Metal Accumulation In Plants Research Articles

ТЯЖЕЛЫЕ МЕТАЛЛЫ В ПОЧВАХ И В РАСТЕНИЯХ ПШЕНИЦЫ В ЗОНЕ ВОЗДЕЙСТВИЯ ПРЕДПРИЯТИЯ ПО ПРОИЗВОДСТВУ СТРОИТЕЛЬНЫХ МАТЕРИАЛОВ

Studies of sod-podzolic soils of forest and agricultural lands in the zone of impact of the enterprise for the production of building materials have shown that gas and dust emissions significantly affect the content of heavy metals in soils. The assessment of the content of gross forms of heavy metals in sod-podzolic soils of forest and agricultural lands adjacent to the territory of JSC «Krasnoselskstroymaterialy» showed widespread soil contamination with cadmium, arsenic and zinc. Soil contamination of forest and agricultural lands with lead is fragmentary. The highest occurrence of samples with an excess of hygienic standards for soils of forest lands was established for gross forms of zinc, and for soils of agricultural lands - for gross forms of cadmium and arsenic. The assessment of mobile forms of metals revealed soil contamination mainly with zinc and lead. Soil contamination with cadmium is insignificant and is fragmentary. It should be noted that the sod-podzolic soils of agricultural lands in the north-eastern direction from the enterprise are characterized by a high level of contamination with mobile forms of zinc and lead. The studies did not reveal an excess of the maximum permissible safe levels of cadmium and lead content in wheat grain and straw, however, the maximum concentrations of these elements in plants of this crop were on average 25-60 % higher in some areas compared to those in control areas, which indicates the presence of local zones in which there is an increased accumulation of heavy metals in agricultural plants. In this regard, it is necessary to organize monitoring of the quality of crop production for the content of heavy metals in the zone of influence of JSC «Krasnoselskstroymaterialy».

Heavy Metal Accumulation in Rice and Aquatic Plants Used as Human Food: A General Review.

Aquatic ecosystems are contaminated with heavy metals by natural and anthropogenic sources. Whilst some heavy metals are necessary for plants as micronutrients, others can be toxic to plants and humans even in trace concentrations. Among heavy metals, cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and mercury (Hg) cause significant damage to aquatic ecosystems and can invariably affect human health. Rice, a staple diet of many nations, and other aquatic plants used as vegetables in many countries, can bioaccumulate heavy metals when they grow in contaminated aquatic environments. These metals can enter the human body through food chains, and the presence of heavy metals in food can lead to numerous human health consequences. Heavy metals in aquatic plants can affect plant physicochemical functions, growth, and crop yield. Various mitigation strategies are being continuously explored to avoid heavy metals entering aquatic ecosystems. Understanding the levels of heavy metals in rice and aquatic plants grown for food in contaminated aquatic environments is important. Further, it is imperative to adopt sustainable management approaches and mitigation mechanisms. Although narrowly focused reviews exist, this article provides novel information for improving our understanding about heavy metal accumulation in rice and aquatic plants, addressing the gaps in literature.

Metal and metalloid accumulation in native plants around a copper mine site: implications for phytostabilization

Mining activities can result in a pollution legacy of metal and metalloid containing soils and wastes. In this study concentrations of the metals and metalloids Al, As, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Zn, and the non-metals (P, S) were measured in the shoots of 35 different plant species spontaneously growing at four contaminated sites around the Sungun Copper Mine in East Azerbaijan (Iran) in order to evaluate their potential in phytoremediation of this area. The results show that metal and metalloid accumulation differed between the different species. None of the plant species exceeded the relevant trace element hyperaccumulation thresholds. Plant accumulation of Al was found to be relatively high in Achillea vermicularis (Asteraceae, with up to 5,280 μg g−1) and in Trifolium fragiferum (Fabaceae, with up to 4,895 µg g−1). Papaver dubium (Papaveraceae) had relatively high foliar Cu concentrations (with up to 294 µg g−1) while growing in the waste Rrock dump. Teucrium polium (Lamiaceae) had the highest concentrations of Pb (with up to 62 µg g−1). Most of the native species can be classed as metal-tolerant “excluder”-type species, and may, therefore, be suitable for phytostabilization of the mining wastes around the Sungun Copper Mine.

The effect of amendment addition drill cuttings on heavy metals accumulation in soils and plants: Experimental study and artificial network simulation

A greenhouse experiment was carried out to evaluate the influence of drill cuttings addition on the accumulation of heavy metals in soil, in plant biomass (Trifolium pretense L.) cultivated on soils with the addition of this type of waste. The transfer and transformation of heavy metals in the soil with drill cuttings– Trifolium pretense L were discussed. Drilling waste in the amount of 2.5%, 5%, 10% and 15% of dry weight were added to acidic soil. The concentrations of heavy metals in the soil and plant materials were determined by an inductively coupled plasma mass spectrometry method. Results indicated that drilling wastes addition had a positive influence on the growth of Trifolium pretense L. However, the concentrations of heavy metals increased in the prepared mixtures along with the dose of drilling wastes. The drilling wastes addition also changed the metal accumulation capacity in plant parts. Nevertheless, the concentrations of heavy metals in soils and above-ground parts of plants did not exceed the permissible values in respective legal standards. The values of the heavy metals bioconcentration coefficient in Trifolium pretense L at the highest dose of drill cuttings were as follows: in the above-ground parts Cd>Cu>Ni>Cr>Pb>Zn, in roots Cd>Ni>Cr>Zn>Pb>Cu. An artificial neural network model was developed in order to predict the concentration of heavy metals in the plants cultivated on the soils polluted with drill cuttings. The input (drill cuttings dose, pH, organic matter content) and the output data (concentration of heavy metals in the shoot cover) were simulated using an artificial neural network program. The results of this study indicate that an artificial neural network trained for experimental measurements can be successfully employed to rapidly predict the heavy metal content in clover. The artificial neural network achieved coefficients of correlation over 90%.

Mutation in OsFWL7 Affects Cadmium and Micronutrient Metal Accumulation in Rice.

Micronutrient metals, such as Mn, Cu, Fe, and Zn, are essential heavy metals for plant growth and development, while Cd is a nonessential heavy metal that is highly toxic to both plants and humans. Our understanding of the molecular mechanisms underlying Cd and micronutrient metal accumulation in plants remains incomplete. Here, we show that OsFWL7, an FW2.2-like (FWL) family gene in Oryza sativa, is preferentially expressed in the root and encodes a protein localized to the cell membrane. The osfwl7 mutation reduces both the uptake and the root-to-shoot translocation of Cd in rice plants. Additionally, the accumulation of micronutrient metals, including Mn, Cu, and Fe, was lower in osfwl7 mutants than in the wildtype plants under normal growth conditions. Moreover, the osfwl7 mutation affects the expression of several heavy metal transporter genes. Protein interaction analyses reveal that rice FWL proteins interact with themselves and one another, and with several membrane microdomain marker proteins. Our results suggest that OsFWL7 is involved in Cd and micronutrient metal accumulation in rice. Additionally, rice FWL proteins may form oligomers and some of them may be located in membrane microdomains.

Depth-related dynamics of physicochemical characteristics and heavy metal accumulation in mangrove sediment and plant: Acanthus ilicifolius as a potential phytoextractor

The focus of this study was to determine the depth-wise variability of physicochemical properties (i.e., pH, TOC, TN, and EC), and heavy metals (i.e., Pb, Cu, Zn, As, and Cr) concentration, and the associated biological and ecological risks of the mangrove sediment. The accumulation of metal contents and the phytoremediation and phytoextraction were also investigated in a mangrove species, Acanthus ilicifolius. The mangrove sediment consists of a higher proportion of sand fraction (56.6–74.7%) followed by clay (10–28%) and silt (10.1–15. 7%) fractions. The concentrations (mg/kg) of Pb, Cu, Zn, As, and Cr were ranged from 22.05–34.3, 8.58–22.77, 85.07–114, 5.56–12.91, and 0.98–5.12 in all the sediment layers. The hierarchy of the mean metal concentration in sediment was Zn (102 mg/kg) > Pb (25.6 mg/kg) > Cu (14.8 mg/kg) > As (8.79 mg/kg) > Cr (2.74 mg/kg) respectively. The examined metal concentrations were below the respective average shale values (ASVs). The degree of environmental, ecological, and biological risks was minimal according to various pollution indices like geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). According to sediment quality guidelines (SQGs), the adverse biological risk effect was not likely to occur. The result of the potential ecological risk index (PERI) demonstrated that the study area was in the low-risk condition as the corresponded RI value < 100. A combined influence of geogenic and anthropogenic factors was identified as the metal sources by multivariate analysis. The study found that the accumulation rate of the metal contents was higher in leaves than that of roots. The mean descending metal concentration values were Zn (107) > Pb (28. 7) > Cu (16.9) > As (11.2) > Cr (4.99) in leaves and Zn (104.32) > Pb (27.02) > Cu (15.29) > As (10.39) > Cr (3.80) in roots. The translocation and bioaccumulation factors of heavy metals suggested that the mangrove plant species, A. ilicifolius can be used for phytoremediation and phytoextraction since the bio-concentration factor and translocation factor > 1. The studied species exhibited the metal tolerance associated with two following strategies, metal exclusion, and metal accumulation. However, excess metal tolerance can impact the surrounding marine environment.

Overexpression of ZNT1 and NRAMP4 from the Ni Hyperaccumulator Noccaea caerulescens Population Monte Prinzera in Arabidopsis thaliana Perturbs Fe, Mn, and Ni Accumulation.

Metalliferous soils are characterized by a high content of metal compounds that can hamper plant growth. The pseudometallophyte Noccaea caerulescens is able to grow on metalliferous substrates by implementing both tolerance and accumulation of usually toxic metal ions. Expression of particular transmembrane transporter proteins (e.g., members of the ZIP and NRAMP families) leads to metal tolerance and accumulation, and its comparison between hyperaccumulator N. caerulescens with non-accumulator relatives Arabidopsis thaliana and Thlaspi arvense has deepened our knowledge on mechanisms adopted by plants to survive in metalliferous soils. In this work, two transporters, ZNT1 and NRAMP4, expressed in a serpentinic population of N. caerulescens identified on the Monte Prinzera (Italy) are considered, and their expression has been induced in yeast and in A. thaliana. In the latter, single transgenic lines were crossed to test the effect of the combined over-expression of the two transporters. An enhanced iron and manganese translocation towards the shoot was induced by overexpression of NcZNT1. The combined overexpression of NcZNT1 and NcNRAMP4 did perturb the metal accumulation in plants.

Assessing heavy metal accumulation in plants and soil with sewage sludge application under rice–wheat system in an Indo-Gangetic Inceptisol

Assessing heavy metal accumulation in plants and soil with sewage sludge application under rice–wheat system in an Indo-Gangetic Inceptisol

The use of water spinach plants (Ipomoea aquatica Forsk.) for phytoremediation of hospital waste

Water spinach (Ipomoea aquatica Forsk.) has the ability to accumulate pollutants so that it can be useful for wastewater treatment processes. The purpose of this study was to determine the phytoremediation technique in hospital wastewater using kale in improving the quality of hospital wastewater and to determine the level of accumulation of Pb and Cr metals in plants. The study used a completely randomized design with four treatments, namely treatment 0 days (without treatment), 2 days, 4 days and 6 days. Parameters include the physical and chemical quality of the waste as well as the content of Pb and Cr in the waste and plants. To determine the effect of phytoremediation on the quality of household waste and metal content, ANOVA analysis and further testing with the BNT test level of 5% were used. Phytoremediation with kale was able to reduce the temperature of the waste on the 4th day of treatment and dissolved oxygen on the 4th treatment and increase the pH. The accumulation of Pb and Cr on each day is different. The highest accumulation of Pb and Cr occurred on day 6, namely 0.1587 mg/L for Pb metal and 0.2167 mg/L for Cr metal. Kale plants are very possible to be used in the phytoremediation process.

Metal accumulation potential and tolerance responses in Alternanthera dentata grown under multi metal treatment

Present study investigates metal accumulation potential, enzymatic and non-enzymatic tolerance responses of a tropical perennial plant Alternanthera dentata grown under multi metal (Cr, Cd, As and Ni) treatment at different concentration i.e. 0, 5, 20 and 50 ppm for 60 d in pot culture with garden soil as control. Results revealed accumulation of appreciable amount of toxic metals in the root of Alternanthera dentata , as maximum concentration of Cr (2402.65 μ g g −1 dw), As (1485.81 μ g g −1 dw), Cd (1258.9 μ g g −1 dw) and Ni (1215 μ g g −1 dw) recorded at 50 ppm of multi metal treatment. High concentration of toxic metals in the biomass of Alternanthera dentata indicates its high potential for metal accumulation. Biochemical changes particularly increase in synthesis and concentration of phenol, carotenoid and cysteine in metal treated plant provide non-enzymatic tolerance. Similarly, increased antioxidant activities of Ascorbate Peroxidase (APX) and Guaiacol Peroxidase (GPX) provide better tolerance for growth and survival at higher concentration of toxic metals. The plant Alternanthera dentata grown worldwide, thrive in humid condition, has heat and metal tolerance, thus it could be efficiently used for metal removal globally. Therefore, Alternanthera dentata has emerged as an efficient metal accumulator plant with better tolerance to toxic metals and may be exploited as a bioresource in developing innovative and sustainable technology to remove toxic metals from soil, contaminated due to industrial discharge or geological processes for ecological restoration, environmental cleanup and health safety • The plant Alternanthera dentata showed better tolerance and growth under multi metal treatment. • Alternanthera dentata accumulate more metals in the root and leaves. • Maximum accumulation of Cr (2402.65 μ g g −1 dw) recorded in the roots. • As (1485.81), Cd (1258.9) and Ni (1215) μ g g −1 dw accumulated in roots. • Metal accumulation potential and tolerance indicate feasibility of Alternanthera dentata to be used in phytoremediation.

Effect of leachate effluent water reuse on the phytotoxicity and micropollutants accumulation in agricultural crops

This research comparatively investigated the effects of effluents from three biological wastewater treatment systems on the phytotoxicity, seed germination, and accumulation of micropollutants and heavy metals in plants irrigated with the effluents under study. The three biological wastewater treatment systems were two-stage activated sludge (AS), two-stage moving bed bioreactor (MBBR), and two-stage moving bed bioreactor with microfiltration (MBBR/MF). The systems were operated in parallel with identical landfill leachate concentrations under different hydraulic retention time (HRT) (24, 18, and 12 h). The phytotoxicity experiments were carried out with golden pothos (Epipremnum aureum) planted in soil irrigated with AS, MBBR, and MBBR/MF effluent and those raised in the effluent (without soil). The malondialdehyde (MDA) concentrations in the plants were used to determine the plant stress. To evaluate the effect of water reuse to agricultural crops, this research measured the seed germination rates of lettuce (Lactuca sativa) irrigated with AS, MBBR, and MBBR/MF effluent and the accumulation of micropollutants and heavy metals. The results showed that under 24 h HRT, the AS, MBBR, and MBBR/MF systems could achieve high treatment efficiency of organics and nutrients and micropollutant degradation (73.4 – 100%). With shorter HRT (18 and 12 h), the treatment efficiency and micropollutant degradation of MBBR and MBBR/MF remained relatively unchanged (68.7 – 100%), unlike in the AS system. The MBBR/MF effluent exhibited the comparatively lowest MDA concentrations. Furthermore, the MBBR/MF effluent minimally affected the growth of lettuce, as evidenced by highest seed germination rates. No micropollutants and heavy metals were present in lettuce irrigated with MBBR/MF effluent. However, traces of bisphenol A and di-(ethylhexyl)-phthalate were detected in lettuce watered with AS and MBBR effluents. As a result, the MBBR/MF system is operationally and environmentally ideal for treating landfill leachate for high-quality effluent which can be reused to irrigate crop and replenish surface water.

Effect of insect feces (Hermetia illucens) on rice growth and heavy metal migration from polluted soil to rice plant.

Insect feces are a new kind of biological organic fertilizer. Little is known about the influences of insect feces on rice growth and heavy metal migration from soil to rice plant. In this study, the effects of different amounts (CK (0%), T1 (2%), T2 (4%), T3 (6%), and T4 (8%)) of black soldier fly larvae (BSFL) feces on the rice growth and the migration/accumulation of heavy metals (Cd and Pb) were investigated by pot experiments within 2years. The application of insect feces remarkably increased the contents of soil pH, organic matter, ammonium nitrogen, available phosphorus, and potassium. Meanwhile, the insect feces application reduced the weak acid-soluble contents of soil Cd and Pb by 8.3-56.8%, but increased those in the oxidizable (by 22.4-165.7%) and residual (by 1.8-225.6%) states. Except for the T4 treatment in the first year, all fertilization treatments increased the rice yield (up to 43.7% and 195.5% higher than those of CK within 2years). Moreover, the insect feces application reduced the contents of Cd (8.3-66.7%) and Pb (6.4-61.8%) in different parts of rice. Under the same treatment, the metal contents in each part of rice in the second year were lower than those in the first year. The insect feces application decreased the absorption coefficients (24.4-57.5%) and secondary transport coefficients (3.6-44.1%) of Cd and Pb by rice plant. The findings implied that the insect feces might act as effective organic fertilizers for rice plants as well as reducing heavy metal accumulation in rice plants growing in polluted soil.

Jasmonic acid (JA) and gibberellic acid (GA3) mitigated Cd-toxicity in chickpea plants through restricted cd uptake and oxidative stress management

Cadmium stress is one of the chief environmental cues that can substantially reduce plant growth. In the present research, we studied the effect of jasmonic acid (JA) and gibberellic acid (GA3) applied individually and/or in combination to chickpea (Cicer arietinum) plants exposed to 150 µM cadmium sulphate. Cadmium stress resulted in reduced plant growth and pigment contents. Moreover, chickpea plants under cadmium contamination displayed higher levels of electrolytic leakage, H2O2, and malonaldehyde, as well as lower relative water content. Plants primed with JA (1 nM) and those foliar-fed with GA3 (10–6 M) showed improved metal tolerance by reducing the accumulation of reactive oxygen species, malonaldehyde and electrolytic leakage, and increasing relative water content. . Osmoprotectants like proline and glycinebetaine increased under cadmium contamination. Additionally, the enzymatic activities and non-enzymatic antioxidant levels increased markedly under Cd stress, but application of JA as well as of GA3 further improved these attributes. Enzymes pertaining to the ascorbate glutathione and glyoxylase systems increased significantly when the chickpea plants were exposed to Cd. However, JA and GA3 applied singly or in combination showed improved enzymatic activities as well as nutrient uptake, whereas they reduced the metal accumulation in chickpea plants. Taken together, our findings demonstrated that JA and GA3 are suitable agents for regulating Cd stress resistance in chickpea plants.

Recent advances in physiological and molecular mechanisms of heavy metal accumulation in plants.

Among abiotic stress, the toxicity of metals impacts negatively on plants' growth and productivity. This toxicity promotes various perturbations in plants at different levels. To withstand stress, plants involve efficient mechanisms through the implication of various signaling pathways. These pathways enhance the expression of many target genes among them gene coding for metal transporters. Various metal transporters which are localized at the plasma membrane and/or at the tonoplast are crucial in metal stress response. Furthermore, metal detoxification is provided by metal-binding proteins like phytochelatins and metallothioneins. The understanding of the molecular basis of metal toxicities signaling pathways and tolerance mechanisms is crucial for genetic engineering to produce transgenic plants that enhance phytoremediation. This review presents an overview of the recent advances in our understanding of metal stress response. Firstly, we described the effect of metal stress on plants. Then, we highlight the mechanisms involved in metal detoxification and the importance of the regulation in the response to heavy metal stress. Finally, we mentioned the importance of genetic engineering for enhancing the phytoremediation technique. In the end, the response to heavy metal stress is complex and implicates various components. Thus, further studies are needed to better understand the mechanisms involved in response to this abiotic stress.

Ақмола облысының жағдайында жұпаргүл түрлерін интродукциялау

Мақалада Орталық Қазақстан қалаларының жасыл аумақтарына төзімді түрлі ағаштар мен бұталардыңарасында жерсіндіруге мүмкіншілік тудыратын жұпаргүлдер түрлері қарастырылған. Осы аумақтың қалаларын жасылдандыру үшін ағаш өсімдіктері мен бұталарының биоалуантүрлілігі өте маңызды екені, олардың қысқаша интродукциялану тарихы жарияланды. Зерттеу барысында авторлар жерсіндіруге арналған жұпаргүл түрлеріне (Амур жұпаргүлі (Syrínga amurénsis), Облата жұпаргүліне, (S.oblata), Үлпек жұпаргүліне (S. pubescens), Пекин жұпаргүліне (S.pekinensis) мониторинг жүргізу ережелерін ұсынды. Олардың таксациялық көрсеткіштері 50,0; 86,4; 23,3; 71,7 пайызды құрайды. Осы түрлердің ішінде Ақмола облысындағы аумақта морфологиялық бейімделуі Облата (86,4) жəне Пекин (71,7) жұпаргүлдерінде қарқынды. Өсімдіктердегі интродукция қарқындылығын бағалауға фотосинтездің белсенділігі анықталды. Облата жұпаргүлінде(0,75 мкг/г) фотосинтетикалық белсенділіктің біршама төмендігі байқалған, басқа жұпаргүлдердің үшеуінде де жоғарылау (0,78 мкг/г). Зерттелген Syringеa түрлерінде ауыр металдардың арасында кадмий, қорғасын Амур жұпаргүлі жапырағында басқаларға қарағанда 2,5 есеге дейін жоғары болды. Темір өте жоғары деңгейде Амуржұпаргүлінде жинақталып (3833,69 мкг/г), шектеулі рауалы концентрациядан(ШРК) 13 есе артқан. Мыс мөлшері Облата жұпаргүлінде ШРК-дан1,1 есе жоғары. Мырыш мөлшері барлық зерттеу өсімдіктерінде бірдей, көрсеткіштері ШРК-дан аспайды. Cu жəнеFe жұпаргүл жапырақтары ШРК-дан көп жинайтыны байқалды. Аккумуляциялық қасиеті Жоғары Амур жұпаргүлі, себебі ол ең улы ауырметалдарды интенсивті сіңіретінін байқатты. Қорытындылай келе, ауыр металдар əр өсімдік түрінде əртүрлі концентрацияда жинақталады.

Ammonium regulates redox homeostasis and photosynthetic ability to mitigate copper toxicity in wheat seedlings

As an essential plant micronutrient, copper (Cu) is required as a component of several enzymes, but it can be highly toxic to plants when present in excess quantities. Nitrogen (N) application can help to alleviate the phytotoxic effects of heavy metals, including Cu, and different N forms significantly affect the uptake and accumulation of heavy metals in plants. The aim of this study was to determine the effects of different N forms, i.e., ammonium (NH4+) and nitrate (NO3−), on Cu detoxification in wheat seedlings. The inhibition of seedling growth under excess Cu was more obvious in wheat plants supplied with NO3− than in those supplied with NH4+. This growth inhibition was directly induced by excess Cu accumulation and reduced absorption of other mineral nutrients by the plants. Compared with seedlings treated with NO3−, those treated with NH4+ showed a decrease in Cu-induced toxicity as a result of increased antioxidant capacity in the leaves and a lower redox potential in the rhizosphere. Furthermore, treatment with NH4+ decreased the loss of mineral nutrients in wheat seedlings exposed to excess Cu. In conclusion, compared with supplying NO3−, supplying NH4+ to wheat seedlings under Cu stress improved their ability to maintain their nutritional and redox balance and increased their antioxidant capacity, thereby preventing a decline in photosynthesis. According to our results, NH4+ is more effective than NO3− in reducing Cu phytotoxicity in wheat seedlings.

The changes of rhizosphere characteristics contributed to enhanced Pb accumulation in Athyrium wardii (Hook.) Makino after nitrilotriacetic acid application.

Chelant-assisted phytoremediation may modify plant rhizosphere, which is closely related to heavy metal (HM) accumulation in plants. This work focused on the effects of nitrilotriacetic acid (NTA) on rhizosphere characteristics to investigate the mechanisms of lead (Pb) accumulation in Athyrium wardii (Hook.) Makino with exposure to 800 mg kg-1 Pb. After NTA application, Pb accumulation in the underground part of A. wardii increased by 14.3%, accompanying with some changes for the rhizosphere soils. Soil pH decreased by 0.37 units, and the dissolved organic carbon (DOC) content in the rhizosphere soils significantly increased by 7.6%. The urease, acid phosphatase, and catalase activities in the rhizosphere soils significantly increased by 104.8%, 19.7%, and 27.1%, respectively. However, a slight inhibition on microbial activities was observed in the rhizosphere of A. wardii after NTA application. Soil respiration decreased by 8.9%, and microbial biomass carbon decreased by 8.9% in the rhizosphere soils, indicating that NTA addition might recruit some microorganisms to maintain rhizosphere functions in Pb-contaminated soils while inhibiting others with low tolerance to Pb. Results suggest that lower pH, more DOC exudation, and higher soil enzyme activities after NTA application contributed to the increase of Pb accumulation in A. wardii. This study gave some preliminary evidence for NTA-assisted Pb remediation by A. wardii by modifying rhizosphere characteristics.

Heavy Metal Contamination in Soils and Crops Irrigated by Kali River in Uttar Pradesh, India.

The study investigated concentrations, distribution, and bioaccumulation of heavy metals in agriculture soil and crops irrigated by the Kali River of Uttar Pradesh, India. Soils and crop samples were collected from 17 locations along the river and analyzed for heavy metal concentrations. Metals in soil and plant were recorded as Fe > Zn > Mn > Cu > Ni > Pb > Cr > Cd and Mn > Fe > Zn > Cu > Cr > Ni > Pb > Cd, respectively. The bioaccumulation factor was < 1 that indicates lesser accumulation of metals in plants except for Cd, Mn, and Zn. Metal pollution index ranged between 1.84 and 6.62 and shows that crops growing at the S10 to S17 sites accumulate greater metal concentrations. Cluster analysis showed agglomeration of Cr-Pb-Cd, Cu-Ni-Mn, and Fe-Zn which revealed different sources of metal pollution. The present study shows low to moderate heavy metal pollution in Kali River irrigated areas thus consumption of agriculture produce may cause adverse health effects.

Competition for light induces metal accumulation in a metal hyperaccumulating plant.

Plants can respond to competition with a myriad of physiological or morphological changes. Competition has also been shown to affect the foraging decisions of plants belowground. However, a completely unexplored idea is that competition might also affect plants' foraging for specific elements required to inhibit the growth of their competitors. In this study, we examined the effect of simulated competition on root foraging and accumulation of heavy metals in the metal hyperaccumulating perennial plant Arabidopsis halleri, whose metal accumulation has been shown to provide allelopathic ability. A. halleri plants originating from both metalliferous and non-metalliferous soils were grown in a "split-root" setup with one root in a high-metal pot and the other in a low-metal one. The plants were then assigned to either simulated light competition or no-competition (control) treatments, using vertical green or clear plastic filters, respectively. While simulated light competition did not induce greater root allocation into the high-metal pots, it did result in enhanced metal accumulation by A. halleri, particularly in the less metal-tolerant plants, originating from non-metalliferous soils. Interestingly, this accumulation response was particularly enhanced for zinc rather than cadmium. These results provide support to the idea that the accumulation of metals by hyperaccumulating plants can be facultative and change according to their demand following competition.

Efficiency of transporter genes and proteins in hyperaccumulator plants for metals tolerance in wastewater treatment: Sustainable technique for metal detoxification

Environmental contamination of heavy metals is now becoming increasingly a concern and a significant problem due to its harmful effects worldwide. The plant-meditated approach is encouraging to eliminate toxins avoiding side effects from polluted wastewater. For the development of appropriate plant species for the mechanisms of heavy metal absorption, transport, detoxification, identification, and signaling pathways would be important facts. Transporter genes like ATP-phosphoribosyl transferase (ATP-PRT), Yellow Stripe-like (YSL), NAS (nicotinamide synthase), SAMS (S-adenosyl-methionine synthetase), FER (ferritin Fe (III) binding), HMA (heavy metal ATPase), IREG (iron-regulated transporter), and proteins like cation diffusion facilitators (CDF), ZRT, IRT-like protein (ZIP), and natural resistance-associated macrophage protein (NRAMP) are active in heavy metal accumulation, translocalisation, sequestration, and resistance. Besides, chelating agents and metabolites can be used either to increase heavy metal bioavailability, which facilitates heavy metal accumulation in plants and further promote plant growth and fitness. This review paper addresses key roles and potential transporter genes and proteins for the remediation of heavy metals from hyperaccumulator plants. This review specifically focuses on the efficacy of transporter genes and proteins in hyperaccumulator plants in metal restoration, discussing the use of these plants for wastewater treatment processes. • Discusses the efficiency of hyperaccumulator plant for removal of metals. • Summarizes transporter gene and proteins in heavy metal uptake and tolerance. • Proposes improved prospects for wastewater treatment.