Alleviate Cd Toxicity Research Articles

Foliar Spraying of Selenium Combined with Biochar Alleviates Cadmium Toxicity in Peanuts and Enriches Selenium in Peanut Grains.

Cadmium (Cd) pollution in soil, particularly in peanut production, is a problem that has attracted global concern and needs solutions urgently. Selenium (Se) can alleviate Cd toxicity; however, the underlying mechanisms are not completely understood. Therefore, two varieties of peanut (Arachis hypogaea Linn.), “Huayu 23” and “Huayu 20”, were chosen as the target crops for this study. A pot experiment was conducted to investigate the effects of two Se application methods combined with biochar on the accumulation of Cd and Se, and the best application method was identified. In addition, the role of Se in alleviating Cd toxicity in peanuts was studied. The results indicated that both Se and biochar decreased the Cd content in peanuts and alleviated Cd toxicity. However, the combined application of foliar Se and biochar significantly increased the peanut biomass by 73.44–132.41%, increased the grain yield of Huayu 23 by 0.60–1.09 fold, and Huayu 20 by 2.38–3.48 fold. Additionally, Cd content in peanut grains was decreased by 32.81–50.07%, and Se content was increased by 31.57–99.75 folds. Biochar can decrease the absorption of Cd from the soil, while Se can increase the accumulation of Cd in cell vacuoles by increasing glutathione and phytochelatin to decrease the movement of Cd into the grains. Therefore, our results indicate that the combined application of foliar Se and biochar can effectively promote the enrichment of Se in peanuts and suppress Cd toxicity.

Hydrogen sulphide alleviates cadmium stress in Trigonella foenum-graecum by modulating antioxidant enzymes and polyamine content.

Cadmium (Cd) toxicity reduces growth and yield of crops grown in metal-polluted sites. Research was conducted to estimate the potential of hydrogen sulphide (H2 S) to mitigate toxicity caused by Cd in fenugreek seedlings (Trigonella foenum-graecum L.). Different concentrations of CdCl2 (Cd1-1 mM, Cd2-1.5 mM, Cd3-2mM) and H2 S (HS1-100 µM, HS2-150 µM, HS3-200 µM) were assessed. Seeds of fenugreek were primed with sodium hydrosulphide (NaHS), as H2 S donor. Seedlings growing in Cd-spiked media treated with H2 S were harvested after 2 weeks. Cd stress affected growth of fenugreek seedlings. Cd toxicity decreased leaf relative water content (LRWC), intercellular CO2 concentration, net photosynthesis, stomatal conductance and transpiration. However, application of H2 S significantly improved seedling morphological attributes by increasing the activity of antioxidant enzymes, i.e. APX, CAT and SOD, in Cd-contaminated soil. H2 S treatment also regulated phenolic and flavonoid content. H2 S-induced biosynthesis of spermidine (Spd) and putrescine (Put) could account for the enhancement of growth and physiological performance of fenugreek seedlings under Cd stress. H2 S treatment also reduced H2 O2 production (38%) and electrolyte leakage (EL, 51%) in seedlings grown in different concentrations of Cd. It is recommended to evaluate the efficacy of H2 S in alleviating Cd toxicity in other crop plants.

Metabolomic and antioxidant enzyme activity changes in response to cadmium stress under boron application of wheat (Triticum aestivum).

Boron (B) has previously been shown to inhibit cadmium (Cd) uptake in wheat. Here, we investigated the physiological response of external B application (C for no B added, B for B added, B+Cd for B and Cd added, B/Cd for B 24 h pretreatment before Cd added, B and Cd were 46.2 μM and 5 μM, respectively) on wheat growth under Cd stress. The results showed that the wheat growth was significantly weaker under Cd treatment, while B application did not significantly improve the wheat growth under Cd stress. However, B application decreased Cd concentrations and malondialdehyde (MDA) concentrations of shoot and root. The key enzyme activities including superoxide dismutase (SOD) and peroxidase (POD) significantly increased under Cd treatments while decreased under B treatments. Further, a total of 198, 680 and 204 of the differential metabolites were isolated between B and C treatment, Cd and C treatment and B+Cd and Cd treatment, respectively. The metabolites with up-accumulation in B application (B+Cd) roots were mainly galactaric acid, citric acid, N6-galacturonyl-L-lysine, D-glucose, while the metabolites with down-accumulation were mainly threoninyl-tryptophan and C16 sphinganine. The differential metabolic pathways were mainly concentrated in linoleic acid metabolism, galactose metabolism, sphingolipid metabolism, glycolysis/gluconeogenesis, propanoate metabolism in diabetic complications between B+Cd treatment and B treatment. The results indicate that B alleviates Cd toxicity in winter wheat by inhibiting Cd uptake, increasing antioxidant enzyme activity and changing metabolites.

GABA-mediated inhibition of cadmium uptake and accumulation in apples

GABA, a four-carbon non-protein amino acid, plays an important role in animals and plants. We previously found GABA could alleviate alkali stress in apple seedlings. However, its physiological mechanism under heavy metal cadmium (Cd) stress need to be further studied. Thus, we explored its biological role in response to Cd stress. It was verified that 0.5 mM GABA could effectively alleviate Cd toxicity. Using NMT technique, we found that exogenous GABA could significantly reduce the net Cd2+ fluxes in apple roots, and Cd content was significantly lower than that in roots under Cd stress. Further analysis indicated exogenous GABA could significantly reduce the expression of genes related to the uptake and transport of Cd in apples under Cd stress. In addition, exogenous GABA could significantly increase the content of amino acids in apple roots under Cd stress. GAD is a key enzyme in GABA synthesis, we obtained transgenic apple roots of overexpression MdGAD1. Compared with the control, transgenic roots accumulated less Cd, maintained lower Cd uptake by roots, and lower expression of related transport genes. These results showed that GABA could effectively alleviate Cd toxicity in apple seedlings and provide a new perspective of GABA to alleviate Cd stress.

Selenate regulates the activity of cell wall enzymes to influence cell wall component concentration and thereby affects the uptake and translocation of Cd in the roots of Brassica rapa L

Selenium (Se) can be used to counteract cadmium (Cd) toxicity in plants. However, mechanisms underlying the alleviation of Cd toxicity by Se have not been completely elucidated, especially those by which Se reduces Cd translocation. A hydroponic experiment was performed to illustrate the regulatory mechanisms of Cd transport by selenate (Se (VI)) in pakchoi (Brassica rapa L., LvYou 102). The results showed that this plant had a high accumulation capacity for Cd, and Se(VI) addition restricted Cd translocation from roots to shoots. Se(VI) exposure stimulated the concentrations of pectins and hemicellulose II but reduced the concentration of hemicellulose I in the roots. In many cases, the enzymes pectin methylesterase, polygalacturonase, and β-galactosidase were dose-dependently triggered by Se(VI) under Cd exposure, but root calcium concentration was significantly lowered (p < 0.05). Xyloglucan endoglycosidase (hydrolase) was triggered by Se(VI) under 2 mg L−1 Cd exposure and cellulase was generally activated by Se(VI) under Cd stress. The above results suggest that Se(VI) up-regulates pectin methylesterase activity, stimulates synthesis of pectins, and down-regulates root Ca concentration to release free carboxyl groups to combine Cd. In this study, the relationships between enzyme activity (e.g., peroxidase, superoxidase and β-galactosidase), hydrogen peroxide, cell wall structure strengthening/loosening, and Cd toxicity affected by Se(VI) were also discussed.

Immobilization of cadmium in soil-plant system through soil and foliar applied silicon

We conducted a pot experiment to evaluate the potential for soil- and foliar-applied silicon (Si), alone and in combination, to a Cd-contaminated soil in order to evaluate the effects on such amendments on the Cd translocation from soil to wheat root, shoot and grains. Five treatments were used, T1) control with no external factor added, T2 received only Cd, while T3–T5 treatments received Cd in combination with soil, foliar and soil plus foliar applied Si. Except control (T1), soil was contaminated with Cd at 10 mg kg−1 in all the treatments and 1% solution of Si as an amendment was used for soil and/or foliar application or their combination. Overall, while Si application improved both plant growth and yield in Cd-contaminated soil. Control and combined soil- and foliar-applied Si in Cd contaminated treatments showed equally positive (2.5%) increase in plant height over Cd contaminated treatment. Grain yield was also highest in the treatment receiving Cd plus soil-applied Si (29%) followed by control (26%). It was concluded that Si can alleviate Cd toxicity in wheat irrespective of whether the Si was soil-applied or applied via a foliar method, but soil applied Si proved the best in this regard. Novelty statement Immobilization of metals i.e., cadmium (Cd) with soil-applied amendments like biomaterials and organic manure to decrease Cd concentration in plants have already been widely investigated. Silicon (Si) is a cheap in-organic and readily available element in the nature and also used for the same purpose. It can be applied both in soil as well as by foliar and soil + foliar application to decrease the metals concentration in soil and plants. However, comparative effectiveness of these three methods have not been checked simultaneously. In this study, we have studied the comparative effectiveness of Si application to soil, foliar and their combination (soil + foliar) to decrease Cd concentration during wheat crop.

Copper oxide nanoparticles alleviate cadmium toxicity in cereal crops

Pre-treatment with low concentration of CuO NPs alleviated Cd toxicity in rice and barley, attributing to inhibition of Cd uptake and enhancement of antioxidative capacity, which might be an alternative approach for crops to fight against Cd pollution.

Physiological of biochar and \u03b1-Fe2O3 nanoparticles as amendments of Cd accumulation and toxicity toward muskmelon grown in pots

BackgroundDue to the severe cadmium (Cd) pollution of farmland soil, effective measures need to be taken to reduce the Cd content in agricultural products. In this study, we added α-Fe2O3 nanoparticles (NPs) and biochar into Cd-contaminated soil to investigate physiological responses of muskmelon in the whole life cycle.ResultsThe results showed that Cd caused adverse impacts on muskmelon (Cucumis melo) plants. For instance, the chlorophyll of muskmelon leaves in the Cd alone treatment was reduced by 8.07–32.34% in the four periods, relative to the control. The treatments with single amendment, α-Fe2O3 NPs or 1% biochar or 5% biochar, significantly reduced the soil available Cd content, but the co-exposure treatments (α-Fe2O3 NPs and biochar) had no impact on the soil available Cd content. All treatments could reduce the Cd content by 47.64–74.60% and increase the Fe content by 15.15–95.27% in fruits as compared to the Cd alone treatment. The KEGG enrichment results of different genes in different treatments indicated that single treatments could regulate genes related to anthocyanin biosynthesis, glutathione metabolism and MAPK signal transduction pathways to reduce the Cd toxicity.ConclusionsOverall the combination of biochar and α-Fe2O3 NPs can alleviate Cd toxicity in muskmelon. The present study could provide new insights into Cd remediation in soil using α-Fe2O3 NPs and biochar as amendments.Graphic

Silicon Fertilization: A Step towards Cadmium-Free Fragrant Rice.

Soil contamination with toxic cadmium (Cd) is becoming a serious global problem and poses a key hazard to environments and the health of human beings worldwide. The present study investigated the effects of foliar applications of three forms of silicate chemicals (calcium silicate, sodium silicate, and potassium silicate) at four rates (0.25%, 0.5%, 0.75%, and 1.0%) at tillering stage on rice growth and the accumulation of Cd under Cd stress (30 mg kg−1). The results showed that Cd stress reduced the yield-related traits and enlarged Cd contents in different rice organs. The leaf gas exchange attributes and yield traits were enhanced, and the Cd accumulation and bioaccumulation factor in rice organs were reduced, especially in grains, through silicon application. In shoots, roots, and grains, foliar spray of Si reduced Cd contents by 40.3%, 50.7%, and 47.9%, respectively. The effectiveness of silicate compounds in reducing Cd toxicity varied with the kind of chemicals and doses of foliar applications. Foliar application of potassium silicate, at a rate of 0.5%, at tillering stage, showed the best effectiveness in improving grain yield, while mitigating Cd accumulation in rice grains. The outcome of this study provides a promising practicable approach in alleviating Cd toxicity in rice and preventing the entrance of Cd into the food chain.

Exogenous ascorbic acid application alleviates cadmium toxicity in seedlings of two wheat (Triticum aestivum L.) varieties by reducing cadmium uptake and enhancing antioxidative capacity.

The aggravation of soil cadmium (Cd) pollution is a serious threat to human food health and safety. To reduce Cd uptake and alleviate Cd toxicity in staple food of wheat, a completely random experiment was performed to investigate the effect of exogenous ascorbic acid (AsA) on Cd toxicity in two wheat varieties (L979 and H27). In this study, the treatments with combinations of Cd (0, 5, and 10µmol L-1) and AsA (0, 50, and 200µmol L-1) were applied in a hydroponic system. Toxicity induced by Cd inhibited biomass accumulation; decreased wheat growth, photosynthesis, and chlorophyll content; increased lipid peroxidation; and reduced activity of superoxide dismutase (SOD), but stimulated catalase (CAT) and peroxidase (POD). The addition of AsA significantly improved the growth status by increasing the wheat biomass, chlorophyll content, photosynthetic rate, protein concentrations, and antioxidant enzyme activity. Besides, AsA significantly decreased Cd concentration of shoot and root by 14.1-53.9% and 20.8-59.5% in L979 and 23.7-58.8% and 22.1-58.1% in H27 under Cd5, and 23.7-53.6% and 16.6-57.1% in L979 and 21.5-51.6% and 15.3-54.0% in H27 under Cd10, respectively. Malondialdehyde (MDA) accumulation was decreased remarkably with the addition of AsA by 31.2-32.9% in L979 and 27.1-45.2% in H27 under Cd10, respectively. Overall, exogenous application of AsA alleviated the Cd toxicity in wheat plants by improving the wheat growth, soluble protein content, photosynthesis, and antioxidant defense systems, and decreasing MDA accumulation.

Foliar spray with rutin improves cadmium remediation efficiency excellently by enhancing antioxidation and phytochelatin detoxification of Amaranthus hypochondriacus

Rutin is a flavonoid with strong antioxidative effects on plant metabolism that facilitates resistance to environmental stress. The effect of foliar rutin on cadmium (Cd) uptake in Amaranthus hypochondriacus (K472) was studied. The results showed that a foliar spray of rutin alleviated Cd toxicity, promoted plant growth, improved Cd transfer to and storage in aerial plant parts and Cd accumulation with positive effects over time. A rutin concentration of 1.5 mg/mL showed the strongest promotion effect: the biomass and Cd content were increased at 13 days by 68.62% and 405.54% compared to 3 days, respectively, whereas a high concentration of rutin (5 mg/mL) inhibited plant growth and hindered Cd absorption. Two stages of Cd detoxification were identified in K472 after appropriate rutin application. First, an antioxidant system including an enzymatic antioxidant (superoxide dismutase [SOD]) and nonenzymatic antioxidants (glutathione [GSH] and flavonoids) was activated to enhance plant stress resistance. Quercetin and phytochelatin (PC) synthesis were then enhanced to perform detoxification synergistically with the antioxidant system to improve stress tolerance and achieve stable Cd detoxification. The results demonstrated that appropriately prolonging the application time of exogenous rutin to K472 is an effective way to improve the Cd remediation efficiency.

PSIV-B-22 Comparative effects of nanoparticle-selenium, selenium-enriched yeast and sodium selenite antagonize cadmium-induced cardiotoxicity in chicken (Gallus gallus) via modulating AHR/CAR/PXR/Nrf2 pathways

Abstract Selenium (Se), a nutritionally essential mineral for human and animals, has a significant antagonistic effect on heavy metal cadmium (Cd) biotoxicity. Still, the impact of different Se source on alleviating Cd toxicity has received only limited attention. Therefore, the purpose of the current study was to assess the mitigation level of Cd-induced cardiotoxicity by different sources such as nanoparticles of selenium (Nano-Se), selenium-rich yeast (SY) and sodium selenite (SS). Two hundred of male, 1-day old Hy-Line Variety White chickens were randomly, equally divided into five groups (n = 25). These chicken groups were assigned to (1) basal diet (Con), (2) 140 mg/kg CdCl[2] of basal diet Cd (Cd), (3) 1 mg/kg Nano-Se plus 140 mg/kg CdCl[2] of basal diet (Nano-Se + Cd), (4) 3 mg/kg selenium-enriched yeast plus 140 mg/kg CdCl[2] of basal diet (SY + Cd group), and (5) 3 mg/kg sodium selenite plus 140 mg/kg CdCl[2] of basal diet (SS+ Cd group). The results evidenced that presence of Cd led to a significant increase in biochemical parameters such as lactate dehydrogenase (LDH) and creatine kinase (CK), as well as histopathological lesions in the heart of chickens. Cd exposure also resulted in more extensive effects on phase I metabolism enzymes and transcript CYP isoforms, elevated the levels of MDA and H[2]O[2] and depressed total superoxide dismutase (T-SOD), Cu-Zn SOD, total antioxidant capacity (T-AOC) and catalase (CAT) activities. The expression of nuclear receptors (NRs), AHR, CAR and PXR was declined, down-regulated Nrf2 and its downstream targets in the Cd-treat group. Notably, Se sources application alleviated Cd toxicity by triggering AHR/CAR/PXR/Nrf2 signaling pathway to promote restoring antioxidant defense system and phase I metabolism enzymes system. However, when compared the effectiveness of antagonism, the Nano-Se was superior in relieving Cd-induced cardiotoxicity via AHR/CAR/PXR/Nrf2 pathway activation than other Se- sources.

Comparative physiological and transcriptomic analyses reveal ascorbate and glutathione coregulation of cadmium toxicity resistance in wheat genotypes

BackgroundCadmium (Cd) is a heavy metal with high toxicity that severely inhibits wheat growth and development. Cd easily accumulates in wheat kernels and enters the human food chain. Genetic variation in the resistance to Cd toxicity found in wheat genotypes emphasizes the complex response architecture. Understanding the Cd resistance mechanisms is crucial for combating Cd phytotoxicity and meeting the increasing daily food demand.ResultsUsing two wheat genotypes (Cd resistant and sensitive genotypes T207 and S276, respectively) with differing root growth responses to Cd, we conducted comparative physiological and transcriptomic analyses and exogenous application tests to evaluate Cd detoxification mechanisms. S276 accumulated more H2O2, O2−, and MDA than T207 under Cd toxicity. Catalase activity and levels of ascorbic acid (AsA) and glutathione (GSH) were greater, whereas superoxide dismutase (SOD) and peroxidase (POD) activities were lower in T207 than in S276. Transcriptomic analysis showed that the expression of RBOHA, RBOHC, and RBOHE was significantly increased under Cd toxicity, and two-thirds (22 genes) of the differentially expressed RBOH genes had higher expression levels in S276 than inT207. Cd toxicity reshaped the transcriptional profiling of the genes involving the AsA-GSH cycle, and a larger proportion (74.25%) of the corresponding differentially expressed genes showed higher expression in T207 than S276. The combined exogenous application of AsA and GSH alleviated Cd toxicity by scavenging excess ROS and coordinately promoting root length and branching, especially in S276.ConclusionsThe results indicated that the ROS homeostasis plays a key role in differential Cd resistance in wheat genotypes, and the AsA-GSH cycle fundamentally and vigorously influences wheat defense against Cd toxicity, providing insight into the physiological and transcriptional mechanisms underlying Cd detoxification.

Hydrogen sulphide and salicylic acid regulate antioxidant pathway and nutrient balance in mustard plants under cadmium stress.

Cadmium (Cd), a pervasive noxious heavy metal, is a key threat to agricultural system. It is rapidly translocated and has detrimental effects on plant growth and development. Hydrogen sulphide (H2 S) is emerging as a potential messenger molecule for modulating plant tolerance to Cd. Salicylic acid (SA), a phenolic signalling molecule, can alleviate Cd toxicity in plants. The present study investigated the mediatory role of H2 S (100 µM) and SA (0.5 mM), individually and in combination, in modulating antioxidant defence machinery and nutrient balance to impart Cd (50 µM) resistance to mustard. Accumulation of Cd resulted in oxidative stress (TBARS and H2 O2 ), mineral nutrient imbalance (N, P, K, Ca), decreased leaf gas exchange and PSII efficiency, ultimately reducing plant growth. Both H2 S and SA independently attenuated phytotoxic effects of Cd by triggering antioxidant systems, enhancing the nutrient pool, eventually leading to improved photosynthesis and biomass of mustard plants. The positive effects were more pronounced under combined application of H2 S and SA, indicating a synergistic relationship between these two signalling molecules in mitigating the detrimental effects of Cd on nutrient homeostasis and overall health of mustard, primarily by boosting antioxidant pathway. Our findings provide new insights into H2 S- and SA-induced protective mechanisms in mustard plants subjected to Cd stress and suggest their combined use as a feasible strategy to confer Cd tolerance.

Methyl Jasmonate and Sodium Nitroprusside Jointly Alleviate Cadmium Toxicity in Wheat (Triticum aestivum L.) Plants by Modifying Nitrogen Metabolism, Cadmium Detoxification, and AsA-GSH Cycle.

The principal intent of the investigation was to examine the influence of joint application of methyl jasmonate (MeJA, 10 μM) and a nitric oxide–donor sodium nitroprusside (SNP, 100 μM) to wheat plants grown under cadmium (Cd as CdCl2, 100 μM) stress. Cd stress suppressed plant growth, chlorophylls (Chl), and PSII maximum efficiency (Fv/Fm), but it elevated leaf and root Cd, and contents of leaf proline, phytochelatins, malondialdehyde, and hydrogen peroxide, as well as the activity of lipoxygenase. MeJA and SNP applied jointly or singly improved the concentrations of key antioxidant biomolecules, e.g., reduced glutathione and ascorbic acid and the activities of the key oxidative defense system enzymes such as catalase, superoxide dismutase, dehydroascorbate reductase, glutathione S-transferase, and glutathione reductase. Exogenously applied MeJA and SNP jointly or singly also improved nitrogen metabolism by activating the activities of glutamine synthetase, glutamate synthase, and nitrate and nitrite reductases. Compared with individual application of MeJA or SNP, the combined application of both showed better effect in terms of improving plant growth and key metabolic processes and reducing tissue Cd content, suggesting a putative interactive role of both compounds in alleviating Cd toxicity in wheat plants.Main findingsThe main findings are that exogenous application of methyl jasmonate and nitric oxide–donor sodium nitroprusside alleviated the cadmium (Cd)–induced adverse effects on growth of wheat plants grown under Cd by modulating key physiological processes and up-regulating enzymatic antioxidants and the ascorbic acid–glutathione cycle–related enzymes.

Differential amelioration of cadmium toxicity by sodium nitroprusside and citric acid in Brassica juncea (L.) Czern and Coss

Cadmium (Cd) is a highly toxic heavy metal for the living world. Cd toxicity leads to plants growth retardation; decrease in chlorophyll content, photosynthetic efficiency and food grain quality-quantity due to increased oxidative damage (quantitated in terms of malondialdehyde, MDA content and hydrogen peroxide H 2 O 2 levels) and suppresses the antioxidant defense systems. Through this present investigation, we tried to have an insight into the differential responses due to sodium nitoprusside (SNP, an important source of nitric oxide) and citric acid (CA) in Cd treated mustard seedlings in terms of metal accumulation and stress tolerance in Brassica juncea. Mustard seedlings when treated with Cd in combination SNP and CA in hydroponic culture for three days led to recovery of growth and biomass, suppression of oxidative damage and enhancement in the activities of antioxidant enzymes. The results clearly depict that SNP and CA plays crucial part in alleviation of Cd toxicity in mustard seedlings. Further among the two agents used for amelioration of Cd toxicity, SNP was found to be more efficient than CA. Besides we also observed that SNP reduces the translocation of Cd in above ground portion of mustard plant which might also lead to reduction of Cd accumulation in the edible parts of the plant. • Sodium nitroprusside treatment leads to lesser accumulation of Cd in plants. • Sodium nitroprusside and citric acid both improves photosynthetic efficiency. • Sodium nitroprusside and citric acid enhances the antioxidant enzymatic activities. • Sodium nitroprusside rendered better tolerance to Cd toxicity than citric acid.

Knockout of FER decreases cadmium concentration in roots of Arabidopsis thaliana by inhibiting the pathway related to iron uptake

Identifying the genes that affect cadmium (Cd) accumulation in plants is a prerequisite for minimizing dietary Cd uptake from contaminated edible parts of plants by genetic engineering. This study showed that Cd stress inhibited the expression of FERONIA (FER) gene in the roots of wild-type Arabidopsis. Knockout of FER in fer-4 mutants downregulated the Cd-induced expression of several genes related to iron (Fe) uptake, including IRT1, bHLH38, NRAMP1, NRAMP3, FRO2 andFIT. In addition, the Cd concentration in fer-4 mutant roots reduced to approximately half of that in the wild-type seedlings. As a result, the Cd tolerance of fer-4 was higher. Furthermore, increased Fe supplementation had little effect on the Cd tolerance of fer-4 mutants, but clearly improved the Cd tolerance of wild-type seedlings, showing that the alleviation of Cd toxicity by Fe depends on the action of FER. Taken together, the findings demonstrate that the knockout of FER might provide a strategy to reduce Cd contamination and improve the Cd tolerance in plants by regulating the pathways related to Fe uptake.

Identification of Cd-resistant microorganisms from heavy metal-contaminated soil and its potential in promoting the growth and Cd accumulation of bermudagrass

Phytoremediation has been increasingly used as a green technology for the remediation of heavy metal contaminated soils. Microorganisms could enhance phytoremediation efficiency by solubilizing heavy metal and improve plant growth by producing phytohormones in the heavy metal contaminated soils. In this study, we investigated the abundance and composition of soil microbial communities in heavy metal contaminated soils. Furthermore, we identified a Cd-resistant fungal strain Penicillium janthinellum ZZ-2 and assessed its potential in improving plant growth, Cd accumulation and Cd tolerance in bermudagrass. The results indicated that long-term heavy metal pollution decreased microbial biomass and activity by inhibiting microbial community diversity, but did not significantly affect community composition. Mainly, the relative abundance of some specific bacterial and fungal taxa, such as Actinobacteria, Chloroflexi, Bacteroidetes, Ascomycota and Basidiomycota, changes under metal pollution. Furthermore, at genus level, certain microbial taxa, such as Pseudonocardiaceae, AD3, Latescibacteria, Apiotrichum and Paraboeremia, only exist in polluted soil. One Cd-resistant fungus ZZ-2 was isolated and identified as Penicillium janthinellum. Further characterization revealed that ZZ-2 had a greater capacity for Cd2+ absorption, produced indole-3-acid (IAA), and facilitated plant growth in the presence of Cd. Interestingly, ZZ-2 inoculation significantly increased Cd uptake in the stem and root of bermudagrass. Thus, ZZ-2 could improve plant growth under Cd stress by reducing Cd-toxicity, increasing Cd uptake and producing IAA. This study suggests a novel fungus-assisted phytoremediation approach to alleviate Cd toxicity in heavy metals contaminated soils.

Dark septate endophyte Falciphora oryzae-assisted alleviation of cadmium in rice

Dark septate endophytes (DSEs) are the typical representatives of root endophytic fungi in heavy metal (HM)-contaminated environments. However, little is known about their roles in the HMs tolerance of hosts and the underlying mechanism. Here, we investigated the biological roles and molecular mechanisms of a DSE strain Falciphora oryzae in alleviating cadmium (Cd) toxicities in rice. It was found that F. oryzae possessed a capacity of accumulating Cd in its vacuoles and chlamydospores. During symbiosis, F. oryzae conferred improved Cd tolerance to rice, decreasing Cd accumulation in roots and translocation to shoots. F. oryzae alleviated Cd toxicity to rice by sequestering Cd in its vacuoles. Further application of F. oryzae as fertilizer in the field could reduce Cd content in rice grains. We identified a SNARE Syntaxin 1 gene through proteomics, which participated in Cd tolerance of F. oryzae by regulating chlamydospore formation and vacuole enlargement. This study provided novel insights into how the DSEs and their host plants combat Cd stress.

Exogenous Glutathione Alleviates Cadmium Toxicity in Wheat by Influencing the Absorption and Translocation of Cadmium

Cadmium (Cd), a toxic heavy metal, is harmful to plants and human health. Glutathione (GSH) could alleviate Cd toxicity of plant species, whereas its mechanism responsible for wheat remains poorly understood. Here, we found that exogenous GSH application significantly increased the fresh and dry weight, root elongation, chlorophyll contents, while decreased the contents of malondialdehyde (MDA) and GSH, and translocation factor of Cd compared with Cd treatment. Moreover, GSH application significantly increased activities of antioxidant enzymes and expression of related genes, which involved in GSH synthesis, especially in roots. In addition, we found that GSH application suppressed Cd-induced expression of metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1 and TaIRT2 in roots. Taken together, our results suggested that GSH could alleviate Cd toxicity in wheat by increasing GSH synthesis gene expression or suppressing Cd transporter genes expression, and further affecting Cd uptake and translocation in wheat plants.