Cr Accumulation In Roots Research Articles

Integrative approach to mitigate chromium toxicity in soil and enhance antioxidant activities in rice (Oryza sativa L.) using magnesium-iron nanocomposite and Staphylococcus aureus strains.

Pollutantsin soil, particularly chromium (Cr), posehigh environmental and health risks due to their persistence, bioavailability, and potential for causing toxicity. Cr impairment in plants act as a deleterious environmental pollutant that enters the food chain and eventually disturbs human health. Current study demonstrated the potential of integrative foliar application of magnesium-iron (Mg +Fe) nanocomposite with Staphylococcus aureus strains to alleviate Cr toxicity in rice (Oryza sativa) crops by improving yield and defense system. Growth and yield traits such as shoot length (15%), root length (17%), shoot fresh weight (14%), shoot dry weight (9%), root fresh weight (23%), root dry weight (7%), number of tillers (33%), number of grains (10%) and spike length (13%) improved by combined application of Mg + Fe (20mgL-1) nanocomposite and S. aureus strains with Cr (110mgkg-1), compared to when applied alone. Mutual Mg + Fe and S. aureus strains application augmented the SPAD value (9%), total chlorophyll (11%), a (12%), b (17%), and carotenoids (32%), with Cr (110mgkg-1), compared to alone. Malondialdehyde (13%), hydrogen peroxide (H2O2) (11%), and electrolyte leakage (7%) were significantly regulated in shoots with combined Mg + Fe and S. aureus strains application with Cr (110mgkg-1) contrasted to alone. Peroxidase (20%), superoxide dismutase (17%), ascorbate peroxidase (18%), and catalase (20%) were increased in shoots with combined Mg + Fe and S. aureus strains application with Cr (110mgkg-1) in comparison to alone. The combined application of Mg + Fe (20mgL-1) nanocomposite and S. aureus strains with Cr (110mgkg-1) enhanced the macro-micronutrients in shoots compared to alone. Cr accumulation in roots (21%), shoots (25%), and grains (47%) were significantly reduced under Cr (110mgkg-1) with combined Mg + Fe and S. aureus strains application, compared to alone. Subsequently, applying combined Mg + Fe and S. aureus strains is a sustainable solution to boost crop production under Cr toxicity.

Effect of soil additives on biogeochemistry of ultramafic soils—an experimental approach with Brassica napus L

Ultramafic soils are characterized by low productivity due to the deficiency of macroelements and high content of Ni, Cr, and Co. Incorporation of ultramafic soils for agricultural and food production involves the use of fertilizers. Therefore, this study aims to find the soil additive that decreases the metallic elements uptake by plant using Brassica napus as an example. In this study, we evaluate the effect of manure (0.5 g N/kg of soil), humic acids (1 g of Rosahumus/1 dm3 H2O; 44% C), KNO3 (0.13 g K/kg of soil), lime (12.5 g/kg of soil), (NH4)2SO4 (0.15 g N/kg of soil), and Ca(H2PO4)2) (0.07 g P/kg of soil) on the phytoavailability of metallic elements. The effect of soil additives on metallic elements uptake by Brassica napus was studied in a pot experiment executed in triplicates. Statistical analysis was applied to compare the effects of additives in ultramafic soil on plant chemical composition relative to control unfertilized ultramafic soil (one-way ANOVA and Kruskal–Wallis test). The study shows that in almost all treatments, metallic elements content (Ni, Cr, Co, Al, Fe, Mn) is higher in roots compared to the aboveground parts of Brassica napus except for (NH4)2SO4, in which the mechanism of Mn accumulation is opposite. The main differences between the treatments are observed for the buffer properties of soil and the accumulation of specific metals by studied plants. The soils with the addition of lime and manure have the highest buffer properties in acidic conditions (4.9-fold and 2.1-fold increase relative to control soil, respectively), whereas the soil with (NH4)2SO4 has the lowest effect (0.8-fold decrease relative to control soil). Also, the addition of manure increases the biomass of aboveground parts of B. napus (3.4-fold increase) and decreases the accumulation of Ni (0.6-fold decrease) compared to plants cultivated in the control soil. On the contrary, the addition of (NH4)2SO4 noticeably increases the accumulation of Ni, Co, Mn, and Al in aboveground parts of B. napus (3.2-fold, 18.2-fold, 11.2-fold, and 1.6-fold, respectively) compared to plant grown in control soil, whereas the humic acids increase the accumulation of Cr in roots (1.6-fold increase). Therefore, this study shows that manure is a promising fertilizer in agricultural practices in ultramafic soil, whereas (NH4)2SO4 and humic acids must not be used in ultramafic areas.

Amelioration of chromium toxicity in wheat plants through exogenous application of nano silicon

Chromium (Cr) contamination in agricultural soils poses a risk to crop productivity and quality. Emerging nano-enabled strategies show great promise in remediating soils contaminated with heavy metals and enhancing crop production. The present study was aimed to investigate the efficacy of nano silicon (nSi) in promoting wheat growth and mitigating adverse effects of Cr-induced toxicity. Wheat seedlings exposed to Cr (K2Cr2O7) at a concentration of 100 mg kg−1 showed significant reductions in plant height (29.56%), fresh weight (35.60%), and dry weight (38.92%) along with enhanced Cr accumulation in roots and shoots as compared to the control plants. However, the application of nSi at a concentration of 150 mg kg−1 showcased substantial mitigation of Cr toxicity, leading to a decrease in Cr accumulation by 27.30% in roots and 35.46% in shoots of wheat seedlings. Moreover, nSi exhibited the capability to scavenge oxidative stressors, such as hydrogen peroxide (H2O2), and malondialdehyde (MDA) and electrolyte leakage, while significantly enhancing gas exchange parameters, total chlorophyll content, and antioxidant activities (enzymatic and nonenzymatic) in plants grown in Cr-contaminated soil. This study further found that the reduced Cr uptake by nSi application was due to downregulating the expression of HMs transporter genes (TaHMA2 and TaHMA3), alongwith upregulating the expression of antioxidant-responsive genes (TaSOD and TaSOD). The findings of this investigation highlight the remarkable potential of nSi in ameliorating Cr toxicity. This enhanced efficacy could be ascribed to the distinctive size and structure of nSi, which augment its ability to counteract Cr stress. Thus, the application of nSi could serve as a viable solution for production of crops in metal contaminated soils, offering an effective alternative to time-consuming and costly remediation techniques.

Co-application of titanium nanoparticles and melatonin effectively lowered chromium toxicity in lemon balm (Melissa officinalis L.) through modifying biochemical characteristics.

Chromium (Cr) toxicity can negatively affect plant growth and development, impacting agricultural productivity and posing risks to human health. Metallic nanoparticles (MNPs) such as titanium dioxide (TiO2) and natural growth regulators such as melatonin (MT) become a promising technology to manage heavy metal-contaminated soils and promote safe food production. The present work was conducted to find the effect of foliar application of TiO2 NPs (15 mg L-1) and MT (100 µM) on growth, biochemical attributes, and Cr accumulation in plant tissues of Melissa officinalis L. under Cr toxicity (50 and 100 mg Cr kg-1 soil). The results showed that Cr toxicity led to decreased plant performance, where 100 mg Cr kg-1 soil led to notable decreases in shoot weight (28%), root weight (27%), essential oil (EO) yield (34%), chlorophyll (Chl) a + b (33%), while increased malondialdehyde (MDA, 30%), superoxide dismutase (SOD) activity (51%), and catalase (CAT) activity (122%). The use of TiO2 NPs and MT, particularly their co-application, remarkably reduced Cr toxicity by enhancing plant weight, Chl content, and lowered MDA and antioxidant activity. Total phenolic content (TPC), total flavonoid content (TFC), EO percentage, and rosmarinic acid in plants treated with Cr at 50 mg Cr kg-1 soil and co-application of TiO2 NPs and MT were relatively higher than in other treatments. Under 100 mg Cr kg-1 soil, the synergic effect of TiO2 NPs and MT-enhanced rosmarinic acid content (22%) but lowered Cr accumulation in roots (51%) and shoots (72%). Heat map analysis showed that CAT, SOD, MDA, and EO yield had the maximum variability under Cr, TiO2 NPs, and MT. Exogenous TiO2 NPs and MT can be recommended to modulate Cr toxicity in lemon balm under soil Cr toxicity.

Effect of stabilization time and soil chromium concentration on Sesbania virgata growth and metal tolerance

Sesbania virgata is a pioneer shrub from the Fabaceae family, native to riparian environments in northeast of Argentina, southern of Brazil and Uruguay. In peri-urban riparian soils, metal contamination is a frequent problem, being its bioavailability partly determined by the stabilization time and frequency of contamination events. The effect of time elapsed between chromium (Cr) soil enrichment and plant seeding and Cr doses on S. virgata tolerance and metal absorption were evaluated. Treatments were developed by adding Cr (80–400 ppm) to the soil and allowing two days or fifteen months to elapse before sowing, and a control treatment without Cr addition. After 150 days from seeding, bioaccumulation and translocation factors, growth parameters (dry biomass and its aerial/radical allocation pattern, stem length and its elongation rate), morphological parameters (root volume and leaf area), and physiological parameters (chlorophyll content) of the specimens were determined. The emergence of S. virgata was inhibited since 150 ppm when Cr was added to the soil two days before seeding, with Cr accumulation in roots starting at 80 ppm (17.4 ± 2.5 mg kg−1). Under 15 months of metal stabilization, S. virgata plants survived across the entire range of Cr doses tested, with accumulation in roots since 100 ppm (35.5 ± 0.2 mg kg−1) and metal translocation to aerial tissues only under 400 ppm. The results obtained showed that S. virgata did not have high BCF and TF values, suggesting that it cannot be classified as bioaccumulator of Cr under the tested conditions. However, its presence in environments contaminated with Cr can be beneficial, as it helps to stabilize the metal in the soil.

Plant growth-promoting rhizobacteria effect on maize growth and microbial biomass in a chromium-contaminated soil

ABSTRACT Chromium contamination in soils affects plant growth and this metal can accumulate in plants tissues. In addition, Cr can affect soil microbial biomass and activity. On the other hand, plant growth-promoting rhizobacteria (PGPR) can protect plants against metals and, at the same time, promote plant growth and could alleviate adverse effects on microbial biomass. This study evaluated five PGPR on maize growth, Cr accumulation and soil microbial biomass in a Cr-contaminated soil. Five PGPR (LCC04, LCC41, LCC69, LCC81 and IPA403), isolated from soil under permanent application of composted tannery sludge and contaminated with Cr, were inoculated in maize plants grown in soils with (+Cr) and without (–Cr) Cr. In Cr-contaminated soil, LCC41 promoted the highest growth of maize, while LCC04 contributed with the highest N accumulation. The shoots of maize accumulated less Cr with LCC81, while LCC41 contributed to the highest Cr accumulation in roots. The translocation of Cr was highest with IPA403, while LCC81 contributed to reduce Cr translocation. In conclusion, LCC41 and LCC81 could be effective as PGPR inoculants to promote plant growth and reduce Cr accumulation in maize, respectively, in Cr contaminated soil.

Proteomic analysis reveals the role of exogenous cysteine in alleviating chromium stress in maize seedlings

Cysteine (Cys) is incorporated into several compounds which are involved in detoxification of heavy metals. It is evident from recent studies that Cys is effective in alleviating the toxicity of heavy metals. Nevertheless, little is known about the Cys-mediated alleviation of chromium (Cr) toxicity. In our study, the impacts of exogenous Cys on Cr-stressed maize (Zea mays L.) were examined by using physiological and proteomic analyses. The results showed that Cr (100 µM) increased the accumulation of hydrogen peroxide, decreased cell viability, enhanced lipid peroxidation and consequently inhibited plant growth. The application of Cys (500 µM) attenuated the adverse effects of Cr on seedling growth. Cys supplementation to Cr treated plants decreased Cr accumulation in the shoots and increased Cr accumulation in roots. Cys treatment also modulated the activities of antioxidant enzymes and increased endogenous Cys content. Sixty proteins in root tissue were significantly affected by exogenous Cys under Cr stress using two-dimensional electrophoresis. Forty-six differentially expressed proteins were successfully identified by MALDI-TOF/TOF mass spectrometry. These differentially expressed proteins were involved in various biological pathways such as stress response (41.3%), energy and carbohydrate metabolism (21.7%), protein metabolism (6.5%), amino acid metabolism (6.5%), and others of unknown functions. The defense response-related proteins including glutathione peroxidase, glutathione S-transferases, pathogenesis-related proteins, glyoxalases and superoxide dismutase were differently regulated by Cys suggesting their roles in the Cys-mediated Cr tolerance.

Contrasting effects of Cr(III) and Cr(VI) on lettuce grown in hydroponics and soil: Chromium and manganese speciation

Chromium (Cr) is a toxic element among which hexavalent chromium [Cr(VI)] is more toxic than trivalent chromium [Cr(III)]. Chromium can be reduced or oxidized in soil because soil is a complex medium and various soil components affect redox reaction of Cr in soil. Therefore, Cr speciation in hydroponics and soil was compared and Cr uptake and speciation by lettuce grown in the media were evaluated. Higher phytotoxicity was found in Cr(III) spiked soil than in Cr(VI) spiked soil, while Cr toxicity was higher in Cr(VI) treated hydroponics than Cr(III) treated hydroponics. Chromium was mainly accumulated in lettuce roots as Cr(III), and more Cr was translocated from roots to shoots grown in Cr(VI) treated hydroponics than Cr(III) treated hydroponics. Accumulation of Cr in roots grown in Cr(III) treated nutrient solution reduced Fe, K, Ca, Mg, and P uptake in lettuce. Chromium valence state was Cr(III) in lettuce leaves and roots grown in both Cr(III) and Cr(VI) treated hydroponics and soil. Chromium speciation in hydroponically grown lettuce roots was Cr(III) coordinated with 6 oxygens in the first shell and 2 or 4 carbons in the second shell as analyzed by X-ray absorption spectroscopy (XAS), which was similar to chromium acetate. The valence state of Cr in Cr(III) and Cr(VI) treated nutrient solution was not changed, while Cr(VI) was reduced to Cr(III) in Cr(VI) spiked soil by soil organic matter. Spiking of Cr(III) induced reduction of Mn in soil, which resulted in an increase of bioavailable Mn concentration in the Cr(III) spiked soil. Therefore, the increased phytotoxic effect for lettuce in Cr(III) spiked soil can be attributed to the reduction of Mn and subsequent release of Mn(II). For Cr(III) contaminated soil, Mn speciation should be considered, and bioavailable Mn concentration should be monitored although Cr existed as Cr(III) in soil.

Sub-cellular localization and quantitative estimation of heavy metals in lemongrass plants grown in multi-metal contaminated tannery sludge

Major objective of the study was to assess the localization pattern of heavy metals in different parts of lemongrass plant when grown in multi-metal contaminated sites. Microscopic and quantitative investigations (by ICP-OES) were carried out in root and leaves of plant to examine the compartmentalization of heavy metals. Along with it, the morphological variations in the size of trichomes in test plants were also perceived. Differential distribution of Cr, Pb, Ni and Cd was observed in root and leaf sections. Localization of these heavy metals in different parts of the plant cultivated in sole tannery sludge was compared with the plants grown in garden soil; which served as control. Histochemical methods for Pb, Cd and Ni detection revealed their significant accumulation in the root and leaf sections. Cr accumulation in roots of test plants was confirmed by fluorescence staining. Translocation factor <1 was recorded for Cr but greater than 1 for Ni and Pb. Moreover, Bioaccumulation factor >1 was observed for Ni and Pb. SEM studies revealed that the size of trichomes enlarged in plants grown in tannery sludge. Hence, our study provides an insight into the localization pattern of heavy metals in lemongrass plants and suggests that lemongrass can serve as a Ni and Pb phytoextractor when grown in multi- metal contaminated sites. In addition, enhancement in the size of trichomes was detected due to heavy metal stress which may prompt increment in essential oil yield thus; cultivation of lemongrass in heavy metal contaminated sites can also prove profitable economically.

Imbalance of redox homeostasis and antioxidant defense status in maize under chromium (VI) stress

The present study assesses the toxicity of hexavalent chromium [Cr(VI)] on maize (Zea mays L.) seedlings. Three different levels of Cr stress [50, 100 and 200 mg/l CrO3] were imposed and maize seedling growth performances were monitored at 2d and 4d. Modulation of antioxidant genes expression, metabolites, membrane damage, in vivo ROS detection, foliar H2O2 and proline accumulation were studied in detail to get an overview of Cr stress response of maize. Prime stress responses included marked reduction in plant height and biomass, loss of root cell viability with decreased APX-1, Cu/Zn SOD and DHAR expression and high accumulation of Cr in roots with little translocation to shoots. Higher uptake of Evans blue by Cr challenged roots indicates loss of root cells viability. In vivo detection of superoxides and H2O2 as dark blue and deep brown spots in stressed leaves supported with CM-H2DCFDA and DHE staining of roots strongly suggest severe oxidative burst under Cr stress. Marked decline in MDAR and DHAR expression in 200 mg/l Cr challenged leaves at 4d with non-significant change in AsA/DHA ratio indicate futile recycling of ascorbate pool which might lead to disturbance in redox homeostasis. Isolated increase in GR expression coupled with high GSH/GSSG do not seem to prevent cells from oxidative damages, as evident from high foliar MDA level in Cr challenged seedlings. Moreover, enhanced proline accumulation in maize leaves does not give much protection against Cr stress. Over all, this study facilitates our understanding of the plant’s adaptive mechanisms to Cr stress.

Combined effect of Cr-toxicity and temperature rise on physiological and biochemical responses of Atriplex halimus L.

An experiment was conducted to evaluate the combined effect of temperature (26 and 30 °C) and Cr toxicity (0, 100 and 1000 μM Cr) on growth, photosynthesis, water content, Cr and nutrients uptake and translocation. The role of antioxidative enzyme towards stresses tolerance was also investigated. Results showed that the maximum relative growth rate and leaf area per plant of Atriplex halimus L. were recorded at 100 μM Cr and 26 °C. However, presence of Cr reduced net photosynthetic and stomatal conductance rates. Overall, temperature rise enhanced the toxic effect of Cr by reducing growth and photosynthesis and inducing antioxidant enzymes activities. Furthermore, temperature rise increased nutrient uptake, as well as nutrient translocation to aboveground tissues; while it diminished Cr translocation. Finally, roots were the main sink for Cr accumulation in A. halimus. At 1000 μM Cr, root Cr concentrations reached 7.2 and 9.1 mg g−1 at 26 and 30 °C, respectively; while shoot Cr concentrations were 0.45 and 0.44 mg g−1 (26 and 30 °C, respectively). The high Cr-accumulation in roots suggests that A. halimus presents a great potential for phytoremediation, especially phytostabilisation of Cr contaminated soils.

Analysis of gene expression profiles for metal tolerance protein in rice seedlings exposed to both the toxic hexavalent chromium and trivalent chromium

The mechanisms of heavy metal tolerance in plants have been characterized extensively and metal tolerance proteins (MTPs) are one group of specific transporters involved in sequestration of heavy metal ions. This study focused on transcriptome analysis of osMTP genes in rice seedlings exposed to hexavalent chromium Cr(VI), or trivalent Cr(III) using real-time quantitative RT-PCR. Distribution of Cr and other mineral elements (Fe, Cu and Mn) in rice seedlings tissues was also determined. Results showed that exposures to both valents of Cr caused significantly more accumulation of Cr in roots rather than shoots, while accumulation and distribution of Fe, Zn and Mn in rice tissues was variable between two Cr treatments. PCR analysis displayed that heterologous expression patterns of individual isogenes from the osMTP gene family were observed in plant tissues as well as in Cr variants. Homologues, LOC_Os02g53490.1 (osMTP8)/LOC_Os03g12530.1 (osMTP8.1) and LOC_Os01g62070.1 (osMTP11)/LOC_Os05g38670.1 (osMT11.1), were also expressed differently under treatments with both forms of Cr. Data analysis indicated that distribution of mineral elements in rice tissues did not agree with changes of expression patterns of these corresponding osMTP genes. These results suggest that inconsistent expression of osMTP genes in rice tissues is largely due to Cr accumulation; at nutrient levels, the role of OsMTPs in storage and transport of mineral elements in plant materials is still open to discussion.

&lt;b&gt;Chromium accumulation in maize and cowpea after successive applications of composted tannery sludge

Chromium (Cr) accumulation in soil and plants has been reported after successive applications of tannery sludge, which is a matter of concern because Cr can promote environmental contamination and affect the food chain. In this study, we evaluated the growth of and Cr accumulation in maize and cowpea after seven years of consecutive applications of composted tannery sludge (CTS) under field conditions. The experiment consisted of application of CTS at five levels: 0 (control), 2.5, 5, 10, and 20 Mg ha -1 (dry basis). The growth of and Cr accumulation in maize and cowpea were evaluated at 75 and 65 days after plant emergence, respectively. CTS application increased the shoot biomass of maize and cowpea. Accumulation of Cr was similar for both plant species, with higher accumulation in roots. However, Cr accumulation in grains differed as the CTS doses increased; cowpea accumulated more Cr while maize did not accumulate more Cr in grains with higher CTS doses. In conclusion, application of CTS led to higher growth of maize and cowpea plants, and both species exhibited similar Cr accumulation in roots and shoots.

The role of exogenous proline in amelioration of lipid peroxidation in rice seedlings exposed to Cr(VI)

Lipid peroxidation was hydroponically investigated in rice seedlings (Oryza sativa L. cv. XZX 45) treated with different doses of hexavalent chromium (Cr(VI)) in the presence or absence of exogenous proline. Results showed that Cr(VI) induced lipid peroxidation was observed as indicated by higher accumulation of malondialdehyde (MDA) in roots of rice seedlings without application of proline. Cr(VI) also caused inhibition of relative growth rate and increase of root cell death of rice seedlings compared with control. Additionally, changes of roots phenotype traits were evident in roots of rice seedlings under Cr(VI) stress. Exogenous proline significantly increased Cr accumulation in roots, compared with rice seedings without proline treatment. However, less lipid peroxidation was detected in proline-treated rice seedlings as displayed by decreases in MDA content and root cell viability. Hierarchical cluster analysis was also performed using varieties of Cr accumulation, MDA content, root viability and root phenotype traits to further elucidate the role of exogenous proline in amelioration of lipid peroxidation. It is suggestive from the present study that exogenous proline is able to effectively reduce Cr(VI)-induced lipid peroxidation in rice seedlings.

Biochemical and molecular changes in rice seedlings (Oryza sativa L.) to cope with chromium stress.

Chromium (Cr) is very toxic to both humans and plants. This investigation aimed to understand the physiological and molecular responses of rice seedlings to Cr stress. Cr toxicity did not significantly affect morphological features and Cr accumulation in roots and shoots in Pokkali but not in BRRI 51, although there was a reduction in chlorophyll concentration in leaves of both genotypes. These results imply that Pokkali has mechanisms to cope with Cr supplementation. We therefore performed quantitative real-time PCR on the expression pattern of two chelator genes, OsPCS1 and OsMT1, but there were no significant changes in expression in roots and shoots of Pokkali and BRRI 51 following Cr stress. This suggests that there was no metal sequestration following heavy metal stress in roots of these genotypes. Moreover, no expression of two heavy metal transporter genes, OsHMA3 and OsNRAMP1, was induced after Cr stress in roots and shoots, suggesting that these transporter genes are not induced by Cr stress or might not be involved in Cr uptake in rice. We also performed a targeted study on the effect of Cr on Fe uptake mechanisms. Our studies showed a consistent reduction in Fe uptake, Fe reductase activity and expression of Fe-related genes (OsFRO1 and OsIRT1) under Cr stress in both roots and leaves of Pokkali. In contrast, these parameters and genes were significantly increased in Cr-sensitive BRRI 51 under Cr stress. The results confirm that limiting Fe uptake through the down-regulation of Fe reductase and Fe transporter genes is the main strategy of Cr-tolerant Pokkali to cope with Cr stress. Finally, increased CAT, POD and GR activity and elevated glutathione and proline synthesis might provide strong antioxidant defence against Cr stress in Pokkali. Taken together, our findings reveal that Cr stress tolerance in rice (Pokkali) is not related to metal sequestration but is associated with reduced Fe transport and increased antioxidant defence.

PHYTOREMEDIATION POTENTIAL OF HELIANTHUS ANNUUS L IN SEWAGE-IRRIGATED INDO-GANGETIC ALLUVIAL SOILS

The study of phytoremediation potential of Helianthus annuus L was conducted in the sewage-irrigated Indo-Gangetic alluvial soils, India. Calcium @ 1.0% and Zn @ 40ppm enhanced the yield of H. annuus L and minimized the toxicity of Cr in the investigated soils. The study indicated that H. annuus L is highly sensitive to Cr and Zn in terms of metallic pollution; and may be used as indicator plant. For Cr-phytoremediation, humic acid treatment @ 500 mL/acre induced the Cr-accumulation in roots (p < 0.007) and in shoots (p < 0.015), which was recorded 3.21 and 3.16 mg/kg in root and shoot of H. annuus L, respectively. We suggest that H. annuus L fulfils the necessary condition for efficiently increasing species bioaccumulation after soil treatment with humic acid in Cr-polluted sewage-irrigated soils through soil- plant rhizospheric processes.

Plant growth and metal distribution in tissues of Prosopis juliflora-velutina grown on chromium contaminated soil in the presence of Glomus deserticola.

Arbuscular mycorrhizal fungi have been known to increase metal uptake in plants. In this study, mesquite (Prosopis juliflora-velutina) inoculated with Glomus deserticola or amended with EDTA were grown for 30 days in soil containing Cr(III) or Cr(VI) at 0, 40, 80, and 160 mg kg(-1). Total amylase activity (TAA) was monitored as a stress indicator. Element concentrations and distribution in tissue were determined using ICP-OES, electron scanning microprobe, and TEM. Inoculated Cr(VI) treated plants had 21% and 30% more Cr than uninoculated and EDTA treated roots, respectively, at 80 mg Cr kg(-1) treatment. In the case of Cr(III), EDTA produced the highest Cr accumulation in roots. TAA was higher in inoculated plants grown with Cr(III) at 80 and 160 mg kg(-1) and Cr(VI) at 40 and 160 mg kg(-1). The X-ray mapping showed higher metal concentrations in the vascular system of inoculated plants and the TEM micrographs demonstrated the presence of G. deserticola in roots.

Chromium-induced changes in ultramorphology and secondary metabolites of Phyllanthus amarus Schum &amp; Thonn. – an hepatoprotective plant

Chromium (Cr) concentration in the environment is increasing day by day due to its excessive use in leather processing, refractory steel, and chemical manufacturing industries. Excess Cr in the environment causes hazardous effects on all living beings including plants. In this context attempts have been made to see the effect of Cr on a very important medicinal plant Phyllanthus amarus Schum and Thonn. It has focused as a hepatoprotective plant curing hepatitis 'B' in modern research. The P. amarus seedlings of approximately same height and weight were grown in similar conditions in experimental garden. After 30 days plants were harvested and chlorophyll, protein, sugar, starch and secondary metabolites concentration were estimated in these plants as per standard methods. Besides ultramorphological variations in leaves and Cr accumulation in roots and aerial parts were also checked with the help of scanning electron microscope and atomic absorption spectrophotometer respectively. The study revealed that Cr causes significant decrease in fresh and dry weight, length of root and shoot, protein, sugar, chlorophyll and carotenoids in P. amarus. On the other hand it is interesting to note that the concentration of therapeutically active secondary metabolites - phyllanthin and hypophyllanthin increased up to certain level of Cr. It may be due to stress caused by the accumulation of Cr. Besides, ultramorphological changes viz. wide stomatal opening and less wax deposition on both the surfaces of leaves were also observed.

Disruption of Elements Uptake due to Excess Chromium in Indian Medicinal Plants

Chromium and its compounds may cause disturbance in the nutrient level of the plants. Iron, manganese, copper, and zinc are essential nutrient elements and required for balanced growth and development of plants, but chromium uptake sometimes disturbed their concentration in plants. Therefore, in the present paper, an effort has been made to observe the effect of different levels of Cr on nutrient uptake of Phyllanthus amarus and Solanum nigrum, the medicinally important plants of indigenous systems of medicine having hepatoprotective and diuretic properties. The study revealed that Cr causes significant changes in nutrient uptake as compared to control plants. Besides, Cr-treated plants showed growth depression and decrease in fresh and dry weight too. With the increase in Cr supply, accumulation of Cr in roots was increased significantly. Concentration of manganese and zinc was also increased. However, copper concentration in both the plants seemed less affected by Cr.

Phytotoxic lesions of chromium in maize

Chromium (Cr) is fairly abundant in the earth’s crust and ranks fourth among the 29 elements of biological importance. Besides natural sources, Cr enters biotic components of the ecosystem in various ways. Of other major industrial sources, tanning and chrome-plating industries are prominent sources. Cr(VI) form of chromium is highly reactive and influences both plants and animals. Due to Mn present in soil, Cr(III) is oxidized to Cr(VI) which remains in soil for a long time and can affect plant growth and development. Since maize is an important food and fodder plant for human beings and cattle, a study was conducted to investigate the effects of Cr on some metabolic activities of maize ( Zea mays L. cv. Ganga 5). Chromium caused visible lesions of interveinal chlorosis. Young leaves showed vein clearing. Also, a papery appearance was observed in leaves. Margins of leaves were curled and the leaves appeared pale at greater Cr exposure. Concentrations of both chlorophyll a and b were reduced by exposure to Cr, the activities of ribonuclease and phenyl phosphatase were greater while the activity of iron–porphyrin enzyme catalase was less and the activity of amylase was also much less in plants exposed to Cr. Chromium also caused retardation of soluble protein. Accumulation of Cr in roots was much at all the levels of chromium supply. Exposure to Cr resulted in reduction in grain production and quality.