scholarly journals Effect of Lead and Copper on Photosynthetic Apparatus in Citrus (Citrus aurantium L.) Plants. The Role of Antioxidants in Oxidative Damage as a Response to Heavy Metal Stress

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 155
Author(s):  
Anastasia Giannakoula ◽  
Ioannis Therios ◽  
Christos Chatzissavvidis
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Heavy Metal ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Membrane Integrity ◽  
Photosynthetic Apparatus ◽  
Heavy Metal Stress ◽  
Photosynthetic Parameters ◽  
Citrus Aurantium

Photosynthetic changes and antioxidant activity to oxidative stress were evaluated in sour orange (Citrus aurantium L.) leaves subjected to lead (Pb), copper (Cu) and also Pb + Cu toxicity treatments, in order to elucidate the mechanisms involved in heavy metal tolerance. The simultaneous effect of Pb− and Cu on growth, concentration of malondialdehyde (MDA), hydrogen peroxide (H2O2), chlorophylls, flavonoids, carotenoids, phenolics, chlorophyll fluorescence and photosynthetic parameters were examined in leaves of Citrus aurantium L. plants. Exogenous application of Pb and Cu resulted in an increase in leaf H2O2 and lipid peroxidation (MDA). Toxicity symptoms of both Pb and Cu treated plants were stunted growth and decreased pigments concentration. Furthermore, photosynthetic activity of treated plants exhibited a significant decline. The inhibition of growth in Pb and Cu-treated plants was accompanied by oxidative stress, as indicated by the enhanced lipid peroxidation and the high H2O2 concentration. Furthermore, antioxidants in citrus plants after exposure to high Pb and Cu concentrations were significantly increased compared to control and low Pb and Cu treatments. In conclusion, this study indicates that Pb and Cu promote lipid peroxidation, disrupt membrane integrity, reduces growth and photosynthesis and inhibit mineral nutrition. Considering the potential for adverse human health effects associated with high concentrations of Pb and Cu contained in edible parts of citrus plants the study signals that it is important to conduct further research into the accessibility and uptake of the tested heavy metals in the soil and whether they pose risks to humans.

scholarly journals Silicon-Mediated Enhancement of Heavy Metal Tolerance in Rice at Different Growth Stages

2018 ◽  
Vol 15 (10) ◽  
pp. 2193 ◽  
Author(s):  
Fei Huang ◽  
Xiao-Hui Wen ◽  
Yi-Xia Cai ◽  
Kun-Zheng Cai
Keyword(s):  
Heavy Metal ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Membrane Integrity ◽  
Dry Weight ◽  
Growth Stages ◽  
Photosynthetic Parameters ◽  
Cell Membrane Integrity ◽  
Zn Toxicity ◽  
Different Growth Stages

Silicon (Si) plays important roles in alleviating heavy metal stress in rice plants. Here we investigated the physiological response of rice at different growth stages under the silicon-induced mitigation of cadmium (Cd) and zinc (Zn) toxicity. Si treatment increased the dry weight of shoots and roots and reduced the Cd and Zn concentrations in roots, stems, leaves and grains. Under the stress of exposure to Cd and Zn, photosynthetic parameters including the chlorophyll content and chlorophyll fluorescence decreased, while the membrane permeability and malondialdehyde (MDA) increased. Catalase (CAT) and peroxidase (POD) activities increased under heavy metals stress, but superoxide dismutase (SOD) activities decreased. The magnitude of these Cd- and Zn-induced changes was mitigated by Si-addition at different growth stages. The available Cd concentration increased in the soil but significantly decreased in the shoots, which suggested that Si treatment prevents Cd accumulation through internal mechanisms by limiting Cd2+ uptake by the roots. Overall, the phenomena of Si-mediated alleviation of Cd and excess Zn toxicity in two rice cultivars could be due to the limitation of metal uptake and transport, resulting in an improvement in cell membrane integrity, photosynthetic performance and anti-oxidative enzyme activities after Si treatment.

scholarly journals Melatonin Confers Heavy Metal Tolerance of a Dark Septate Endophyte (DSE) Exophiala Pisciphila Via Lowering Oxidative Stress and Heavy Metal Accumulation

2020 ◽  
Author(s):  
Yang Yu ◽  
Zhaowei Teng ◽  
Zongmin Mou ◽  
Yan Lv ◽  
Tao Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heavy Metal ◽  
Metal Accumulation ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Heavy Metal Stress ◽  
Heavy Metal Accumulation ◽  
Metal Stress ◽  
Dark Septate Endophyte ◽  
Exophiala Pisciphila

Abstract Background: The high antioxidant capacity of melatonin contributing to heavy metal tolerance for plants and animals is widely studied, while researches on microorganisms especially in filamentous fungi are rare. One typical dark septate endophyte (DSE), Exophiala pisciphila, showed significant resistance to heavy metals.Results: In this study, exogenous melatonin was verified to reduce heavy metal damage via relieving oxidative stress, activating antioxidant systems, and decreasing heavy metal accumulation in E. pisciphila. Melatonin biosynthesis enzyme genes were upregulated under heavy metal stress. Furthermore, the overexpression of E. pisciphila TDC1 (EpTDC1) and E. pisciphila ASMT1 (EpASMT1) responsible for melatonin biosynthesis in Escherichia coli and Arabidopsis thaliana, enhanced heavy metal stress tolerance for the two organisms by lowering the oxidative stress and reducing the Cd accumulation in the whole plants, especially in the roots.Conclusions: Our results indicate that melatonin confers heavy metal resistance in E. pisciphila by lowering oxidative stress and heavy metal accumulation.

scholarly journals Heavy metal tolerance of Pontechium maculatum (Boraginaceae) from several ultramafic localities in Serbia

2019 ◽  
Vol 43 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Ksenija Jakovljevic ◽  
Sanja Djurovic ◽  
Mina Antusevic ◽  
Nevena Mihailovic ◽  
Uros Buzurovic ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Heavy Metal Stress ◽  
Balkan Peninsula ◽  
Major And Trace Elements ◽  
Soil Samples ◽  
Plant Tissues ◽  
Trace Element Profiles ◽  
Range Of Values

Pontechium maculatum, a facultative metallophyte, was collected from four ultramafic localities in Serbia and analysed in terms of micro- and macroelement accumulation. The aim of the study was to reveal trace element profiles and differences in uptake and translocation of heavy metals in populations growing under heavy metal stress. The concentrations of major and trace elements in soil samples (Ca, Mg, Fe, Mn, Ni, Pb, Cr, Zn, Cu, Co, Cd) and in plant tissues (Fe, Mn, Ni, Pb, Cr, Zn, Cu, Co, Cd) are presented. The results of our analysis indicate that P. maculatum efficiently absorbs Zn and Cr, while for most of the other elements accumulation levels fit in the range of values obtained for several other species from ultramafic localities on the Balkan Peninsula.

Overcoming the Bacteriostatic Effects of Heavy Metals on A. thiooxidans Direct Bioleaching of Saprolitic Ni Laterite Ores

2015 ◽  
Vol 1130 ◽  
pp. 263-267 ◽  
Author(s):  
Hee Chan Jang ◽  
Marjorie Valix
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Heavy Metal Stress ◽  
Lag Phase ◽  
Tolerance Index ◽  
Acid Generation ◽  
Laterite Ores ◽  
Laterite Ore

In this study, the adaptation of A. thiooxidans to heavy metals leached from saprolitic Ni laterite ores was performed by gradual acclimatisation. The bacteria was cultivated in heavy metals (Ni, Co, Fe, Mg, Cr and Mn) with total concentrations of 2400 to 24000 ppm equivalent to total dissolution of 1 to 10% (w/v) pulp densities of the saprolitic Ni laterite ore. Adaptation evolution mapped from its tolerance index was found to be dependent on metal concentration, acid generation, and period of adaptation. Bio-stimulation of cell growth and acid production was promoted by heavy metal stress on the bacteria. Pre-established heavy metal tolerance of the bacteria improved the leaching rate in its early phase; 20% and 7% increase in Ni and Co metal recoveries were observed in using adapted bacteria. However heavy metal tolerance was also achieved by the bacteria during the leaching process, albeit delayed by a lag phase. These results confirm the robust nature and suitability of A. thiooxidans in direct biomining of Ni ores.

Physiological response to silver toxicity in the extremely halophilic archaeon Halomicrobium mukohataei

2019 ◽  
Vol 366 (18) ◽  
Author(s):  
Doriana-Mădălina Buda ◽  
Paul-Adrian Bulzu ◽  
Lucian Barbu-Tudoran ◽  
Alina Porfire ◽  
Laura Pătraș ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heavy Metal ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Enzymatic Antioxidants ◽  
Halophilic Archaeon ◽  
Capacity Measurement ◽  
Energy Dispersive Spectrometry Analysis ◽  
Potential Measurement ◽  
Extremely Halophilic Archaeon

ABSTRACT Adaptive strategies responsible for heavy metal tolerance were explored in the extremely halophilic archaeon Halomicrobium mukohataei DSM 12286. The tested strain was seemingly able to overcome silver-induced oxidative stress (assessed by malondialdehyde quantification, catalase assay and total antioxidant capacity measurement) mainly through non-enzymatic antioxidants. Energy dispersive spectrometry analysis illustrated the presence of colloidal silver in Hmc. mukohataei cultures exposed to AgNO3. Bright-field and transmission electron microscopy images, as well as dynamic light scattering analysis, demonstrated the presence of intracellular nanoparticles, mostly spherical, within a size range of 20–100 nm. As determined by the zeta potential measurement, the biosynthesized nanoparticles were highly stable, with a negative surface charge. Our research is a first attempt in the systematic study of the oxidative stress and intracellular silver nanoparticle accumulation, generated by exposure to silver ions, in members of Halobacteria class, thus broadening our knowledge on mechanisms supporting heavy metal tolerance of microbial cells living under saline conditions.

scholarly journals Role of Silicon in Mitigation of Heavy Metal Stresses in Crop Plants

Plants ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 71 ◽  
Author(s):  
Javaid Akhter Bhat ◽  
S. M. Shivaraj ◽  
Pritam Singh ◽  
Devanna B. Navadagi ◽  
Durgesh Kumar Tripathi ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Tolerance ◽  
Abiotic Factors ◽  
Heavy Metal Tolerance ◽  
Heavy Metal Stress ◽  
Crop Plants ◽  
Metal Stress ◽  
Growth And Yield

Over the past few decades, heavy metal contamination in soil and water has increased due to anthropogenic activities. The higher exposure of crop plants to heavy metal stress reduces growth and yield, and affect the sustainability of agricultural production. In this regard, the use of silicon (Si) supplementation offers a promising prospect since numerous studies have reported the beneficial role of Si in mitigating stresses imposed by biotic as well as abiotic factors including heavy metal stress. The fundamental mechanisms involved in the Si-mediated heavy metal stress tolerance include reduction of metal ions in soil substrate, co-precipitation of toxic metals, metal-transport related gene regulation, chelation, stimulation of antioxidants, compartmentation of metal ions, and structural alterations in plants. Exogenous application of Si has been well documented to increase heavy metal tolerance in numerous plant species. The beneficial effects of Si are particularly evident in plants able to accumulate high levels of Si. Consequently, to enhance metal tolerance in plants, the inherent genetic potential for Si uptake should be improved. In the present review, we have discussed the potential role and mechanisms involved in the Si-mediated alleviation of metal toxicity as well as different approaches for enhancing Si-derived benefits in crop plants.

Abiotic Stress Responses in Plants: Potential Targets on Studying Heavy Metal Stress tolerance in Bryophytes

2017 ◽  
Vol 3 (01) ◽  
pp. 41-51
Author(s):  
Anjana Singh ◽  
Rekha Tyagi ◽  
Anjuli Sood ◽  
P. L. Uniyal
Keyword(s):  
Heavy Metal ◽  
Abiotic Stress ◽  
Stress Tolerance ◽  
Stress Responses ◽  
Metal Tolerance ◽  
Heavy Metal Tolerance ◽  
Heavy Metal Stress ◽  
Experimental Models ◽  
Metal Stress ◽  
Common Elements

Pollution of the biosphere with heavy metals has phenomenally increased since the commencement of industrial revolution. It poses several environment and health concerns. High regeneration and metal accumulation capacity the possibility of genetic transformation by homologous recombination extend the candidature of bryophytes as promising experimental models for heavy metal stress tolerance studies. Plants use several abiotic stress pathways which share common elements that are potential “nodes” for cross talks. Common elements/ molecules, which are likely to occur early in several stress response cascades in bryophytes seem to be the potential targets for heavy metal tolerance studies that can be worked out in future, at biochemical, protein and gene level.

scholarly journals Characterization of bacterial communities associated with the exotic and heavy metal tolerant wetland plant Spartina alterniflora

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ying Yang ◽  
Jian Ding ◽  
Yulang Chi ◽  
Jianjun Yuan
Keyword(s):  
Heavy Metal ◽  
Spartina Alterniflora ◽  
Metal Tolerance ◽  
Bacterial Species ◽  
Heavy Metal Tolerance ◽  
Acc Deaminase ◽  
Heavy Metal Stress ◽  
Bacterial Strains ◽  
Invasion Mechanisms ◽  
Biochemical Assays

Abstract Heavy metal pollution has seriously disrupted eco-balance and transformed estuaries into sewage depots. Quanzhou bay is a typical heavy metal-contaminated estuary, in which Spartina alterniflora has widely invaded. Plant-associated microbial communities are crucial for biogeochemical cycles, studies of which would be helpful to demonstrate the invasion mechanisms of plants. Meanwhile, they are indispensable to phytoremediation by enhancing the heavy metal tolerance of plants, facilitating heavy metal absorption rate and promoting growth of plants. In the present study, S. alterniflora-associated rhizo- and endobacterial communities from 3 experimental sites were investigated by 454-pyrosequencing. Heavy metal screening generated 16 culturable isolates, further biochemical assays suggested these clones possess various abilities such as phosphate solubilization, indole-3-acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production to accelerate heavy metal uptake and growth of the host. This study revealed the bacterial community structures and characterized the predominant resident bacterial strains of S. alterniflora-associated rhizo- and endobacteria under heavy metal stress, and isolated several bacterial species with potential ecological function.

scholarly journals Alleviation of zinc induced oxidative stress by polyamines in Plantago ovata Forsk

2021 ◽  
Author(s):  
Paulami Pramanick ◽  
Anindita Chakraborty ◽  
Sarmistha Sen Raychaudhuri
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Heavy Metal ◽  
Chlorophyll Content ◽  
Quantitative Methods ◽  
Antioxidant Properties ◽  
Membrane Integrity ◽  
Antioxidant Systems ◽  
Plantago Ovata ◽  
Induced Stress

Abstract Zinc causes toxicity to the plants in an excess concentration and it is manifested by chlorosis, rolling of leaf margins, and disruption of membrane integrity. The heavy metal stress also triggers the stimulation of enzymatic and non-enzymatic antioxidant systems. Polyamines are naturally occurring, secondary metabolites, protecting plants from heavy metal-induced stress. Plants also up-regulate the mRNA expression of Metallothionein in response to heavy metal-induced oxidative stress. The alteration in Metallothionein type 2 (PoMT2) expression of a medicinally important herb Plantago ovata in presence of polyamines like Putrescine, Spermidine, and Spermine in addition to ZnSO4.H2O by the semi-quantitative and the quantitative methods have been demonstrated in the present study. We have observed reductions in the expression of the Metallothionein type 2 gene in the presence of the aforementioned polyamines which implies their protective and antioxidant properties to fight against the zinc induced stress. 1 mM Put has been more efficient in increasing the total chlorophyll content (compared to 2 mM Put) by about 36% each in 1000 µM ZnSO4 treated P. ovata seedlings. Spermidine also enhanced chlorophyll content. 2 mM Put and 0.5 mM Spm have shown even better efficiencies in increasing the total antioxidant and DPPH radical scavenging activities. The lipid peroxidation has been found to decrease in Put and Spm supplemented samples by up to about 47% in both cases. Significant reductions in lipid peroxidation and down-regulation of PoMT2 gene expression indicate the roles of polyamines in partially alleviating Zn-induced oxidative damage.

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