Cadmium distribution and its effects on molybdate-containing hydroxylases in Phragmites australis

The influence of cadmium (Cd) on physiological and biochemical parameters was studied to elucidate the mechanism of Cd resistance in Phragmites australis. Cadmium concentrations in roots, stems and leaves increased with exogenous Cd concentration, but Cd content in roots was much higher than in shoots. X-ray microanalysis was used to reveal compartments in which Cd accumulated in root cortex. Cadmium concentrations followed a gradient with the sequence: intercellular space > cell wall > vacuole > cytoplasm, indicating that most Cd was immobilized in the apoplast or sequestered into the vacuolar lumen. Sequential extraction of various Cd chelates revealed that more than half of extractable Cd was bound to proteins, whereas 26% was bound to organic acids. Cd-binding protein fractions were found in the roots after gel filtration chromatography, among which a polypeptide with an apparent molecular mass of 14 kDa bound Cd most avidly. One newly synthesized polypeptide of low molecular mass (1 kDa) appeared under Cd pollution, whereas a prominent fraction of 72 kDa disappeared. Four aldehyde oxidase (AO) isoenzyme activities increased significantly in roots under Cd pollution. Cd stress also enhanced xanthine dehydrogenase (XDH) activities in roots. Two AO polypeptides of different molecular sizes were detected in the roots by Western blot assay. The abundance of the 160 kDa subunit correlated with Cd stress, but the amount of the 90 kDa polypeptide did not change under Cd treatment. Enhanced abscisic acid (ABA) contents were observed in roots of P. australis exposed to Cd. The involvement of Cd distribution in plant tissues and subcellular compartments and of AO and XDH enzymatic activities in the acclimation mechanism of P. australis to Cd pollution is discussed herein.     

铅污染下芦苇体内铅的分布和铅胁迫相关蛋白

用Pb(NO3 ) 2 10mmol/L处理芦苇幼苗 7d后 ,检测铅在其不同器官、细胞不同区隔和不同化学状态之间的分布以及铅胁迫相关蛋白。结果显示 ,受铅污染后芦苇幼苗根、地下茎、茎和叶片的铅含量增加 ,它们的大小顺序为根 >地下茎 >茎 >叶片。细胞不同部分铅含量的大小顺序为细胞间隙 >细胞壁 >液泡 >细胞质。在根部和叶片中 ,均以活性较低的醋酸可提取态铅和盐酸可提取态铅占优势。在铅胁迫下 ,从芦苇根和叶片中检测出一些铅结合蛋白。另外 ,铅除诱导芦苇合成一种新的不结合铅的蛋白质外 ,还导致一种分子量大约为 72 0 0 0的蛋白质消失。芦苇抗铅胁迫有以下几种机制 :根部比地上部分积累较多的铅 ;铅在体内形成难溶性化合物 ;铅沉淀在质外体内 ;形成铅结合蛋白质和诱导蛋白     

芦苇抗镉污染机理研究

研究了芦苇幼苗体内 Cd的积累、亚细胞微区分布、存在形态和其诱导蛋白以及植物络合素合成抑制剂 (BSO)对芦苇光合作用和生长的影响。在 Cd污染条件下 ,芦苇幼苗植株和根皮层细胞中可积累大量的Cd,但 Cd在芦苇各器官和根皮层细胞亚细胞结构中的分布显著不均 ;Cd在芦苇幼苗体内的分配为 :根 >叶片 >茎 >地下茎 ,在根皮层细胞中的分布为 :细胞间隙 >细胞壁 >液泡 >细胞质。受 Cd污染的芦苇幼苗体内的 Cd以不同化学形态存在 ,其中 Na Cl提取态的 Cd在根和叶片中占的比例均为最大 ,其次为根内的醋酸提取态 ;在叶片中以水提取态为主 ,其它形态的含量相对较低。层析结果表明 ,根和叶片中各存在一种Cd结合蛋白 ,其中根内的 Cd结合蛋白可能是一种植物络合素聚合体。受 Cd诱导 ,芦苇幼苗根中还新合成了一种小分子蛋白或多肽 ,但另有一种蛋白因 Cd影响而消失。此外 ,BSO实验证明了植物络合素对 Cd的解毒作用。可见 ,芦苇的抗 Cd机理与以下几个方面有关 :根部截留 ,细胞间隙积累 ,细胞壁沉淀 ,液泡区域化 ,形成活性较低的难溶化合物 ,形成 Cd结合蛋白     

Zinc isotopic fractionation in Phragmites australis in response to toxic levels of zinc

Stable isotope signatures of Zn have shown great promise in elucidating changes in uptake and translocation mechanisms of this metal in plants during environmental changes. Here this potential was tested by investigating the effect of high Zn concentrations on the isotopic fractionation patterns of Phragmites australis (Cav.) Trin. ex Steud. Plants were grown for 40?d in a nutritive solution containing 3.2?μM (sufficient) or 2?mM (toxic) Zn. The Zn isotopic composition of roots, rhizomes, shoots, and leaves was analysed. Stems and leaves were sampled at different heights to evaluate the effect of long-distance transport on Zn fractionation. During Zn sufficiency, roots, rhizomes, and shoots were isotopically heavy (δ(66)Zn(JMC Lyon)=0.2‰) while the youngest leaves were isotopically light (-0.5‰). During Zn excess, roots were still isotopically heavier (δ(66)Zn=0.5‰) and the rest of the plant was isotopically light (up to -0.5‰). The enrichment of heavy isotopes at the roots was attributed to Zn uptake mediated by transporter proteins under Zn-sufficient conditions and to chelation and compartmentation in Zn excess. The isotopically lighter Zn in shoots and leaves is consistent with long-distance root to shoot transport. The tolerance response of P. australis increased the range of Zn fractionation within the plant and with respect to the environment.     

干旱区湿地芦苇各器官生态化学计量对土壤因子的响应

了解植物养分浓度及其化学计量对土壤因子的响应,对预测脆弱而敏感生态系统对环境变化的响应至关重要。以敦煌阳关湿地优势种芦苇(Phragmites australis)为对象,通过野外调查与实验分析,研究芦苇不同器官生态化学计量特征及其影响因素。结果表明:芦苇各器官C、P含量为叶>根>茎,N含量及N∶P为叶>茎>根,C∶N为根>茎>叶,C∶P则为茎>根>叶。叶、根C含量显著高于茎(P<0.05),叶、根C含量之间无显著差异(P>0.05),根、茎和叶N、P含量及C∶N、C∶P和N∶P差异显著(P<0.05);芦苇根N∶P<14,叶片N∶P>16,茎N∶P介于14~16;C含量在各器官之间均无显著相关性(P>0.05),根与茎、叶N含量之间呈极显著正相关(P<0.01),根与茎P含量呈极显著正相关(P<0.01),茎与叶N含量呈显著正相关(P<0.05);土壤盐分与芦苇根和茎N含量呈极显著正相关(P<0.01),土壤P含量与茎P含量呈极显著正相关(P<0.01),土壤有效P与根、茎N含量呈极显著正相关(P<0.01);土壤P是影响芦苇根、茎化学计量的主要因素,土壤盐分是影响叶片化学计量的主要因素,芦苇趋向提高各器官N含量来应对高盐、低P的土壤环境。     

氮磷肥对茶树锌硒等中微量元素吸收与分配的影响

锌（Zn）和硒（Se）及其他中微量元素（铝Al，钙Ca，铁Fe，铜Cu，锰Mn）是茶叶品质的重要指标，但茶树吸收Zn、Se能力及氮（N）磷（P）肥影响中微量元素吸收与分配的过程尚不清楚。以红壤丘陵区福鼎大白茶树为研究对象，开展Zn+Se、Zn+Se+N、Zn+Se+P、Zn+Se+N+P和对照共5种处理3次重复随机化区组试验，处理第3年春季分茶叶、成熟叶、吸收根、运输根和储藏根采集植物样品，测定其元素含量。结果表明，茶树地上和地下器官Zn和Se及其他中微量元素对N、P、Zn、Se添加的响应具分异性。与对照相比，茶树地上和地下器官Zn和Se含量均显著增加，与Zn+Se相比，施N和/或P肥仅显著提高茶叶和成熟叶Se含量（P<0.05）；与对照相比，施肥处理均显著提高吸收根和运输根Al、Fe含量以及储藏根Cu含量；运输根Mn含量表现为Zn+Se+N、Zn+Se+P、Zn+Se+N+P显著高于对照，储藏根Mn含量为Zn+Se+N+P显著高于其他处理；茶树各器官Ca含量对施肥处理无显著响应。此外，茶叶和成熟叶的Zn含量与吸收根显著正相关，而Se含量则与储藏根显著正相关。茶树具有吸收和积累Zn和Se的能力，而施N、P肥有助于提高茶叶Se含量，研究结果为红壤丘陵区培育高品质锌硒茶及营建生态高值茶园提供了依据。     

Effects of land irrigation with partially-treated wastewater on Frankia survival and infectivity

Phytoextraction of Cd by some populations of Thlaspi caerulescens which have the ability to co-hyperaccumulate Cd and Zn requires information about the distribution of both metals within the plant at the organ-level. This work was conducted to determine whether the distribution and solubility of Cd and Zn in Thlaspi caerulescens are affected by the age of plant and organ, and whether Cd and Zn have a common distribution in the plant in soils contaminated by both metals. A series of pot experiments were conducted where a Cd- and Zn-hyperaccumulating population was grown on soils contaminated by Cd and Zn. Temporal changes in metal concentration of roots and of shoots was recorded, along with the water and CaCl₂ solubility of metals in the plant organs. Also, leaves were grouped according to their age and their respective content of Cd and Zn was measured. Both metals were present at higher concentrations in leaves than in roots. The whole-plant content of Zn decreased with time while that of Cd increased or remained unchanged. At harvest, young leaves exhibited higher Cd concentration than older, but the reverse was true for Zn. Both metals were more soluble in dry leaves and senescent leaves than in fresh material, and Zn was more water-soluble than Cd. In conclusion, the distribution of Cd and Zn in the hyperaccumulator T. caerulescensvaried according to the organ and plant age, and Cd and Zn were shown to have a different distribution within the plant.     

Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

Cellular compartmentation of cadmium and zinc in relation to other elements in the hyperaccumulator Arabidopsis halleri

The cellular compartmentation of elements was analysed in the Zn hyperaccumulator Arabidopsis halleri (L.) O'Kane & Al-Shehbaz (=Cardaminopsis halleri) using energy-dispersive X-ray microanalysis of frozen-hydrated tissues. Quantitative data were obtained using oxygen as an internal standard in the analyses of vacuoles, whereas a peak/background ratio method was used for quantification of elements in pollen and dehydrated trichomes. Arabidopsis halleri was found to hyperaccumulate not only Zn but also Cd in the shoot biomass. While large concentrations of Zn and Cd were found in the leaves and roots, flowers contained very little. In roots grown hydroponically, Zn and Cd accumulated in the cell wall of the rhizodermis (root epidermis), mainly due to precipitation of Zn/Cd phosphates. In leaves, the trichomes had by far the largest concentrations of Zn and Cd. Inside the trichomes there was a striking sub-cellular compartmentation, with almost all the Zn and Cd being accumulated in a narrow ring in the trichome base. This distribution pattern was very different from that for Ca and P. The epidermal cells other than trichomes were very small and contained lower concentrations of Zn and Cd than mesophyll cells. In particular, the concentrations of Cd and Zn in the mesophyll cells increased markedly in response to increasing Zn and Cd concentrations in the nutrient solution. This indicates that the mesophyll cells in the leaves of A. halleri are the major storage site for Zn and Cd, and play an important role in their hyperaccumulation. Received: 4 April 2000 / Accepted: 16 May 2000     

Bioaccumulation of heavy metals in Dactylis glomerata L. growing in a calcareous soil amended with sewage sludge

The total and DTPA-extractable concentrations of Pb, Ni, Zn, Cu, Cr and Cd were measured in a calcareous soil amended with different doses of sewage sludge under field conditions. The same metals were also measured in the roots and leaves of Dactylis glomerata at the end of the first vegetative period after the sludge was added. The root concentrations of all the metals were unrelated to their concentrations in the soil. Leaf concentrations of Zn and Cr correlated with total (Zn) and DTPA-extractable (Zn and Cr) concentrations in the soil. DTPA extraction did not appear to be very useful for evaluating the bioavailability of metals in this kind of soil as it gave very low correlation coefficients with leaf content (r = 0.684, P = 0.0049 for Zn and r = 0.557, P = 0.0249 for Cr). Concentrations of Pb, Ni, Cu, and Cd in roots and leaves of Dactylis glomerata were unrelated to the total or DTPA-extractable concentrations in the sludge-amended soil.     

Contribution of the VA mycorrhizal hyphae in acquisition of phosphorus and zinc by maize grown in a calcareous soil

An investigation was carried out to test whether the mechanism of increased zinc (Zn) uptake by mycorrhizal plants is similar to that of increased phosphorus (P) acquisition. Maize (Zea mays L.) was grown in pots containing sterilised calcareous soil either inoculated with a mycorrhizal fungus Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe or with a mixture of mycorrhizal fungi, or remaining non-inoculated as non-mycorrhizal control. The pots had three compartments, a central one for root growth and two outer ones for hyphal growth. The compartmentalization was done using a 30-m nylon net. The root compartment received low or high levels of P (50 or 100 mg kg^–1 soil) in combination with low or high levels of P and micronutrients (2 or 10 mg kg^–1 Fe, Zn and Cu) in the hyphal compartments.Mycorrhizal fungus inoculation did not influence shoot dry weight, but reduced root dry weight when low P levels were supplied to the root compartment. Irrespective of the P levels in the root compartment, shoots and roots of mycorrhizal plants had on average 95 and 115% higher P concentrations, and 164 and 22% higher Zn concentrations, respectively, compared to non-mycorrhizal plants. These higher concentrations could be attributed to a substantial translocation of P and Zn from hyphal compartments to the plant via the mycorrhizal hyphae. Mycorrhizal inoculation also enhanced copper concentration in roots (135%) but not in shoots. In contrast, manganese (Mn) concentrations in shoots and roots of mycorrhizal plants were distinctly lower, especially in plants inoculated with the mixture of mycorrhizal fungi.The results demonstrate that VA mycorrhizal hyphae uptake and translocation to the host is an important component of increased acquisition of P and Zn by mycorrhizal plants. The minimal hyphae contribution (delivery by the hyphae from the outer compartments) to the total plant acquisition ranged from 13 to 20% for P and from 16 to 25% for Zn.     

铜锌复合污染对铜富集植物大聚藻抗氧化酶活性的影响

以前期筛选的铜富集植物大聚藻为材料,采用两因素随机区组试验设计,通过盆栽试验研究了不同浓度铜锌复合污染对大聚藻抗氧化酶活性的影响,以揭示铜富集植物大聚藻对重金属的耐性机理,为芦溪河及其它类似污染河流的生态恢复与植被重建提供参考依据。结果表明:(1)铜锌复合污染条件下,大聚藻生物量都表现出低促高抑现象。(2)铜锌复合污染时,大聚藻MDA含量随铜锌浓度升高表现出先升高后降低的变化。(3)铜锌复合污染对大聚藻抗氧化酶系统活性均有不同程度的影响,低浓度铜锌复合污染对SOD(超氧化物歧化酶)、POD(过氧化物酶)和CAT(过氧化氢酶)有促进作用,而随浓度的升高则表现出不同的规律。研究发现,铜锌胁迫下,大聚藻细胞应急防御系统被启动,SOD、POD和CAT发挥作用,体内过量自由基及时被清除,使大聚藻能够保持高的耐性。     

Influence of [S, S]-EDDS on phytoextraction of copper and zinc by Elsholtzia splendens from metal-contaminated soil

Two pot experiments were conducted to investigate the time course effects of the (S, S)-N, N'-ethylenediamine disuccinic acid (EDDS) addition to contaminated soil on the uptake of Cu and Zn by the Cu accumulator Elsholtzia splendens and on plant Cu and Zn concentrations at different growth stages. EDDS increased the amounts of Cu and Zn soluble in the soil, taken up by plants, concentrated in the xylem sap, and translocated from roots to stems and leaves. The increase in soil-soluble metals, especially Cu, resulted in a corresponding increase in metal concentrations in the xylem sap and leaves. The addition of EDDS to the soil increased plant Cu and Zn concentrations, especially in the leaves, and changed the proportions of Cu and Zn taken up by different plant parts. The proportions of Cu and Zn taken up by the roots were higher than by the leaves of control plants, but EDDS-treated plants showed the opposite trend. EDDS exerted greater effects at the end of the vegetative growth stage than at the start of the flowering or reproductive stages.     

镉胁迫对小报春幼苗生长及生理特性的影响

该研究采用盆栽控制试验,测定不同浓度(0、5、50、100、150、200 mg/kg)土壤Cd胁迫下小报春幼苗生长及生理生化指标,以探究小报春(Primula forbesii Franch.)对重金属镉(Cd)污染的抗性和敏感性,为新型香花地被植物应用于Cd污染土壤提供理论依据。结果表明:(1)低浓度(5 mg/kg)Cd胁迫能促进小报春株高和根长的伸长,高浓度(≥150 mg/kg)Cd胁迫下株高、根长和生物量明显降低。(2)随Cd胁迫浓度增加,小报春幼苗叶片光合作用、叶绿素含量、SOD和CAT活性先上升后下降,而其超氧阴离子产生速率、过氧化氢、丙二醛含量、叶相对电导率和POD活性持续升高。(3)在Cd胁迫条件下,小报春体内K、Zn含量降低,叶和根中Ca、Mg含量显著增加,体内Cd含量明显升高,且根系Cd含量远远高于叶和叶柄。研究发现,小报春幼苗对Cd胁迫具有一定的耐性,低浓度(5 mg/kg)Cd胁迫对小报春生长影响较小,但高浓度(≥150 mg/kg)Cd胁迫对小报春产生明显的毒害作用,影响其正常生长;小报春可能通过增强体内抗氧化酶系统活性、增加叶和根中Ca、Mg含量和根系截留镉来减轻镉胁迫的伤害,提高自身耐受镉胁迫能力。     

Metals (Fe, Mn, Zn) in the root plaque of submerged aquatic plants collected in situ: Relations with metal concentrations in the adjacent sediments and in the root tissue

We have investigated the extent of iron oxyhydroxide deposition on the roots of two common freshwater species, Vallisneria americana Michx. and Heteranthera dubia (Jacq.) MacM., collected from different sites in the St. Lawrence River, Québec, Canada, and have related metal concentrations in the root plaques both to the geochemical conditions prevailing in the host sediments (pH; metal partitioning) and to the metal concentrations within the plant root tissue. Possible effects of root plaque on sediment geochemistry are also discussed.At those sites where the two submerged plants co-existed, the amounts of Fe deposited on their respective root surfaces were positively correlated, indicating that sediment geochemistry (pH; concentration of labile metal) exerted a more important influence on plaque formation than did inter-species differences (root physiology, morphology). Iron and Mn concentrations in the root plaque were positively correlated with each other, and with the readily extractable fractions (F1, 172) of these metals in the adjacent sediments. In contrast, Zn concentrations in the root plaque of V. americana were not related to Zn concentrations in the sediments — the dominant geochemical process at the root surface is Fe deposition, such that the quantities of Zn deposited on the roots are determined not by Zn geochemistry per se but rather by the amount of Fe deposition. Indeed the Zn/Fe ratios in the root plaque were related to the Zn/Fe ratios in the surrounding sediments (NH₂OHHCl extract).On a concentration basis (g/g), more Fe, Mn and Zn was found outside the root, in the iron plaque, than inside the root tissues. For all 3 metals, significant relationships were observed between the metal concentrations in the plaque and those inside the roots. For Zn, however, the best statistical relationship was not with [Zn]_plaque, but rather with the [Zn]/[Fe] ratio in the plaque. It is hypothesized that the Zn/Fe ratio in the root plaque reflects the free Zn²⁺ concentration adjacent to the root surface, and that this in turn affects Zn uptake by the plant root. For a given value of Zn in the sediments or in the root plaque, the Zn content of the root is inversely related to the concentration of Fe oxyhydroxides, implying that Fe plays a protective role in regulating Zn bioavailability.     

Inoculation of Paenibacillus illinoisensis alleviates root mortality, activates of lignification-related enzymes, and induction of the isozymes in pepper plants infected by Phytophthora capsici

To investigate the variations of the enzymes responsible for lignification, after inoculation with Phytophthora capsici and/or Paenibacillus illinoisensis KJA-424, in relation to biocontrol of Phytophthora blight in pepper, roots of two-month-old plants were inoculated with P. capsici inoculation (P), and co-inoculation of P. capsici and P. illinoisensis cell cultures (P + A). Root mortality of pepper plants induced by inoculation of P. capsici was completely recovered by co-inoculation with antagonistic KJA-424. At day 7, peroxidase (POD) activity increased by 36.7% in P-treated roots but by 7.1% only in P + A-treated, compared with control. Polyphenol oxidase (PPO) activity increased for 3 days and then drastically decreased in P-treated roots but maintained a constant level in control and P + A-treated. At day 7, PPO activity in P-treated leaves decreased but recovered to the level of control in the P + A-treated. Three major POD isozymes (45, 53, and 114 kDa) were shown in P-treated roots, while two major (53 and 114 kDa) in control and P + A-treated, suggesting that the 45 kDa of POD was actively induced in P-treated roots but not induced in P + A-treated roots. A PPO isozyme of 80 kDa was induced in P-treated roots but not induced by co-treated with KJA-424. In leaves, the POD isozyme of 45 kDa appears to be systemically induced in P-treated only. The PPO isozyme of 80 kDa in leaves was not induced by pathogen challenge but recovered by co-inoculated with P. illinoisensis. All these results suggest that the inoculation of an antagonist, P. illinoisensis alleviates root mortality, activates of lignification-related enzymes and induction of the isozymes in pepper plants infected by P. capsici.     

Effect of heavy metals on peppermint and cornmint

Heavy metal pollution of agricultural soils and air is one of the most severe ecological problems on a world scale and in Bulgaria in particular. The biggest sources of pollution in Bulgaria are some non-ferrous metals smelters, such as the Non-Ferrous Metals Combine (NFMC) near Plovdiv, situated on very fertile soils. Vegetable, arable and animal production in this area results in contaminated produce with excessive amounts of Cd, Pb, Cu, Mn and Zn.In order to discover some crops which could be grown on these areas without contamination of the end product, we conducted (in 1991–1993) field experiments in the vicinities of NFMC near Plovdiv. As experimental material we used Mentha piperita L. (cv Tundza and Clone No 1) and Mentha arvensis var piperascens Malinv. (cv Mentolna-14). Plants have been grown on three Plots: Plot No 1-at a distance of 400 m from the source of pollution; Plot No 2-at 3 km from the source of pollution and on a control Plot-in the experimental gardens of University of Agriculture in Plovdiv, at 10 km from the source of pollution. It was established that heavy metal pollution of soil and air at a distance of 400 m from the source of pollution decreased the yields of fresh herbage by 9–16% and the yield of essential oil by up to 14% compared to the control, but did not negatively affect the essential oil content and its quality.Oils obtained from Plot 1 at a distance of 400 m from the source of pollution have not been contaminated with heavy metals.Cultivar response to heavy metal pollution was established. A positive correlation between Pb concentration in leaves and in essential oil was found.Heavy metal concentration in the plant parts was found to be in order: for Cd roots > leaves > rhizomes > stems; Pb roots = leaves > rhizomes = stems; Cu roots > rhizomes = stems = leaves; Mn roots > leaves > stems = rhizomes; Zn leaves > roots > stems = rhizomes.The tested cultivars of peppermint and cornmint could be successfully grown in highly heavy metal polluted areas, as in the area around NFMC near Plovdiv, without contamination of the end product-the essential oils.Despite of the yield reduction (up to 14%), due to heavy metal contamination, mint still remained a very profitable crop and it could be used as substitute for the other highly contaminated crops.     

Jasmonic acid induced changes in protein pattern, antioxidative enzyme activities and peroxidase isozymes in peanut seedlings

Protein pattern, ammonia content, glutamine synthetase activity, lipid peroxidation, superoxide dismutase, catalase, peroxidase and peroxidase isoforms were studied in the leaves and roots of 7-d-old peanut (Arachis hypogaea L. cv. JL-24) seedlings treated by 25, 100 and 250 μM jasmonic acid (JA). SDS-PAGE protein profile of leaves and roots after JA application showed a significant increase in 18, 21, 30, 45, 47 and 97.4 kDa proteins and significant decrease in 22 and 36 kDa proteins. Pathogenesis related PR-18 was specific in leaves at 250 μM JA and PR-21 have cross reacted differently with 21 and 30 kDa proteins in leaves and roots treated by all JA concentrations. Further, the immunoblot analysis with glutamine synthetase, GS-45 antibodies revealed a specific cross reaction with 45 and 47 kDa proteins of both control and JA treated leaves, however, higher at 100 and 250 μM JA treated leaves than control ones. Further, the malondialdehyde (MDA) content significantly increased in leaves and roots treated with JA, indicated membrane damage with JA treatments that led to the generation of peroxidation products. The peroxidase isozymic pattern showed two specific isoforms. Besides, the activities of SOD and catalase were significantly elevated in JA treated leaves.     

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.     

Isolation of two cDNA clones from tomato containing two different superoxide dismutase sequences

A cDNA library was derived from the poly(A)⁺ RNA of young tomato leaves. The library was cloned in a gt11 system and screened by synthetic oligonucleotide probes having sequences that match the codes of conserved regions of amino acid sequences of Cu,Zn superoxide dismutase (SOD) proteins from a wide range of eukaryotic organisms. Two cDNAs were isolated, cloned and sequenced. One of the cDNAs, P31, had a full-size open reading frame of 456 bp with a deduced amino acid sequence having an 80% homology with the deduced amino acid sequence of the cytosolic SOD-2 cDNA of maize. The other cDNA, T10 (extended by T1), had a 651 bp open reading frame that revealed, upon computer translation, 90% homology to the amino acid sequence of mature spinach chloroplast SOD. The 5 end of the reading frame seems to code for a putative transit peptide. This work thus suggests for the first time an amino acid sequence for the transit peptide of chloroplast SOD. Northern hybridizations indicated that each of the P31 and T10 clones hybridized to a blotted poly(A)⁺ RNA species. These two species are differentially expressed in the plant organs: e.g., the species having the T10 sequence was detected in the leaves but not in roots, while the one with the P31 sequence was expressed in both leaves and roots. The cDNA clones P31 and T10 were also hybridized to Southern blots of endonuclease fragmented tomato DNA. The clones hybridized to specific fragments and no cross hybridization between the two clones was revealed under stringent hybridization conditions; the hybridization pattern indicated that, most probably, only one locus is coding for each of the two mRNA species.