镉在水生植物中的富集与亚细胞分布及其化学形态特征

以7种水生植物(长苞香蒲、水生美人蕉、黑藻、粉绿狐尾藻、花叶芦竹、香根鸢尾、水葫芦)为研究材料,构建生物塘系统,通过差速离心法和五步提取法,提取植物各亚细胞组分和不同化学形态的镉,并用原子吸收分光光度法测定镉含量,分析镉在水生植物体中富集特征,揭示植物对镉的耐性机制。结果表明:(1)水生植物根中镉富集量大于茎和叶;3种类型水生植物富集镉能力表现为沉水植物(粉绿狐尾藻、黑藻)浮水植物(水葫芦)挺水植物(长苞香蒲、水生美人蕉、花叶芦竹、香根鸢尾)。(2)镉在黑藻、水葫芦和花叶芦竹中的亚细胞分布量均呈现为细胞壁可溶组分原生质体线粒体,所占比例分别为37.16%~50.86%、20.69%~31.21%、10.81%~23.83%、8.15%~19.83%。(3)赋存化学形态表现为以氯化钠提取态、醋酸提取态为主,所占比例分别为29.37%~56.27%和15.06%~36.19%。研究发现,粉绿狐尾藻、水葫芦、水生美人蕉和花叶芦竹4种植物为富集镉较好的植物,而黑藻、香根鸢尾和长苞香蒲3种植物的镉富集能力相对较弱;镉主要以果胶酸盐、蛋白质结合态或吸附态存在于植物根的细胞壁和液泡中,以减弱镉对根细胞器和植物地上部分的毒害。     

霞多丽苗木中镉的积累、亚细胞分布及化学存在形态

以一年生盆栽葡萄品种霞多丽(Vitis vinifera L.cv.Chardonnay)自根苗及SO4砧嫁接苗为试材,采用CdCl2和CaCl2根部灌入的方法,研究了镉在霞多丽植株内的亚细胞分布和存在形态,以及外源添加氯化钙对植株镉吸收的影响.结果表明:大部分镉积累在霞多丽自根苗及嫁接苗的地下部器官;4 mmol·L-1浓度的CdCl2处理下,镉在自根苗根及根颈部分的积累量占77.1％,在叶片中的积累量占1.4％,而嫁接苗中镉在嫁接口以下部分的积累量高达93.9％,叶片中的积累量仅占0.1％;5 mmol·L-1外源钙缓解了植株对镉的吸收积累,而10mmol ·L-1外源钙则显著增加了植株对镉的吸收积累.镉在根系和叶片中的亚细胞分布规律为细胞壁＞可溶性部分＞细胞器,且在细胞壁中积累50％以上;镉在根系中主要以氯化钠提取态存在,其次为乙酸提取态,去离子水提取态含量最少.随着镉处理浓度的增加,各提取态含量有所变化.     

铯对印度芥菜幼苗生长的影响及其亚细胞分布和化学形态

以印度芥菜为材料,用含铯(Cs+)[8.24(CK),25,50,100,200mg·L~(-1)]的Hoagland营养液培养印度芥菜种子和幼苗,采用IMAGE-J软件测定根、茎长度,通过差速离心法、化学试剂提取法分别提取幼苗根、茎、叶各亚细胞组分及不同化学形态的Cs+,并用火焰原子分光光度计测定Cs+含量,分析Cs+对幼苗生长的影响及其亚细胞分布和化学形态,进而探讨Cs+对植物的伤害机理。结果显示:(1)Cs+对印度芥菜幼苗生长具有明显的抑制作用,根、茎的EC50(相对抑制率达到50%的Cs+浓度)分别为112.09和118.42mg·L~(-1);(2)各器官中Cs+的积累量总体表现为叶根茎;Cs+在印度芥菜中的亚细胞分布呈现为可溶性组分细胞壁组分细胞器组分,三者所占比例分别为52.86%~79.19%、20.81%~45.05%和1.43%~9.00%;(3)Cs+在印度芥菜各器官中主要以无机盐和水溶态赋存,两种形态根、茎、叶占比分别达到88.02%~92.20%、97.33%~100%和95.06%~100%。研究表明:印度芥菜积累过量的Cs+可抑制其根、茎生长,导致叶片枯萎,主要是因为Cs+在印度芥菜体内大部分以无机盐态和水溶态形式存在,使Cs+在植物体内具有较强迁移能力和毒理生物有效性,更易分布到重金属的毒性敏感区(如细胞器),导致细胞器受到功能性损伤,从而使植物表现出明显中毒症状。     

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.     

Cd、Zn及其交互作用对互花米草中重金属的积累、亚细胞分布及化学形态的影响

通过盆栽试验,研究了Cd、Zn及其交互作用下互花米草中Cd、Zn的含量及积累量,并分析了Cd、Zn在互花米草中的亚细胞分布及化学形态。结果表明：Cd-Zn处理组互花米草地上部及根部Cd含量显著高于Cd处理组;Cd-Zn处理组根部Zn含量显著低于Zn处理组,但地上部差异不显著,说明Zn促进Cd的吸收,Cd抑制Zn的吸收。Cd-Zn处理组互花米草地上部Cd积累量显著高于Cd处理组,但是根部Cd积累量却显著低于Cd处理组;Zn处理组地上部及根部Zn积累量均显著高于对照组及Cd-Zn处理组。Cd单因素胁迫下,Cd主要分布在细胞壁,Cd-Zn交互作用下,Cd在胞液中的分配比例高于其他细胞组分;Zn单因素及Cd-Zn交互作用下,Zn在胞液中的分配比例均较高,总的分配比例呈现以下趋势：胞液>细胞壁>细胞器,说明Zn的添加影响了Cd的亚细胞分布,Cd的出现对Zn在互花米草细胞中的分布影响不明显。Cd和Zn在互花米草叶中主要以氯化钠提取态存在,表明互花米草中Cd和Zn多以果胶酸盐结合态或蛋白质结合态存在。     

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.     

铅在茶树体内的分布及化学形态特征

采用水培试验,结合亚细胞组分分离和化学形态提取技术,研究了茶树品种龙井43和迎霜不同器官的Pb含量,及其在根系亚细胞中的分布和化学结合形态.结果表明： 在Pb胁迫下,两个品种茶树根系的形态特征不同;龙井43新叶中Pb含量随营养液Pb浓度的提高显著增加,而迎霜的变化不显著.两个品种茶树根系亚细胞中Pb的含量分布及结合形态均存在差异,低浓度Pb处理下, 龙井43根亚细胞组分（除可溶物质外）中Pb含量均低于迎霜;而高浓度Pb处理下,龙井43根亚细胞组分（除细胞壁外）中Pb含量均高于迎霜;龙井43根中醋酸(HAc)提取态的Pb含量比例最高,其他化学形态的高低顺序为NaCl提取态>HCl提取态/H₂O提取态>乙醇提取态;而迎霜根中NaCl提取态Pb成分比例最高,其他化学形态的高低顺序为HAc提取态>HCl提取态/H₂O提取态>乙醇提取态.迎霜对Pb毒害的耐受能力强于龙井43.     

黑土中几种重金属的化学形态

在自然界中,重金属元素的总浓度不能正确反映出它们对生物的效应和地球化学的过程。重金属的毒性在很大程度上取决于它们存在的化学形态。重金属进入土壤这个有机、无机复合体后,通过溶解、沉淀、凝聚、络合、吸附等各种反应,形成重金属的不同化学形态,并表现出不同的活性。东北地区的黑土,其主要特征是富含有机质,为了探索土壤有机质含量与土壤重金属的亲合力及其在土壤中存在的各种形态,我们用A.Tesser等提出的连续浸提法,作了重金属元素在黑土中存在形态的研究,这对进一步研究土壤净化功能与土壤环境容量具有一定意义。     

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%。     

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。     

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.     

Subcellular distribution and chemical forms of antimony in Ficus tikoua

Ficus tikoua (F. tikoua) was a potential species for antimony (Sb) phytoremediation due to its wide growth in the mining area. However, little was known about its tolerance mechanisms toward Sb. The determination of the distribution and chemical speciation of Sb in F. tikoua is essential for understanding the mechanisms involved in Sb accumulation, transportation, and detoxification. The present study investigated the subcellular distribution and chemical forms of Sb in F. tikoua. The plant was exposed to different Sb concentrations (0, 30, 90, and 180 μmol/L) for 30 days. The results showed that F. tikoua possessed a marked ability to tolerate and accumulate Sb. The proportional Sb increased with increasing Sb concentration in the solution, and the highest Sb concentration occurred in roots (1274.5–1580.9 mg/kg), followed by stems (133.5–498.9 mg/kg) and leaves (4.1–15.7 mg/kg). In the subcellular sequestration of Sb in F. tikoua, the largest accumulation of Sb occurred in cell walls (72.4–87.5%) followed by cytoplasmic organelles (8.2–18.6%) and cytoplasmic supernatant. The results suggested that cell walls act as important protective barriers against Sb toxicity in F. tikoua. Although Sb in all plant tissues found primarily in the fractions extracted by ethanol and distilled water, the current study found that the Sb amounts in the HAc-extractable fraction, HCl-extractable fraction, and residue fraction increased at the highest Sb level (180 μmol/L) compared to that under lower Sb levels. These results indicate that excessive Sb accumulated in F. tikoua under Sb stress is bound to non-dissolved or low-bioavailable compounds, a biochemical mechanism that benefits F. tikoua because it helps alleviate Sb toxicity.     

Subcellular distribution and chemical forms of cadmium in Morus alba L.

Morus alba L. (mulberry) is a perennial woody tree and a species with great potential for Cd phyremediation owing to its large biomass and extensive root system. The mechanisms involved in Cd detoxification were investigated by analyzing the subcellular distribution and chemical forms of Cd in mulberry in the present study. These results indicated that 53.27–70.17% of Cd mulberry accumulated was stored in the root and only about 10% were in the leaves. Lots of the Cd was located in the cell wall of the mulberry root and in soluble fraction of the mulberry leaf. Moreover, in roots, the largest amount of Cd was in the form of undissolved Cd-phosphate. While in mulberry leaves and stems, most of the Cd was extracted by 2% Acetic acid and 0.6 M HCl, representing Cd-phosphate and Cd-oxalate. It could be concluded that the Cd combination with peptides and organo-ligands in vacuole of leaf or complexed with proteins or cellulose in the cell wall of root might be contributed to the tolerance of mulberry to Cd stress. The mulberry could be used to remediate the Cd polluted farmland soils.     

Effects of extended growth periods on subcellular distribution,chemical forms,and the translocation of cadmium in Impatiens walleriana

Impatiens walleriana plants accumulate sufficiently high concentrations of cadmium (Cd) for this species to be considered a potential Cd hyperaccumulator. Rooted cuttings were grown hydroponically for 25 and 50 days in solutions spiked with various Cd concentrations. The subcellular distribution and chemical forms of Cd in different organs were analyzed, and its upward translocation was also assessed. The plants accumulated large amounts of Cd; the Cd concentration in the roots and shoots reached 120–1900 and 60–1600 mg/kg, respectively. Regardless of the growth period, the Cd accumulated in the roots was primarily compartmentalized in the soluble fraction or ethanol and deionized water extractable chemical forms with high migration abilities. Translocation to the shoots was followed by an association of Cd mainly in the cell wall or with pectate and protein. The roots’ Cd showed a high migration capacity for predicting the shoots’ Cd concentrations. Different exposure periods significantly affected the subcellular distribution of Cd in the stems, and thus the upward translocation.     

Subcellular distribution,chemical forms and thiol synthesis involved in cadmium tolerance and detoxification in Siegesbeckia orientalis L.

Siegesbeckia orientalis L. is a promising species for cadmium (Cd) phytoextraction with large biomass and fast growth rate, while little information about their intracellular mechanisms involved in Cd tolerance and detoxification has been explored. A soil pot experiment with total target Cd concentrations of 0, 10, 50, 100, and 150 mg kg^?1 were designed to investigate the subcellular distribution, chemical forms and thiol synthesis characteristics of Cd in S. orientalis. More than 90% of Cd was bound to the soluble fractions (48.4–76.5%) and cell walls (19.9–46.3%). Increasing soil Cd concentrations enhanced Cd sequestration into the cell walls. Most of the Cd (69.8–82.7%) in the plant organ was mainly in the forms of pectate and protein integrated Cd and undissolved Cd phosphate, while a minor portion (6.8–20.9%) was in the forms of the inorganic Cd and the water soluble Cd. Nonprotein thiols and phytochelatins significantly increased with increasing soil Cd treatment levels, while glutathione concentrations had no obvious change trends. Therefore, intracellular detoxification mechanisms of Cd in S. orientalis mainly rely on formation of less toxic Cd chemical forms, store of a large amount of Cd in cell wall and synthesis of thiol compounds.     

土壤中重金属形态分析及其环境学意义

介绍了土壤重金属的形态及各种分析方法,重点说明了土壤中重金属形态分布及影响因素;讨论了影响土壤环境中重金属形态转化的因素,重金属形态与重金属在土壤中的迁移性、可给性、活性的关系,重金属污染土壤修复与重金属形态分布的关系.形态分析在一定程度上反映自然与人为作用对土壤中重金属来源的贡献,并反映重金属的生物毒性.重金属可以因形态中某一个或几个方面不同而表现出不同的毒性和环境行为.     

Subcellular distribution,chemical forms,and physiological response to cadmium stress in Hydrilla verticillata

This study investigated the subcellular distribution and chemical forms of cadmium (Cd) in Hydrilla verticillata and the physiological mechanism underlying H. verticillata responses to Cd stress. Hydrilla verticillata was grown in a hydroponic system and was treated with various Cd concentrations (0, 10, 50, 100, 125, and 150?µM) for 7?days. Cadmium analysis of the leaves at the subcellular level showed that Cd was mainly stored in the soluble fraction (77.98–83.62%) and in smaller quantities in the cell wall fraction (11.99–17.30%) and the cell organelles (4.30–4.88%). The Cd taken up by H. verticillata was in different chemical forms. In the leaves and stems, the Cd was mostly extracted using 1?M NaCl and smaller amounts of Cd were extracted using 2% acetic acid. The malondialdehyde content significantly increased at all Cd concentrations, which indicated oxidative stress. The superoxide dismutase, guaiacol peroxidase, and catalase activities were enhanced. The proline, ascorbate, and glutathione contents increased at lower Cd concentrations, but decreased consistently as the Cd concentration rose. These results suggest that H. verticillata can be successfully used in the phytoremediation of Cd-contaminated water.     

镉在互花米草中积累、转运及亚细胞的分布

研究了在不同Cd浓度(0、5、100、200μg·g-1)处理下,互花米草花序、叶、茎、根茎、须根中Cd含量、积累量、转运特征,及Cd在互花米草体内的亚细胞分布。结果表明,Cd在互花米草不同器官中的积累能力存在较大差异。茎、根茎、须根中Cd含量及积累量随处理浓度的增加而升高,其中须根中Cd含量及积累量均高于其他器官。Cd处理浓度为100gμ·g-1时,花序和叶中Cd含量达到最大值,分别为8.65和7.82μg·g-1。在Cd处理浓度为200μg·g-1时,须根中Cd含量可高达390.00μg·g-1,积累量达3200μg·株-1。Cd在互花米草体内转运能力极低,绝大部分Cd积累在地下部位。Cd在互花米草亚细胞中的分布规律为细胞壁>胞液>细胞器。随着Cd处理浓度的增加,Cd在细胞壁中的分配比例增大,胞液中Cd分布比例则相应减小,细胞壁和胞液相互协调,增强互花米草对重金属Cd的耐性。