Cd Kg-1 Research Articles

Arbuscular mycorrhiza contribution to the growth performance and heavy metal uptake of Helianthus annuus LINN in pot culture

A greenhouse experiment was conducted to assess the arbuscular mycorrhiza contribution to the growth performance and heavy metals (Cd and Pb) uptake ofHelianthus annuus L. from polluted soils. Cadmium sulfate (CdSO4.8H2O) and lead acetate ((CH3COO)2Pb.3H2O) were applied at the concentrations: Cd- 0,20,40,60,80 mg kg-1 and Pb-0,250,500,750,1000 mg kg-1 in 90 plastic pots filled with 5 kg of topsoil each. Propagules of Glomus mosseae (GM) and Glomus intraradices (GI) at 25 g per pot were applied. Non-inoculated pots served as controls. Each treatment was replicated thrice in completely randomized design. Data were analysed using ANOVA and descriptive statistics. Results showed that arbuscular mycorrhiza (AM) fungi significantly (p ≤ 0.05) influenced the number of leaves, plant height and stem girth of sunflower plants only at 80 mg Cd kg-1concentration. Highest values of 0.11 mg Cd kg-1 and 0.29 mg Pb kg-1 were obtained with GI in the dry shoot of Helianthus annuus while 0.05 mg Cd kg-1 and 0.23 mg Pb kg-1 were remediated with GM application. Least values of Cd and Pb were removed when no AM was applied. GM and GI fungi enhanced the growth ofHelianthus annuus and the uptake of Cd and Pb; but GI performed better. Also, a significant (p < 0.05) reduction of AM fungi colonization percentage was obtained with increase in Cd and Pb concentrations. Key words: Glomus mosseae, Glomus intraradices, Helianthus annuus,phytoremediation, polluted soil.

Determinação de As, Cd e Pb em amêndoas e mesocarpo de babaçu, sapucaia, xixá e castanha-do-pará por espectrometria de absorção atômica

This work describes methods for the simultaneous determination of Cd and Pb by graphite furnace atomic absorption spectrometry and As by hydride generation atomic absorption spectrometry in Brazilian nuts. The samples (~ 0.300 g) were digested to clear solutions in a closed vessel microwave oven. The pyrolysis and atomization temperatures for simultaneous determinations of Cd and Pb were 1100 and 2100 °C, respectively, using 0.5% (w v-1) NH4H2PO4 + 0.03% (w v-1) Mg(NO3)2 as chemical modifier. The limits of detection (3Δ) were 3.8 μg kg-1 for As, 0.86 μg kg-1 for Cd and 13 μg kg-1 for Pb. The reliability of the entire procedures was confirmed by peach leaves (No. 1547 - NIST) certified reference material analysis and addition and recovery tests. The found concentrations presented no statistical differences at the 95% confidence level.

Comparisons in Agronomic and Physiological Traits of Rice Genotypes Differing in Cadmium-Tolerance

Cadmium (Cd) is one of major contaminants in agricultural soil, threatening agricultural production and human health. To understand agronomic and physiological characteristics of rice genotypes differing in Cd-tolerance would have great signifi-cance in selecting or breeding a Cd-tolerant cultivar. In this study, two Cd-tolerant rice genotypes of Shanyou 63 (indica hybrid) and Yangjing 9538 (japonica) and two Cd-susceptible genotypes of Yangdao 6 (indica) and Wuyunjing 7 (japonica) were pot-grown at a farm of Yangzhou University, Yangzhou, Jiangsu Province in 2004 and 2005. 150 mg kg-1 Cd was added into pot soil before seedling transplanting (Cd treatment), and no Cd addition was taken as control (CK). Under the Cd treatment, the grain yield was reduced by 6.2–8.9% for the Cd-tolerant genotypes and by 38.3–47.1% for the Cd-susceptible ones when compared with their respective CKs. The reduction in grain yield was mainly attributed to the reductions of panicles per pot and spikelets per panicle. The differences in seed-setting rate and 1 000-grain weight were not significant between the Cd treatment and CK. The Cd treatment markedly inhibited the tillering of the Cd-susceptible genotypes, resulting in the reduction in dry matter accumula-tion during the whole growth period. Cd little affected the translocation of non-structural carbohydrate from culms and sheaths and harvest index. For Cd-susceptible genotypes, the Cd treatment significantly reduced root oxidation activity and photosynthetic rate, activities of superoxide dismutase and catalase of leaves, and obviously increased contents of superoxidate radical and hy-drogen peroxide and ethylene evolution rate of leaves, and the concentration of 1-aminocylopropane-1-carboxylic acid in root bleedings from the tillering to jointing stages, while the Cd treatment much less affected the above physiological traits for the Cd-tolerant genotypes. The differences in the above traits at heading and afterwards and abscisic acid content in leaves during the whole growth period were not significant between the Cd treatment and CK. The results indicate that the effects of Cd on ricegrowth and development are mainly during the early growth period (from tillering to jointing), and more tillers, stronger root ac-tivity and antioxidative defense system, and less ethylene synthesis in the plants during this period would be considered as agro-nomic and physiological traits of Cd-tolerant genotypes of rice.

A Market Survey of Vegetables in Bangalore for Heavy Metal Contamination in Relation to Human Health

Vegetable samples from one of the main whole sale markets of Bangalore city were collected over two years and analysed for heavy metals such as Cd, Pb, Cr and Ni. Heavy metal content of vegetables ranged from 0.24 to 2.54 mg Cd kg-1, 2.16 to 10.40 mg Pb kg-1, 3.08 to 16.2 mg Cr kg-1 and 1.66 to 11.52 mg Ni kg-1. Leafy vegetables accumulated higher concentration of heavy metals followed by root vegetables. Fruit vegetables accumulated the lowest content of heavy metals. But the heavy metal content of all the vegetables crossed the safe limits permitted for human consumption to a far greater extent except that Cd content of root and fruit vegetables were within the safe levels. Among leafy vegetables, amaranthus and palak accumulated the highest content of all the four heavy metals studied.

Background value of soil heavy metal in the Three Gorges Reservoir District

The background values of soil heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were investigated based on extensive investigation in the Three Gorges Reservoir District (TGRD). After analyzing the samples under strict quality control and assurance procedures, the heavy metal concentrations in the soils were calculated using simple statistical method. The background soil values of the heavy metals in TGRD are 5.835 mg·kg-1 for As, 0.134 mg·kg-1 for Cd, 78.03 mg·kg-1 for Cr, 25.00 mg·kg-1 for Cu, 0.046 mg·kg-1 for Hg, 29.47 mg·kg-1 for Ni, 23.88 mg·kg-1 for Pb and 69.88 mg·kg-1 for Zn. Compared with the recommended background value by China National Environmental Monitoring Center (CNEMC) in 1990, As and Hg are low, Pb and Zn slightly lower, while Cd and Cr are high and Cu and Ni slightly higher than CNEMC standards. Based on the research, actual conditions are only realistically reflected by continuous field environmental quality appraisal in TGRD, which favors soil environmental quality management.

Effects of Irrigation Regimes during Grain Filling on Grain Quality and the Concentration and Distribution of Cadmium in Different Organs of Rice

The objective of this study was to investigate whether the grain quality could be improved and the proportion of cad-mium(Cd)be reduced in grains through a proper irrigation regime when rice was planted in Cd-contaminated soil.Two rice cul-tivars of Yangjing 9538(japonica)and Yangdao 6(indica)were pot-grown.150 mg kg-1 Cd was added into pots before seedling transplanting(Cd treatment),and no Cd addition was taken as control(CK).Three irrigation regimes,well-watered(WW),mod-erate dry-wet alternate irrigation(MD,soil was re-watered when soil water potential reached at-20 kPa),and severe dry-wet al-ternate irrigation(SD,soil was re-watered when soil water potential reached at-40 kPa),were imposed from 7 d after heading to maturity.The results showed that under the same Cd concentration in soil and when compared to WW,MD significantly increased,whereas SD significantly reduced,seed-setting rate,1 000-grain weight,grain yield,brown rice rate,milled rice rate,and head rice rate.MD markedly reduced,while SD increased,chalkiness.There were no significant differences in the seed-setting rate,1 000-grain weight,and each index of rice quality between the Cd treatment and the control.Under the Cd treatment and com-pared to WW,MD,and SD significantly increased the concentration and proportion of Cd in roots,while significantly reduced Cd concentration in stems and leaves and reduced Cd proportion in grains.Cd concentrations in grains and milled rice were signifi-cantly higher under SD than under WW,and exhibited no significant difference between MD and WW.SD showed lower propor-tion of Cd in milled rice,when compared to MD or WW.The two cultivars behaved the same.The results indicate that a moderate dry-wet alternate irrigation during grain filling could increase grain yield,improve milling and appearance quality and not in-crease Cd concentration or even reduce Cd proportion in grains.Reasons for variations in grain yield,quality,and the concentra-tion and proportion of Cd under different irrigation regimes were analyzed from the aspects of root activity,photosynthetic cha-racters,and Cd translocation.

Cadmium tolerance and hyperaccumulation by Thlaspi caerulescens populations grown in hydroponics are related to plant uptake characteristics in the field.

In order to fully understand the hyperaccumulation process and to increase the potential of plants for phytoextraction purposes, there is a need for more investigation of hyperaccumulating species or populations. Five Swiss populations of Thlaspi caerulescens J. & C. Presl originating from non-metalliferous but naturally Cd-rich soils (1.1-9.2 mg Cd kg-1) were compared with Ganges and Prayon populations and a non-accumulating species, Thlaspi perfoliatum (L.) F.K. Meyer, for their tolerance (shoot and root dry weight and root length) and Cd hyperaccumulation in hydroponics (0, 1, 5, 10, 20 and 50 μm Cd). In the field, the Swiss populations accumulated Zn and clearly hyperaccumulated Cd (up to 505 mg Cd kg-1 dry weight). The general response was significantly different between populations but in general an increasing Cd concentration in solution led to a decrease in dry weight production and an increase in Cd concentration in shoots. The shoot dry weight was a more discriminating parameter for tolerance than root dry weight and total root length. The Swiss populations behaved similarly to the Ganges population but differently from the Prayon population. Cadmium concentrations in shoots were above 100 mg kg-1 when plants were grown in 1 μm Cd, except for the Prayon population and T. perfoliatum. In addition, as 1 μm Cd did not induce any visible toxicity symptoms, it was found to be adequate to test Cd hyperaccumulation. However, the most striking feature was the positive linear relationship observed between the transfer factor (TF) calculated in the field and the response of a population to increasing Cd concentrations in solution, indicating that plant uptake in the field had an influence on the plant response in solution.

963. MITF as a Potential Molecular Target for Gene Therapy for Human Melanoma; a Synergistic Inhibitory Effect of Inactivation of Both MITF and BRAFV600E on Melanoma Growth

Top of pageAbstract MITF (microphthalmia-associated transcription factor) is a family of transcriptional factors controlling melanocyte differentiation. However, the roles of MITF on the cell proliferation have been controversial. Previous works have suggested that MITF negatively regulates cell proliferation or apoptosis in melanocytes, which is mediated by induction of p16INK4a, p21 or Bcl-2. But a recent study showed gene amplification of MITF in melanoma tissues (10-21%) associated with increase of the MITF protein. Furthermore, MITF gene amplification was a prognostic factor for survival, and several in vitro studies suggested that the MITF protein is attributed to increased cell proliferation, suggesting that MITF is an oncogene. Presently, the role of MITF in melanoma and melanomagenesis is not clear. We have attempted to investigate the role of MITF in malignant phenotypes of melanoma cells by using HIV-mediated RNA interference (RNAi) in a panel of melanoma cell lines with different status of the MITF expression to clarify the significance of MITF as a target for gene therapy, and to find any factors affecting sensitivity for the MITF inactivation. Furthermore, we have attempted to evaluate any additional effects by simultaneous suppression of both MITF and BRAFV600E on the melanoma growth, since BRAFV600E, the most frequent form of human BRAF mutation, is attributed to the enhanced MAPK signaling and several malignant phenotypes of melanoma. We have constructed two short hairpin RNA (shRNA) HIV vectors for MITF, and one control shRNA HIV vector (GL3B; for firefly luciferase). An HIV vector expressing two shRNAs for MITF and BRAFV600E was also constructed by tandemly aligning two shRNA expression cassettes in one HIV vector. Seven melanoma cell lines were infected with these shRNA HIV vectors, and the effects of MITF RNAi on the cell growth and apoptosis were evaluated. In six of 7 melanoma cell lines with substantial expression of the MITF protein, the MITF RNAi induced significant inhibition of cell growth, associated with G1 arrest. One melanoma cell line, A375, without any detectable expression of MITF was resistant to the MITF RNAi. One melanoma cell line showed significant apoptotic changes represented by the increase of subG1 population (7.23-7.60%) and increase of cleaved caspase-3 and caspase-9, following the MITF RNAi. Interestingly, the MITF RNAi induced G1 arrest in most melanoma cell lines tested, however, no clear correlation was observed between the protein levels of cdk inhibitors and G1 arrest. Finally, three melanoma cell lines with the simultaneous inhibition of both MITF and BRAFV600E, showed synergistic inhibition of cell growth, which was associated with more G1 arrest. Our results suggest that MITF could be a molecular target for gene therapy for most human melanoma, and the synergistic therapeutic effects of MITF and BRAFV600E indicate the possibly more potent gene therapy for melanoma by simultaneous down-regulation of these molecules.

Cannabis sativa L. growing on heavy metal contaminated soil: growth, cadmium uptake and photosynthesis

The effects of different cadmium concentrations [17 mg(Cd) kg-1(soil) and 72 mg(Cd) kg- 1(soil)] on Cannabis sativa L. growth and photosynthesis were examined. Hemp roots showed a high tolerance to Cd, i.e. more than 800 mg(Cd) kg-1(d.m.) in roots had no major effect on hemp growth, whereas in leaves and stems concentrations of 50 - 100 mg(Cd) kg-1(d.m.) had a strong effect on plant viability and vitality. For control of heavy metal uptake and xylem loading in hemp roots, the soil pH plays a central role. Photosynthetic performance and regulation of light energy consumption were analysed using chlorophyll fluorescence analysis. Seasonal changes in photosynthetic performance were visible in control plants and plants growing on soil with 17 mg(Cd) kg-1(soil). Energy distribution in photosystem 2 is regulated in low and high energy phases that allow optimal use of light and protect photosystem 2 from overexcitation, respectively. Photosynthesis and energy dissipation were negatively influenced by 72 mg(Cd) kg-1(soil). Cd had detrimental effects on chlorophyll synthesis, water splitting apparatus, reaction centre, antenna and energy distribution of PS 2. Under moderate cadmium concentrations, i.e. 17 mg(Cd) kg-1(soil), hemp could preserve growth as well as the photosynthesis apparatus, and long-term acclimation to chronically Cd stress occurred.

Involvement of CUL4 Ubiquitin E3 Ligases in Regulating CDK Inhibitors Dacapo/p27Kip1 and Cyclin E Degradation

The CUL4 (cullin 4) proteins are the core components of a new class of ubiquitinE3 ligases that regulate replication and transcription. To examine the roles of CUL4 incell cycle regulation, we analyzed the effect of inactivation of CUL4 in both Drosophilaand human cells. We found that loss of CUL4 in Drosophila cells causes G1 cell cyclearrest and an increased protein level of the CDK inhibitor Dacapo. Co-elimination ofDacapo with CUL4 abolishes the G1 cell arrest. In human cells, inactivation of CUL4Ainduces CDK inhibitor p27Kip1 stabilization and G1 cell cycle arrest which is dependenton the presence of p27, suggesting that this regulatory pathway is evolutionarilyconserved. In addition, we found that the Drosophila CUL4 also regulates the proteinlevel of cyclin E independent of Dacapo. We provide evidence that human CUL4B, aparalogue of human CUL4A, is involved in cyclin E regulation. Loss of CUL4B causesthe accumulation of cyclin E without a concomitant increase of p27. The human CUL4Band cyclin E proteins also interact with each other and the CUL4B complexes canpolyubiquitinate the CUL4B-associated cyclin E. Our studies suggest that the CUL4-containing ubiquitin E3 ligases plays a critical role in regulating G1 cell cycleprogression in both Drosophila and human cells.

The Mitotic Exit Network Mob1p-Dbf2p Kinase Complex Localizes to the Nucleus and Regulates Passenger Protein Localization

The Saccharomyces cerevisiae mitotic exit network (MEN) is a conserved signaling network that coordinates CDK inactivation, cytokinesis and G1 gene transcription. The MEN Cdc14p phosphatase is sequestered in the nucleolus and transiently released in early anaphase and telophase. Cdc14p mediates mitotic exit by dephosphorylating Cdk1p substrates and promoting Cdk1p inactivation. Cdc14p also regulates the localization of chromosomal passenger proteins, which redistribute from kinetochores to the mitotic spindle during anaphase. Here we present evidence that the MEN protein kinase complex Mob1p-Dbf2p localizes to mitotic nuclei and partially colocalizes with Cdc14p and kinetochore proteins. Chromatin immunoprecipitation (ChIP) experiments reveal that Mob1p, Dbf2p, and Cdc14p associate with centromere DNA and require the centromere binding protein Ndc10p for this association. We establish that Mob1p is essential for maintaining the localization of Aurora, INCENP, and Survivin chromosomal passenger proteins on anaphase spindles, whereas Cdc14p and the Mob1p-Dbf2p-activating kinase Cdc15p are required for establishing passenger protein localization on the spindle. Moreover, Mob1p, but not Cdc15p, is required for dissociating Aurora from the kinetochore region. These findings reveal kinetochores as sites for MEN signaling and implicate MEN in coordinating chromosome segregation and/or spindle integrity with mitotic exit and cytokinesis via regulation of chromosome passenger proteins.

Heavy Metal Uptake, Translocation, and Bioaccumulation Studies of Triticum aestivum Cultivated in Contaminated Dredged Materials

Phytoremediation is a technology that uses vegetation to remediate contaminants from water, soil, and sediments. Unlike traditional remediation techniques such as soil washing or vitrification, phytoremediation offers a technology that is solar-driven, aesthetically pleasing, and cost effective. Recent studies indicate that winter wheat (Triticum aestivum L.) is a potential accumulator for heavy metals such as lead (Pb) and cadmium (Cd) in hydroponic systems. Based on these findings, a laboratory study was conducted with the primary objective of determining the phytoaccumulation capability of this plant species for heavy metals from contaminated dredged materials (DMs) originating from two confined disposal facilities (CDF). The United States Army Corps of Engineers (USACE) manages several hundred million cubic meters of DMs each year, and 5 to 10 % of these DMs require special handling because they are contaminated with hazardous substances that can move from the substrates into food webs causing unacceptable risk outside CDFs. Phytoremediation may offer an alternative to decrease this risk. Chemical analyses by USACE personnel identified 17 metals in various DMs, but in this present study, only zinc (Zn) and Cd were investigated. Pre-germinated seeds of the test plants were planted under laboratory conditions in pots containing the various DMs and reference soil. Four weeks after planting, plants were harvested and separated into roots and shoots for biomass production and tissue metal concentrations analyses. Results showed that T. aestivum plants have the capacity to tolerate and grow in multiple-metal contaminated DMs with the potential of accumulating various amounts of Zn and Cd. Root and shoot biomass of T. aestivum were not significantly affected by the DMs on which the plants were grown suggesting that this plant species can grow just as well on DMs contaminated by various metals as in the reference soil. No significant differences in the Zn tissue concentrations were observed, differences in Cd tissue concentrations were noted. A maximum concentration of 26 mg Cd kg(-1) DW was detected in T. aestivum shoots. Although Cd tissue concentrations of T. aestivum plants in this study were below the Cd plant hyperaccumulation criterion of >100 mg kg(-1) Cd found in other studies, this plant species however may still have beneficial uses for phytoremediation studies. T. aestivum plants may serve as an indicator plant for environmental assessment and management, in which the concentration of heavy metals (e.g. Cd) mirrors the concentration in the substrate without dying due to phytotoxicity at low metal concentrations.

Efeitos da aplicação do lodo de esgoto enriquecido com cádmio e zinco na cultura do arroz

A utilização do lodo de esgoto, como fonte de nutrientes para as plantas, pode ser limitada pela presença de metais, que podem causar contaminação no solo, nos aqüíferos e nas plantas. Lodo de esgoto urbano produzido na Estação de Tratamento da Ilha do Governador (ETIG), Rio de Janeiro (RJ), foi enriquecido com 1.667 mg kg-1 de Cd e 8.000 mg kg-1 de Zn e, após 20 dias de incubação, sob umidade constante (50 % g g-1), foi utilizado em doses de 0, 20, 40 e 80 t ha-1, em amostras de dois solos: Latossolo Vermelho-Amarelo (LV) e Argissolo Vermelho-Amarelo (PV). Para avaliar o efeito do Cd e do Zn no crescimento de arroz (IAC-47) foi feito um experimento em casa de vegetação, durante 126 dias, com amostras dos solos LV e PV incubadas com o lodo de esgoto enriquecido. Adotou-se um delineamento experimental de blocos ao acaso com quatro repetições. Foram coletados raízes, folhas e grãos e determinados a produção de matéria seca e teores de Cd e Zn. As elevadas doses de Cd e Zn aplicadas no solo, decorrentes da aplicação do lodo de esgoto, não mostraram efeito na produção de matéria seca; nas plantas, os metais concentraram-se nas raízes, com baixa translocação para as folhas. Os níveis de Cd e de Zn encontrados na planta inteira demonstraram a tolerância da variedade de arroz IAC-47 a elevados teores de Cd e Zn.

Effects of Different Cadmium Concentrations on Survival Reproduction and Adaptation ofEisenia Fetida Californica

The article deals with the effects of different Cd concentrations (5 and 50 mg kg-1) in municipal sewage sludge compost on survival, activity and adaptation of Eisenia fetida californica earthworms. Investigations were carried out under laboratory conditions. Experiments were also conducted on adaptation of second-generation juveniles to Cd-contaminated sludge substrates. Dynamics of Cd concentrations in sludge, earthworm tissues and compost-grown lettuce was constantly monitored. Cd concentrations in earthworms were found to be 4.1 (5 mg Cd kg-1 variant) and 2.8 (50 mg Cd kg-1 variant) times higher than those present in sludge compost. Cd concentrations accumulated in earthworms had no direct impact on their survival and reproduction. On average, 2.7 and 3.3 juveniles per cocoon hatched in substrates with 5 and 50 mg Cd kg-1, respectively. Second-generation juveniles hatched in Cd-contaminated substrates successfully adapted to the given Cd concentrations.

CHRONIC Cd TOXICITY OF BEAN PLANTS CAN BE PARTIALLY REDUCED BY SUPPLY OF AMMONIUM SULPHATE

The effect of ammonium sulphate supply on plant Cd uptake, growth and photosynthesis of bean plants (cv. Limburgse vroege) grown in Cd-contaminated artifi cial soil was studied. The experiments were performed at controlled conditions in absence or presence of Cd (0 or 50 mg Cd kg-1 soil) and with or without supply of ammonium sulphate [0 or 0.687 g (NH4)2SO4 kg-1]. Cadmium inhibited both growth and photosynthetic activity of bean plants. The supply of ammonium sulphate had no signifi cant effect on plant Cd uptake and growth inhibition, but to some extend, reduced Cd-induced stress and its negative impact on the photosynthetic performance.

Co-segregation analysis of cadmium and zinc accumulation in Thlaspi caerulescens interecotypic crosses.

• Cadmium (Cd) hyperaccumulation in Thlaspi caerulescens varies among ecotypes. Here we investigated segregation of Cd and zinc (Zn) accumulation in F2 crosses between high (Ganges) and low (Prayon) Cd-accumulating ecotypes. • Accumulation was measured in plants grown in compost treated with 5 and 100mg kg-1 Cd and Zn, respectively, and in hydroponics with 50m Zn and 10 or 50m Cd. Another hydroponic experiment examined the relationship between Cd tolerance and accumulation. • Parental phenotype distributions for shoot metal concentrations were distinct for Cd, but not consistent for Zn. Shoot Cd and Zn in F2 s varied continuously, with significant transgression for Zn in all treatments. Shoot Cd correlated strongly with shoot manganese (Mn), and to a lesser degree with shoot Zn. Shoot Cd concentrations in the Cd nontolerant F2 s were lower than, or similar to, those in the Cd-tolerant F2 s. • We conclude that Cd and Zn accumulation is governed by multiple genes, and that Cd tolerance and accumulation are independent traits in T.caerulescens. Two uptake systems with distinctive affinities for Cd, Zn and Mn are proposed.

Response of Pinus Sylvestris Seedlings to Cadmium and Mycorrhizal Colonisation

Effects of Cd and mycorrhizal colonisation on seedling growth and Cd accumulation in Pinus sylvestris seedlings were studied. While colonisation by Suillus bovinus improved shoot growth, colonisation by Paxillus involutus had no effect on growth of seedlings. There was no Cd-ameliorating effect of colonisation in terms of either shoot or root growth. Colonisation by P. involutus did not decrease Cd transport from roots to shoots, whereas colonisation by S. bovinus significantly reduced the level of Cd in shoots in the 100 mg Cd kg-1 treatment. The proportion of healthy mycorrhizal root tips of S. bovinus-inoculated seedlings was reduced as a result of Cd addition. However, no such effect was found in P. involutus-inoculated seedlings.

Cadmium-Induced Changes in Chloroplast Lipids and Photosystem Activities in Barley Plants

Fatty acid content and composition of chloroplast membranes, ethylene production associated with thylakoid lipids degradation as well as photosynthetic electron transport involving photosystems 1 and 2 were used to determine the effects of increasing Cd concentrations in the growth medium [0, 14, 28, and 42 mg (Cd) kg-1(sand)] on the photosynthetic performance of barley plants (H. vulgare L., cv. CE9704). High concentrations of Cd triggered serious disturbances of the chloroplast membranes. Ethylene production increased whereas a drop of 18:3 fatty acid content occurred, indicating that Cd mediates lipid peroxidation in the thylakoids. The enhanced ethylene production could be used as an early indicator of Cd-induced membrane degradation, yet at very high concentration (42 mg kg-1) Cd decreased ethylene production.

Cadmium and zinc accumulation by the hyperaccumulator Thlaspi caerulescens from soils enriched with insoluble metal compounds

Thlaspi caerulescens J. & C. Presl is a hyperaccumulator of both Zn and Cd. A pot experiment was carried out to investigate whether T. caerulescens (the Ganges ecotype) could utilize Cd and Zn from insoluble sources. An uncontaminated soil was enriched with either insoluble Cd compounds (CdS or CdC03), or soluble Cd (CdS04) at a rate of 56 mg Cd kg-1 soil. In a separate experiment, soil was enriched with either ZnS04, Zn3(P04)2, or ZnS at a rate of 100 mg Zn kg-1. Neither soluble nor insoluble forms of Cd or Zn affected the growth of T. caerulescens . The Cd concentration of the shoots of the plants grown on the unenriched soil was 40 mg kg-1 dry wt., whereas the concentration in the case of the enriched soil reached 2,050 to 2,900 mg kg-1 dry wt. However, there were no significant differences in the shoot Cd concentration between the treatments with soluble or insoluble Cd compounds, even though the Cd concentration in the soil solution was in the order of CdS04 ≫CdC03 < CdS. T. caerulescens grown on the ZnS-enriched soil accumulated up to 6,900 mg kg-1 Zn in the shoots, although Zn accumulation was 1.5-fold higher with the addition of the more soluble compounds Zn3(P04)2 or ZnS04. These results indicate that the Ganges ecotype of T. caerulescens is able to utilize both insoluble Cd and Zn compounds.

Phytotoxicity of cadmium and its effect on two genotypes of Brassica juncea L.

By using two Brassica juncea, L. (Indian mustard) genotypes (Varuna and DHR-9504) agreenhouse experiment was carried out to study the effect of cadmium (Cd) on growth, yield and concentration of cadmium (Cd) in different plant parts at the Agricultural Research Station, Bilaspur Chhattisgarh, India during 2002-2003. Plants were grown under controlled climatic conditions and subjected to increasing Cd supply in the form of CdCl2 @ 0, 20, 40, 60, 80 and 100 mg Cd kg-1 soil. Cdphytotoxicity was shown by growth retardation of Varuna and DHR-9504. Varuna showed greater sensitivity to Cd toxicity than DHR-9504. Increasing Cd supply markedly reduced the seed, stem and root dry weight of both genotypes (Varuna and DHR-9504), and these decreases were more marked in Varuna.Due to increased level of Cd application, the Cd concentration increased significantly in various plant parts in both the Brassica genotypes tested. Increase in Cd concentration of about 5 times in seeds, 7 times in stems and 9 times in roots was noted with an application of 20 mg Cd kg-1 soil more than the control. Cd was accumulated in the roots in much higher amounts than in the stem and seeds, especially in the case of DHR-9504, indicating that there is limited transport of Cd from the root system to the above ground plant parts in DHR-9504 genotype due to the presence of strong Cd-binding proteins in the roots. GenotypeDHR-9504 had significantly less uptake of Cd than genotype Varuna. More data are needed to ascertain the findings of this study.