Heavy Metals In Roots Research Articles

Removal of Heavy Metals from Wastewater in Hawassa Textile Factory Treatment Ponds by Shoenoplectus Lacustris: Opportunity of Phytoremediation by Aquatic Macrophyte

A phytoremediation study was made on Hawassa Textile Factory Treatment ponds to assess the potential of Shoenoplectus lacustris to accumulate heavy metals in the plant tissues with reference to water. To achieve the objectives of this study, roots and shoots of Shoenoplectus lacustris along with surface water in the two treatment ponds having the macrophyte at their shoreline were analyzed by EPA standard methods for six heavy metals, i.e., Cd, Cr, Cu, Pb, Mn and Zn. The results showed that the concentration of heavy metals were higher in macrophytes than water. The accumulation of heavy metals in water and in the macrophytes had the same pattern with descending order of Zn>Mn>Cu>Cr>Cd while Cu and Zn were more accumulated in macrophytes. Lead was below detection in all samples analyzed for heavy metals. There were significant differences in accumulation of the different heavy metals in roots and shoots of Shoenoplectus lacustris . Results from both ponds showed that higher heavy metals accumulation generally occurred in the root of Shoenoplectus lacustris than the shoot. However, the shoot accumulated higher concentration of Mn than the root. Therefore, the present study revealed that Shoenoplectus lacustris can serve as bioremediant due to its ability to remove heavy metals from contaminated water and accumulate in its roots and shoots thereby improving water quality. Thus, in order to improve the efficiency of biological lagoons constructed for the treatment of the city sewage industry wastes, it is very important to growth the Shoenoplectus lacustris. Keywords : Heavy metals, Bioremediant, Macrophytes, Phytoremediation, Ponds, Textile factory DOI : 10.7176/JEES/9-4-02 Publication date : April 30 th 2019

Procjena potencijala konoplje (Cannabis sativa L.) za akumulaciju teških metala

Heavy metals accumulation in crops and soils poses a significant threat to the human health. A study was carried out in 2016 in order to assess hemp (Cannabis sativa L.) ability to accumulate heavy metals and to reveal its possibility as a phytoaccumulator or phytostabilizer. Two soil types from Croatia were used in experimental pots: Gleysoils (alkaline soil) and Stagnic Luvisol (acid soil). Majority of the varieties accumulated more heavy metals in roots than in above-ground biomass. Removal of Cd, Ni, Pb, Hg, Co, Mo and As was higher in acid soil. Potential ability for phytostabilization was observed in alkaline soil in order Cu > Cr > Cd > Mo > Hg > Zn > Ni > Co > As > Pb, while for acid soil in order Zn > Cd > Cr > Ni > Hg > Cu > Mo > As > Co > Pb. Some varieties exhibited a translocation coefficient (TC) more than 1 and shown the ability of hyper-accumulation for Zn, Hg, Mo and Cd. Higher accumulation of heavy metals in some varieties could lead to their general application for phytoaccumulation of heavy metals from polluted soils.

Arbuscular mycorrhizal fungi enhance antioxidant defense in the leaves and the retention of heavy metals in the roots of maize.

In this study, we investigated the effects of the arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae and Diversispora spurcum on the growth, antioxidant physiology, and uptake of phosphorus (P), sulfur (S), lead (Pb), zinc (Zn), cadmium (Cd), and arsenic (As) by maize (Zea mays L.) grown in heavy metal-polluted soils though a potted plant experiment. F. mosseae significantly increased the plant chlorophyll a content, height, and biomass; decreased the H2O2 and malondialdehyde (MDA) contents; and enhanced the superoxide dismutase (SOD) and catalase (CAT) activities and the total antioxidant capacity (T-AOC) in maize leaves; this effect was not observed with D. spurcum. Both F. mosseae and D. spurcum promoted the retention of heavy metals in roots and increased the uptake of Pb, Zn, Cd, and As, and both fungi restricted heavy metal transfer, resulting in decreased Pb, Zn, and Cd contents in shoots. Therefore, the fungi reduced the translocation factors for heavy metal content (TF) and uptake (TF') in maize. Additionally, F. mosseae promoted P and S uptake by shoots, and D. spurcum increased P and S uptake by roots. Moreover, highly significant negative correlations were found between antioxidant capacity and the H2O2, MDA, and heavy metal contents, and there was a positive correlation with the biomass of maize leaves. These results suggested that AMF alleviated plant toxicity and that this effect was closely related to antioxidant activation in the maize leaves and increased retention of heavy metals in the roots.

Phytoremediation capability of nickel and manganese polluted soil by Sorghum biocilor L.

A pot experiment was conducted based on a factorial study and complete random block design with three replicates to investigate the phytoremediation potential of Sorghum biocilor L. in soils polluted with nickel and manganese during 2017-2018. The first factor was nickel nitrate (0, 60, and 120 mg kg-1 soil) and the second factor comprised of manganese sulphate (0, 50, and 100 µM). The characteristics under investigation were shoot height, root length, shoot dry weight, root dry weight, nickel concentration of shoots and roots, manganese concentration of shoots and roots, and nickel and manganese translocation factors. Findings suggested that under nickel and manganese stress, shoot height, root length, shoot dry weight, and root dry weight reduced. Also, with an increase in the soil nickel and manganese, so did the concentration of these heavy metals in roots and shoots of the plants under study. Maximum effect of nickel and manganese were recorded in the treatments comprising 120 mg Kg-1 Nickel and 100 µM manganese sulphate, respectively while compared with nickel, manganese caused less damage to the plants under study. Application of nickel to the soil increased the translocation factor while there was no difference between the two levels of nickel applied. On the other hand, application of manganese did not affect the translocation factor compared to the control and the translocation factors for both elements were less than 1. Therefore, based on the findings of the study, sorghum showed a relatively good tolerance to nickel and manganese, the absorbed nickel and manganese were mostly concentrated in the plant root, and Sorghum biocilor L. is not recommended for phytoremediation.

Phytoremediation potential of heavy metals by two native pasture plants (Eucalyptus grandis and ailanthus altissima) assisted with AMF and fibrous minerals in contaminated mining regions

The current study assesses the effect of fibrous clay minerals’ amendments and arbuscular mycorrhiza incubation on heavy metal uptake and translocation in Eucalyptus grandis and Ailanthus altissima plants. For doing so, Eucalyptus and ailanthus trees have been grown in a soil sample, contaminated with heavy metal iron ore mining and collected from southern Iran. The area under study is arid, with the majority of trees being ailanthus and eucalyptus. Amounts of Cd, Pb, Zn, Cu, and Mn have initially been at toxic levels which declined after cultivation. Fibrous clay minerals have been added to soils as a natural adsorbent to adsorb heavy metals like Pb, Cd, Zn, and Mn. Accumulation of the elements in the roots and shoots has been in the following order: Cu>Zn>Mn>Cd>Pb>Fe. The organ metal concentrations have not statistically translocated from roots to shoots of plants, except for Zn and Cu whose concentrations have been significantly higher in roots. Eucalyptus is well capable of extracting elements from contaminated soils, compared to ailanthus, particularly in case of Cu and Cd. The percentage of mycorrhizal colonization proves to be more in pots with ailanthus plants grown in contaminated soil, suggesting enhanced effect of high metal concentrations on plant infection by G. mosseae. AMF assists soil remediation by enhancing the growth and retention of toxic elements by ailanthus, while no substantial change has been observed between inoculated and non-inoculated eucalyptus plants by AFM, regarding translocation of elements to plants. The possibility of increasing metal accumulation in roots is interesting for phytoremediation purposes, since most high-producing biomass plants, such as eucalyptus, retain heavy metals in roots.

Erratum to: Removing heavy metals from Isfahan composting leachate by horizontal subsurface flow constructed wetland.

Composting facility leachate usually contains high concentrations of pollutants including heavy metals that are seriously harmful to the environment and public health. The main purpose of this study was to evaluate heavy metals removal from Isfahan composting facility (ICF) leachate by a horizontal flow constructed wetland (HFCWs) system. Two horizontal systems were constructed, one planted with vetiver and the other without plant as a control. They both operated at a flow rate of 24 L/day with a 5-day hydraulic retention time (HRT). The average removal efficiencies for Cr (53 %), Cd (40 %), Ni (35 %), Pb (30 %), Zn (35 %), and Cu (40 %) in vetiver constructed wetland were significantly higher than those of the control (P < 0.05). Accumulations of heavy metals in roots were higher than shoots. Cd and Zn showed the highest and the lowest bioconcentration factor (BCF), respectively. Vetiver tolerates the extreme condition in leachate including high total dissolved solids.

Leaves and roots of Typha latifolia L. and Iris pseudacorus L. as bioindicators of contamination of bottom sediments by heavy metals

Abstract The paper concerns the bioaccumulation of zinc, nickel, iron and manganese in leaves and roots of selected macrophytes from the Krzynia Reservoir (northern Poland). The research was conducted within the area of 10 stations situated in the littoral zone of the reservoir. Samples of surface waters, bottom sediments and plants were taken in summer. Heavy metal content was determined by the atomic absorption spectrometry method (ASA). The concentration of heavy metals in the waters of Krzynia Reservoir was low and noinfluence of anthropogenic factors was found. Concentration of heavy metals in the examined bottom sediments was low and remained within the limits of the geochemical background for Zn and Fe. In the case of Ni and Mn it sporadically exceeded the level of the geochemical background. The tested plants mainly accumulated heavy metals in roots, with the exception of nickel which appeared in larger quantities in leaves. The relationships among the content of the determined elements in the organs of macrophytes was identical for the tested species and could be arranged into the following sequences: Mn&gt;Fe&gt;Ni&gt;Zn in leaves and Fe&gt;Mn&gt;Zn&gt;Ni in roots. Statistically significant differences were found in the content of Mn in leaves and Zn and Fe in the roots of Typha latifolia L. and Iris pseudacorus L. By accumulating substantial quantities of heavy metals in their organs, macrophytes constitute an effective protective barrier for the waters and bottom sediments.

Simulation of the Absorption, Migration and Accumulation Process of Heavy Metal Elements in Soil-crop System

Soil-crop system is an important way that heavy metals harm the ecological environment and human health. To research and understand the process of heavy metal absorption, migration and accumulation in soil-crop system is important for the prevention and control of heavy metal pollution and the health of human beings. In this paper, we established a model for crop uptake of heavy metals to calculate the heavy metals contents of wheat roots, stems, leaves and grains, and we analyzed the accumulation process of heavy metals in roots, stems, leaves and grains in the growth cycle of wheat. The predicted values were compared with the measured values to test the accuracy of the model. The results demonstrated that different parts of wheat had different heavy metal absorption capacity, the absorption of the roots was the strongest, followed by leaves, and the absorption capacity of stems and grains was weak. In addition, the contents of different heavy metals in each part of wheat were also significantly different. The content of Cu was the highest, followed by Ni, while the contents of Pb and Cd were small. In the process of wheat growth, the heavy metal accumulation rate of stem, leaf and grain began to slow down at 90, 60 and 100 days respectively, and the concentration of heavy metals reached the maximum gradually, while the accumulation rate of heavy metals in roots showed a growing trend. We studied the process of absorption, migration and accumulation of heavy metals in soil-crop system by using numerical simulation technology, which can provide scientific basis for preventing the ecological and health risks of heavy metal pollution.

Removing heavy metals from Isfahan composting leachate by horizontal subsurface flow constructed wetland.

Composting facility leachate usually contains high concentrations of pollutants including heavy metals that are seriously harmful to the environment and public health. The main purpose of this study was to evaluate heavy metals removal from Isfahan composting facility (ICF) leachate by a horizontal flow constructed wetland (HFCWs) system. Two horizontal systems were constructed, one planted with vetiver and the other without plant as a control. They both operated at a flow rate of 24L/day with a 5-day hydraulic retention time (HRT). The average removal efficiencies for Cr (53%), Cd (40%), Ni (35%), Pb (30%), Zn (35%), and Cu (40%) in vetiver constructed wetland were significantly higher than those of the control (P < 0.05). Accumulations of heavy metals in roots were higher than shoots. Cd and Zn showed the highest and the lowest bioconcentration factor (BCF), respectively. Vetiver tolerates the extreme condition in leachate including high total dissolved solids.

How do roots of the metal-resistant perennial bush Zygophyllum fabago cope with cadmium and zinc toxicities?

Background and aims Zygophyllum fabago is a perennial species tolerating high concentrations of Cd and Zn through protection of photosynthetically active leaves and regulation of Cd and Zn translocation from the roots to the shoots. This study aimed to assess metabolites involved in detoxification of those heavy metals in roots in relation to their coordination.

Phytoaccumulation of Heavy Metals in Natural Vegetation at the Municipal Wastewater Site in Abbottabad, Pakistan

Heavy metal accumulation in crops and soils from wastewater irrigation poses a significant threat to the human health. A study was carried out to investigate the removal potential of heavy metals (HM) by native plant species, namely Cannabis sativa L., Chenopodium album L., Datura stramonium L., Sonchus asper L., Amaranthus viridus L., Oenothera rosea (LHer), Xanthium stramonium L., Polygonum macalosa L., Nasturtium officinale L. and Conyza canadensis L. growing at the municipal wastewater site in Abbottabad city, Pakistan. The HM concentrations varied among plants depending on the species. Metal concentrations across species varied in the order iron (Fe) > zinc (Zn) > chromium (Cr) > nickel (Ni) > cadmium (Cd). Majority of the species accumulated more HM in roots than shoots. Among species, the concentrations (both in roots and shoots) were in the order C. sativa > C. album > X. stramonium > C. canadensis > A. viridus > N. officinale > P. macalosa > D. stramonium > S. asper > O. rosea. No species was identified as a hyperaccumulator. All species exhibited a translocation factor (TF) less than 1. Species like C. sativa, C. album and X. stramonium gave higher (> 1) biological concentration factor (BCF) and biological accumulation coefficient (BAC) especially for Fe, Cr and Cd than other species. Higher accumulation of heavy metals in these plant species signifies the general application of these species for phytostabilization and phytoextraction of HM from polluted soils.

Absorption of different sorghum accessions on heavy metals in polluted soil

利用重金属含量较高的污水污染土壤, 以未污染土壤作对照, 种植8个甜高粱品种、2个饲用高粱品种和1个粒用高粱品种, 检测8种重金属在高粱植物体内不同器官的含量, 以研究不同高粱种质对重金属的吸收特性。结果表明: 甜高粱对汞(Hg)、镉(Cd)、锰(Mn)和锌(Zn)的吸收在两种土壤间差异显著, 对钴(Co)、铬(Cr)、铅(Pb)和铜(Cu)的吸收差异不显著。Mn在甜高粱体内含量表现为未污染土壤高于污染土壤; 而Zn含量在不同器官之间存在差异, 未污染土壤叶中含量远高于穗, 穗中含量远高于茎和根。不同重金属在甜高粱体内的储存部位不同, 污染土壤上Hg、Cd、Co、Cr和Zn在根中积累量较高, Cu、Mn和Pb在穗中的积累量较高。甜高粱、饲用高粱和粒用高粱对重金属的吸收、运输及储存在品种之间差异较大, 同一品种对不同重金属的吸收也存在差异。饲用高粱表现为叶部对Cr和Zn的储存量较高, 而粒用高粱'晋中0823'则显示了茎对多种重金属的储存能力。高粱根对土壤中重金属的富集系数较高, 为0.02(Pb)~0.23(Cd), 转移系数变幅为0.21(Co)~3.42(Pb)。对同一种重金属的吸收量品种间差异较大, 甜高粱'西蒙'根对Co、Cr、Cu、Mn、Pb和Zn具有高富集系数, 粒用高粱'晋中0823'茎对Hg、Cd、Mn、Pb和Zn富集系数较高。高粱对重金属的吸收能力与转移能力不同步, 甜高粱'绿能1号'具有对多种重金属的高转移能力, 粒用高粱'晋中0823'只对Zn有较高的转移能力。因此本文认为甜高粱对不同重金属的吸收和转移有选择性。对Zn吸收并转移到地上部后, 首先储存在叶和穗中, 当吸收量足够大时, 茎和根也成为储存器官; 对Mn的吸收与其他重金属的吸收存在竞争作用, Hg吸收后很少向地上部转移; 而对Cu、Mn和Pb吸收后在穗部的储存量较大。饲用高粱与甜高粱相比对重金属的吸收未显示明显的不同, 甜高粱'西蒙'根对多种重金属具有强储存能力, 而粒用高粱'晋中0823'的茎秆显示了比甜高粱更强的储存能力, 甜高粱'绿能1号'对多种重金属的转移能力较强。所以, 选择富集和转移能力均强的高粱品种能更有效地吸收土壤中的重金属, 达到修复污染土壤的目的。

Akumulasi Logam Berat Timbal (Pb) dan Pengaruhnya Terhadap Histologi Akar Mangrove Avicennia marina (Forssk). Vierh. di Perairan Mangunharjo Semarang

Mangunharjo areas water is an area of coastal waters and the sea which close to the settlement industry and community activities. Where feared result of industrial waste were dumped around it that cause pollution. One form of pollution is the waste produced in the form of lead (Pb) heavy metals is a heavy metal element that can not be broken down by natural processes. The existence of Pb in nature have an impact on coastal vegetation is mangrove. Mangroves are coastal ecosystems which have an important role in estuarine areas. Other mangrove function is to absorb organic and non-organic materials. The purpose of this research was to study the accumulation of lead (Pb) heavy metals in Avicennia marina mangrove roots and influences the type of heavy metal accumulation of lead (Pb) to root tissue in Avicennia marina waters Mangunharjo. This research was conducted with descriptive analytic method. The results showed the amount of heavy metals on the roots of Avicennia marina Pb higher than the Pb content of heavy metals in sediment and water indicating that these plants are able to accumulate heavy metals in the roots to absorb these elements in sediments and water. Observations cell histology showed no change in root tissues of Avicennia marina.

Chemometrics applied to the analysis of induced phytochelatins in Hordeum vulgare plants stressed with various toxic non-essential metals and metalloids

Hordeum vulgare plants were stressed with Hg, Cd and As and their phytotoxicity was evaluated in terms of growth inhibition and total metal uptake by the plant. The synthesised phytochelatins ((γ-Glu-Cys)n-Gly, n=2-5; PCs) were determined by HPLC with amperometric detection at a glassy carbon electrode. The results indicate that H. vulgare is a good phytostabilisation plant due to its capacity to accumulate heavy metals in roots. Cd and Hg are the most uptake toxic elements, being Cd the most potent inducer of PCs. The data obtained on the different PCs and related peptides induced by each heavy metal were used to perform a Principal Component Analysis (PCA) of the results as a function of the contaminating toxic element or its concentration level. The nature of the stressor element could be predicted from the pattern of PCs and related peptides identified by PCA. PCs were the most strongly induced peptides under Cd and Hg stress, whereas As only tended to synthesise small thiols such as glutathione and γ-glutamylcysteine, both precursors of PCs synthesis. This finding indicates that PCs are induced at different rates depending on the metal stressor used.

Heavy Metal Contamination in Green Leafy Vegetables Collected From Different Market Sites of Kathmandu and Their Associated Health Risks

The present study was carried out to assess contamination of five heavy metals (As, Cd, Cr, Pb and Zn) in five different types of green leafy vegetables viz., mustard (Brassica campestris), garden crees (Lepidium sativum), fennel (Foeniculum vulgare), coriander (Coriandrum sativum), and spinach (Spinacea oleracea) collected from different market sites of Kathmandu. Atomic absorption spectrometer was used to determine the concentrations of these metals in a total of 45 test vegetables. Results showed a substantial accumulation of heavy metals in roots and leafy shoots of the vegetables. The range of various metals was 0.9-12.0, 2.7-12.5 and 16.8-158.7 mg kg-1 in roots and 3.2-19.1, 5.3- 32.9 and 23.9-223.1 mg kg-1 in leafy shoots of the test vegetables for Cd, Pb and Zn respectively. However, the levels of As and Cr were found below the detection limits. Results revealed that the average concentrations of all metals (both leafy shoots and roots together) in the vegetables were found in order of their abundance as Zn&gt;Pb&gt;Cd. It was also found that Pb and Cd levels exceeded the maximum permissible limits set by FAO/WHO for human consumption. Daily intake of heavy metals through consumption of the vegetables was also investigated. From the present study, we conclude that a monitoring plan and a health risk assessment are necessary to evaluate the levels of metal concentration in vegetables in order to develop the proper measures for reducing excessive build-up of these metals in the food chain. Scientific World, Vol. 11, No. 11, July 2013, page 37-42 DOI: http://dx.doi.org/10.3126/sw.v11i11.8550

Trace element accumulation and distribution in sunflower plants at the stages of flower bud and maturity

The aim of this study was to analyze the accumulation and distribution of cadmium (Cd), zinc (Zn) and copper (Cu) in different portions of plants of sunflower (Helianthus annuus L., cv. Oleko) grown in soil with contaminants (5, 300, 400 mg kg–1 of Cd, Zn and Cu, respectively) and without (untreated soil as a control) from the emergence of cotyledon leaves until to two phenological stages: flower bud (R-1) and maturity (R- 9). Sunflower accumulated considerable amounts of heavy metals in both phenological stages showing slight reductions of dry matter production. At R-1 stage, Cd, Zn and Cu were accumulated mainly in the roots with concentrations respectively up to 5.4, 233 and 160 mg kg–1 of dry matter with a low translocation from roots to the aerial part. Yet at the R-1 stage, the bioconcentration factor (BCF) of Cd showed a significantly higher value in the Cd-Zn-Cu treatment (0.27) with respect to the untreated control (0.02), vice versa was observed for Cu, whereas no significant difference between treatments was observed for Zn (0.12 on average). However among metals, Cd showed the highest value of BCF. Referring only to the epigeous portion, differences in the accumulation and distribution of the three metals in the treated plants were found in both phenological stages; indeed passing from flower bud to the maturity stage, Cd, Zn and Cu concentrations increased in the stems and leaves, particularly in the old ones, whereas decreased in the heads. Metal accumulation in the achenes was very low and never exceed the toxicity threshold value considered for livestock. The high storage of heavy metals in roots and the probable re-translocation of the three metals along the plant during the growing cycle could be considered as a strategy of sunflower to preserve young metabolically-active leaves and reproductive organs from toxic metal concentrations.

Impact of Urban Wastewater on Soil Properties and Lepidium sativum in an Arid Region

The reuse of wastewater for purposes such as agricultural irrigation can reduce the amount of water that needs to be extracted from environmental water sources. The aims of the study were the effects of municipal wastewater on soil properties and Lepidium sativum. Soil samples of 0 to 20 cm depth were taken from agricultural field in Isfahan (center of Iran). Lepidium sativum was transplanted in pots containing 7 kg of these soils. The experiment consisted of two treatments (with three replications) including soil irrigation with water (T1) and soil irrigation with wastewater (T2). After 30 days, samples were taken for testing. Soil properties such as electrical conductivity, organic matter, total nitrogen, sodium ions, chloride ions and heavy metals were measured. Morphological parameters of Lepidium sativum and accumulation of heavy metals in this plant were measured. The evidences provided by this experiment indicated that the application of wastewater caused an increase of EC, OM, TN, Cl, Na, Cr, Ni, Fe, Mn and Zn in soil. The irrigation with wastewater caused accumulation of heavy metals in Lepidium sativum. Accumulation of heavy metals in roots was important than in leaves. Results also showed that Lepidium sativum irrigated with wastewater caused an increase of root length and shoot length.

Calcium- and ammonium ion-modification of zeolite amendments affects the metal-uptake of Hieracium piloselloides in a dose-dependent way

The role of natural zeolite and of two types of modified zeolite (with ammonium and with calcium ions) in reducing the accumulation of ions of heavy metals in roots and leaves of Hieracium piloselloides grown on tailing ponds was investigated. The variation of the content of zeolite (5% w/w and 10% w/w) is another parameter that significantly and positively affects the accumulation of the metal ions in Hieracium piloselloides. The results showed that zeolite used as an amendment in the soil in tailing ponds significantly reduces the accumulation of heavy metal ions in Hieracium piloselloides. The highest concentrations of heavy metals were accumulated in plants grown on soil without zeolite, being followed by the plants grown on the substrate with natural zeolite. Moreover, the translocation factors of heavy metal ions uptake in roots and leaves grown on substrates with modified zeolites are lower than those calculated for the organs grown on the substrate amended with natural zeolite. This behaviour has demonstrated the positive effect of those changes of zeolite amendments in the potential phytoremediation practice.

Transcriptional and posttranscriptional regulation of chloroplast gene expression by heavy metals in barley seedlings

The effects of Cd, Cu, and Ni ions on chloroplast gene expression were studied in 7-day-old barley (Hordeum vulgare L.) seedlings. Toxicity of heavy metals (HM) was estimated from their effects on root and shoot growth and from the accumulation of HM in roots and leaves of seedlings grown in roll culture. Root growth was affected by HM to a higher extent than shoot growth. A statistically significant inhibition of root growth was observed at concentrations of all studied HM ≥100 μM. Leaf growth was inhibited by Cu and Ni at concentrations ≥400 μM, while the inhibitory effect of Cd on leaf growth was observed at concentrations ≥100 μM. The translocation of Cu from roots to shoots of barley seedlings proceeded slower than the accumulation of Cu in roots. Unlike Cu, Ni was actively accumulated by shoots in addition to its strong absorption by roots. Using the run-on transcription and RT-PCR (reverse transcription-polymerase chain reaction), we showed that HM at a concentration of 100 μM regulated the expression of individual chloroplast genes. The presence of either Cd, Cu, or Ni ions in the plant growth solution enhanced transcription of rpl16, rpl23, and rpl12 genes encoding ribosomal proteins, and of ndhA encoding the subunit 1 of plastid NADH-plastoquinone oxidoreductase. Transcription of sixteen other studied plastid genes was not affected by HM. The activation of transcription of the studied genes was not always accompanied by an increase in the transcript copy number. Northern blot analysis showed that Cd impaired the splicing of rpl16, a chloroplast gene that contains an intron. Thus, this study proves that HM regulate not only the transcriptional activity of chloroplast genes but also the splicing of rpl16 transcripts.

Proteomic characterization of copper stress response in Cannabis sativa roots

Cannabis sativa is an annual herb with very high biomass and capability to absorb and accumulate heavy metals in roots and shoots; it is therefore a good candidate for phytoremediation of soils contaminated with metals. Copper is an essential micronutrient for all living organisms, it participates as an important redox component in cellular electron transport chains; but is extremely toxic to plants at high concentrations. The aim of this work was to investigate copper effects on the root proteome of C. sativa, whose genome is still unsequenced. Copper stress induced the suppression of two proteins, the down-regulation of seven proteins, while five proteins were up-regulated. The resulting differences in protein expression pattern were indicative of a plant adaptation to chronic stress and were directed to the reestablishment of the cellular and redox homeostasis.