山生态型地上部积累的Zn占植株总积累量的90％以上,其中叶片和茎分别占41.66％±5.46％和54.75％±5.87％;非矿山生态型各器官中积累的Zn远远低于古老铅锌矿山生态型,各器官中积累的Zn以茎>根系>叶片。本研究表明,这两种生态型东南景天的发现,为今后探讨植物耐高Zn胁迫和超积累Zn的微进化过程提供了非常有价值的材料,也为Zn污染土壤的植物修复提供了一种很有潜力的候选材料。     

Role of EDTA in alleviating lead toxicity in accumulator species of Sedum alfredii H

The effects of Pb chelater (EDTA-Pb) and ionic Pb (Pb(NO(3))(2)) on root cell death, Pb accumulation, changes of ROS, activities of antioxidant enzymes and uptake of mineral elements in response to Pb toxicity in Sedum alfredii H. were compared. Loss of plasma membrane integrity became serious by increasing Pb concentration in the medium, 200 microM Pb + 200 microM EDTA has alleviated the root cell death. The biomass was significantly affected by high concentration of Pb, and root growth was also affected by EDTA-Pb compared with ionic Pb. Lead accumulation was higher in the samples treated with ionic lead than that of the control. The concentration of reactive oxygen species (ROS) was determined by fluorescence microscopy, which indicates that the Pb stress increased the content of ROS significantly, whereas the EDTA-Pb decreased the burst of H(2)O(2). High Pb concentrations increase the activity of SOD and LOX. The Cu concentration in root increased significantly under Pb and EDTA-Pb treatment, and 200 microM Pb markedly increased the Fe content in roots. Under ionic Pb condition, the contents of Mg, Ca and K in shoots decreased, whereas they were significantly increased in case of EDTA-Pb. These results suggested that accumulating ecotype of S. alfredii roots were inefficient in uptake of higher concentration of EDTA-chelated Pb for long treatment duration, and that lead toxicity could be alleviated by EDTA.     

Variations in Metal Tolerance and Accumulation in Three Hydroponically Cultivated Varieties of Salix integra Treated with Lead

Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb) tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou), a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI) and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production), but a low translocation factor (TF), indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests.     

Hydroponic screening of willows (Salix L.) for lead tolerance and accumulation

Lead tolerance and accumulation in five willow clones were investigated using a nutrient film technique. Plants were exposed to 0, 48, 121, 169, or 241 microM Pb for 14 days. Tolerance indices (TI) and critical toxicity thresholds (EC50) were determined for five willow clones. SX61 had the highest TI values (92%) in the 48 and 121 microM Pb treatments, as well as the highest EC50 threshold values (70.5 microM for roots, 155.9 microM for aboveground tissue), indications of a high degree of tolerance to Pb. This clone also developed the highest biomass of all the clones tested. We found significant variation in willows' lead accumulation. The highest Pb content in roots (24 mg plant(-1)) and aboveground tissue (7.6 mg plant(-1)) was recorded in the 48 microM Pb treatment in SX61. Based on high biomass, TI, ECso, and Pb content in plant tissues, SX61 holds promise for phytoextraction of lead.     

行道树毛白杨树干中重金属元素分布

采用电感耦合等离子体发射光谱法(ICP),测定分析首都机场高速公路旁毛白杨(Populus tomentosa Carr.)树干中Pb、Cd、Cr、Cu、Zn、Ni和Mn 7种重金属元素的含量及积累量,比较分析树干不同组织、不同方位、不同龄级年轮重金属含量差异及与交通量、关键气候因子的相关性。结果表明:树干木质部中各重金属平均含量由大到小依次为Zn、Cu、Cr、Mn、Ni、Pb、Cd,树皮中依次为Zn、Mn、Cr、Pb、Cu、Cd、Ni,树皮中各重金属元素的含量明显高于木质部;同一树干木质部中,各重金属元素在不同方位的分布有所差异,其中,靠近车道一侧的各重金属元素含量均高于背离车道一侧,南北向比较中,Ni、Zn为南侧含量高于北侧,其他5种重金属元素均为北侧高于南侧;以5a为一个龄级将年轮划分为5个龄组,各龄级年轮中重金属含量随时间的变化趋势各异,其中Pb、Cd、Cu、Zn总体呈递减趋势,且与年降水量、最低气温、日照时数、雨天日数和大风日数呈正相关趋势,与年平均气温和最高气温呈负相关趋势;各元素在毛白杨树干木质部中的积累量表现为ZnCrCuMnPbNiCd。     

Lead (Pb)-Induced Regulation of Growth, Photosynthesis, and Mineral Nutrition in Maize (Zea mays L.) Plants at Early Growth Stages

The phytotoxic effects of lead (Pb) on seed germinability, seedling growth, photosynthetic performance, and nutrient accumulation (K(+) and Cu(2+)) in two maize genotypes (EV-1098 and EV-77) treated with varying levels of PbSO(4) (0.01, 0.1, and 1.0 mg L(-1)) were appraised in this study. In the seed germination experiment, lead stress significantly reduced seed germination percentage and index, plumule and radicle lengths as well as fresh and dry weights in both genotypes. In the second experiment, lengths and fresh and dry weights of shoots and roots decreased due to Pb in both genotypes with increase in plant age. Higher Pb levels also decreased photosynthetic rate (A), water use efficiency (A/E), and intrinsic water use efficiency (A/g(s)), but increased transpiration rate (E) and C(i)/C(a) ratio as a result of increase in stomatal conductance (g(s)). The concentrations of K(+) and Cu(2+) decreased in root, stem, and leaves of both genotypes, which could be a direct consequence of multifold increase in Pb concentration in these tissues. Overall, cv. EV-1098 had better Pb tolerance potential than EV-77 because the former genotype showed less reduction in seed germinability parameters, photosynthetic performance, and K(+) and Cu(2+) accumulation in shoot and root under lead stress.     

芦竹修复镉汞污染湿地的研究

以湿土盆栽方法研究了芦竹在Cd和Hg污染模拟湿地中的富集能力及其在植株中的分布.结果表明,芦竹在101mg·kg^-1Hg污染环境中生长8个月后,对Hg的富集量是根系>茎>叶片,植物地上部分对Hg富集量为200±20mg·kg^-1DW;而在115mg·kg^-1Cd污染环境中生长8个月后,其对Cd的富集量是叶片>根系>茎,芦竹叶片对Cd的富集量在160±26mg·kg^-1DW.重金属在芦竹各器官内的含量随种植时间的延长而增加,8个月生长期富集量比4个月生长期富集量高30%～50%.芦竹生物富集系数(Bio concentrationfactorBCF)随土壤中重金属含量增加而减小.在污染土壤中,芦竹叶、茎对Hg的BCF为1.9和2.1、对Cd为1.5和0.3;在未受污染的空白对照湿土中(含Hg6.8mg·kg^-1,Cd8.5mg·kg^-1),芦竹叶、茎对Hg的BCF为6.8和12.2,对Cd为7.0和2.7,表明芦竹具有生物量大、根系发达、适应性强等特点,对Cd、Hg有较大富集量和较好的耐受性.     

硅对土壤-烟草系统中铅迁移及形态分布的影响

通过盆栽试验,以烟草为对象,研究了硅对土壤 烟草系统中铅的迁移以及土壤、烟草中铅形态分布的影响.结果表明： 施硅使非根际土壤可交换态铅向铁锰氧化物结合态转化,使根际土中交换态铅向铁锰氧化物结合态和残渣态转化,降低了土壤中铅的植物有效性与迁移性.施硅显著提高了烟草根部和叶部的生物量,显著降低了烟草铅的总吸收量和烟草各器官的铅含量,其中烟草铅的总吸收量降低了6.5%～44.0%,烟叶铅含量降低了3.1%～60.4%.施硅使烟草根、茎和叶中乙醇提取态、去离子水提取态和氯化钠提取态向盐酸提取态和残渣态转化,降低了烟草体内铅的毒性与迁移性.土壤-烟草系统中土壤向烟草根部的移动指数和根部向茎部的移动指数随施硅量的增加而降低,烟草茎部向叶部的移动指数随着施硅量的增加呈先增高后降低的趋势.硅通过降低土壤铅有效性、缓解铅对烟草的毒害、改变烟草体内铅的形态分布,进而抑制土壤中铅向烟草叶部的迁移,降低烟叶中的铅含量.施硅是降低土壤铅的迁移性及烟叶铅含量的有效措施.     

大冶铜绿山矿区海州香薷(Elsholtzia hai-chowensis)植物地球化学特征分析

研究了大冶钢绿山矿区海洲香薷(Elsholtziahaichowensis)及其群落中几种主要植物Cu、Mn、Zn、Cd、Pb的累积分布,植物与土壤元素、Cu矿的关系,并对海洲香薷的重金属耐受性、铜矿的指示作用作了初步探讨.结果显示海洲香薷植物中的元素表现为Cu＞Mn＞Zn＞Pb＞Cd.其中Cu、Mn、Pb元素含量表现为根＞叶＞茎,Zn、Cd表现为叶＞根＞茎.和其它植物相比,海洲香薷中的Cu、Mn、Cd含量均高于其它植物,是其它植物的1～10倍.海洲香薷与土壤元素关系中,Cu的相关性最显著,其次为Pb.海洲香薷集中分布于矿区内含Cu较高的土壤上(1645～8950ug/g),其分布与Cu密切相关.     

水蓼对汞积累与分布的水培实验

通过水培实验,研究不同浓度的汞(0、0.5、1、10、20和50μg·L-1)对水蓼生长的影响及水蓼的耐受性表现。结果表明:在所处理的浓度范围内,水蓼生长与生理表现未受影响。水蓼根部具有最强的汞富集能力,富集系数高达531.5%。培养液中的汞浓度与水蓼茎、叶和根中汞的富集量呈显著正相关。在同一浓度时,随着培养时间的增长,水蓼体内汞含量不断增加。水蓼茎、叶和根亚细胞中的汞分布规律表现为:细胞壁>细胞器>细胞液,细胞壁对进入植物体内的汞有很强的束缚作用,限制其进入细胞质内部。     

Lead bioaccumulation,subcellular distribution and chemical form in sugarcane and its potential for phytoremediation of lead-contaminated soil

Abstract

Sugarcane is a promising species for lead (Pb) phytoextraction due to its large biomass and high tolerance toward Pb content. To understand the mechanisms involved in Pb tolerance and detoxification and its potential for phytoremediation in sugarcane, the bioaccumulation, subcellular distribution, and chemical forms of Pb in different tissues were investigated through pot cultivation sugarcane with increasing Pb concentrations in the present study. Results showed that sugarcane could tolerate high concentrations of Pb (up to 1250.0–1750.0?mg/kg); the Pb content in roots and shoots increased with increasing Pb concentration. A large amount of Pb content was stored in roots. The subcellular distribution of Pb in sugarcane revealed that the majority of Pb was bound to the cell wall. Meanwhile, the greatest amount of Pb was extracted by 2.0% acetic acid and 0.6?mol/L HCl, which indicated that most of Pb was combined with undissolved phosphate and oxalate. These results implied that the Pb formation of undissolved salts and compartmentalization in the cell wall may be a key strategy for Pb detoxicity and tolerance in sugarcane.     

EVALUATION OF THREE ORNAMENTAL PLANTS FOR PHYTOREMEDIATION OF PB-CONTAMINED SOIL

Characteristics of accumulation and tolerance of lead (Pb) in Quamolit pennata, Antirrhinum majus L. and Celosia cristata pyramidalis were investigated to identify Pb-accumulating plants. In this study, pot culture experiment was conducted to assess whether these plants are Pb-hyperaccumulators or accumulators. The results indicated that the Pb enrichment factor (concentration in plant/soil) and Pb translocation factor (concentration in shoot/root) of these plants were principally <1 in pot culture and concentration gradient experiments. However, the Pb concentration in Celosia cristata pyramidalis shoots was higher than 1000 mg kg^?1, the threshold concentration for a Pb-hyperaccumulator. Shoot biomass of Celosia cristata pyramidalis had no significantly (p < 0.05) variation compared to the control. Based on these results, only Celosia cristata pyramidalis could be identified as a Pb-accumulator.     

As,Pb, Sb,and Zn transfer from soil to root of wild rosemary: do native symbionts matter?

Background and aims

This is an in natura study aimed to determine the potential of Rosmarinus officinalis for phytostabilization of trace metal and metalloid (TMM)-contaminated soils in the Calanques National Park (Marseille, southeast of France). The link between rosemary tolerance/accumulation of As, Pb, Sb, and Zn and root symbioses with arbuscular mycorrhizal (AM) fungi and/or dark septate endophytes (DSE) was examined.

Methods

Eight sites along a gradient of contamination were selected for soil and root collections. TMM concentrations were analyzed in all the samples and root symbioses were observed. Moreover, in the roots of various diameters collected in the most contaminated site, X-ray microfluorescence methods were used to determine TMM localization in tissues.

Results

Rosemary accumulated, in its roots, the most labile TMM fraction in the soil. The positive linear correlation between TMM concentrations in soil and endophyte root colonization rates suggests the involvement of AM fungi and DSE in rosemary tolerance to TMM. Moreover, a typical TMM localization in root peripheral tissues of thin roots containing endophytes forming AM and DSE development was observed using X-ray microfluorescence.

Conclusions

Rosemary and its root symbioses appeared as a potential candidate for a phytostabilization process of metal-contaminated soils in Mediterranean area.     

Variation in selenium tolerance and accumulation among 19 Arabidopsis thaliana accessions

Selenium (Se) is an essential element for many organisms but also toxic at higher levels. The objective of this study was to identify accessions from the model species Arabidopsis thaliana that differ in Se tolerance and accumulation. Nineteen Arabidopsis accessions were grown from seed on agar medium with or without selenate (50 microM) or selenite (20 microM), followed by analysis of Se tolerance and accumulation. Tissue sulfur levels were also compared. The Se Tolerance Index (root length+Se/root length control) varied among the accessions from 0.11 to 0.44 for selenite and from 0.05 to 0.24 for selenate. When treated with selenite, the accessions differed by two-fold in shoot Se concentration (up to 250 mgkg(-1)) and three-fold in root Se concentration (up to 1000 mgkg(-1)). Selenium accumulation from selenate varied 1.7-fold in shoot (up to 1000 mgkg(-1)) and two-fold in root (up to 650 mgkg(-1)). Across all accessions, a strong correlation was observed between Se and S concentration in both shoot and root under selenate treatment, and in roots of selenite-treated plants. Shoot Se accumulation from selenate and selenite were also correlated. There was no correlation between Se tolerance and accumulation, either for selenate or selenite. The F(1) offspring from a cross between the extreme selenate-sensitive Dijon G and the extreme selenate-tolerant Estland accessions showed intermediate selenate tolerance. In contrast, the F(1) offspring from a cross between selenite-sensitive and -tolerant accessions (Dijon GxCol-PRL) were selenite tolerant. The results from this study give new insight into the mechanisms of plant selenium (Se) tolerance and accumulation, which may help develop better plants for selenium phytoremediation or as fortified foods.     

不同径级国槐行道树重金属富集效能比较

采用ICP-OES测定北京市台基厂大街行道树国槐各器官中7种重金属(Cd、Cr、Ni、Cu、Mn、Pb、Zn)含量,比较不同径级国槐重金属富集效能。结果表明:国槐中重金属含量因胸径级、器官、元素种类不同而存在差异。各径级国槐重金属含量大小总体趋势为ZnMnCuPbCrNiCd,各器官中树皮和根对重金属的吸收能力最强,其次是叶和枝,树干对重金属的吸收能力最弱。不同径级国槐对重金属的富集能力存在差异,表现为小径级中径级大径级。国槐各器官中重金属积累量大小顺序为根干枝叶,重金属积累量随着胸径级扩大和生物量的增加而增加。综合比较不同径级国槐重金属年均积累量、单位面积富集量和单位空间富集量,小径级(20≤DBH30 cm)国槐富集效能最高。     

外源NO对Cu胁迫下番茄Cu的亚细胞分布和化学形态的影响

采用营养液培养方法,研究外源NO供体硝普钠(SNP)处理对50 μmol·L^-1Cu²⁺胁迫下番茄幼苗Cu的亚细胞分布和化学形态的影响.结果表明： Cu胁迫下,番茄幼苗的生物量和株高显著降低33.7%和23.1%,外源NO能够显著缓解这种抑制作用,但各器官中Cu的含量和累积量仍显著升高.Cu胁迫下,番茄幼苗各器官的Cu含量和累积量大小依次为根系>叶片>茎>叶柄,幼苗根系吸收的Cu向地上部的转运大幅降低,外源NO只能缓解而不能消除这种作用.外源NO可以使Cu胁迫下幼苗各器官的液泡和细胞壁中Cu含量显著上升,细胞器中Cu含量降低,从而减轻过多Cu对胞质生理生化代谢的伤害,增强组织细胞对Cu的耐性.外源NO可以提高番茄幼苗根系中醋酸提取态铜（F_HAc）、茎中氯化钠提取态铜（F_NaCl）、叶柄中F_HAc、叶片中乙醇提取态铜（F_E）和F_NaCl的含量,降低水溶态铜（F_W）的含量与比例,以降低过多铜的生物毒性.     

Characteristics of distribution and chemical forms of Pb in tea plant varieties

A hydroponics experiment combined with subcellular fractionation and sequential extraction was conducted to study the Pb concentration in different organs of two tea plant varieties (Longjing 43 and Yingshuang) and the Pb subcellular distribution and chemical forms in the roots of the varieties. Under Pb stress, the root system of the two varieties had different features in morphology. With the increasing concentration of Pb in culture solution, the Pb concentration in Longjing 43 young leaves increased, but that in Yingshuang' s had no significant variation. A marked difference was observed in the Pb subcellular distribution and its chemical forms in roots between the two varieties under Pb stress. In Longjing 43 roots, all subcellular fractions except soluble ones had a lower Pb concentration at low Pb stress, and all the subcellular fractions except cell wall ones had a higher Pb concentration at higher Pb stress, compared with those in Yingshuang's. In Longjing 43 roots, the HAc-extractable Pb occupied the greatest proportion, followed by NaCl-extractable Pb, HCl- and H2O- extractable Pb, and ethanol-extractable Pb; while in Yingshuang's, NaCl-extractable Pb had the greatest proportion, followed by HAc-extractable Pb, HCl- and H2O-extractable Pb, and ethanol-extractable Pb. Based on these findings, tea plant variety Yingshuang was likely to possess a higher tolerance to Pb than Longjing 43 did.