Aneta Piechalak

Accumulation and detoxification of lead ions in legumes.

This study focuses on lead accumulation in roots, stems and leaves of three plant species of the Fabacea family: Vicia faba, Pisum sativum and Phaseolus vulgaris grown hydroponically in a medium supplemented with 1 mM concentration of lead. The largest amount of lead, up to 75 mg Pb/g dry weight, was accumulated in roots of P. vulgaris. The highest rate of Pb ions uptake from the medium took place during the first 10 h of incubation with lead and after 96 h of incubation lead content in the medium decreased by half. Thus, it was suggested that P. vulgaris could be used in rhizofiltration--the use of plant roots to absorb pollutants from water contaminated with lead. At the same time we studied the influence of lead on acid soluble thiol, glutathione, homoglutathione contents and the synthesis of phyto- and homophytochelatins in roots of V. faba, P. sativum and P. vulgaris grown hydroponically. Activation of the detoxicative-phytochelatin system was observed in the cytosol of root cells of the tested plants. This system was composed of phytochelatins (PCs) in roots of V. faba, homophytochelatins (hPCs) in P. vulgaris roots and both PCs and hPCs in P. sativum roots. The total content of PCs and hPCs in roots of P. sativum was very high and reached around 4800 (expressed in nmol SH x g(-1)FW) and induction of their synthesis occurred after only 2 h of treatment with 1 mM Pb.

Enhancing phytoremediative ability of Pisum sativum by EDTA application

The aim of our research was to demonstrate how the presence of EDTA affects resistance of pea plants to Pb and Pb-EDTA presence, and to show the effectivity of lead ions accumulation and translocation. It was determined that EDTA not only increased the amount of Pb taken up by plants but also Pb ion transport through the xylem and metal translocation from roots to stems and leaves. It can be seen in the presented research results that addition of the chelator with Pb limited metal phytotoxicity. We also demonstrated a significant effect of EDTA not only on Pb accumulation and metal transport to the aboveground parts but also on the profile and amount of thiol compounds: glutathione (GSH), homoglutathione (hGSH) or phytochelatins (PCs), synthesized by the plants. We observed a significant effect of the synthetic chelator on increasing the level of Pb accumulation in roots of plants treated with Pb including EDTA (0.5 and 1 mM). Pisum sativum plants treated only with 1 mM Pb(NO3)2 accumulated over 50 mg Pb x g(-1) dry wt during 4 days of cultivation. Whereas in roots of pea plants exposed to Pb+0.5 mM EDTA 35% more Pb was observed. When 1 mM EDTA was applied roots of pea accumulated over 67% more metal. The presence of EDTA also increased metal uptake and transport to the aboveground parts. In pea plants treated only with 1 mM lead nitrate less than 3 mg Pb x g(-1) dry wt was transported, whereas in P. sativum treated with Pb-EDTA doubled amount of Pb was observed in stems and leaves.

Determination of cadmium and lead species and phytochelatins in pea (Pisum sativum) by HPLC-ICP-MS and HPLC-ESI-MSn.

An analytical approach based on hyphenated techniques was used for studying the speciation of cadmium and lead in Pisum sativum. Proper preservation conditions were employed to avoid the oxidation of -SH groups and corresponding decomposition of metal-binding complexes. SEC column was washed with 5 mM beta-mercaptoethanol and then samples were analysed using ICP-MS as a detector. Results showed that cadmium is the inhibitor of lead uptake. HPLC-ESI-MS(n) assays revealed fragmentation pathways of phytochelatins.

An analysis of long-distance root to leaf transport of lead in Pisum sativum plants by laser ablation–ICP–MS

Laser ablation (LA) inductively coupled plasma mass spectrometry (LA–ICP–MS) has been applied to determine the nature of lead (Pb) distribution in plant tissues. Plants were cultivated hydroponically in Hoagland medium supplemented with 0.5 mM Pb(NO3)2. After 96 h, parts of root were cut off from Pisum sativum and analysed. The difference in the amount of Pb transported through the vascular tissues was expressed as the level of signal intensity. Mapping in vivo tissues reveals the metal pathway in the plant which may be particularly helpful in understanding of the mechanisms of heavy metal accumulation and transport in the plant.

Rhizoremediation of Diesel-Contaminated Soil with Two Rapeseed Varieties and Petroleum degraders Reveals Different Responses of the Plant Defense Mechanisms

Plant-assisted bioremediation (rhizoremediation) stands out as a potential tool to inactivate or completely remove xenobiotics from the polluted environment. Therefore, it is of key importance to find an adequate combination of plant species and microorganisms that together enhance the clean-up process. To understand the response of plants upon bioaugmentation, the antioxidative and detoxification system was analyzed in high and low erucic acid rapeseed varieties (HEAR and LEAR, respectively), after 8 weeks of their treatment with petroleum degraders and 6000 mg diesel oil/kg dry soil. The oxidative stress was enhanced in LEAR being exposed to sole diesel oil, in comparison with HEAR. However, when LEAR plants were additionally inoculated with bacteria, suppression of total catalase (CAT) and ascorbate peroxidase (APX) activity were observed. Interestingly, glutathione transferase (GST) activity was found in these plants at a much higher level than in HEAR, which correlated with a more efficient diesel removal performed by LEAR in the polluted soil and upon bioaugmentation. A distinct profile of polycyclic aromatic hydrocarbons (PAH) was detected in leaves of these plants. Neither LEAR nor HEAR experienced any changes in the photosynthetic capacity upon diesel pollution and presence of petroleum degraders, which supports the usefulness of rhizoremediation with rapeseed.

Effects of binary metal combinations on zinc, copper, cadmium and lead uptake and distribution in Brassica juncea

The interaction between lead, copper, cadmium and zinc in their binary combinations was investigated in Indian mustard seedlings (Brassica juncea L. var. Malopolska). Fourteen-days-old seedlings were treated with Pb(NO3)2, CuSO4, CdCl2, ZnSO4 at 50μmol of metal ion concentration and at 25μmol of each metal ion in combinations. Metal combinations were generally more inhibiting in terms of biomass production. This inhibiting effect followed an order: Cu+Cd>Cu+Zn, Cd+Pb>Cu+Pb>Zn+Pb, Cu>Cd>Zn>Zn+Cd>Pb. We observed synergistic and antagonistic effects of metal uptake in binary metal treatments, suggesting metal crosstalk at the plant uptake site. Metal content in plant tissues varied among different combinations. The metal concentrations followed an order of Pb>Cu>Zn>Cd in roots, Zn>Cu>Pb>Cd in the stem and Zn>Cu>Cd>Pb in leaves. Presence of metals altered the distribution of micronutrients (Cu, Zn) in plants: Cu concentration was lowered in roots and leaves and increased in stems; Zn content was increased in plants, with stems having up to 4 or 5 times more Zn than in control plants.

Analysis of oxidised and reduced phytochelatins in pea and lupin plants using HPLC/MSn

Plants exposed to heavy metals activate a detoxification system capable of chelating and transporting these harmful ions to vacuoles. Phytochelatins–low molecular weight oligopeptides containing thiols such as glutathione and cystein–have been reported to play a very important role in this respect. High performance liquid chromatography coupled to the electospray ion trap mass spectrometer (HPLC-ESI-IT-MS) was used for identification of phytochelatins induced by Cd2+ and Pb2+ in roots, stems and leaves of pea (Pisum sativum L.) and yellow lupin (Lupinus luteus L.). This approach enabled unambiguous identification of phytochelatins in plant tissues and detection of phytochelatins and homophytochelatins in reduced as well as in oxidised form. Significant differences were detected in phytochelatin relative amounts and profiles in different parts of plants treated with heavy metals. Roots of both plant species contained mainly reduced phytochelatins, reduced and oxidised forms of these peptides were observed in stems in similar amounts, whereas only the oxidised phytochelatins were present in leaves.

High Peroxide Level May Be a Characteristic Trait of a Hyperaccumulator

Under various abiotic stresses, plants overproduce reactive oxygen species (ROS) such as superoxide anion (O2•−), hydroxyl radical (OH•), and hydrogen peroxide (H2O2). When in excess, these highly reactive molecules cause oxidative stress, thus damaging proteins, lipids, and DNA. Therefore, plants evolved an enzymatic defense machinery that involves such enzymes as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APOX). Various plant families, species and even specimens differ in their ability to withstand the abiotic stress. A study has been undertaken to assess the differences in response to trace metals between two species: a resistant hyperaccumulator Indiana mustard (Brassica juncea) and a metal-sensitive pea (Pisum sativum). We observed that trace elements (Cu, Zn, Cd, Pb) changed the activity of antioxidative enzymes (SOD, APOX, CAT) and the rate of ROS generation. However, in the control plants and at a point 0′ of the treatment, we have noticed a large disproportion in the hydrogen peroxide level, with B. juncea maintaining naturally higher H2O2 level (up to 40 times higher). We believe that this may be a distinguishing trait common to plants being resistant to oxidative stress.

Metal/Metalloid Phytoremediation: Ideas and Future

This chapter addresses some of the most significant issues in phytoremediation. We described the most important developments in this environment, cleaning method and presented some significant ways for future development. Additionally, this work presents the impact of endo- and exogenous salicylic acid on plant tolerance to presence of metal ions and the biochemical response to metals. Finally, we discuss one of the most significant aspects described in many studies: the genetic background of plant hyperaccumulation and adaptation to toxic concentrations of metals/metalloids.

Esterquat herbicidal ionic liquids (HILs) with two different herbicides: evaluation of activity and phytotoxicity

Herbicidal ionic liquids (HILs) constitute a new concept in crop protection products. Their main advantage is the potential to combine the efficiency of traditional herbicides with low vapour pressure and adjustable water solubility which leads to improved environmental safety in the agricultural sector. Among many strategies to obtain new HILs, esterquats seem to be well suited for modification since both the cation and anion may be constituents of herbicides. In the framework of this study 16 new esterquat HILs were synthetized based on standard herbicides: 2,4-D, MCPA, MCPP, 4-CPA, Clopyralid and Dicamba. Germination tests performed on agricultural soil using cornflower indicated the best two HILs. Furthermore, analysis of the toxicological effects of HILs on wheat plants revealed an additional advantage of the two selected HILs. The glutathione (GSH) content and glutathione S-transferase (GST) activity showed a lower oxidative stress level in wheat plants treated with examined HILs, respectively, in comparison to a mixture of reference compounds. Finally the Ames test was applied in order to analyse the mutagenic activity of the two selected HILs.