螯合剂对重金属超量积累植物Thlaspicaerulescens的锌,铜,锰？…

由螯合剂ＥＤＴＡ和ＤＴＰＡ对重金属超量积累植物Ｔｈａｓｐｉｃａｅｒｕｌｅｓｃｅｎｓ吸收Ｚｎ、Ｃｕ、Ｍｎ、Ｆｅ和Ｐ的影响表明：营养液含Ｚｎ１０μｍｏｌ／Ｌ条件下,植株地上部全Ｚｎ含量和根系吸Ｚｎ速率分别达到１６８１ｍｇｋｇ＾－１干重和４４８ｍｇｋｇ＾－１根干重ｄ＾－１;４３．２μｍｏｌ／Ｌ的ＥＤＴＡ或ＤＴＰＡ处理显著抑制植株的生长,也减少植株单位根重吸收的Ｚｎ量,降低地上部和根系全Ｚｎ全Ｃｕ、全Ｍｎ     

重金属超量积累植物研究进展

重金属超量积累植物具有极高的吸收和积累重金属的能力。本文介绍了超量积累植物的特性、种类,对重金属的吸收与忍耐机理,及其在治理污染土壤中的潜力等方面的最新研究进展。     

利用重金属超量积累植物净化被重金属污染的土壤

随着人口的增长和工业的发展,废物废水的排放和矿山废弃地不断增加,加之各种化学物质在人类活动中的广泛使用,重金属污染已成为人们日益关注的环境问题之一。土壤被重金属污染以后,一方面直接影响作物生产并通过食物链危害人类;另一方面由于大多数重金属元素进入土壤以后很难移动,使治理重金属污染的土壤变得十分困难。自然净化过程极其漫长,一般需要成千上万年的时间。采用客土法和淋溶法治理,不仅成本昂贵,需要特殊仪器和经过培训的专业人员,还不能从根本上解决问题。随着人OJ对环境保护的日益重视,一些科学家开始探索在不破…     

植物对重金属的吸收和分布

植物修复是利用植物来清除污染土壤中重金属的一项技术。该技术成功与否取决于植 物从土壤中吸取金属以及向地上部运输金属的能力。植物对金属的吸收主要取决于自由态离子活度。许多螯合剂能诱导植物对重金属的吸收。金属离子在液泡中的区域化分布是植物耐 重金属的主要原因。同时,细胞内的金属硫蛋白、植物螯合肽等蛋白质以及有机酸、氨基酸等在金属贮存和解毒方面也起重要作用。本文还论述了重金属在植物体内运输的生理及分子 方面的研究进展。     

水生生物对重金属吸收和积累研究进展

综述了国内外在水生生物对重金属吸收和积累研究方面的最新进展。着重阐述了重金属毒性影响因素和鱼类对重金属吸收和积累机理方面的研究现状和趋势。     

3种湿地植物对锌的吸收分配及其与根表铁氧化物胶膜的关系

在室内培养条件下,以灯心草、茭白和美人蕉3种湿地植物为材料,研究了湿地植物对锌的吸收分配能力与根表铁氧化物胶膜之间的关系.结果表明:(1)3种湿地植物积累锌的总量大小顺序为:茭白>美人蕉>灯心草,茭白积累锌的总量是灯心草的1.79倍;它们根表铁氧化物胶膜含量表现为灯心草>茭白>美人蕉,且其间存在显著差异(P<0.05).(2)锌在湿地植物中分配比例表现为;根中锌量>地上部分锌量>根表铁氧化物胶膜上吸附锌量;锌主要积累在湿地植物根中,地上部分和根表铁氧化物胶膜上吸附的锌量无显著差异.(3)湿地植物根表铁氧化物胶膜上吸附锌的数量与湿地植物地下部分锌含量呈极显著正相关(r=0.983 5**),增加根表铁氧化物胶膜上锌的数量就能明显提高地下部分锌含量;每千克土壤加入1 g FeSO4后,3种湿地植物积累锌的总量平均增加了21%.可见,湿地植物根表铁氧化物胶膜对锌的吸附也是湿地植物固定或积累锌的重要途径之一.     

植物对重金属的吸收和分布

植物修复是利用植物来清除污染土壤中重金属的一项技术。该技术成功与否取决于植物从土壤中吸取金属以及向地上部运输金属的能力。植物对金属的吸收主要取决于自由态离子活度。许多螯合剂能诱导植物对重金属的吸收。金属离子在液泡中的区域化分布是植物耐重金属的主要原因。同时,细胞内的金属硫蛋白、植物螯合脓等蛋白质以及有机酸、氨基酸等在金属贮存和解毒方面也起重要作用。本文还论述了重金属在植物体内运输的生理及分子方面的研究进展。     

东南景天对锌、镉复合污染的反应及其对锌、镉的吸收和积累特性

东南景天(Sedum alfredii Hance)已被鉴定为一种中国原生的新的锌超积累植物。 本文主要研究了锌(Zn)、镉(Cd)复合处理水平对东南景天的生长及其对锌、镉的吸收积累特性的影响。 结果表明,在Zn/Cd复合水平为500/100 祄ol/L时,植物生长最佳。Zn/Cd在东南景天叶片、茎部和根系中含量随着Zn/Cd处理水平的提高而增高。在Zn/Cd 复合水平为50/400 祄ol/L时茎叶中Cd含量达最高,其中叶片Cd含量达12.1 g/kg;在Zn/Cd 复合水平为1 000/50 祄ol/L时茎叶中Zn含量达最高, 其中茎中Zn含量达 23.2 g/kg。 植株各部位Cd含量的分布为:叶片>茎>>根系,而Zn在体内的分布为: 茎>叶片>>根系。 Zn、Cd在地上部和根部的积累量也随着处理水平的提高而增加,分别在Zn/Cd复合水平为250/400和500/100 祄ol/L下达高峰值。 东南景天地上部积累最高Zn和Cd的量分别达11和5 g/plant, 其比根系的积累量分别大10和25余倍。 Zn、Cd对东南景天的生长、吸收积累的相互作用依赖于Zn/Cd复合水平和植物部位。 在适宜Zn/Cd 处理水平范围内,Zn和Cd的吸收和积累具有相互促进作用。 高Zn或高Cd处理均抑制了植物对Zn和Cd的吸收和积累。 本研究结果表明,东南景天不仅具有忍耐高Zn/Cd复合污染,而且具有超量积累Zn和Cd的特异能力。 它为进一步研究植物Zn、Cd     

植物超积累重金属的生理机制研究进展

土壤重金属污染已经成为一个全球性问题。重金属超积累植物在修复土壤重金属污染中具有重要的应用前景。重金属超积累植物通常具备三个基本特征,即：根系具有从土壤中吸收重金属的强大能力、能从根到地上部分高效转运重金属、在叶片中能解毒和隔离大量重金属。本文总结了重金属超积累植物吸收、转运、隔离和解毒重金属的生理机制研究进展,以期为进一步阐明植物超积累重金属的机制及其在植物修复中的应用提供参考。     

油茶微量元素铜铁锌吸收和积累特征

为弄清油茶(Camellia oleifera)对微量元素铜、铁、锌的吸收利用特征,对5年生‘长林4号’各器官的铜、铁、锌元素含量及其年变化进行了研究。结果表明,油茶植株中铁元素的含量最高,其次为锌和铜元素;单株油茶对锌、铜元素的年积累量分别为62.97 mg和22.60 mg,约为3∶1。从果实发育期至成熟期,锌元素的单株吸收积累量为40.18 mg,约占年吸收积累量的63.81%,从抽梢期至果实成熟期,铜元素的单株吸收积累量为20.04 mg,占年吸收积累量的88.67%,从休眠期至抽梢期,油茶地上部分生长所需的铜、锌元素分别有30.25%和57.90%来源于根系贮存的营养;油茶对铁元素的吸收积累则集中在抽梢期至果实发育期,单株吸收量达0.34 g。这些为指导油茶科学施肥提供了理论依据。     

Uptake of Metals by Plants Sharing a Rhizosphere with the Hyperaccumulator Thlaspi caerulescens

The hyperaccumulator Thlaspi caerulescens was grown with Hordeum vulgare and Lepidium heterophyllum in a split pot experiment to examine the effect of rhizosphere interactions on metal uptake. The objective was to assess the viability of such intercropping as either (1) a system of ‘phytoprotection’ for nonaccumulating plants or (2) a means of enhancing phytoextraction with large-biomass crops through increased metal mobilization within the shared rhizosphere. The plants were separated by (1) an impermeable barrier, (2) a permeable root barrier, or (3) no physical barrier to allow different degrees of root interaction. Studies of rhizosphere effects using split pot experiments are subject to considerable uncertainty by the need to relate test results to appropriate control plants. This was resolved by comparing plant metal concentrations to ‘equivalent’ control plants, with the same yield, based on the observed variation in metal concentration with yield under similar growing conditions.

Cadmium concentration in H. vulgare was increased by a factor of 2.4 when it was grown alongside T. caerulescens without a barrier. In contrast, the uptake of zinc by H. vulgare was significantly decreased, probably through metal depletion within the zone of the Zn-hyperaccumulator's rhizosphere. T. caerulescens also apparently increased the concentration of Cd in H. vulgare by a factor of 1.4 when the roots of the two plants were separated by a permeable barrier that allowed movement of soil solution but prevented physical mixing of roots. The concentrations of all the metals studied (Cd, Zn, Cu, Pb, Ni) were greater in T. caerulescens when the hyperaccumulator was grown alongside either L. heterophyllum or H. vulgare without a root barrier — probably through successful exploitation of a greater volume of soil. However, this effect was not seen in the presence of a partial barrier, except in the case of Cu when T. caerulescens was grown alongside H. vulgare.

These results suggest that T. caerulescens may alter conditions in shared rhizospheres and thereby affect the availability of selected metals to neighboring plants. Thus, it is possible that under-sowing some plants with small hyperaccumulators may potentially offer an alternative form of management for marginally contaminated soils. There was limited evidence of an intercropped hyperaccumulator mobilizing selected metals and restricting the availability of others. However, changes in uptake of selected metals by the larger plant may be quite small compared with the requirements of crop protection or the short-term requirements of many land remediation programs.     

Compartmentation of Zinc in Roots and Leaves of the Zinc Hyperaccumulator Thlaspi caerulescens J & C Presl

Thlaspi caerulescens is a metallophyte that is able to hyperaccumulate Zn. In the present study the subcellular compartmentation of Zn was investigated in roots and leaves of this species by means of X-ray microanalysis. Leaves accumulated higher average Zn concentrations than roots. In roots of plants exposed to 10 μM Zn, Zn concentrations in the apoplast were similar to those in vacuoles, while in plants treated with 100 μM Zn considerably higher Zn concentrations were detected in vacuoles than in the apoplast. In epidermal and sub-epidermal cells of leaves of plants from both treatments, Zn mainly accumulated in vacuoles and, to a lesser extent, in the apoplast. In vacuoles from plants exposed to 100 μM Zn, high Zn concentrations were associated with variable amounts of P, Ca and K. In leaves, the highest Zn concentrations (13,600 μg g^?1 d.m.) were found in globular crystals present in many vacuoles of epidermal and subepidermal cells. Smaller deposits with a variable Zn concentration between 1,000 and 18,300 μg g^?1 d.m. were observed in the epidermal and subepidermal cells of roots. Both the high Zn/P element ratios found in the crystals and the absence of Mg indicate that, in contrast to other plant species, myo-inositol hexaphosphate (phytate) is not the main storage form for Zn in Thlaspi caerulescens.     

Uptake and transport of zinc in the hyperaccumulator Thlaspi caerulescens and the non-hyperaccumulator Thlaspi ochroleucum

Growth and zinc uptake of the hyperaccumulator species Thlaspi caerulescens J. & C. Presl and the non-hyperaccumulator species Thlaspi ochroleucum Boiss. & Heldr. were compared in solution culture experiments. T. caerulescens was able to tolerate 500 mmol m^?3 (32.5 g m^?3) Zn in solution without growth reduction, and up to 1000 mmol m^?3 (65 g m^?3) Zn without showing visible toxic symptoms but with a 25% decrease in dry matter (DM) yield. Up to 28 g kg^?1 of Zn in shoot DM was obtained in healthy plants of T. caerulescens. In contrast, T. ochroleucum suffered severe phytotoxicity at 500 mmol m^?3 Zn. Marked differences were shown in Zn uptake, distribution and redistribution between the two species. T. caerulescens had much higher concentrations of Zn in the shoots, whereas T. ochroleucum accumulated higher concentrations of Zn in the roots. When an external supply of 500 mmol m^?3 Zn was withheld, 89% of the Zn accumulated previously in the roots of T. caerulescens was transported to the shoots over a 33 d period, whereas in T. ochroleucum only 32% was transported. T. caerulescens was shown to have a greater internal requirement for Zn than other plants. Increasing the supply of Zn from 1 to 10 mmol m^?3 gave a 19% increase in the total DM of this species. liven the shoots from the 1 mmol m^?3 Zn treatment which showed Zn deficiency contained 10 times greater Zn concentrations than the widely reported critical value for Zn deficiency to occur in many other plant species. The results obtained suggest that strongly expressed constitutive sequestration mechanisms exist in the hyperaccumulator T. caerulescens, which detoxify the large amount of Zn present in shoot tissues and decrease its physiological availability in the cytosol. Both T. caerulescens and T. ochroleucum had constitutively high concentrations of malate in shoots, which were little affected by different Zn treatments. Although malate may play a role in Zn chelation because of the high concentrations present, it cannot explain the species specificity of Zn tolerance and hyperaccumulation.     

Soil pH Effects on Uptake of Cd and Zn by Thlaspi caerulescens

For phytoextraction to be successful and viable in environmental remediation, strategies that can optimize plant uptake must be identified. Thlaspi caerulescens is an important hyperaccumulator of Cd and Zn, whether adjusting soil pH is an efficient way to enhance metal uptake by T. caerulescens must by clarified. This study used two soils differing in levels of Cd and Zn, which were adjusted to six different pH levels. Thlaspi caerulescens tissue metal concentrations and 0.1 M Sr(NO₃)₂ extractable soil metal concentrations were measured. The soluble metal form of both Cd and Zn was greatly increased with decreasing pH. Lowering pH significantly influenced plant metal uptake. For the high metal soil, highest plant biomass was at the lowest soil pH (4.74). The highest shoot metal concentration was at the second lowest pH (5.27). For low metal soil, due to low pH induced Al and Mn toxicity, both plant growth and metal uptake was greatest at intermediate pH levels. The extraordinary Cd phytoextraction ability of T. caerulescens was further demonstrated in this experiment. In the optimum pH treatments, Thlaspi caerulescens extracted 40% and 36% of total Cd in the low and high metal soils, respectively, with just one planting. Overall, decreasing pH is an effective strategy to enhance phytoextraction. But different soils had various responses to acidification treatment and a different optimum pH may exist. This pH should be identified to avoid unnecessarily extreme acidification of soils.     

Uptake and degradation of EDTA by Escherichia coli

It was found that Escherichia coli exhibited a growth by utilization of Fe(III)EDTA as a sole nitrogen source. No significant growth was detected when Fe(III)EDTA was replaced by EDTA complexes with other metal ions such as Ca²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, and Zn²⁺. When EDTA uptake was measured in the presence of various ions, it was remarkable only when Fe³⁺ was present. The cell extract of E. coli exhibited a significant degradation of EDTA only in the presence of Fe³⁺. It is likely that the capability of E. coli for the growth by utilization of Fe(III)EDTA results from the Fe³⁺-dependent uptake and degradation of EDTA.     

缺Cu~（2＋）和Zn~（2＋）对水稻OsNRAMP家族基因表达与主要金属离子吸收的影响

对野生型水稻进行缺Cu2＋和Zn2＋处理,利用定量RT-PCR技术分析OsNARAMP家族不同基因的表达情况,并采用ICP-MS技术检测在水稻根、茎叶中Fe、Zn、Cu和Mn等元素的积累情况。结果表明水稻中OsNRAMP家族有9个基因,可分为3个亚类;OsNRAMP5可能参与了Cu2＋的吸收和转运,而OsNRAMP2和OsNRAMP3可能参与Zn2＋吸收和转运。同时缺Cu2＋和Zn2＋能刺激Fe2＋离子在水稻根和茎叶中的积累,减缓Mn2＋离子在根中的吸收;而缺Cu2＋减缓水稻中Zn2＋离子的吸收。这些金属离子吸收的情况和OsNRAMP家族可能存在密切关系。     

Influence of Complexation on the Uptake by Plants of Iron, Manganese, Copper and Zinc: II. EFFECT OF DTPA IN A MULTI-METAL AND COMPUTER SIMULATION STUDY

Barley (Hordeum vulgare L.) plants were grown in nutrient solutionscontaining the chelating agent, DTPA. The experiments replicatedthose reported in the preceding paper in which EDTA was thechelating agent used. The concentrations of all the chemicalspecies of metals were stimulated using the program NUTRIENT.The concentrations of DTPA used were chosen to give a similarrange of complexation as used in the EDTA experiments. The effectof complexation by DTPA on the uptakes of the metal ions Fe³⁺,Mn²⁺, Cu²⁺, and Zn²⁺ and on plant growth were sufficiently differentfrom those with EDTA to indicate some dependence on the natureof the chelating agent used. The biggest difference betweenthe EDTA and DTPA experiments occurred in the solutions containingthe largest concentrations of these reagents. With DTPA, chlorosiswas seen only in the early stages; otherwise the plants showednormal growth. A simple chemical model for metal uptake is discussed. Key words: DTPA, EDTA, micronutrients, trace metals, computer simulation, plants, absorption, iron, manganese, copper, zinc     

Influence of Complexation on the Uptake by Plants of Iron, Manganese, Copper and Zinc: I. EFFECT OF EDTA IN A MULTI-METAL AND COMPUTER SIMULATION STUDY

After growing barley (Hordeum vulgare L.) in nutrient solutionscontaining EDTA, uptake of the nutrient metals was determinedat three harvests and concentrations of the various chemicalspecies of each metal in the growth solutions was modelled bycomputer simulation. Complexation with EDTA had different effectson the uptake of the ions Fe³⁺, Mn²⁺, Cu²⁺, and Zn²⁺. At thehighest EDTA level (EDTA/Fe=2/l) the plants were chlorotic andgrowth was inhibited. This is attributed to a deficiency inZn rather than in Fe. The critical level of free Zn²⁺ requiredin nutrient solutions for healthy growth was found to be approximately10^–1010^–10 mol dm^–3, which is consistent withthat found by earlier workers for other plant species. Barleytolerated much lower levels of the free ions of copper and ironwithout exhibiting any obvious adverse effects. Key words: EDTA, micronutrients, trace metals, computer simulation, deficiencies, absorption, iron, manganese, copper, zinc     

Accumulation of Nickel by Excluder Thlaspi arvense and Hyperaccumulator Noccaea caerulescens upon Short-Term and Long-Term Exposure

Russian Journal of Plant Physiology - The ability to accumulate nickel (Ni) was compared in hyperaccumulator Noccaea сaerulescens F.K.&nbsp;Mey and excluder Thlaspi arvense L. after a...     

Complexation and Toxicity of Copper in Higher Plants. II. Different Mechanisms for Copper versus Cadmium Detoxification in the Copper-Sensitive Cadmium/Zinc Hyperaccumulator Thlaspi caerulescens (Ganges Ecotype)

The cadmium/zinc hyperaccumulator Thlaspi caerulescens is sensitive toward copper (Cu) toxicity, which is a problem for phytoremediation of soils with mixed contamination. Cu levels in T. caerulescens grown with 10 μm Cu²⁺ remained in the nonaccumulator range (<50 ppm), and most individuals were as sensitive toward Cu as the related nonaccumulator Thlaspi fendleri. Obviously, hyperaccumulation and metal resistance are highly metal specific. Cu-induced inhibition of photosynthesis followed the “sun reaction” type of damage, with inhibition of the photosystem II reaction center charge separation and the water-splitting complex. A few individuals of T. caerulescens were more Cu resistant. Compared with Cu-sensitive individuals, they recovered faster from inhibition, at least partially by enhanced repair of chlorophyll-protein complexes but not by exclusion, since the content of Cu in their shoots was increased by about 25%. Extended x-ray absorption fine structure (EXAFS) measurements on frozen-hydrated leaf samples revealed that a large proportion of Cu in T. caerulescens is bound by sulfur ligands. This is in contrast to the known binding environment of cadmium and zinc in the same species, which is dominated by oxygen ligands. Clearly, hyperaccumulators detoxify hyperaccumulated metals differently compared with nonaccumulated metals. Furthermore, strong features in the Cu-EXAFS spectra ascribed to metal-metal contributions were found, in particular in the Cu-resistant specimens. Some of these features may be due to Cu binding to metallothioneins, but a larger proportion seems to result from biomineralization, most likely Cu(II) oxalate and Cu(II) oxides. Additional contributions in the EXAFS spectra indicate complexation of Cu(II) by the nonproteogenic amino acid nicotianamine, which has a very high affinity for Cu(II) as further characterized here.Many heavy metals are well known to be essential microelements for plants, but elevated concentrations of these metals cause toxicity (for review, see Prasad and Hagemeyer, 1999; Küpper and Kroneck, 2005), as explained in more detail in our companion article (Küpper et al., 2009) on copper (Cu) complexation and toxicity in Crassula helmsii. Plants developed a number of strategies to resist this toxicity, including active efflux, sequestration, and binding of heavy metals inside the cells by strong ligands. Among the zinc (Zn) and cadmium (Cd) hyperaccumulators (Brooks, 1998; Lombi et al., 2000), the best known species is Thlaspi caerulescens, which has been proposed as a hyperaccumulator model species by several authors (Assunção et al., 2003; Peer et al., 2003, 2006). An enhanced uptake of metals into the root symplasm was found in T. caerulescens compared with the related nonaccumulator Thlaspi arvense (Lasat et al., 1996, 1998), and a reduced sequestration into the root vacuoles was associated with the higher root-to-shoot translocation efficiency of T. caerulescens (Shen et al., 1997; Lasat et al., 1998). This is likely related to elevated expression of xylem-loading transporters in the roots (Papoyan and Kochian, 2004; Weber et al., 2004). One of these, the Cd/Zn-pumping P_1b-type ATPase TcHMA4, was recently purified as a protein, which revealed posttranslational processing, and its biochemical characterization showed Cd and Zn transport affinity in the submicromolar range (Parameswaran et al., 2007). Studies of cellular metal compartmentation have shown that in most hyperaccumulators, the metal is sequestered preferentially into compartments where it does no harm to the metabolism. These are, in most cases studied so far, the epidermal vacuoles (Küpper et al., 1999, 2001; Frey et al., 2000; Bidwell et al., 2004; Broadhurst et al., 2004), where concentrations of several hundred mmol L⁻¹ can be reached in the large metal storage cells (Küpper et al., 1999, 2001). The latter showed that hyperaccumulation must be mediated by active pumping of the heavy metals into their storage sites, which was shown to be achieved by an extremely increased expression of metal transport proteins in leaves of hyperaccumulators compared with nonaccumulators (Pence et al., 2000; Assunção et al., 2001; Becher et al., 2004; Papoyan and Kochian, 2004; Küpper et al., 2007b). Strong sulfur (S) ligands like phytochelatins were shown not to be relevant for Cd detoxification in the Cd hyperaccumulator T. caerulescens. Phytochelatin levels are lower in this plant than in the related nonaccumulator T. arvense (Ebbs et al., 2002), inhibition of phytochelatin synthase in hyperaccumulators does not affect their Cd resistance (Schat et al., 2002), and direct measurements of the Cd ligands by EXAFS (Küpper et al., 2004). Thus, the main detoxification strategy in hyperaccumulators is clearly not binding to strong ligands but sequestration of the hyperaccumulated heavy metals. However, the nonproteogenic amino acid nicotianamine (NA) seems to play an important role in metal homeostasis of plants. According to several studies, it binds iron, Zn, and Cu, mainly for long-distance transport in the vascular bundle (Stephan and Scholz, 1993; Pich et al., 1994; Schmidke and Stephan, 1995; Stephan et al., 1996, Pich and Scholz, 1996; von Wiren et al., 1999; Liao et al., 2000), and NA synthase has been shown to be highly overexpressed in hyperaccumulators compared with nonaccumulator plants (Becher et al., 2004; Weber et al., 2004; van de Mortel et al., 2006, 2008).

Table I.

Explanation of technical terms