Phytoremediation of Pb Spiked Soils Amended with Iron Impregnated Rice Husk Ash Using Ricinus communis L. (Castor bean)

Heavy metals pose a serious risk to the environment and living biota. Pot studies were carried out to determine the competence of Fe-coated rice husk in Pb spiked soils vegetated with Ricinus communis. Physicochemical properties of Fe- coated rice husk ash (Fe-RHA) were characterized on dry weight basis. Pot experiments were carried out with seedlings of R.communis for 60 days amended with Fe-RHA (0, 2.5% and 5% w/w) and Pb(NO3) [0, 400 and 800 mg kg−1]. Addition of Fe-coated rice husk ash to Pb cntaminated soils improved soil pH and fertility. Treatment with 5% Fe-RHA decreased Pb accumulation in roots by 84%. Addition of Fe-RHA significantly (p<0.05) increased plant physiological parameters such as height, leaf diameter, nodes, and leaf number by 64%, 49%, 62% and 66% and chlorophyll contents (12–29%) compared to unamended plants. Our findings conclude that Fe-RHA is a low-cost, environmentally friendly and efficient adsorbent for stabilization of Pb spiked soils

Metal- biomolecule complexes in plants: Occurrence, functions, and applications

lants growing in metal contaminated env i ro n m e n t s would inevitably accumulate trace and abundant metal ions. Certain trace metals are important for metabo-lism of plants while a number of them are not essential imposing stress on the metabolic functions (Fig. 1). Since plants cannot move unlike animals and organisms hav i n g powerful locomotory organs, they efficiently compartmen-talize these toxic metals into various parts (mostly in roots and/or older leaves) and organelles of cell where damage due to their accumu l ation is least [1,2]. Th u s, o rga n i s m s exposed to excess of toxic metals would eventually evolve mechanisms of metal resistance (Tabs. I and II). The pub-lished data indicates that metal compart m e n t ation at the whole plant level can be divided into 3 cat ego ries (Fi g s. 2a-c). Mechanisms of resistance to metal toxicity in plants Primarily two types of mechanisms may explain the resis-tance to the toxicity of metal ions in plants. They are (i), avoidance, involving various ways of preventing toxic ions to reach their target sites, and (ii), tolerance to metal ions t h at entered the symplasm [1,2]. Va rious types of heav y metal adaptation strategies in plants are depicted in figure 3. The prominent metal complexation processes are the syn-thesis of phytochelatins and of other metal chelating pep-tides [1-6]. Phytochelatins were found to be induced by Ag

Metal-accumulating plants from serpentine habitats of Kızıldağ, Konya Province, Turkey

Serpentine (ultramafic) soils are generally deficient in essential plant nutrients such as phosphorus (P), potassium (K) and calcium (Ca) and often also have elevated concentrations of toxic trace elements such as, for example, nickel (Ni), chromium (Cr) and manganese (Mn). However, some serpentine areas have a species-rich plant cover, often with a few endemics. Thus, serpentine areas host valuable bioresources for understanding plant–metal interactions. In the present study, metal-accumulating plants from serpentine habitats in Kızıldağ, Konya Province, Turkey, viz., Aethionema spicatum, Alyssum murale ssp. murale var. murale, Arenaria acerosa, Bornmuellera kiyakii, Cerastium macranthum, Dianthus crinitus. var. crinitus, Dianthus zonatus var. hypochlorus, Iberis sempervirens, Minuartia anatolica var. anatolica, Noccaea camlikensis, Saponoria kotschyi and Silene ozyurtii, belonging to the families Brassicaceae and Caryophyllaceae, were investigated. All plant specimens collected were deposited in the Herbarium of the Biology Department of Akdeniz University. Samples of different plant parts, namely roots, stems, leaves and flowers, were analysed for Ni, Cr, cobalt (Co), Mn, copper (Cu), zinc (Zn), and iron (Fe) by inductively coupled plasma–optical emission spectroscopy. Noccaea camlikensis, Alyssum murale and Bornmuellera kiyakii accumulated 16 650 μg g–1, 12 570 μg g–1 and 8780 μg g–1 Ni, respectively. Noccaea camlikensis is a new addition to the list of Ni hyperaccumulators. The majority of the floristic elements investigated were found to be tolerant to serpentine soil chemistry. A small proportion of the plant assemblages were endemics. Nickel hyperaccumulators were the least abundant in terms of number of species. The study assumes importance in understanding bioconcentration in different plants and, eventually, for gaining a knowledge of plant–metal interactions and applications in biogeochemistry and bioprospecting for metals, including phytoremediation

Computer simulation meets experiment: Molecular dynamics simulaitons of spin labeled proteins.

EPR spectroscopy of site-directed spin labeled proteins is extremely informative in the studies of protein dynamics; however, it is difficult to interpret the spectra in terms of the conformational dynamics in atomic detail.In the present work we aimed to investigate the site-specific structural dynamics of proteins by using MD simulations upon analyzing and interpreting the EPR data. The major goal of this work is to know how far the computer simulations can meet the experiments. As a first step, MD simulations are performed to identify the location and orientation of the tyrosine radical in the R2 subunit of ribonucleotide reductase. The MD results show that the tyrosine is moving away from the diiron center in its radical state. This data is in agreement with EPR results and suggests reorientation of the tyrosine radical when compared to its neutral state. In further studies, the behavior of a methanethiosulfonate spin label, R1, in various environments of the protein is characterized by using MD simulations. RMSD analysis and angle ß distributions of the nitroxide show that R1 in buried sites in a protein helix is significantly immobile and in surface exposed sites it is highly mobile. Analyses of MD data suggest that internal rotations of x4 and x5 dihedrals of R1 are dominant in the R1 dynamics.Our studies also show that interaction with the surrounding residues show significant influence on the dynamics of R1. MD simulations data of the vinculin tail protein, both in water and in vacuo, are compared to the experimental results for further analysis of 12 different R1 sites in various environments.In a study on the photosynthetic reaction center(RC),MD is used to identify the location of the R1 binding site (H156)and thereby exploring the conformational dynamics in the RC protein upon light activation. The distance between the primary quinone, QA, and H156R1 determined from MD is in reasonable agreement with that measured by EPR

Heavy Metal Stress in Plants : From Biomolecules to Ecosystems

xiv,462 hal,;ill,;22 c

Defense manifestations of enzymatic and non-enzymatic antioxidants in Ricinus communis L. exposed to lead in hydroponics

Lead (Pb) is a major inorganic pollutant with no biological significance and has been a global concern. Phytotoxicity of lead induces toxic effects by generating reactive oxygen species (ROS), which inhibits most of the cellular processes in plants. Hydro-ponic experiments were performed with Ricinus communis to investigate the toxicity and antioxidant responses by exposing to different concentrations of lead (0, 200 and 400 µM) for 10 days. Pb stress caused a significant increase in electrolyte leakage, non-enzymatic antioxidants (phenols and flavonoids) and a decrease in the elemental profile of the plant. Histochemical visualization clearly indicates the significant increase of H2O2 production in dose-dependent manner under Pb stress. Likewise, an increase in catalase, guaiacol peroxidase and superoxide dismutase activity was also evident. Ascorbate peroxidase and MDAR, on the other hand, responded biphasically to Pb treatments showing a decrease in concentration. The decline in redox ratio GSH/GSSG was imposed by the indirect oxidative stress of Pb. Hence these findings showed the ameliorative potential of R. communis to sustain Pb toxicity under oxidative stress

Optimization of DNA isolation and PCR protocol for RAPD analysis of selected medicinal and aromatic plants of conservation concern from Peninsular India

Genetic analysis of plants relies on high yields of pure DNA samples. Here we present the optimization of DNA isolation and PCR conditions for RAPD analysis of selected medicinal and aromatic plants of conservation concern from Peninsular India containing high levels of polysaccharides, polyphenols and secondary metabolites. The method involves a modified CTAB extraction employing polyvinyl pyrrolidone while grinding, successive long-term Chloroform : lsoamyalcohol extractions, an overnight RNase treatment with all steps carried out at room temperature. The yield of DNA ranged from 1-2 μg/μl per gram of the leaf tissue and the purity (ratio) was between 1.6-1.7 indicating minimal levels of contaminating metabolites. The technique is ideal for isolation of DNA from different plant species and the DNA isolated was used for randomly amplified polymorphic DNA (RAPD) analysis. RAPD protocol was optimized based on the use of higher concentration of MgCl2 (3 mM), lower concentrations of primer (0.5 μM) and Taq polymerase (0.2 units), 50 ng of template DNA and an annealing temperature of 37°C, resulted optimal amplification. Reproducible amplifiable products were observed in all PCR reactions. Thus the results indicate that the optimized protocol for DNA isolation and PCR was amenable to plant species belonging to different genera which is suitable for further work on diversity analysis

Abiotic Stress Responses in PlantsMetabolism, Productivity and Sustainability /

XV, 473p. 61 illus., 14 illus. in color.online re

Environmental Adaptations and Stress Tolerance of Plants in the Era of Climate Change

XVI, 515p. 85 illus., 40 illus. in color.online r