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Insights into the tolerance and phytoremediation potential of Coronopus didymus L. (Sm) grown under zinc stress
Abstract
Zinc (Zn) is a vital micronutrient for plants, but its abundance can be calamitous. In this study, a screenhouse experiment was conducted over a 6-week period to assess the effect of soil enrichment with Zn regimes (100, 250 and 500 mg kg-1) on growth, Zn accumulation, photosynthetic pigment concentration, oxidative stress markers and activities of antioxidant enzymes in Coronopus didymus. Results revealed that Zn concentration in C. didymus roots and shoots reached up to 1848 mg kg-1 DW and 1845 mg kg-1 DW at 500 mg kg-1 Zn regime, respectively. The plant growth (root-shoot length and biomass) increased, while leaf pigment concentration and soluble protein content in C. didymus tissues decreased progressively with the increased Zn regimes in the soil. At 500 mg kg-1 Zn regime, hydrogen peroxide and malondialdehyde level increased ∼219% and 111% in roots, while ∼170% and 105% in shoots, with respect to the control. Likewise, superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase activities increased significantly with elevated Zn levels. Contrarily, compared to the control, CAT activity declined gradually and reached a minimum of ∼45% in roots and 12% in shoots under highest Zn regime. The results suggested that C. didymus displayed high Zn accumulation and emerged as a tolerant plant species towards Zn stress. Elevated Zn regimes provoked reactive oxygen species generation in C. didymus tissues which was effectively neutralised and scavenged by the antioxidant enzymes, thus marked its efficacy to be potentially employed in phytoremediation and reclamation of Zn-contaminated soils.
... Therefore, Zn deficiency in plants can hamper all these important biophysicochemical processes involved in normal plant functioning and detoxification under stress conditions. Nevertheless, plant exposure to excess Zn can drive several toxic impacts in transition element biophysicochemical processes of plants (Bankaji et al., 2019;Sidhu et al., 2020;Tibbett et al., 2021;Yusefi-Tanha et al., 2020). Zinc toxicity provokes deficiency of other essential nutrients owing to similar ionic radii and interfering with their phytouptake and movement inside plants (Bankaji et al., 2019). ...
... Excess Zn causes a decrease in plant growth, structural integrity and induces leaf chlorosis (Chakraborty and Mishra, 2020;Mateos-Naranjo et al., 2018). Moreover, toxic levels of Zn can provoke oxidative damage by enhancing the levels of reactive oxygen species (ROS) and thereby spurring deterioration of proteins, lipids, RNA and DNA in plants (Bernardy et al., 2020;Sidhu et al., 2020). ...
... Another effect of Zn deficiency is reduced plant pigments and interference with the process of photosynthesis (Sidhu et al., 2020;Souza et al., 2020). The Zn-deficiency-mediated decrease in the net photosynthetic is a common phenomenon (Table S10, Fig. 2). ...
Zinc (Zn) plays an important role in the physiology and biochemistry of plants due to its established essentiality and toxicity for living beings at certain Zn concentration i.e., deficient or toxic over the optimum range. Being a vital cofactor of important enzymes, Zn participates in plant metabolic processes therefore, alters the biophysicochemical processes mediated by Zn-related enzymes/proteins. Excess Zn can provoke oxidative damage by enhancing the levels of reactive radicals. Hence, it is imperative to monitor Zn levels and associated biophysicochemical roles, essential or toxic, in the soil-plant interactions.
This data-analysis review has critically summarized the recent literature of (i) Zn mobility/phytoavailability in soil (ii) molecular understanding of Zn phytouptake, (iii) uptake and distribution in the plants, (iv) essential roles in plants, (v) phyto-deficiency and phytotoxicity, (vi) detoxification processes to scavenge Zn phytotoxicity inside plants, and (vii) associated health hazards. The review especially compares the essential, deficient and toxic roles of Zn in biophysicochemical and detoxification processes inside the plants. To conclude, this review recommends some Zn-related research perspectives. Overall, this review reveals a thorough representation of Zn bio-geo-physicochemical interactions in soil-plant system using recent data.
... Se (Martins et al. 2018, Souza et al. 2020. A reduction of Chl content may be associated with degradation due to oxidative stress (Santos Sidhu et al. 2020). Indeed, under Zn stress, alterations of the enzymatic and nonenzymatic status of the antioxidant system have been reported (Bernardy et al. 2020, Santos et al. 2020, Sidhu et al. 2020. ...
... A reduction of Chl content may be associated with degradation due to oxidative stress (Santos Sidhu et al. 2020). Indeed, under Zn stress, alterations of the enzymatic and nonenzymatic status of the antioxidant system have been reported (Bernardy et al. 2020, Santos et al. 2020, Sidhu et al. 2020. Nevertheless, the different Zn concentrations did not change the Chl a/b ratio. ...
Deleterious effects induced by high zinc (Zn) concentrations can be alleviated with selenium (Se) co-exposure. Therefore, we analyzed the morphophysiological changes of Billbergia zebrina in response to Zn and Se co-exposure. Plants were cultured in media containing three Zn concentrations (0, 30, and 300 μM) combined with two Se concentrations (0 and 4 μM), for a total of six treatments. At 75 d of culture, the leaf anatomy, chlorophyll (Chl) a fluorescence, and contents of photosynthetic pigments (Chl) and nutrients were analyzed. The total Chl content declined with rising Zn concentrations. Plants cultured with Se presented a decrease in the Chl a/b ratio and greater total Chl content. Positive L- and K-bands were verified under Se absence and with 30 and 300 μM Zn. Plants showed bioaccumulation capacity and tolerance to excess Zn. Se acted as a modulator to alleviate the Zn stress.
... Proline was found to reduce harmful heavy metal toxicity by acting as a hydroxyl radical scavenger in the cytoplasm [17]. Furthermore, POD, SOD, and CAT were found in high concentrations in response to heavy metal scavenging [17][18][19]. Similarly, in response to heavy metal toxicity, sugars can function as ROS eliminators or cell signals in response to metal toxicity in plants [19]. ...
Copper(II) (Cu2+) is essential for plant growth and development. However, high concentrations are extremely toxic to plants. We investigated the tolerance mechanism of cotton under Cu2+ stress in a hybrid cotton variety (Zhongmian 63) and two parent lines with different Cu2+ concentrations (0, 0.2, 50, and 100 μM). The stem height, root length, and leaf area of cotton seedlings had decreased growth rates in response to increasing Cu2+ concentrations. Increasing Cu2+ concentration promoted Cu2+ accumulation in all three cotton genotypes’ roots, stems, and leaves. However, compared with the parent lines, the roots of Zhongmian 63 were richer in Cu2+ and had the least amount of Cu2+ transported to the shoots. Moreover, excess Cu2+ also induced changes in cellular redox homeostasis, causing accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Conversely, antioxidant enzyme activity increased, while photosynthetic pigment content decreased. Our findings indicated that the hybrid cotton variety fared well under Cu2+ stress. This creates a theoretical foundation for the further analysis of the molecular mechanism of cotton resistance to copper and suggests the potential of the large-scale planting of Zhongmian 63 in copper-contaminated soils.
... Soluble proteins that could combine with HMs would increase with the uptake of HMs in plants to ensure the normal growth of plants. The resistance of Coronopus didymus L. to Zn was reflected by the content of soluble proteins (Sidhu et al., 2020), which was consistent with our studied result. Soluble protein concentration was the highest after adding PASP (Fig. 1B), which was that PASP promoted plant biomass. ...
Three kinds of fortifiers, polyaspartic acid (PASP), aminotriacetic acid (NTA), and tea saponin (TS) were applied in strengthening the phytoremediation efficiency of nickel by Bidens pilosa L. (B. pilosa) in nickel-pyrene-contaminated soil. The growth of B. pilosa, Ni distribution in B. pilosa, chemical morphology of Ni, and soil microbial community structure were investigated by pot experiment in this study. Results showed that the removal rate of Ni increased by 10.02% in the PASP treatment and 8.81% in the PASP-TS treatment, compared with the only planting B. pilosa treatment. The Ni content in roots of these two treatment groups was increased by 86.8% and 87.9%, and Ni content in the cell wall and soluble fraction of roots were increased by 99.31% and 82.60% and 109.05% and 43.69%, respectively. More inorganic and water-soluble Ni was converted to Ni bounded to polysaccharides or proteins. In addition, the residual and organic matter-bounded state of Ni in soil greatly transformed into the iron-manganese oxide-bounded state after adding PASP. The relative abundance of bacteria related to Ni transformation increased significantly. Sphingomonas was promoted to 19.2% in PASP-TS treatment. Correlation analysis showed that plant extraction and soil microbial transformation were obviously related to Ni removal. The application of NTA and TS had little effect on the remediation efficiency of Ni. In conclusion, the use of PASP was conducive to the remediation effect of Ni in co-contaminated soil by B. pilosa.
... Excessive Zn causes deficiencies of other essential nutrients, disturbs photosynthesis and transpiration, induces leaf chlorosis, and decreases plant growth and structural integrity [12][13][14]. Moreover, excessive Zn can disturb normal plant metabolic processes and cause oxidative damage, leading to the damage of RNA and DNA and the degradation of protein in plants [15,16]. Therefore, it is crucial to provide an optimum supply of Zn for plants to maintain normal metabolic functions to prevent deficiency and phytotoxicity [1,9]. ...
Sedum alfredii Hance (S. alfredii) is a native hyperaccumulator plant species in China that has strong tolerance and accumulation ability for Zn and Cd. In addition, it is a good material for the phytoextraction of soil heavy metal pollutants. However, the specific effect of high Zn concentrations on the growth of S. alfredii and its metabolic mechanisms are not clear. Using an untargeted metabolomics method, we analysed the differential metabolites of the two ecotypes in S. alfredii roots under different Zn treatments. The results showed that high Zn levels significantly promoted plant growth in the hyperaccumulating ecotype (HE), while growth was inhibited in the non-hyperaccumulating ecotype (NHE). We detected 624 metabolites in the roots of S. alfredii. Under the high Zn treatment, lots of lipids and lipid-like molecules, such as glyceryl monooleate and 9,12,13-trihydroxyoctadecane-10-enoic acid, along with organic acids, such as lauramidopropylbetaine, L-malic acid, and their derivatives, decreased significantly in HE roots. Differential metabolites, such as some lipids and lipid-like molecules, were significantly upregulated in NHE roots. The above results indicate that the exogenous high Zn treatment induces the downregulation of HE differential metabolites in response to Zn, but significantly induces the upregulation of differential metabolites in NHE.
... Compared to the reference soil composition (Table S4), it was found at EF that the trace element concentrations in the soils surrounding the plant are moderately enriched with Sr, Th, P, Sc, Cr, Co, Ni, Cd, Cu, Zn, Mo, Pb, TI, Bi, As, S, Sn, and Sb within 500 m of SSP, are very high enriched with Cr at site SS5, and extremely highly enriched with Th within 500 m northeast of SSP, and with Pb in the soils surrounding the plant. The EF values determined here are consistent with literature values for soils near industrial and similar facilities [73][74][75], confirming the extremely high impact of the Sulaimani steel plant on the environment. The differences in the enrichments obtained using different reference materials are due to the fact that when local soils are used, their mean element concentrations are higher than the background values, which further confirms the widespread environmental impact of SSP. ...
Citation: Hamarashid, R.A.; Fiket, Ž.; Mohialdeen, I.M.J. Environmental Impact of Sulaimani Steel Plant (Kurdistan Region, Iraq) on Soil Geochemistry. Soil Syst. 2022, 6, 86. Abstract: Steel is an indispensable material that is used in a wide range of products and that contributes significantly to economic development. However, steel production can affect soil quality and is associated with the pollution of local areas. Therefore, the objective of this study was to investigate the mineral and geochemical composition of soils in the vicinity of the Sulaimani Steel Plant (SSP) in Bazian Region, Kurdistan, Iraq. A total of 35 soil samples were collected in the vicinity of SSP. The samples were analyzed for their mineral and geochemical composition, including 10 major, and 40 trace and rare earth elements. In addition, the soils were analyzed for their particle size distribution, pH, and organic matter content. The distribution of elements in the soils was found to be influenced by the texture, organic matter content (0.34-9.28%), and prevailing wind direction. The assessment of soil contamination near the steel plant confirmed high to extremely high enrichment with Cr (EF up to 20.7), Ni (EF up to 14.2), Pb (EF up to 80.4), and Th (EF up to 50.4), indicating that it is a significant source of heavy metals and poses a high risk to soil health.
... Abiotic stresses affect plant growth, development, and productivity by degrading cellular metabolism and increasing reactive oxygen species (ROS) generation. During abiotic stress, photorespiration, the photosynthetic system, and mitochondrial respiration pathways contribute to the generation of ROS [55,56]. It has been proven that ROS are generated in different cellular compartments such as mitochondria, chloroplasts, peroxisomes, cytoplasm, and the extracellular region [17,[57][58][59]. ...
Cereals have evolved various tolerance mechanisms to cope with abiotic stress. Understanding the abiotic stress response mechanism of cereal crops at the molecular level offers a path to high-yielding and stress-tolerant cultivars to sustain food and nutritional security. In this regard, enormous progress has been made in the omics field in the areas of genomics, transcriptomics, and proteomics. Omics approaches generate a massive amount of data, and adequate advancements in computational tools have been achieved for effective analysis. The combination of integrated omics and bioinformatics approaches has been recognized as vital to generating insights into genome-wide stress-regulation mechanisms. In this review, we have described the self-driven drought, heat, and salt stress-responsive mechanisms that are highlighted by the integration of stress-manipulating components, including transcription factors, co-expressed genes, proteins, etc. This review also provides a comprehensive catalog of available online omics resources for cereal crops and their effective utilization. Thus, the details provided in the review will enable us to choose the appropriate tools and techniques to reduce the negative impacts and limit the failures in the intensive crop improvement study.
Keywords: abiotic stress; functional genomics; transcriptomics; proteomics; stress response
... Coronopus didymus has also been reported to have antifungal, antioxidant, antimalarial, antitumor, wound healing and anti-inflammatory properties [13,14]. Apart from therapeutic and curative properties, because of its high biomass it is reported to have phytoremediation property for zinc [15], lead [16] and cadmium [16]. ...
Coronopus didymus (Brassicaceae) commonly known as lesser swine cress has been reported to be used for its pharmacological activities. This study aimed to evaluate the medicinal potential of C. didymus extracts against cancer, diabetes, infectious bacteria and oxidative stress and the identification of bioactive compounds present in these extracts. The effects of using different solvents for the extraction of C. didymus on the contents of major polyphenols and biological activities were investigated. Plant sample was shade dried, ground to a fine powder, and then soaked in pure acetone, ethanol and methanol. The highest contents of major polyphenols were found in methanol-based extract, i.e., chlorogenic acid, HB acid, kaempferol, ferulic acid, quercetin and benzoic acid with 305.02, 12.42, 11.5, 23.33, 975.7 and 428 mg/g of dry weight, respectively, followed by ethanol- and acetone-based extracts. The methanol-based extract also resulted in the highest antioxidant activities (56.76%), whereas the highest antiproliferative (76.36) and alpha glucosidase inhabitation (96.65) were demonstrated in ethanol-based extracts. No antibacterial property of C. didymus was observed against all the tested strains of bacteria. Further studies should be focused on the identification of specific bioactive compounds responsible for pharmacological activities.
... The deficiency of Zn also causes the accumulation of excessive reactive oxygen species (ROS) that may be due to the lower concentration of the Cu-Zn-SOD enzyme (Marreiro et al., 2017). Another effect of Zn deficiency is reduced plant pigments and interference with the process of photosynthesis, thereby inhibiting plant growth (Sidhu et al., 2020). ...
Zinc (Zn) is an essential micronutrient for several physiological and biochemical processes. Changes in soil Zn levels can negatively affect plant physiology. Although the mechanism of Zn nutrition has been studied extensively in crops and model plants, there has been little research on steppe plants, particularly live in alkaline soils of arid and semiarid regions. Ceratoides arborescens is used in arid and semiarid regions as forage and ecological restoration germplasm, which is studied can enrich the mechanism of Zn nutrition. The plants were exposed to three different Zn treatments, Zn-deficient (-Zn 0 mM L−1), Zn-normal (Control, 0.015 mM L−1), and Zn-excess (+Zn, 0.15 mM L−1), for 3 weeks. Individual biomass, ion concentrations, photosynthetic system, and antioxidant characteristics were measured. High Zn supply significantly decreased plant biomass and induced chlorosis and growth defects and increased Zn concentration but decreased Fe and Ca concentrations, unlike in controls (p < 0.05). High Zn supply also reduced plant chlorophyll content, which consequently decreased the photosynthesis rate. Increased concentrations of malondialdehyde and soluble sugar and activities of peroxidase and superoxide dismutase could resist the high-level Zn stress. In contrast, low Zn supply did not affect plant growth performance. We also identified a novel protein through RNA transcriptome analysis, named CaMTP, that complemented the sensitivity of a yeast mutant to excessive Zn, which was found to be localized to the endoplasmic reticulum through transient gene expression in Nicotiana benthamiana. The gene CaMTP identified to be highly sensitive to Zn stress is a potential candidate for overcoming mineral stress in dicot crop plants.
... Ideally hyperaccumulators should have a high rate of accumulation, be fast growing, and have a high production of biomass [22,23] and endemic to naturally metal rich soil. It has been hypothesized that hyperaccumulation occurs as a defensive strategy in plants [24]. Decomposition of leaf litter from hyperaccumulators on the soil surfaces reintegrates the metal into the soil causing the hyperaccumulator to obtain competitive advantage over the non-hyperaccumulator through growth inhibition [25]. ...
Environmental pollution is a major concern in recent past; the
toxins pose major havoc to the agricultural activities, and also
affected the ecosystem stability. So the current knowledge on
application of phytoremediation technique is alleviating metal
toxicity in many ways, the plants also classified into indicator,
excluder, accumulator etc., based on their response to heavy
metals. Plant potential for metal removal is recognized by the
Accumulation Factor (AF), Translocation Factor (TF) and Mobility
Index (MI). Based on the level of metal removal plant species
are also categories into phytoextraction, phytovolatilization,
rhizofiltration, rhizosphere degradation etc. these methodologies
are helpful to identify suitable hyperaccumulator for pollute
sites. It suggested that the phytoremediation technology should completely remove pollutants from the soil, water and air and
provide verdant for sustainable agriculture
... Mycorrhizal fungi from contaminated sites are more efficient in stimulating growth than the mycorrhizal fungi from the non- its efficacy to be a potential agent for the phytoremediation of Zncontaminated soils [38]. ...
... Increased globalization and industrialization have exposed plants to different abiotic (drought, heat, flood, cold, and metals) and biotic (bacteria, viruses, and fungi) stresses in their natural ecosystems (Nabi et al., 2019). They hamper the growth and development of plants, modulate physiological metabolism such as photosynthesis thereby disturbing global food security (Chan et al., 2016;Kudo et al., 2017;Sidhu et al., 2017Sidhu et al., , 2018Sidhu et al., , 2020 (Fig. 10.1). Among all the abiotic stresses, drought is the most complex phenomenon that limits the productivity of crops worldwide (Ullah et al., 2018). ...
Brassinosteroids (BRs) are plant steroidal hormones involved in several key physiological and biochemical processes of plants, i.e., vascular differentiation, seed germination, fertility, shoot and root growth, and flowering and also in response to environmental stresses. BRs were first identified in the pollen of Brassica napus in the early 1970s, and later during the same decade several members of the BR family were isolated from different plant species. BRs are synthesized most likely in the endoplasmic reticulum of plant cell and its synthesis is controlled by several transcription factors. External factors such as nutrient availability also influence BR biosynthesis and signaling. Moreover, BR signaling plays a crucial role in regulating diverse processes related to plant growth under normal and suboptimal growth environments. These compounds exist in free and conjugated form and their activity is highly dependent on the presence of hydroxyl group on side chain or steroid ring. Among various forms of BRs, 24-epibrassinolide (EBL) has been identified as the most active BR. During the past five decades, the BRs biosynthesis pathways have been well investigated with reverse and forward genetic techniques and nearly 60 compounds with a structure similar to that of BRs have been detected and isolated from various plant parts. These compounds were found in bryophytes (2 families), algae (6 families), pteridophytes (8 families), gymnosperms (4 families), angiosperms (35 families), and in some other plant-derivative products. This chapter discusses the initiation of research on BRs, their discovery, inhibitors, classification, and biodiversity. Moreover, it also highlights the mechanism of BR biosynthesis and signaling in plants.
... Increased globalization and industrialization have exposed plants to different abiotic (drought, heat, flood, cold, and metals) and biotic (bacteria, viruses, and fungi) stresses in their natural ecosystems (Nabi et al., 2019). They hamper the growth and development of plants, modulate physiological metabolism such as photosynthesis thereby disturbing global food security (Chan et al., 2016;Kudo et al., 2017;Sidhu et al., 2017Sidhu et al., , 2018Sidhu et al., , 2020 (Fig. 10.1). Among all the abiotic stresses, drought is the most complex phenomenon that limits the productivity of crops worldwide (Ullah et al., 2018). ...
The increase in temperature due to climate change events has increased the frequency of heat stress, resulting in severe crop yield losses globally. High temperature stress induces photosynthetic apparatus impairment leading to excessive reactive oxygen species production, which severely hampers plant growth and physiological processes. Brassinosteroids (BRs) are a group of steroid phytohormones and are known to regulate plant growth and development, and tolerance to environmental stresses such as high temperature stress. The present chapter highlights the effect of heat stress on plant growth. It further highlights the role of BR in the amelioration of heat stress–induced disruption in plant morphology, chlorophyll, and photosynthesis. It further discusses the role of BR in the regulation of the antioxidant defense system of plants. Moreover, the mechanism of BR signaling and its cross-talk with abscisic acid (ABA) in response to heat stress has also been discussed.
... Increased globalization and industrialization have exposed plants to different abiotic (drought, heat, flood, cold, and metals) and biotic (bacteria, viruses, and fungi) stresses in their natural ecosystems (Nabi et al., 2019). They hamper the growth and development of plants, modulate physiological metabolism such as photosynthesis thereby disturbing global food security (Chan et al., 2016;Kudo et al., 2017;Sidhu et al., 2017Sidhu et al., , 2018Sidhu et al., , 2020 (Fig. 10.1). Among all the abiotic stresses, drought is the most complex phenomenon that limits the productivity of crops worldwide (Ullah et al., 2018). ...
The climate change events have increased the vulnerability of plants to cold or low temperature stress, leading to reduced plant growth and productivity. Brassinosteroids (BRs) are steroid plant hormones and can enhance cold stress tolerance in plants. BRs are involved in a number of growth and developmental processes of plants including, germination, reproductive development, photosynthesis, hormonal regulation, and gene expression. BRs pretreatment prior to cold stress exposure helps in cold acclimation in plants through physiological and molecular alteration. Likewise, exogenous application to cold stressed plants protects the photosynthetic apparatus and regulates the hormone synthesis and redox homeostasis through inhibiting ROS production in intercellular organelles. Moreover, BR treatment upregulates the enzymatic and nonenzymatic antioxidant activities and triggers the cellular signaling pathways and enhances the expression of genes related to cold stress tolerance. This chapter highlights the role of BRs in the mediation of cold stress–induced damage on plant morphology, physiology, and biochemical traits. It further highlights the interaction of BR with reactive oxygen species (ROS) and the role of BRs in redox homeostasis. Moreover, the molecular basis of BR-induced cold stress tolerance has also been elucidated.
... where Cshoot (mg·kg −1 ) and Croot (mg·kg −1 ) represent the metal concentration in the shoot and root, respectively [27]. ...
To more clearly clarify the relationship between the Epichloë endophyte and its host, F. sinensis, the effects of Epichloë endophyte on F. sinensis performance under heavy metal treatment was investigated. The growth performance and physiology variations of F. sinensis with (E+) and without the endophyte (E−) were evaluated after they were subjected to Zn2+ and Cd2+ treatments. The results showed that heavy metal treatments had significant effects on plants, as the performance of plants under Zn2+ and Cd2+ treatments was significantly different with plants under control treatment (p < 0.05). Cd2+ treatments showed a hormesis effect, whereas Zn2+ did not. The endophyte increased host heavy metal stress tolerance by promoting host growth as the E+ plants had significantly higher plant height, tiller number, root length (p < 0.05). The endophyte also promoted ion uptake by the host and induced endogenous hormone production (p < 0.05). These results suggested that the Epichloë endophyte regulated host growth and physiology to improve association tolerance to environmental conditions. This study provides another example that the Epichloë endophyte can increase plant tolerance to metal stress.
... Heavy metals in soils originate from natural and anthropogenic sources (Sidhu et al., 2018(Sidhu et al., , 2020. Natural sources correspond to lithogenesis, weathering, erosion, and other geological processes (Kabata-Pendias, 2011), while anthropic sources include industrial activities (Antoniadis et al., 2019;Kasemodel et al., 2019), recycling of electronic waste (Jiang et al., 2019), disposal and incineration of solid urban waste (Figueiredo et al., 2019), vehicular emissions (Silva et al., 2017b), and agricultural activities, mainly the use of pesticides and chemical fertilizers (Silva et al., 2016). ...
Food production in areas contaminated by industrial wastes poses a serious risk to farmers and consumers. Here, we evaluate Cd, Cr, Ni, and Pb concentrations in the soils and the edible parts of lettuce, chives, tomatoes, pepper, and cassava plants grown by small farmers in areas contaminated by slag from an abandoned steel plant in Havana, Cuba. The total, environmentally available, and bioavailable concentrations of metals in the soils and the metals bioconcentration factor in the plants were determined. The risks to human health from food and soil ingestion were estimated. The total and environmentally available concentrations of Cd, Cr, and Pb were above values considered safe by international standards, with likely adverse effect on human health. Cadmium was the most bioavailable metal, reflected in the highest accumulation in the crops' edible parts. Even with negligible DTPA-available Cr concentrations in soils, the Cr concentrations in edible parts of the crops exceeded regulatory levels, suggesting that rhizosphere mechanisms may increase Cr availability. The consumption of vegetables represented 70% of the daily intake dose for Cr, Cd, and Ni, while accidental ingestion of contaminated soil is the predominant human exposure route for Pb. Our results demonstrated the health risks associated with cultivating and consuming vegetables grown on metal contaminated soils in Havana and can assist public policies capable of guaranteeing the sustainability of urban agriculture and food security.
... Mycorrhizal fungi from contaminated sites are more efficient in stimulating growth than the mycorrhizal fungi from the non- its efficacy to be a potential agent for the phytoremediation of Zncontaminated soils [38]. ...
Agriculture is the mainstay between humans and the environment. The existence of arbuscular mycorrhizal fungi (AMF), on the earth, is about 600 million years ago. The application of mycorrhizae as biofertilizer is in increasing trend. Mycorrhizae improve several agricultural practices like better nutrient cycling, improving crop yield, and remediation of toxic heavy metals from soil. There is much variation in arbuscular mycorrhizal association although 80% of the plant species are infected with mycorrhizae. Mycorrhizal dependency (MD) is defined as the degree to which a host plant is dependent on AMF to produce maximum growth or yield at a given level of soil
fertility. Plant with high MD need to feed with a higher amount of carbon and lipid to the fungus than a plant with less MD. Mycorrhizae modify, maintain, and create habitat by directly and indirectly
regulating biotic and abiotic environments. Mycorrhizae derived photosynthetically formed C for
the growth and uptake, tolerance against abiotic stress such as drought, heavy metals, salinity as well as protecting from pathogen attack to host plant and preventing from erosion. Application of ZnO would have been the probable solution of mitigating drought.
ZnO treatment decreased the adverse effects of drought stress in plants by enhancing antioxidant enzyme activity and changing physiological parameters. Heat stress affects many processes in a variety of plants as water relations, nutrient uptake, photosynthesis, assimilate partitioning,respiration, growth, and reproduction, and induced oxidative damage. Foliar application of ZnSO4.7H2O effectively alleviated by enhancing Zn concentration, superoxide dismutase activity, chlorophyll content, Fv/Fm ratio, and photosystem II under heat stress. In maize, there is a substantial reduction of germination above 37oC. All the parameters recorded in wheat, namely, no of tillers, plant height, spike length, no of spikelets per spike, no of grains per spike, 1000 grain weight, biological yield, grain yield and harvesting index, Ca, Mg, Fe, Zn, Cu and protein content are significantly affected by the mycorrhizal application. Almost 25% of recommended dose of phosphate fertilizer could be saved as in Niger(Guizotia abyssinica)by inoculating Glomusmosseae.
Zinc is a vital micronutrient for many plants but its excess can be calamitous.
AMF contributes to plant Zn uptake but their role in the edible portion of the crop has not been studied yet. The mycorrhizal pathway of Zn uptake contributed up to 24.3% of the total above-ground Zn in wheat and up to 12% of that Zn in Barley. The greatest contribution by the mycorrhizal pathway was observed in Barley at the lowest Zn addition and in wheat at the .highest one. Besides the grain yield of bread wheat was increased by AMF.
... Mycorrhizal fungi from contaminated sites are more efficient in stimulating growth than the mycorrhizal fungi from the non- its efficacy to be a potential agent for the phytoremediation of Zncontaminated soils [38]. ...
Agriculture is the mainstay between humans and the environment. The existence of arbuscular mycorrhizal fungi (AMF), on the earth, is about 600 million years ago. The application of mycorrhizae as biofertilizer is in increasing trend. Mycorrhizae improve several agricultural
practices like better nutrient cycling, improving crop yield, and remediation of toxic heavy metals from soil. There is much variation in arbuscular mycorrhizal association although 80% of the plant
species are infected with mycorrhizae. Mycorrhizal dependency (MD) is defined as the degree to which a host plant is dependent on AMF to produce maximum growth or yield at a given level of soil fertility. Plant with high MD need to feed with a higher amount of carbon and lipid to the fungus than a plant with less MD. Mycorrhizae modify, maintain, and create habitat by directly and indirectly regulating biotic and abiotic environments. Mycorrhizae derived photosynthetically formed C for the growth and uptake, tolerance against abiotic stress such as drought, heavy metals, salinity as well as protecting from pathogen attack to host plant and preventing from erosion. Application of
ZnO would have been the probable solution of mitigating drought.
ZnO treatment decreased the adverse effects of drought stress in plants by enhancing antioxidant enzyme activity and changing physiological parameters. Heat stress affects many processes in
a variety of plants as water relations, nutrient uptake, photosynthesis, assimilate partitioning, respiration, growth, and reproduction, and induced oxidative damage. Foliar application of ZnSO4.7H2O effectively alleviated by enhancing Zn concentration, superoxide dismutase activity, chlorophyll content, Fv/Fm ratio, and photosystem II under heat stress. In maize, there is a substantial reduction of germination above 37oC. All the parameters recorded in wheat, namely, no of tillers, plant height, spike length, no of spikelets per spike, no of grains per spike, 1000 grain weight, biological yield, grain yield and harvesting index, Ca, Mg, Fe, Zn, Cu and protein content
are significantly affected by the mycorrhizal application. Almost 25% of recommended dose of phosphate fertilizer could be saved as in Niger(Guizotia abyssinica)by inoculating Glomusmosseae.
Zinc is a vital micronutrient for many plants but its excess can be calamitous. AMF contributes to plant Zn uptake but their role in the edible portion of the crop has notb een studied yet. The mycorrhizal pathway of Zn uptake contributed up to 24.3% of the total above-ground Zn in wheat and up to 12% of that Zn in Barley. The greatest contribution by the mycorrhizal pathway was observed in Barley at the lowest Zn addition and in wheat at the .highest one. Besides the grain yield of bread wheat was increased by AMF.
Crop plant remediation and detoxification of Zn-contaminated soils may pose a significant threat to food safety and, thus, human health. Therefore, the current study was carried out to assess the ability of six non-food crop plants (NFCP); Zea mays L. cultivar 360 (T360), Z. mays cultivar 123 (T123), Helianthus annuus L., Brassica juncea (L.) Czern., Ricinus communis L., and Simmondsia chinensis (Link) C.K. Schneid to remediate and restore Zn-contaminated soils. The investigated plants tolerate 150 mg/kg of Zn content of the soil, where they had tolerance index (TI) > 1 for all growth criteria, except the root dry weight (DW) of S. chinensis. Z. mays T123 and R. communis were the most susceptible plants, while B. juncea and S. chinensis were moderately tolerant, while H. annuus was the most tolerant to high Zn concentrations in a growing medium. Increasing the soil Zn content led to a significant increase (p < 0.05) in Zn concentration in the various tissues of the six NFCPs. The studied NFCP did not translocate Zn to their grains/seeds; consequently, they can be used safely for Zn-contaminated soils. The Zn content in root and shoot was negatively correlated with the TI of their length and weight, while the translocation factor (TF) of Zn from root to shoot was positively correlated to the TI of the root length and weight. The six studied NFCPs were arranged based on their phytoremediation efficiency as follows: B. juncea (31.86%) > Z. mays T123 (31.14%) > Z. mays T360 (27.59%) > H. annuus (20.85%) > S. chinensis (20.29%) > R. communis (15.3%). All tested NFCPs accumulated significant concentrations of Zn in their roots and shoots, a high Zn uptake potential, and biomass at 150–450 mg/kg of Zn treatments, indicating that these plants are good candidates for the implementation of a new strategy of cultivating NFCP for phytoremediation of Zn-contaminated soils.
In the present scenario, remediation of heavy metals (HMs) contaminated soil has become an important work to be done for the well-being of human and their environment. Phytoremediation can be regarded as an excellent method in environmental technologies. The present contemporary research explores the Solanum viarum Dunal function as a potential accumulator of hazardous HMs viz. lead (Pb), cadmium (Cd), zinc (Zn), and their combination (CHM). On toxic concentrations of Pb, Cd, Zn, and their synergistic exposure, seeds had better germination percentage and their 90d old aerial tissues accumulated Pb, Cd, and Zn concentrations ranging from 44.53, 84.06, and 147.29 mg kg−1 DW, respectively. Pattern of accumulation in roots was as Zn 70.08 > Pb 48.55 > Cd 42.21 mg kg−1DW. Under HMs treatment, positive modulation in physiological performances, antioxidant activities suggested an enhanced tolerance along with higher membrane stability due to increased levels of lignin, proline, and sugar. Phenotypic variations were recorded in prickles and roots of 120 d old HM stressed plants, which are directly correlated with better acclimation. Interestingly, trichomes of the plant also showed HM accumulation. Later, SEM–EDX microanalysis suggested involvement of S. viarum capitate glandular trichomes as excretory organs for Cd and Zn. Thus, the present study provides an understanding of the mechanism that makes S. viarum to function as potent accumulator and provides information to generate plants to be used for phytoremediation.
Phytoremediation is an excellent method for removing harmful heavy metals from the environment since it is eco-friendly, uses little energy, and is inexpensive. However, as phytoremediated plants can turn into secondary sources for heavy metals, complete heavy metal removal from phytoremediated plants is necessary. Elimination of toxic heavy metals from phytoremediated plants should be considered with foremost care. This review highlights about important sources of heavy metal contamination, health effects caused by heavy metal contamination and technological breakthroughs of phytoremediation. This review critically emphasis about promising strategies to be engaged for absolute reutilization of heavy metals and spectacular approaches of production of commercially imperative products from phytoremediated plants through circular bioeconomy with key barriers. Thus, phytoremediation combined with circular bioeconomy can create a new platform for the eco-friendly life.
In this study, the ecotoxicological effects and bioaccumulation of triclosan (TCS) in Eichhornia crassipes (E. crassipes) were investigated with 28 d exposure experiments. The results showed that chlorophyll content was increased after 7 d exposure to 0.05–0.1 mg·L⁻¹ TCS, while it was inhibited significantly by 0.5 mg·L⁻¹ TCS after 21 d exposure. The concentrations of soluble protein in the leaves increased during the initial stage (7 d and 14 d), whereas they decreased during 21 d and 28 d. The concentrations of soluble protein in the roots gradually reduced during the exposure time. The antioxidant enzyme activities in roots decreased continually with the exposure time. However, the antioxidant enzyme (SOD and CAT) activities in leaves decreased after exposure longer than 14 d. Moreover, differentially expressed genes (DEGs) were observed in the root of E. crassipes after a 28 d exposure to 0.5 mg·L⁻¹ TCS, with 11023 DEGs down-regulated and 3947 DEGs up-regulated. 5 SOD down-regulated genes and 3 CAT down-regulated genes were identified from transport and catabolism in cellular processes. After 28 d exposure, the TCS content in roots and leaves stressed by 0.5 mg·L⁻¹ TCS were up to 13.04 μg·g⁻¹ and 1.97 μg·g⁻¹, respectively. CAT in leaves was negatively correlated with TCS content in leaves, SOD in roots was negatively correlated with TCS content in roots. These results provide experimental data to assess the ecological risk of TCS with long exposure in aquatic systems.
Zinc (Zn), which is regarded as a crucial micronutrient for plants, and is considered to be a vital micronutrient for plants. Zn has a significant role in the biochemistry and metabolism of plants owing to its significance and toxicity for biological systems at specific Zn concentrations, i.e., insufficient or harmful above the optimal range. It contributes to several cellular and physiological activities of plants and promotes plant growth, development, and yield. Zn is an important structural, enzymatic, and regulatory component of many proteins and enzymes. Consequently, it is essential to understand the interplay and chemistry of Zn in soil, its absorption, transport, and the response of plants to Zn deficiency, as well as to develop sustainable strategies for Zn deficiency in plants. Zn deficiency appears to be a widespread and prevalent issue in crops across the world, resulting in severe production losses that compromise nutritional quality. Considering this, enhancing Zn usage efficiency is the most effective strategy, which entails improving the architecture of the root system, absorption of Zn complexes by organic acids, and Zn uptake and translocation mechanisms in plants. Here, we provide an overview of various biotechnological techniques to improve Zn utilization efficiency and ensure the quality of crop. In light of the current status, an effort has been made to further dissect the absorption, transport, assimilation, function, deficiency, and toxicity symptoms caused by Zn in plants. As a result, we have described the potential information on diverse solutions, such as root structure alteration, the use of biostimulators, and nanomaterials, that may be used efficiently for Zn uptake, thereby assuring sustainable agriculture.
Soil pollution has become a serious environmental problem worldwide due to rapid industrialization and urbanization. Zinc (Zn) contamination has raised concerns about potential effects on plants and human health. This study was conducted to assess the capability of four biofuel plants: Abelmoschus esculentus, Avena sativa, Guizotia abyssinica, and Glycine max to remediate and restore Zn contaminated soil. Selected plants were grown in soil exposed to different Zn treatments (50, 100, 200, 300, 400, 600, 800 and 1000 mg Zn kg-1) for 12 weeks. Soil without spike taken as control. Zn induced toxicity significantly (p < 0.05) reduced seed germination and inhibited plant growth and leaf chlorophyll content. The investigated plants can tolerate a soil content of 800 mg Zn kg-1 with the exception of A. sativa, which was most tolerant to high Zn concentrations (1000 mg Zn kg-1) for all growth criteria. Moreover, increasing Zn content in soil resulted in a significant (p < 0.05) increase in Zn accumulation in various tissues of the four biofuel plants. According to phytoremediation efficiency, the four biofuel plants studied were arranged as follows: A. sativa (5.05%) > A. esculentus (4.15%) > G. max (2.31%) > G. abyssinica (1.17%). This study concluded that all tested biofuel plants species, especially A. sativa exhibited high Zn concentrations in roots and shoots, high Zn uptake capability, high tolerance, and high biomass at 50–800 mg Zn kg-1 treatments. Consequently, these biofuel plants are excellent candidates for phytoremediation in Zn contaminated soils.
Zinc (Zn) occurs naturally in all types of soils. In addition, Zn and its diversified compounds concentrate on topsoil through atmospheric deposition, anthropogenic activities, and agricultural practices. This heavy metal plays an important role for plant physiology and metabolism, abiotic stress resistance, and productiveness. At high concentrations, it accumulates in various plant compartments like stems, roots, and leaves; through its all life cycle. Zinc is a heavy metal contaminating soils all over the world and negatively affects soil functionalities, plant growth, and soil microbiome at their higher concentrations. Conventional methods including physical, chemical, and biological techniques or their combinations seem to be effective in zinc bioremediation of polluted soils. Globally, this chapter tries to deal and discuss the current background level, occurrence, speciation, bioavailability, uptake detoxification mechanisms, and management of Zn-polluted soils to an acceptable and safe level.
Under barium chloride stress, a laboratory investigation was done to assess the phtoextraction capability of hyper accumulator (Brassica juncea
Hk. F. & T.). The hypoaccumulator (Vigna radiata (L.) Wilczek.) and the low-accumulating plant (Vigna radiata (L.) Wilczek.) were co-cultivated
(hperaccumlator). At varying amounts of barium, the accumulation, translocation, and mobility of barium from the soil to the roots and leaves of
co-cultivated hyperaccumulator (Brassica juncea Hk. F. & T.) and hypoaccumulator (Vigna radiata) plants were investigated. Brassica juncea
gathered four times as much barium in its roots, shoots, and leaves as Vigna radiata. When grown alone, Vigna radiata seedlings were shown to be
susceptible to barium, with low values for the accumulation factor, translocation factor, and metal mobility. This is generally understood that
Brassica juncea showed more barium accumulation, more barium translocation from root to shoot, and good barium mobility was raised from level
1 to level 3. It was discovered that Brassica juncea had higher barium accumulation in the root and shoot than Vigna radiata. The current
investigation indicates that Vigna radiata is a hypoaccumulator and sensitive to barium. Because Brassica juncea is a hyperaccumulator of barium,
it accumulates more metal when co-cultivated with Vigna radiata, resulting in reduced metal toxicity.
Environmental adversities like heat, cold, drought, salinity, ultraviolet radiation and flooding induces abiotic distress in plants and are the pioneer limiting factors for plant growth, development and productivity. Anthropogenic activities have fuelled changes in global climatic conditions and these changes have incremented multiple abiotic stresses in crop plants. Researchers are making unprecedented efforts to intercept heavy crop losses and in turn to generate more food and feed to meet the demands of the ever-increasing human population. Highlighting the techniques involved to combat abiotic stresses, their role in regulating plant growth and development under unfavourable climatic factors holds substantial importance. This chapter reviews the role of osmoprotectants, polyamines, flavonoids and phytohormones in plant growth and development under abiotic stress conditions and their metabolic engineering for producing abiotic stress-tolerant transgenic plants. This strategy can prove a vital tool to minimise heavy crop losses and alleviate the problem of increasing food demand of human populations.
Ethylenediaminetetraacetic acid (EDTA) is one of the most effective chelating agents for enhancing lead (Pb) accumulation in various plant organs. However, it has a higher risk of causing secondary pollution than other chelating agents. To reduce such environmental risks and increase remediation efficiency, EDTA can be combined with degradable chelating agents for use in phytoremediation, but there are few reports on the combination of EDTA and nitrilotriacetic acid (NTA). This study evaluated the effects of combined EDTA and NTA application at different concentrations (900, 1200, or 1500 mg/kg) and with different methods (1 application or 3 applications) on dwarf bamboo (Sasa argenteostriata (Regel) E.G. Camus) growth and phytoremediation efficiency and on the soil environment in pot experiments with Pb-contaminated soil. Applying EDTA and NTA together resulted in lower soil water-soluble Pb concentrations than applying EDTA alone and therefore resulted in lower environmental risk. The increased availability of soil Pb produced a stress response in the dwarf bamboo plants, which increased their biomass significantly. Moreover, under the chelating treatments, the soil Pb availability increased, which promoted Pb translocation in plants. The Pb content in the aerial parts of the dwarf bamboo increased significantly in all treatments (translocation factors increased by 300~1500% compared with that in CK). The Pb content increase in the aerial parts caused high proline accumulation in dwarf bamboo leaves, to alleviate Pb toxicity. Maximum Pb accumulation was observed in the EN1500 treatment, which was significantly higher than that in the other treatments except the EN900 treatment. This study elucidates the choice of remediation techniques and the physiological characteristics of the plants used in such studies. In conclusion, the EN900 treatment resulted in the lowest environmental risk, greatest biomass production, and highest phytoremediation efficiency of all treatments, indicating that it has great potential for application in phytoremediation with dwarf bamboo in Pb-contaminated soil.
Heavy metal pollutants in the environment are emerging global concern. Barium is one of the heavy metal abundantly used in the manufacture of firecrackers and match industries. This work is aim to eradicate barium from these industrial sites; the new-flanged phytoextraction technology is used to mitigate the metal pollution through hyperaccumulators. Plant used in phytoextraction should accumulate and translocate specific pollutants especially heavy metals. This work aims to assess the tolerance mechanism of Amaranthus viridis L. a selective native hyperaccumulator under barium chloride stress. Morphometric, biochemical, enzymatic activity, accumulation, translocation and mobility of barium form soil to root and leaves were studied in co-cultivated hyperaccumulator (Amaranthus viridis) and hypoaccumulator (Abelmuscus esculentus) at various concentration levels of barium. Amaranthus viridis accumulated fourfold to fivefold barium in roots, shoots and leaves than Abelmuscus esculentusL. This is well understand that Amaranthus viridis showing higher accumulation of barium, more translocation of barium from root to shoot and good mobility. The mobility of barium was increased form level 1 to level 3. It was revealed that the accumulation of barium was more in root and shoot of Amaranthus viridis. It is inferred from the present study that A.esculentus is a hypoaccumulator and is sensitive to barium. When co-cultivated with Amaranthus viridis showing less of metal toxicity because Amaranthus viridis being hyperaccumulator of barium, accumulate more metal and save Abelmuscus esculentus. It is strongly suggest that the hyperaccumulator Amaranthus viridis L. should grown in the barium polluted sites and make the environment sans heavy metal pollution.
Keywords: Phytoextraction, barium pollutant, accumulation factor, mobility index, metal pollution.
Phytoremediation is a technique for treatment areas with medium or low heavy metals concentrations. A pot experiment was carried out to determine the usefulness of Canna indica L. as phytoremediator species. The plants were treated with three increasing Zn(II) and Cu(II) solutions. 21 days later, dry weight, relative membrane conductivity, chlorophyll, carotene, malondialdehyde, soluble proteins, proline, and Zn(II) and Cu(II) contents were measured. Zn(II) and Cu (II) treatments caused a decline in the dry weight, chlorophyll, carotene, and soluble proteins content, whereas the relative conductivity, malondialdehyde, and proline content showed the opposite pattern. The bioaccumulation reached values approximately 48 and 15 times higher (5293 mg kg−1 and 1425 mg kg−1), compared with the control, for Zn(II) and Cu(II), respectively. Our results suggest that this species can be used for the phytoremediation of polluted soils with moderate concentrations of Zn(II) and Cu(II).
Trace metal pollution in soils is one of the universal environmental problems in the world. Phytoremediation is a green, safe, ecological, and economic method to achieve continuous reduction of soil pollutants. Turfgrass is a plant with great landscape value and has considerable biomass when used for remediation of trace metal contaminated soil. However, its remediation ability needs to be improved in future application. The combined application of turfgrass, citric acid (CA) and auxin (gibberellin, GA3) were applied in the phytoremediation of an artificial nutritive soil derived from sludge, and a field scale orthogonal experiment (L9) was conducted to understand the interaction effect and obtain the optimum phytoremediation. Experimental results showed that the types and cultural patterns of turfgrass mainly determined plant height, root length and trace metal concentration in turfgrass, however CA treatment was prone to increase the aboveground biomass and the concentrations of most trace metals in turfgrasses, especially the concentration of Ni in turfgrass. GA3 spraying significantly increased the concentration of Cd in turfgrass. The culture patterns of turfgrass played 42.4% influence on acid-extractable Cd, while CA applying had 53.8% influence on the acid-extractable Ni. The annual phytoextraction amount of trace metals based on five mowing a year were proposed to assess the remediation ability of treatments, which of the combination treatment (T3, intercropping Zoysia matrella and Lolium perenne, and applying 400 mg kg⁻¹ CA and 30 mg kg⁻¹ GA3) were 1.6–2.1 times higher CK group. This research provides technical reference for intercropping turfgrass for remediation of trace metals in sludge-derived nutritive soil.
Brassinosteroids constitute naturally occurring plant hormones that are involved in the regulation of various metabolic functions associated with morphological, physiological, and developmental processes in plants. The polyhydroxylated steroidal hormones occur widely in the plant kingdom and exhibit structural variations. The recent advancement in different molecular approaches has led to the understanding of various processes involving BR synthesis, signaling, and pathways in plants. BRs not only play an important role in the growth and development of plants but also in providing tolerance against various abiotic and biotic stresses. Current trends indicate a myriad role of BRs in the amelioration of drought stress in plants that results in systematic stress management under fluctuating environmental conditions. This chapter provides insights into drought stress and its effect on the growth of plants. Further, the chapter focuses on the role of BRs in mitigating the negative effect of drought stress that critically hampers the growth and metabolism of plants.
Phytoremediation is an effective, green and economical technique. Different types of phytoremediation methods
can be used for the reduction of heavy metal contaminations, such as phytoextraction, phytovolatilization, phytostabilization and phytofiltration. The biomass of plants and the bioavailability of heavy metals in soil are the
key factors affecting the efficiency of phytoremediation. It's worth noting that the low remediation efficiency and
the lack of effective disposal methods for contaminated biomass have limited its development and application. At
present, biological, physical, chemical, agronomic and genetic approaches have been used to enhance phytoremediation. Disposal methods of contaminated biomass usually include pyrolysis, incineration, composting and
compaction. They are effective, but are costly and have security problems. Improper disposal of contaminated
biomass can lead to leaching of heavy metals. The leaching possibility of different forms of heavy metal in plants
is different. Hence, it has great significance to explore the different forms of heavy metals in plants which can
help to explore appropriate disposal methods. According to the challenges of phytoremediation, we put forward
some views and recommendations for the sustainable and rapid development of phytoremediation technology.
Phytoremediation has been proposed as a cost-effective method for removing potentially toxic elements (PTEs) from the soil. In this regard, biodegradable chelating agents can be used without harming the environment to increase the efficiency of phytoremediation. In the present work, a greenhouse experiment was conducted to investigate the effect of nitrilotriacetic acid (NTA; 0, 15, and 30 mmol L−1 per pot) on the uptake, chemical forms, and subcellular distribution of Cd in maize (Zea mays L.) grown in Cd-spiked soils (0, 25, and 50 mg Cd kg−1 soil) under leaching conditions. NTA application decreased biomass production (18–33%) yet enhanced Cd concentrations in shoots and roots of maize by more than 50%. Subcellular fractionation of NTA-applied Cd-containing leaves indicated that 41–53% of the Cd was localized in cell walls (FCW), 33–39% in soluble fraction (FS), and 13–19% in cellular organelles (FO). Moreover, NTA enhanced inorganic (FE), water-soluble (FW), and pectates and proteins-integrated Cd (FNaCl) forms, but reduced the insoluble forms (FHAc and FHCl). The increase of FNaCl may possibly help the plant to adapt to Cd stress. Also, NTA decreased soil DTPA-extractable Cd significantly, due to the increase in Cd leached and Cd absorbed by plants. The use of NTA can significantly increase the phytoremediation potential of maize, but it may also increase Cd toxicity in plants exposed to high amounts of Cd. Therefore, it is important to determine the optimal amount of chelator for enhancing phytoremediation.
Cadmium (Cd) is a prevalent, non-essential, carcinogenic, and hazardous heavy metal that reduces plant productivity and capacity of arable land area around the globe. In the present substrate-based pot study, seedlings of Brassica napus 180015 were grown equidistantly in the spiked-substrate medium for 60 days under increasing concentrations of Cd (0, 10, 20, 30, 40, 50 mg kg⁻¹). Following harvest, the morpho-physio-biochemical, antioxidative, and Cd-induced tolerance responses were evaluated in B. napus under an increasing Cd stress regime. Additionally, these parameters were also investigated to select the plant's threshold tolerance limit for Cd under the spiked-substrate system. B. napus showed dynamic behavior regarding morpho-physio-biochemical attributes, including agronomic features, biomass, photosynthetic pigments, relative water content under increased Cd toxicity. Cd stress-induced hydrogen peroxide (H2O2) production with high MDA contents and passive EL, followed by the orchestration of both enzymatic (SOD, POD, APX, CAT, and GR) and non-enzymatic antioxidants (flavonoids, TPC, TPA, proline, and total soluble protein) up to a certain limit. In addition, Cd-induced stress upregulated transcriptional levels of antioxidative enzyme SOD, POD, APX, GR, and MT encoded genes in B. napus. The increasing trend of Cd accumulation in different tissues at the highest Cd concentration was as follows: root > leaf > stem. In spiked substrate system, B. napus demonstrated improved metal extractability performance and a high potential for phyto-management of low to moderate Cd contamination, implying that this study could be used for integrative breeding programs and decontaminating heavy metals in real contaminated scenarios.
Novelty statement
This study provides an insight into Cd-coping mechanisms of oilseed rape involved in alleviating toxicity and simultaneous phyto-management of increasing Cd concentration under spiked substrate system. The current study is the first scientific evidence of using a Cd-spiked soilless substrate medium. The present study will further strengthen our understanding of Cd-instigated positive responses in B. napus. Furthermore, it will provide a useful basis for integrative breeding programs and decontaminating heavy metals in real contaminated scenarios.
Global climate change is identified as a major threat to survival of natural ecosystems. Climate change is a dynamic, multifaceted system of alterations in environmental conditions that affect abiotic and biotic components of the world. It results in alteration in environmental conditions such as heat waves, intensity of rainfall, CO2 concentration and temperature that lead to rise in new pests, weeds and pathogens. Climate change is one of the major constraints limiting plant growth and development worldwide. It impairs growth, disturbs photosynthesis, and reduces physiological responses in plants. The variations in global climate have gained the attention of researchers worldwide, as these changes negatively affect the agriculture by reducing crop productivity and food security. With this background, this review focuses on the effects of elevated atmospheric CO2 concentration, temperature, drought and salinity on the morphology, physiology and biochemistry of plants. Furthermore, this paper outlines an overview on the reactive oxygen species (ROS) production and their impact on the biochemical and molecular status of plants with increased climatic variations. Also additionally, different tolerance strategies adopted by plants to combat environmental adversities have been discussed.
Nanotechnology keeps a close eye on one of the most important agricultural control processes, owing to its small size. There are also numerous positive effects, including improved food quality and safety,reduced agricultural inputs, and enhanced soil absorption of nanoscalenutrient content, to name a few. Allow nanotechnology implementation to be a resonant burden. Agriculture, food, and environmental assets are
all part of sustainable development, susceptibility, human health, and maintaining a healthy lifestyle. With novel tools such as disease treatment and monitoring, pesticide distribution, along with green pesticides and biopesticides, sustained and controlled activate of micronutrients and fertilizers, nanotechnology can contribute to the agricultural productionkey elements of a variety of crops, resulting in higher nutritional values.Furthermore, these concepts will support in addressing food protection
and environmental concerns. Nanotechnology could be used as sensor systems to monitor the soil fertility in agricultural areas, ensuring the health of the plant species. This review outlines the key challenges of sustainable practices, food safety, and environmental degradation that researchers and practitioners of nanoscience are addressing to enhance agricultural production.
Keywords: Nanotechnology, Agriculture Field, Crop Improvement,
Environmental
Globally, environmental contamination by potentially noxious metalloids like arsenic is becoming a critical concern to the living organisms. Arsenic is a non-essential metalloid for plants and can be acclimatised in plants to toxic levels. Arsenic acquisition by plants poses serious health risks in human due to its entry in the food chain. High arsenic regimes disturb plant water relations, promote the generation of reactive oxygen species (ROS) and induce oxidative outburst in plants. This review evidences a conceivable tie-up among arsenic levels, speciation, its availability, uptake, acquisition, transport, phytotoxicity and arsenic detoxification in plants. The role of different antioxidant enzymes to confer plant tolerance towards the enhanced arsenic distress has also been summed up. Additionally, the mechanisms involved in the modulation of different genes coupled with arsenic tolerance have been thoroughly discussed.This review is intended to present an overview to rationalise the contemporary progressions on the recent advances in phytoremediation approaches to overcome ecosystem contamination by arsenic.
Key message
Recent updates in JA biosynthesis, signaling pathways and the crosstalk between JA and others phytohormones in relation with plant responses to different stresses.
Abstract
In plants, the roles of phytohormone jasmonic acid (JA), amino acid conjugate (e.g., JA-Ile) and their derivative emerged in last decades as crucial signaling compounds implicated in stress defense and development in plants. JA has raised a great interest, and the number of researches on JA has increased rapidly highlighting the importance of this phytohormone in plant life. First, JA was considered as a stress hormone implicated in plant response to biotic stress (pathogens and herbivores) which confers resistance to biotrophic and hemibiotrophic pathogens contrarily to salicylic acid (SA) which is implicated in plant response to necrotrophic pathogens. JA is also implicated in plant responses to abiotic stress (such as soil salinity, wounding and UV). Moreover, some researchers have recently revealed that JA controls several physiological processes like root growth, growth of reproductive organs and, finally, plant senescence. JA is also involved in the biosynthesis of various metabolites (e.g., phytoalexins and terpenoids). In plants, JA signaling pathways are well studied in few plants essentially Arabidopsis thaliana, Nicotiana benthamiana, and Oryza sativa L. confirming the crucial role of this hormone in plants. In this review, we highlight the last foundlings about JA biosynthesis, JA signaling pathways and its implication in plant maturation and response to environmental constraints.
Sodium salt contamination in the fresh water due to industrial effluents, underground rock salts and inland aquaculture is a major concern needs to be remediated, and subsequently recycled as sustainable bioeconomic strategy. Treatment of saline wastewater requires efficient, cost-effective, rapid, and green technologies, so as to mitigate the negative impacts of salinity on agricultural land. Green technology of phytodesalination is proposed to reduce salinity in the wastewater using salt tolerant plant species. present study was designed with an aim to investigate the sodium (Na⁺) removal capacity of salt tolerant and high biomass producing macrophytes on synthetic saline wastewater. Sesuvium portulacastrum (sea purslane), Pluchea indica (Indian camphorweed), Typha angustifolia (narrow leaf cattail) and Heliconia psittacorum (heliconia) were collected, cultivated in the greenhouse, subsequently treated with 0 (control) and 217 mM NaCl (salt stress) for 4 weeks. Overall growth performance, physiological change and Na⁺ removal rate in root and leaf tissues of the candidate plant species were measured. Plants were able to maintain their growth and physiological abilities except for shoot height in T. angustifolia (reduced by 13.7%) and chlorophyll content in S. portulacastrum (reduced by 64%). Major accumulation of Na⁺ was recorded in the shoots of S. portulacastrum and P. indica (halophytic plant species) and the roots of T. angustifolia and H. psittacorum (glycophytic plant species). Since T. angustifolia and H. psittacorum have high plant biomass, they showed higher Na⁺ removal efficiency at 4.4% and 5.7%, respectively; whereas due to lower plant biomass, S. portulacastrum and P. indica resulted in the removal of only 0.6 and 0.8% Na⁺ from the batch, respectively. Based on the information from this investigation, the selected candidate plant species can further be studied in the constructed wetland together with the controlled environments including optimized flowrate, vertical or horizontal flow system, plant densities and Na-removal rate in relation to swamp habitat.
Novelty statement: T. angustifolia and H. psittacorum have high plant biomass, they showed higher Na⁺ removal efficiency at 4.4% and 5.7%, respectively; whereas due to lower plant biomass, S. portulacastrum and P. indica resulted in removal of only 0.6 and 0.8% Na⁺ from the batch. Based on the information from this investigation, the selected candidate plant species can further be studied in the constructed wetland together with the controlled environments including optimized flowrate, vertical or horizontal flow system, plant densities and Na-removal rate in relation to swamp habitat.
This book provides state of the art description of various approaches, techniques and some basic fundamentals of bioremediation to manage a variety of organic and inorganic wastes and pollutants present in our environment. A comprehensive overview of recent advances and new development in the field of bioremediation research are provided within relevant theoretical framework to improve our understanding for the cleaning up of polluted water and contaminated land. The book is easy to read and language can be readily comprehended by aspiring newcomer, students, researchers and anyone else interested in this field. Renowned scientists around the world working on the above topics have contributed chapters. In this edited book, we have addressed the scope of the inexpensive and energy neutral bioremediation technologies. The scope of the book extends to environmental/agricultural scientists, students, consultants, site owners, industrial stakeholders, regulators and policy makers.
Phytoremediation is a form of bioremediation which deals with the enormous potential of plants for degrading or immobilizing contaminants in soil and groundwater. Anthropogenic activities release huge amounts of chemicals, wastes, and noxious gases into the environment, which alter the physical, chemical, and biological properties of ecosystem, worldwide. Biological agents utilize these contaminants as part of their metabolism and turn them into less toxic or harmless by-products. It reflects the natural ability of certain plants called hyperaccumulators to clean up a variety of contaminants, viz. polyaromatic hydrocarbons, pesticides, heavy metals, etc., in soil, water, or air. The choice of process; biotransformation, phytodegradation, phytostimulation, phytovolatilization, etc., to be opted for clean-up depends upon the habitats, supply of nutrients, contaminants type, and environmental conditions. Phytoremediation involves life forms, and ensures complete degradation of various toxicants without releasing harmful products, hence is an effective and cheaper solution for waste management.
The aim of this study was to assess the potential of the woody nickel hyperaccumulator species Blepharidium guatemalense (Standl.) Standl. for agromining in southeastern Mexico. Pot trials consisting of nickel dosing (0, 20, 50, 100 and 250 mg Ni kg-1), and synthetic and organic fertilization were conducted. Field trials were also undertaken with different harvesting regimes of B. guatemalense. Foliar nickel concentrations increased significantly with rising nickel additions, with a 300-fold increase at 250 mg Ni kg-1 treatment relative to the control. Synthetic fertilization strongly increased nickel uptake without any change in plant growth or biomass, whereas organic fertilization enhanced plant shoot biomass with a negligible effect on foliar nickel concentrations. A 5-year-old stand which was subsequently harvested twice per year produced the maximum nickel yield tree-1 yr-1, with an estimated total nickel yield of 142 kg ha-1 yr-1. Blepharidium guatemalense is a prime candidate for nickel agromining on account of its high foliar Ni concentrations, high bioconcentration (180) and translocation factors (3.3), fast growth rate and high shoot biomass production. Future studies are needed to test the outcomes of the pot trials in the field. Extensive geochemical studies are needed to identify potential viable agromining locations.
Keywords: agronomy, fertilization, hyperaccumulation, neotropics, Ni yield, phytomining.
Earthworms and arbuscular mycorrhizal fungi (AMF) act synergistically in the rhizosphere and may increase host plant tolerance to Cd. However, mechanisms by which earthworm-AMF-plant partnerships counteract Cd phytotoxicity are unknown. Thus, we evaluated individual and interactive effects of these soil organisms on photosynthesis, antioxidant capacity, and essential nutrient uptake by Solanum nigrum, as well as on soil quality following Cd exposure (0–120 mg kg⁻¹). Decreases in biomass and photosynthetic activity, as well as nutrient imbalances were observed in Cd-stressed plants; however, the addition of AMF and earthworms reversed these effects. Cd exposure increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, whereas inoculation with Rhizophagus intraradices decreased those. Soil enzymatic activity decreased by 15–60% with increasing Cd concentrations. However, Cd-mediated toxicity was partially reversed by soil organisms. Earthworms and AMF ameliorated soil quality based on soil enzyme activity. At 120 mg kg⁻¹ Cd, the urease, catalase, and acid phosphatase activities were 1.6-, 1.4-, and 1.2-fold higher, respectively, in soils co-incubated with earthworms and AMF than in uninoculated soil. Cd inhibited shoot Fe and Ca phytoaccumulation, whereas AMF and earthworms normalized the status of essential elements in plants. Cd detoxification by earthworm-AMF-S. nigrum symbiosis was manifested by increases in plant biomass accumulation (22–117%), chlorophyll content (17–63%), antioxidant levels (SOD 10–18%, POD 9–25%, total polyphenols 17–22%, flavonoids 15–29%, and glutathione 7–61%). It also ameliorated the photosynthetic capacity, and macro- and micronutrient statuses of plants; markedly reduced the levels of malondialdehyde (20–27%), superoxide anion (29–36%), and hydrogen peroxide (19–30%); and upregulated the transcription level of FeSOD. Thus, the combined action of earthworms and AMF feasibly enhances metal tolerance of hyperaccumulating plants and improves the quality of polluted soil.
In this study, cadmium (Cd) solution spraying and Cd-contaminated soil pot experiments were conducted to investigate the influence of Cd from atmospheric deposition and soil on the growth, cumulative distribution, chemical morphology, physiological, and biochemical responses of Amaranthus tricolor L. The results indicated that Cd in plants mainly came from soil (92–98%) and was stored in the roots in large quantities while the portion from atmospheric deposition could also effectively increase Cd content in stems and leaves (2–3%). Cd was mainly stored in plant cell walls and would transfer to the soluble part under high-concentration soil stress Cd from atmospheric deposition alone promoted the growth of plants, but high Cd concentrations from soil had the negative influence. The contents of H2O2 and MDA in plants increased under soil and atmospheric Cd stress, indicating that the plant cells were damaged by oxidative stress. The content of antioxidant enzymes such as POD, CAT, SOD, and antioxidants like AsA and GSH increased under low-concentration Cd stress but decreased under elevated stress, suggesting that high Cd-contaminated soil poses severe toxicity on the antioxidant system of the plants. Hence, the accumulation and physiological response of plants under multi-source Cd contamination were mainly affected by high soil Cd concentrations. Though the effect of atmospheric deposition is relatively less, it cannot be ignored.
Plants encounter various abiotic stresses due to their sessile nature which include heavy metals, salt, drought, nutrient deficiency , light intensity, pesticide contamination, as well as extreme temperatures. These stresses impose major constraints limiting crop production and food security worldwide. Abiotic stresses primarily reduce the photosynthetic efficiency of plants, due to their negative consequences on chlorophyll biosynthesis, performance of the photosystems, electron transport mechanisms, gas exchange parameters, and many others. A better understanding of the photochemistry of plants under these abiotic stresses can help in the development of pragmatic interventions for managing these stresses. Interestingly, in this review, we provide an overview of insight into different mechanisms affecting the photosynthetic ability of plants in relation to these abiotic factors. The present review describes how different abiotic stresses can pose deleterious impacts on plant photosynthetic machinery including cellular membranes, cell division and cell elongation, biosynthesis of photosyn-thetic pigments, as well as electron transport chain. It is important to understand the detrimental impacts of various abiotic stresses for better stress management because a comprehensive understanding of plant responses has pragmatic implication for remedies and management.
In the effort to achieve the Sustainable Development Goals (SDGs) related to food, health, water, and climate, an increase in pressure on land is highly likely. To avoid further land degradation and promote land restoration, multifunctional use of land is needed within the boundaries of the soil-water system. In addition, awareness-raising, a change in stakeholders’ attitudes, and a change in economics are essential. The attainment of a balance between the economy, society, and the biosphere calls for a holistic approach. In this paper, we introduce four concepts that we consider to be conducive to realizing LDN in a more integrated way: systems thinking, connectivity, nature-based solutions, and regenerative economics. We illustrate the application of these concepts through three examples in agricultural settings. Systems thinking lies at the base of the three others, stressing feedback loops but also delayed responses. Their simultaneous use will result in more robust solutions, which are sustainable from an environmental, societal, and economic point of view. Solutions also need to take into account the level of scale (global, national, regional, local), stakeholders’ interests and culture, and the availability and boundaries of financial and natural capital. Furthermore, sustainable solutions need to embed short-term management in long-term landscape planning. In conclusion, paradigm shifts are needed. First, it is necessary to move from excessive exploitation in combination with environmental protection, to sustainable use and management of the soil-water system. To accomplish this, new business models in robust economic systems are needed based on environmental systems thinking; an approach that integrates environmental, social, and economic interests. Second, it is necessary to shift from a “system follows function” approach towards a “function follows system” one. Only by making the transition towards integrated solutions based on a socio-economical-ecological systems analysis, using concepts such as nature-based solutions, do we stand a chance to achieve Land Degradation Neutrality by 2030. To make these paradigm shifts, awareness-raising in relation to a different type of governance, economy and landscape and land-use planning and management is needed.
Superoxide dismutases (SODs) are universal enzymes of organisms that live in the presence of oxygen. They catalyze the conversion of superoxide into oxygen and hydrogen peroxide. Superoxide anions are the intended product of dedicated signaling enzymes as well as the byproduct of several metabolic processes including mitochondrial respiration. Through their activity, SOD enzymes control the levels of a variety of reactive oxygen species (ROS) and reactive nitrogen species, thus both limiting the potential toxicity of these molecules and controlling broad aspects of cellular life that are regulated by their signaling functions. All aerobic organisms have multiple SOD proteins targeted to different cellular and subcellular locations, reflecting the slow diffusion and multiple sources of their substrate superoxide. This compartmentalization also points to the need for fine local control of ROS signaling and to the possibility for ROS to signal between compartments. In this review, we discuss studies in model organisms and humans, which reveal the dual roles of SOD enzymes in controlling damage and regulating signaling.
In the present experiment, we aimed to test the impact of hydrogen sulfide (H2S) on growth, key oxidant such as hydrogen peroxide, mineral elements, and antioxidative defense in Capia-type red sweet pepper (Capsicum annuum L.) plants subjected to high concentration of zinc (Zn). A factorial experiment was designed with two Zn levels (0.05 and 0.5 mM) and 0.2 mM sodium hydrosulfide (NaHS) as a donor of H2S supplied in combination plus nutrient solution through the root zone. High level of Zn led to reduce dry mass, chlorophyll pigments, fruit yield, leaf maximum fluorescence, and relative water content, but enhanced endogenous hydrogen peroxide (H2O2), free proline, malondialdehyde (MDA), electrolyte leakage (EL), H2S, as well as the activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) enzymes. Exogenously applied NaHS significantly enhanced plant growth, fruit yield, water status, the levels of H2S and proline as well as the activities of different antioxidant enzymes, while it significantly suppressed EL, MDA, and H2O2 contents in the pepper plants receiving low level Zn. NaHS application to the control plants did not significantly change all these parameters tested except the dry matter which increased significantly. High Zn regime led to increase intrinsic Zn levels in the leaves and roots, but it lowered leaf nitrogen (N), phosphorus (P), and iron (Fe) concentrations. However, NaHS reduces the Zn conc. and enhances Fe and N in leaf and root organs. It can be concluded that NaHS can mitigate the harmful effects of Zn on plant growth particularly by lowering the concentrations of H2O2, Zn, EL, and MDA, and enhancing the activities of enzymatic antioxidants and levels of essential nutrients in pepper plants.
Soil pollution is a key component of the land degradation process, but little is known about the impact of soil pollution on human health in the urban environment. The heavy metals Pb, Zn, Cu, Cr, Cd and Ni were analyzed by acid digestion (method EPA 3050B) and a total of 15 dust samples were collected from streets of three sectors of the city with different land uses; commercial, residential and a highway. The purpose was to measure the concentrations of heavy metals in road sediment samples taken from urban sites under different land uses, and to assess pollution through pollution indices, namely the ecological risk index and geoaccumulation index. Heavy metals concentrations (mg/kg) followed the following sequences for each sector: commercial sector Pb (1289.4) > Cu (490.2) > Zn (387.6) > Cr (60.2) >Ni (54.3); highway Zn (133.3) > Cu (126.3) > Pb (87.5) > Cr (9.4) > Ni (5.3); residential sector Zn (108.3) > Pb (26.0) > Cu (23.7) > Cr (7.3) > Ni (7.2). The geoaccumulation index indicated that the commercial sector was moderately to strongly polluted while the other sectors fell into the unpolluted category. Similarly, using the ecological risk index the commercial sector fell into the considerable category while the other sectors classified as low risk. Road dust increased along with city growth and its dynamics, additionally, road dust might cause a number of negative environmental impacts, therefore the monitoring this dust is crucial.
Plants have gained importance in situ bioremediation of heavy metals. In the present study, different concentrations of zinc (Zn2+) (0.5, 5, 10, 15, 20 mg/l) and lead (Pb2+) (1, 2, 4, 6, 8 mg/l) were used to evaluate metal tolerance level of Lemna minor. L.minor were exposed to metals for 4 days and tested for its dry to fresh weight ratio (DW/FW), photosynthetic pigments production and protein content. The oxidative damage was detected by measuring catalase activity. L.minor showed tolerance against Zn2+ and Pb2+ at a concentration of 10 and 4 mg/l, respectively. Among the metals, Pb2+ showed a significant toxicity at 8 mg/l. High concentration (20 mg/l of Zn2+ and 8 mg/l of Pb2+) of the metals displayed a considerable negative effect on soluble proteins (13 fold decrease with Zn2+ and 4 fold decrease with Pb2+) and photosynthetic pigments (twofold decrease with Zn2+ and onefold decrease with Pb2+) and lead to a consequent reduction in number of fronds. Further, the catalase was greatly increased (twofold decrease with Zn2+ and sixfold decrease with Pb2+) under metal stress. The results indicate that L.minor withstands Zn2+ and Pb2+ toxicity up to the concentration of 10 and 4 mg/l, respectively. Hence, the metal tolerant property of this plant shall be exploited for bioremediation of Zinc and Lead in polluted water. Further, the detailed and wide range of heavy metal toxicity studies should be done to reveal the possible use of this plant on large scale bioremediation purpose.
Excess of heavy metals in agricultural soils is a matter of concern since it may decrease economic yield as a result of toxicity and lower product quality as a result of metal accumulation in edible plant parts. Among plant species and among cultivars within species a natural variation in uptake, translocation and distribution of trace elements occur. The transference of Cd and Zn, from soil to two lettuce (Lactuca sativa L.) cultivars grown in greenhouse, was evaluated in separate experiments for Cd and Zn. Plant dry and fresh matter yield and plant Cd and Zn concentrations were determined. Cultivar CRV showed greater potential for yield than CMM in both experiments. Cadmium and Zn translocation from roots to shoots increased with the increase of soil Cd or Zn, for both cultivars. There was Cd translocation from young to old leaves in CMM but not in CRV whereas for Zn it occurred in both cultivars, being higher in CRV. In both cultivars, old leaves had higher Cd and Zn concentrations (and lower dry matter yield) than young leaves. The CRV and CMM cultivars accumulate Cd differently in the leaves and the higher accumulation occurs in the former. Cultivar CRV also accumulates more Zn compared to CMM.
Growth chamber experiments were conducted to investigate the comparative effect of 24-epibrassinolide (EBL) and 28-homobrassinolide (HBL) at 0.5, 1.0, or 2.0 μM concentrations by foliar application on radish plants growing under Zn(2+) stress. In radish plants exposed to excess Zn(2+), growth was substantially reduced in terms of shoot and root length, fresh and dry weight. However, foliar application of brassinosteroids (BRs) was able to alleviate Zn(2+)-induced stress and significantly improve the above growth traits. Zinc stress decreased chlorophyll a, b, and carotenoids levels in radish plants. However, follow-up treatment with BRs increased the photosynthetic pigments in stressed and stress-free plants. The treatment of BRs led to reduced levels of H2O2, lipid peroxidation and, electrolyte leakage (ELP) and improved the leaf relative water content (RWC) in stressed plants. Increased levels of carbonyls indicating enhanced protein oxidation under Zn(2+) stress was effectively countered by supplementation of BRs. Under Zn(2+) stress, the activities of catalase (CAT), ascorbate peroxidase (APX), and superoxidase dismutase (SOD) were increased but peroxidase (POD) and glutathione reductase (GR) decreased. Foliar spraying of BRs enhanced all these enzymatic activities in radish plants under Zn(2+) stress. The BRs application greatly enhanced contents of ascorbate (ASA), glutathione (GSH), and proline under Zn(2+) stress. The decrease in the activity of nitrate reductase (NR) caused by Zn(2+) stress was restored to the level of control by application of BRs. These results point out that BRs application elevated levels of antioxidative enzymes as well as antioxidants could have conferred resistance to radish plants against Zn(2+) stress resulting in improved plant growth, relative water content and photosynthetic attributes. Of the two BRs, EBL was most effective in amelioration of Zn(2+) stress.
A dose–response study was performed in four commercial clones, Baldo (Populus deltoides), Jean Pourtet (Populus nigra), I-214 (Populus x euramericana) and Villafranca (Populus alba), to investigate the best performing species in terms of metal content and high metal resistance (absence of symptoms) useful in biomass production on contaminated water/land by zinc. Zinc (1 μM as control and 1 mM) was applied for 4 weeks in a hydroponic system. Clone Villafranca was the least damaged, while the most sensitive was clone I-214. The highest zinc concentration in all different parts of plants analysed was recorded in Villafranca > I-214 > Baldo > Jean Pourtet. The higher translocation factor was seen in Baldo, the lowest in Villafranca. Analyses of leaf damage showed a reduction on Chl a in young leaves (96 %) in I-214 stressed plants, whereas in Villafranca, Chl a was about double compared to the control. Regarding other photosynthetic pigments, violaxanthin was significantly correlated to zinc concentration in old leaves. The responses of clones to zinc (Zn) stress were specific: Villafranca was the most resistant, while I-214 showed the highest biomass production under Zn excess. Since these two clones have useful and complementary traits for uptake and detoxification while maintaining high biomass production under Zn excess, they are interesting candidates for understanding the key resistance mechanisms.
Exogenous-applied 24-epibrassinolide (EBR) increased the seedling growth of radish (Raphanus sativus L.) in terms of seedling length, fresh weight and dry weight both in zinc (Zn2+)-stressed and unstressed conditions. Moreover, EBR lowered the Zn2+ uptake and bioaccumulation. Increased oxidation of ascorbate (AsA) and glutathione (GSH) pools to dehydroascorbate and glutathione disulfide respectively was observed in Zn2+-stressed seedlings, a clear indication of oxidative stress. However, exogenous application of EBR to stressed seedlings inhibited the oxidation of ascorbate and glutathione, maintaining redox molecules in reduced form. Under Zn2+ stress, enzymatic activities of ascorbate–glutathione cycle such as ascorbate peroxidase, monodehydroascorbate reductase increased but the dehydroascorbate reductase, glutathione reductase decreased. Zn2+ stress induced the gamma-glutamylcysteine synthetase, and glutathione-s-transferase activities in radish seedlings were further enhanced with EBR application. Zn2+ toxicity decreased the thiol content but, EBR supplementation resulted in restoration of thiol pool. The results of present study clearly demonstrated that external application of EBR modulates the AsA and GSH redox status to combat the oxidative stress of Zn2+ in seedlings via the AsA–GSH cycle and glutathione metabolism as an antioxidant defense system.
Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their "strange" behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs.
The adverse effects of zinc oxide nanoparticles (ZnO NPs) with an average diameter of 25 nm on the aquatic plant Salvinia natans (L.) All. were determined. Growth, superoxide dismutase (SOD) activity, catalase (CAT) activity, peroxidase activity, and chlorophyll content of the plants were measured after 7 days of exposure to different concentrations of ZnO NPs (1 to 50 mg L(-1)). The particle distribution in the culture medium (without plants) during the first 24 h was determined using a Nanotrac 250 particle analyzer. We also investigated the zinc accumulation in leaves and roots of the plant after 7 days of exposure. Exposure to 50 mg L(-1) ZnO NPs significantly increased SOD and CAT activities (P < 0.05) and significantly depressed photosynthetic pigments (P < 0.05). However, plant growth was not significantly affected (P > 0.05). NPs completely precipitated at the bottom of the container at 8 h except for the portions of dissolution and aggregation on the roots. ZnO NPs at a concentration of 50 mg L(-1) can adversely affect S. natans, and their stress is affected by their aggregation and dissolution.
Plants of two tomato cvs., ‘Blizzard’ and ‘Liberto’ were grown in sand culture in a glasshouse at Zn concentrations of 0.15 and 7.70 μmol l⁻¹ in the nutrient solution. Foliar treatments entailed applying zinc as either 0, 0.35 or 3.5 mmol l⁻¹ ZnSO4·7H2O to the tops of plants grown at low zinc (0.15 μmol l⁻¹) in nutrient solution twice a week during the course of the experiment. Plants treated with 0.15 μmol l⁻¹ Zn in the nutrient solution and high levels of zinc (3.5 mmol l⁻¹) applied as a foliar spray showed a significant decrease in the production of dry matter, chlorophyll and green fruit yield as compared with those grown both at 7.70 μmol l⁻¹ zinc in the nutrient solution and at 0.15 μmol l⁻¹ zinc in nutrient solution with 3.5 mmol l⁻¹ zinc applied as a foliar spray. There were differences between the cultivars but no consistent link between these differences and nutrient concentrations within the plant. Concentrations of K, Mg and Zn were lower in the leaves and fruit of both the cultivars in 0.15 μmol l⁻¹ zinc in the nutrient solution treatment as compared with both the 7.70 μmol l⁻¹ in the nutrient solution treatment and with supplementary foliar applications of zinc at 0.35 mmol l⁻¹. Potassium and Mg were also lower in the leaves and fruit of both the cultivars receiving foliar applications of zinc at 3.5 mmol l⁻¹.
Water is polluted by increasing activities of population and the necessity to provide them with goods and services that use water as a vital resource. The contamination of water due to heavy metals (HMs) is a big concern for humankind; however, global studies related to this topic are scarce. Thus, the current review assesses the content of HMs in surface water bodies throughout the world from 1994 to 2019. To achieve this goal, multivariate analyses were applied in order to determine the possible sources of HMs. Among the analyzed HMs in a total of 147 publications, the average content of Cr, Mn, Co, Ni, As and Cd exceeded the permissible limits suggested by WHO and USEPA. The results of the heavy metal pollution index, evaluation index, the degree of contamination, water pollution and toxicity load showed that the examined water bodies are highly polluted by HMs. The results of median lethal toxicity index showed maximum toxicity in As, Co, Cr and Ni in the surface water bodies. Results of ingestion and dermal pathways for adults and children in the current analyzed review showed that As is the major contaminant. Moreover, Cr, Ni, As and Cd showed values that could be considered as a high risk for cancer generation via the ingestion pathway as compared to the dermal route. It is recommended that remediation techniques such as the introduction of aquatic phytoremediation plant species and adsorbents should be included in land management plans in order to reduce human risks.
ZnO nanoparticles (NPs) are studied as a potential solution to alleviate Zn deficiency in human diet due to their special physicochemical properties. However, information for food quality and safety in NP-treated crops is limited. The effects of ZnO NPs and ZnSO 4 on germination and growth of wheat (Triticum aestivum L.) were studied in germination and pot experiments. Zn content increased significantly, ZnO NPs were more effective than ZnSO 4 at increasing grain Zn content, but less effective at increasing leaf Zn, and no ZnO NPs were detected in the wheat tissues by NP-treatments, indicated by XRD. Both ZnO NPs and ZnSO 4 at moderate doses increased grain yield and biomass. Compared with control, the maximum grain yield and biomass of wheat treated with ZnO NPs and ZnSO 4 were increased by 56%, 63% and 55%, 72%, respectively. ZnSO 4 was more toxic than ZnO NPs at high doses as measured by the inhibitory effects in seed germination, root length, shoot length and dry biomass of seedlings. Structural damage in roots and variation in enzyme activities were greater with ZnSO 4 than with ZnO NPs. ZnO NPs did not cause toxicity different from that of ZnSO 4 , which indicates that ZnO NPs used under the current experimental conditions did not cause Nano specific risks.
In 2007, the first edition of Handbook of Plant Nutrition presented a compendium of information on the mineral nutrition of plants available at that time-and became a bestseller and trusted resource. Updated to reflect recent advances in knowledge of plant nutrition, the second edition continues this tradition. With chapters written by a new team of experts, each element is covered in a different manner, providing a fresh look and new understanding of the material. The chapters extensively explore the relationship between plant genetics and the accumulation and use of nutrients by plants, adding to the coverage available in the first edition. The second edition features a chapter on lanthanides, which have gained importance in plant nutrition since the publication of the first edition, and contains chapters on the different mineral elements. It follows the general pattern of a description of the determination of essentiality or beneficial effects of the element, uptake and assimilation, physiological responses of plants to the element, genetics of its acquisition by plants, concentrations of the element and its derivatives and metabolites in plants, interaction of the element with uptake of other elements, diagnosis of concentrations of the element in plants, forms and concentrations of the element in soils and its availability to plants, soil tests and fertilizers used to supply the element. The book demonstrates how the appearance and composition of plants can be used to assess nutritional status and the value of soil tests for assessing nutrition status. It also includes recommendations of fertilizers that can be applied to remedy nutritional deficiencies. These features and more make Handbook of Plant Nutrition, Second Edition a practical, easy-to-use reference for determining, monitoring, and improving the nutritional profiles of plants worldwide.
Zinc (Zn) is a common heavy metal in polluted soils, as it is a widespread pollutant deriving both from natural sources and anthropogenic activities. The antioxidant tolerance/defence mechanisms against oxidative stress induced by subtoxic concentrations of Zn (50 and 150 µM ZnSO4) were studied in a widespread edible plant (lettuce; Lactuca sativa L.) and in an important model plant (Arabidopsis thaliana (L.) Heynh.). After 10 days (Arabidopsis) and 20 days (lettuce) of Zn exposure, Zn uptake/translocation was evaluated in both roots and shoots, while indicators of oxidative stress and stress intensity, total antioxidant capacity, and enzymatic and non-enzymatic antioxidative defence were measured in leaves. From an overall comparison of the two species, Zn root uptake in Arabidopsis subjected to 50 and 150 µM ZnSO4 was approximately 3- and 5-fold lower than in lettuce, while Zn translocation from roots to apical leaves was more efficient in Arabidopsis (23.7 vs 21.3% at 50 µM ZnSO4 and 19.3 vs 12.9% at 150 µM ZnSO4). Generally, a higher degree of Zn-induced oxidative stress (863.8 vs 21.3 μg g−1 FW H2O2 and 1.33 vs 0.75 µM g−1 FW MDAeq at 150 µM ZnSO4) and antioxidant response (441.2 vs 258.5 mM g−1 FW TEAC and 91.0 vs 54.9 % RSA at 150 µM ZnSO4) were found in lettuce. The aim of this study is understanding (a) if subtoxic Zn levels can affect Zn uptake and translocation in the studied species and (b) if this eventual Zn absorption can influence plant oxidative status/antioxidant response. Considering that soil contamination by Zn can affect crop production and quality, the results of this research could be important for environmental, nutritional and human health issues.
Harnessing the sun’s energy via photosynthesis is at the core of sustainable production of food, fuel, and materials by plants, algae, and cyanobacteria. Photosynthesis depends on protection (photoprotection) against the perils of intense sunlight. The first line of defense among a cascade of photoprotective mechanisms is the safe removal of excess excitation energy within the light-harvesting system. The widely used indicator for photoprotective energy dissipation (thermal de-excitation of excited-state chlorophyll) is the quick, facile, and non-destructive assessment of non-photochemical quenching of chlorophyll fluorescence (NPQ). By placing light harvesting and photoprotection into the context of whole-organism function, this book directs the use of NPQ to aid in the identification of plant and algal lines with superior stress resistance and productivity. Furthermore, this volume addresses open questions in the interpretation of the molecular mechanisms of light harvesting and energy dissipation, the resolution of which should aid in the development of artificial photosynthetic systems. A comprehensive picture – from theory to practice, and from single molecules to organisms in ecosystems – is presented. In addition to providing current views of the leading specialists in this area, this book includes basic and practical information for non-specialists. For example, this book critically examines uses and misuses of the term NPQ and of advantages and pitfalls of NPQ measurements, and presents concrete recommendations for all concerned.
Coronopus didymus was examined in terms of its ability to remediate Pb-contaminated soils. Pot experiments were conducted for 4 and 6 weeks to compare the growth, biomass, photosynthetic efficiency, lead (Pb) uptake and accumulation by C. didymus plants. The plants grew well having no visible toxic symptoms and 100% survivability, exposed to different Pb-spiked soils 100, 350, 1500 and 2500 mg kg⁻¹, supplied as lead nitrate. After 4 weeks, root and shoot concentrations reached 1652 and 502 mg Pb kg⁻¹ DW while after 6 weeks they increased upto 3091 and 527 mg Pb kg⁻¹ DW respectively, at highest Pb concentration. As compared to the 4 week experiments, the plant growth and biomass yield were higher after 6 weeks of Pb exposure. However, the chlorophyll content of leaves decreased but only a slight decline in photosynthetic efficiency was observed on exposure to Pb at both 4 and 6 weeks. The Pb accumulation was higher in roots than in the shoots. The bioconcentration factor of Pb was > 1 in all the plant samples but the translocation factor was < 1. This suggested C. didymus as a good candidate for phytoremediation of Pb-contaminated soils and can be used for future remediation purposes.
Coronopus didymus has been emerged as a promising wild, unpalatable plant species to alleviate lead (Pb) from the contaminated soils. This work investigated the hypothesis regarding various metabolic adaptations of C. didymus under lead (Pb) stress. In pot experiments, we assessed the effect of Pb at varied concentrations (500–2900 mg kg−1) on growth, photosynthetic pigments, alteration of macromolecular (protein and carbohydrate) content, and activities of enzymes like protease, α-and β-amylase, peroxidase (POX), and polyphenol oxidase (PPO) in C. didymus for 6 weeks. Results revealed that Pb exposure enhanced the growth, protein, and carbohydrate level, but decreased the leaf pigment concentration and activities of hydrolytic enzymes. The activities of POX and PPO in roots increased progressively by ~337 and 675%, respectively, over the control, at 2900 mg kg−1 Pb treatment. Likewise, contemporaneous findings were noticed in shoots of C. didymus, strongly indicating its inherent potential to cope Pb-induced stress. Furthermore, the altered plant biochemical status and upregulated metabolic activities of POX and PPO indulged in polyphenol peroxidation elucidate their role in allocating protection and conferring resistance against Pb instigated stress. The current work suggests that stress induced by Pb in C. didymus stimulated the POX and PPO activities which impart a decisive role in detoxification of peaked Pb levels, perhaps, by forming physical barrier or lignifications.
In a screenhouse experiment, we investigated the role of two environment friendly chelants, Ammonium molybdate and EDDS for Pb mobilisation and its extraction by Coronopus didymus under completely randomized controlled conditions. Seedlings of C. didymus were grown in pots having Pb-contaminated soil (1200 and 2200 mg kg⁻¹) for 6 weeks. Plants were harvested, 1 week after the addition of A. molybdate and EDDS. Results revealed that A. molybdate and EDDS enhanced the uptake and accumulation of Pb in roots and shoots of C. didymus. At 2200 mg kg⁻¹ Pb level, compared to Pb-alone treatment, the maximal concentration of Pb was increased upto ∼10% and ∼19%, in roots whereas ∼8% and ∼18%, respectively, in shoots on addition of 2 mmol kg⁻¹ A. molybdate and EDDS. Additionally, Pb + EDDS treatments enhanced the plant biomass and triggered strong antioxidative response, more efficaciously than Pb + A. molybdate and Pb-alone treated plants. In this study, EDDS relative to A. molybdate was more efficient in mobilising and extracting Pb from soil. Although, EDDS followed by A. molybdate had good efficacy in mitigating Pb from contaminated soils but C. didymus itself has the inherent affinity to tolerate and accumulate Pb from contaminated soils and hence in future, can be used either alone or with some other eco-friendly amendments for soil remediation purposes.
Nitro blue tetrazolium has been used to intercept O2⁻ generated enzymically or photochemically. The reduction of NBT by O2⁻ has been utilized as the basis of assays for superoxide dismutase, which exposes its presence by inhibiting the reduction of NBT. Superoxide dismutase could thus be assayed either in crude extracts or in purified protein fractions. The assays described are sensitive to ng/ml levels of super-oxide dismutase and were applicable in free solution or on polyacrylamide gels. The staining procedure for localizing superoxide dismutase on polyacrylamide electrophoretograms has been applied to extracts obtained from a variety of sources. E. coli has been found to contain two superoxide dismutases whereas bovine heart, brain, lung, and erthrocytes contain only one.
A photo-induced cyclic peroxidation in isolated chloroplasts is described. In an osmotic buffered medium, chloroplasts upon illumination produce malondialdehyde (MDA)—a decomposition product of tri-unsaturated fatty acid hydroperoxides—bleach endogenous chlorophyll, and consume oxygen. These processes show (a) no reaction in the absence of illumination; (b) an initial lag phase upon illumination of 10-20 minutes duration; (c) a linear phase in which the rate is proportional to the square root of the light intensity; (d) cessation of reaction occurring within 3 minutes after illumination ceases; and (e) a termination phase after several hours of illumination. The kinetics of the above processes fit a cyclic peroxidation equation with velocity coefficients near those for chemical peroxidation.
The stoichiometry of MDA/O2 = 0.02, and O2/Chlbleached = 6.9 correlates well with MDA production efficiency in other biological systems and with the molar ratio of unsaturated fatty acids to chlorophyll. The energies of activation for the lag and linear phases are 17 and 0 kcal/mole, respectively, the same as that for autoxidation. During the linear phase of oxygen uptake the dependence upon temperature and O2 concentration indicates that during the reaction, oxygen tension at the site of peroxidation is 100-fold lower than in the aqueous phase.
It is concluded that isolated chloroplasts upon illumination can undergo a cyclic peroxidation initiated by the light absorbed by chlorophyll. Photoperoxidation results in a destruction of the chlorophyll and tri-unsaturated fatty acids of the chloroplast membranes.
Heavy metals such as Cu and Zn are essential for normal plant growth, although elevated concentrations of both essential and non‐essential metals can result in growth inhibition and toxicity symptoms. Plants possess a range of potential cellular mechanisms that may be involved in the detoxification of heavy metals and thus tolerance to metal stress. These include roles for the following: for mycorrhiza and for binding to cell wall and extracellular exudates; for reduced uptake or efflux pumping of metals at the plasma membrane; for chelation of metals in the cytosol by peptides such as phytochelatins; for the repair of stress‐damaged proteins; and for the compartmentation of metals in the vacuole by tonoplast‐located transporters. This review provides a broad overview of the evidence for an involvement of each mechanism in heavy metal detoxification and tolerance.
New findings are recorded and a dot map with all localities in Greece is included.-from Author
A screenhouse experiment was conducted to assay the effect of Lead (Pb) on oxidative status, antioxidative response and metal accumulation in Coronopus didymus after 6 weeks. Results revealed a good Pb tolerance and accumulation potential of C. didymus towards the increasing Pb concentrations (500, 900, 1800, 2900 mg kg−1) in soil. The content of Pb in roots and shoots elevated with higher Pb levels and reached a maximum of 3684.3 mg kg−1 and 862.8 mg kg−1 Pb dry weight, respectively, at 2900 mg kg−1 treatment. Pb exposure stimulated electrolyte leakage, H2O2 level, MDA content and the activities of antioxidant machinery (SOD, CAT, APX, GPX and GR). However, at the highest Pb concentration, the activities of SOD and CAT declined. The H2O2 level and MDA content in roots increased significantly up to ∼500% and 213%, respectively, over the control, at 2900 mg kg−1 Pb treatment. Likewise, concurrent findings were noticed in shoots of C. didymus, with the increasing Pb concentration. The present work suggests that C. didymus exhibited a good accumulation potential for Pb and can tolerate Pb-induced oxidative stress by an effective antioxidant defense mechanism.