镉在旱柳中亚细胞分布及存在的化学形态

以2个旱柳无性系幼苗为材料,通过营养液培养并结合差速离心与化学试剂提取法,分析了不同浓度Cd2+胁迫下旱柳叶和根中Cd的亚细胞分布及其存在的化学形态.结果显示,(1)随着培养介质Cd2+浓度升高,旱柳无性系幼苗叶和根中各亚细胞组分Cd含量随之增加.叶片的Cd主要富集于细胞壁、叶绿体和可溶性部分,它们的含量分别占65%～69%、14%～22%、6.8%～7.7%,仅少量Cd发现于膜部分;而根中Cd主要积累于细胞壁和可溶性部分,其中含量分别占59%～66%和14%～25%,Cd在根亚细胞组分中积累量依次为细胞壁>可溶性部分>质体>膜部分.(2)旱柳体内Cd以不同的化学形态存在,大部分为HCl(FHCl)、NaCl(FNaCl)、醋酸(HAC,FHAC)提取态,极少部分为乙醇(EtOH,FEtOH)和水提取态(Fwater),叶和根中5种Cd提取态含量依次为FHCl>FNaCl>FHAC>Fwater>FEtOH,而叶和根中HCl和NaCl提取态Cd占有比例大于30%以上.研究表明,旱柳无性系中Cd主要与蛋白质和有机酸螯合或以金属磷酸盐沉淀的形态存在,其根、叶的细胞壁和液泡在Cd忍耐与解毒中起到重要作用.     

不同铅水平下紫茎泽兰细胞内铅的分布和化学形态的分析

该研究运用差速离心法和化学试剂逐步提取法,分析了重金属铅在紫茎泽兰亚细胞内的分布和主要化学形态。结果表明:随着Pb浓度的升高,紫茎泽兰的叶、根、茎中各亚细胞组分Pb含量逐渐增加;紫茎泽兰中的Pb在叶片分布于可溶性部分和细胞壁中,两者占总量的75.34%~84.63%;茎也主要分布于可溶性部分和细胞壁中,占总量的36.10%~57.14%和20.07%~36.52%;而在根中则富集于细胞壁和可溶性部分,分别占39.2%~49.78%和28.27%~37.62%,其他细胞器中的Pb含量均较少。紫茎泽兰叶中的Pb以盐酸提取态和水提取态为主,两者占总量的58.74%~73.04%;茎中的Pb以醋酸提取态和氯化钠提取态为主;而根中的Pb则以醋酸提取态和盐酸提取态占优势,两者占总量的39.15%~52.91%。     

不同类型镉积累水稻细胞镉化学形态及亚细胞和分子分布

利用水培试验结合亚细胞组分分级分离和凝胶过滤等技术,研究了水稻根和叶中镉的化学结合形态及其亚细胞和分子分布,比较了低镉积累品种“广源占No.3”和高镉积累品种 “珍桂矮”的差异.结果表明：随着营养液中镉浓度的升高,根和叶亚细胞镉含量显著上升,大部分镉积累在细胞壁（F_Ⅰ）和细胞可溶部分（F_Ⅲ）.高镉积累品种“珍桂矮”根和叶中可溶部分镉含量显著高于低镉积累品种“广源占No.3”.根和叶各种形态镉中,以氯化钠提取态占优势,其次是醋酸提取态,盐酸提取态镉含量最低.与“广源占No.3”相比,“珍桂矮”中迁移性较强的去离子水和乙醇提取态镉比例较高.凝胶过滤结果表明,两种类型的水稻可溶部分镉的出峰位置与样品流份中可溶性蛋白的出峰位置大致相同.可溶部分中的镉大多与分子量为3kD的物质结合,属于植物鳌合肽（PCs）或低分子量物质.“广源占No.3” 根系中镉与PCs配合的组分（Cd-PCs）含量远小于“珍桂矮”.“广源占No.3”细胞可溶部分较低的镉含量以及根系中较少的Cd-PCs形成量,降低了镉的移动及其向地上部转运的可能性.     

锌在3种乔木中的积累及其亚细胞分布和化学形态

为了探索园林木本植物对重金属锌(Zn)的积累和耐性机制,本研究以栾树(Koelreuteria paniculata)、臭椿(Ailanthus altissima)和银杏(Ginkgo biloba)3种北京常见乔木为试验树种,通过盆栽污染模拟试验,研究不同浓度Zn处理(0、250、500、1000、2000 mg·kg^-1)对3种乔木的叶、枝、根生物量及叶片超微结构的影响,分析各器官中Zn积累含量及Zn在叶、根中的亚细胞分布和化学形态。结果表明: 各浓度Zn处理下3种乔木均能存活,但叶、枝、根的生物量较对照均有所下降。过量的Zn会导致栾树、臭椿的叶片细胞变形、细胞壁破裂、细胞器解体,而银杏叶片细胞尚能保持正常形态,说明银杏对Zn的耐受能力强于栾树和臭椿。随着Zn处理浓度的增加,3种乔木各器官的Zn含量呈上升趋势,栾树和臭椿体内的Zn含量显著高于银杏,说明栾树和臭椿对Zn的积累能力强于银杏。3种乔木叶和根中的Zn主要分布在细胞壁,分别占26.9%～71.8%和28.1%～82.6%,最高浓度Zn处理(2000 mg·kg^-1)下,Zn在可溶性组分(液泡为主)的占比可超过细胞壁。3种乔木叶片中的Zn主要以NaCl、HAc、HCl提取态存在,占57.4%～82.7%,根系中的Zn主要以NaCl、HAc提取态存在,占42.8%～67.2%,均是活性较低的形态。这说明细胞壁固持、液泡区隔化和将Zn以低活性的形态赋存可能是3种乔木积累和耐受Zn的重要机制。     

复合胁迫下茭白体内镉、铅的亚细胞分布和植物络合素的合成

以茭白（Zizania latifoliaTurcz.）的单季茭品种‘蒋墅茭’和双季茭品种‘葑红早’为试材,进行Cd2＋、Pb2＋的单一及复合胁迫处理,测定了茭白根系和叶片中的非蛋白巯基（NPT）、谷胱甘肽（GSH）、植物络合素（PCs）的含量,同时测定了茭白植株各亚细胞组分中Cd2＋、Pb2＋的积累量,以探讨茭白对重金属镉、铅胁迫的耐性机理。结果表明：Cd2＋、Pb2＋的单一及其复合胁迫均能促进两茭白品种根系和叶片中NPT、GSH、PCs的含量及茭白各亚细胞组分中Cd2＋、Pb2＋积累量的显著增加;复合胁迫时两茭白品种的NPT、GSH、PCs含量及各亚细胞组分中Cd2＋、Pb2＋的积累量均高于单一胁迫,茭白的不同部位间,以根系中的NPT、GSH、PCs含量显著高于叶片;茭白各亚细胞组分中Cd2＋、Pb2＋的积累量表现为：细胞壁高于原生质体,而可溶性部分高于细胞器。     

铜尾矿库区土壤与植物中重金属形态分析

对铜陵铜尾矿区土壤和植物中重金属形态进行了研究.结果表明,尾矿库区种植地极端贫瘠,有机质含量仅2.6～.8 g·kg^-1,而土壤Cu、Cd、Pb、Zn含量皆高于对照土壤,其中Cu含量达809.30～1 39.4 mg·kg^-1,Cd含量达3.2～6.3 mg·kg^-1,达到对照土壤30～60倍.结缕草和三叶草体内重金属含量与土壤重金属交换态及有机结合态含量成正相关,与碳酸盐结合态、铁锰氧化物结合态成显著或极显著负相关,与矿物态含量相关性不显著.在两种优势植物中,Cu、Zn、Pb均以活性较低的醋酸提取态、盐酸提取态和残渣态为主;Zn在根系和茎叶中,NaCl提取态占有较大比例,而Cd均以NaCl提取态为主.     

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.     

镉在不同类型蕹菜(Ipomoea aquatica Forsk.)中的积累及其化学形态和分子分布

采用水培幼苗试验研究不同蕹菜品种("台湾308"和"强坤青骨")Cd的积累及其化学形态和分子分布。结果表明,1.0 mg·L-1Cd浓度处理下,"台湾308"和"强坤青骨"叶、茎、根Cd含量分别为3.17、3.55、39.1和2.06、2.35、33.5 mg·kg-1;5.0 mg·L-1Cd浓度处理下,"台湾308"和"强坤青骨"叶、茎、根Cd含量分别为3.75、4.15、55.8和2.68、3.43、83.7 mg·kg-1。2个蕹菜品种Cd化学结合形态研究表明,叶中以乙醇提取态为主,茎、根中以乙醇和氯化钠提取态为主。"台湾308"叶、茎、根中活性较强的水提取态Cd所占比例均明显高于"强坤青骨",而醋酸和盐酸提取态Cd所占比例均明显低于"强坤青骨"。Cd处理水平和蕹菜品种类型对体内Cd化学结合形态均有一定影响,在根中表现尤为明显。分子分布结果表明,蕹菜叶片可溶部分中的Cd大部分与高分子量化合物和小分子量物质相配合,而根中可溶部分的Cd主要与植物螯合肽(PCs)和分子量为10~20 kDa的蛋白质结合。"强坤青骨"根系中Cd与PCs配合的组分(Cd-PCs)含量小于"台湾308",降低了Cd向地上部转运的可能性,进而成为其地上部分Cd含量较低的原因之一。     

NaCl胁迫下平邑甜茶根系线粒体特性和细胞死亡特征

以平邑甜茶(Malus hupehensis var. pingyiensis)实生幼苗为试验材料, 研究NaCl浇灌后根系线粒体H₂O₂含量、膜电位(Δψm)和根系ATP含量的变化以及细胞死亡特征。结果表明, 根系线粒体H₂O₂含量在0.085 mol·L ^-1 NaCl处理的第1-6天逐渐降低, 在第6-15天则快速上升; 线粒体Δψm在0.085 mol·L ^-1 NaCl处理的15天内一直呈下降趋势, 在第6-15天下降速度明显加快; 根系ATP含量在0.085 mol·L ^-1 NaCl处理的15天内始终低于对照, 但保持在一个较稳定的范围内。TUNEL原位末端标记试验显示, 0.085 mol·L ^-1 NaCl处理的第9天, 根系石蜡组织切片上的阳性反应斑点明显增多, 到第15天时阳性反应斑点密集成片, 表明细胞核DNA发生了细胞程序性死亡的特征性断裂。根系中细胞程序性死亡关键酶类caspase3/7活性在0.085 mol·L ^-1 NaCl处理的第1-6天处于较低水平, 其活性在第6-15天成倍上升。这些结果表明, 0.085 mol·L ^-1 NaCl处理6-15天能诱导平邑甜茶根细胞发生程序性死亡, 而且线粒体特性的变化与根系细胞程序性死亡密切相关。     

寒潮过程中4个茶树品种光合特性和保护酶活性变化及品种间差异

以茶树品种龙井43号(Longjing No.43)、鸠坑(Jiukeng)、乌牛早(Wuniuzao)、福鼎大白茶(Fortin white tea)为试材,研究了一次寒潮过程对4个茶树品种叶片的光合特性、叶绿素荧光参数和保护酶活性的影响,并利用主成分分析方法确定4个茶树品种的抗寒性。结果表明:寒潮初期,随着气温的降低,4个茶树品种的叶绿素含量、最大光合速率(P_(max))、表观量子效率(AQY)、最大光化学量子产量(Fv/Fm)、非光化学淬灭(q N)均呈现下降趋势,在气温回升期间随气温升高而有所增加,且福鼎大白茶的叶绿素含量、P_(max)、AQY、Fv/Fm的值为4个品种中最大,q N的平均值以乌牛早为最小,鸠坑最大;4种茶树的过氧化物酶(POD)活性在寒潮及恢复期间持续增强;4种茶树POD活性的平均值以龙井43号最小,福鼎大白茶最大;叶片的气孔限制值(Ls)和丙二醛(MDA)含量在降温和气温回升过程中,表现出先增加后降低的趋势,整个期间的Ls和MDA含量的平均值以福鼎大白茶为最小,龙井43号最大;利用主成分分析法对4品种茶树的光合参数、荧光参数和抗氧化酶活性进行分析,得到4个品种茶树的抗寒性顺序为:福鼎大白茶乌牛早鸠坑龙井43号。研究结果为茶树的引种及茶叶生产布局提供理论依据。     

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.     

低温对茶树叶片膜脂脂肪酸和蛋白质的影响

本文研究低温胁迫过程中龙井43和大叶云峰叶片膜脂脂肪酸的变化。结果发现,低温下不同品种茶树叶片膜脂脂肪酸配比变化趋势不同,较抗寒的龙井43,不饱和脂肪酸指数(IUFA)和亚麻酸(183)比例随低温期间不同阶段呈现出"低-高-低"的变化趋势;而不抗寒的大叶云峰的变化趋势无明显规律性。此外,还研究了越冬过程中龙井43叶片可溶性蛋白和膜蛋白的变化,发现低温期间龙井43叶片可溶性蛋白含量和组分基本稳定,而膜蛋白含量在低温胁迫时大幅度上升,且经低温诱导出现了46KD、38KD两种新的蛋白组分,并在温度升高后消失。     

不同蚕豆品种对铅污染的光合生理响应特征

以3个蚕豆品种(分别为K0883、K0502、K0697)为试验材料,通过大田模拟小剂量Pb污染(浓度为40和250 mg·kg^-1),研究了净光合速率、气孔导度、蒸腾速率、细胞间隙CO₂浓度、水分利用效率、叶绿素含量等光合生理响应特征的变化在不同品种中的差异.结果表明,Pb污染下3个蚕豆品种气孔导度和蒸腾速率没有显著变化,叶绿素含量有不同程度的上升;在250 mg·kg^-1 Pb浓度下,K0883蚕豆品种净光合速率、水分利用效率、细胞间隙CO₂浓度分别升高121.80％、上升193.70％、下降42.76％.3个蚕豆品种对Pb污染的抗性大小顺序为K0883＞K0697＞K0502.蚕豆不同光合生理指标对小剂量Pb污染的响应特征不同.不同蚕豆品种对小剂量Pb污染的响应特征存在差异,这种种内的差异性采用单个生理指标难以反映,只有通过对多个指标的整合分析才能表现出来.     

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.     

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.     

铅胁迫对斜纹夜蛾生长发育与生殖的影响

在植食性昆虫斜纹夜蛾幼虫标准人工饲料中添加不同浓度的重金属铅(Pb),研究Pb胁迫对其生长发育与生殖的影响.结果表明:斜纹夜蛾不同发育阶段(幼虫、蛹和成虫)的存活率和体质量随着饲料中Pb浓度的增加而下降,引起存活率显著下降的最低Pb胁迫浓度是100 mg·kg-1,引起体质量显著减少的最低Pb胁迫浓度是50 mg·kg-1.在取食Pb浓度为25～ 200 mg·kg-1的人工饲料后,斜纹夜蛾成虫的产卵天数显著减少;产卵力和生育力随着饲料中Pb浓度的增加而显著下降;1000粒卵的平均质量显著低于对照;卵孵化率显著下降.重金属Pb胁迫对斜纹夜蛾生长发育和生殖具有显著的抑制作用.     

玉米各器官积累Pb能力的品种间差异

为了研究不同玉米(Zea mays)品种及不同器官对Pb积累能力的差异,在土壤Pb含量为595.55 mg·kg^-1 的高Pb胁迫和含量为195.55 mg·kg^-1的低Pb胁迫(对照)条件下,采用盆栽试验结合火焰原子吸收等方法,测定了25个玉米品种各器官Pb的含量。结果表明:Pb胁迫下供试玉米品种各器官含Pb量表现为根>茎≌叶>籽实;与对照相比,根、茎、叶Pb含量均大幅度提高,籽实含量的提高幅度相对较小;Pb胁迫条件下,有近半数的供试玉米品种的籽实Pb含量超过了国家规定的卫生标准,显示了在受重金属污染农田生产的玉米产品存在着较高的受Pb污染的风险。有22个品种平均籽实生物量在较强Pb胁迫下有所下降,降幅为0.9%~38.7%,但平均降幅仅为12.6%,显示玉米在Pb胁迫下的减产不易察觉,从而增加了在受污染农田中玉米产品受Pb污染的风险。但研究也表明,在较高Pb胁迫下尚有52%的品种籽实Pb含量未超过国家卫生标准最高限量值,因此可以利用这些品种在受Pb污染农田中进行玉米生产,以降低Pb经玉米产品进入人类食物链的风险。研究结果还发现供试玉米品种各营养器官间Pb含量均呈极显著正相关,但营养器官与籽实Pb含量间无显著相关。其中在较强的胁迫条件下营养器官Pb含量特别高的品种No.1的籽实中Pb含量(0.19 mg·kg^-1)比较低,未超过国家卫生标准;品种No.2、No.3和品种No.6也有类似的特点。除上述品种以及品种No.4外,其余品种籽实Pb含量遵循与营养器官Pb含量成正比的一般规律。根中Pb含量特别高的品种No.1,籽实产量在Pb胁迫下略有下降,但下降幅度最小。胁迫条件下,品种No.1的营养器官Pb总量最高(51.69 mg·plant^-1),是对照的近12倍;籽实Pb含量符合国家标准的品种No.2,No.3和No.6的营养器官Pb总量也较高,在36~42 mg·plant^-1之间。由此可见,存在着在受Pb污染农田利用这些品种进行玉米生产同时修复受污染土壤的可能。     

Sorption of Cd(II) and Pb(II) by exopolymeric substances (EPS) extracted from activated sludges and pure bacterial strains: Modeling of the metal/ligand ratio effect and role of the mineral fraction

The present study deals with the sorption of Cd(II) and Pb(II) by exopolymeric substances (EPS) extracted from activated sludges or pure bacterial strains. The percentage of sorbed metal increases with the concentration of the EPS–water solution. Pb(II) always presents a higher affinity than Cd(II) for EPS. For the EPS extracted from pure bacterial strains, only one global binding constant from a simple equilibrium sorption model, may be used to assess the effect of microbial products such as EPS on Cd(II) and Pb(II) speciation or mobility in the environment. However, for EPS extracted from activated sludges, the wide variation of the global binding constants determined for Cd(II) and Pb(II) do not permit such a simple approach. The differences in sorption to metals between the two types of EPS (bacterial, activated sludges) could be explained by the differences in EPS composition: organic macromolecules, as well as the nature of the mineral fraction.     

The role of root damage in the chelate-enhanced accumulation of lead by Indian mustard plants

In the present study, increasing ethylenediaminetetraacetic acid (EDTA) concentration from 0 to 0.5 mmol L(-1) resulted in progressive increases in root elongation and in shoot and root dry matter (DM) of Indian mustard seedlings (Brassica juncea. L.) exposed at 0.5 mmol L(-1) of lead (Pb). The highest concentration of Pb in the shoots of Indian mustard reached 1140 mg kg(-1) dry weight (DW) in the treatment with 0.5 mmol L(-1) of Pb + 0.25 mmol L(-1) of EDTA. A significantly positive correlation was found between the concentrations of Pb and EDTA in the shoots of mustard. Roots were pretreated with an MC (methanol:trichloromethane) solution, 0.1 mol L(-1) of HCl, and 65 degrees C hot water. The plants were then exposed to 0.5 mmol L(-1) of Pb + 3 mmol L(-1) of EDTA in solution for 2 d. The pretreatments with MC, HCl, and hot water all increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Therefore, some physiological damage to roots would be useful to enhance the uptake of metal by plants and to minimize the application of doses of chelates in the practical operation of chelate-assisted phytoremediation.