Search

Soil cadmium (Cd) contamination has emerged as a significant global environmental concern, posing numerous risks to individual organisms and entire ecosystems. Concurrently, the global increase in pesticide usage has elevated the influx of chloride ions (Cl-) into the soil. Given Cl-'s robust ability to coordinate and complex with various heavy metal ions, understanding its influence on the migration and transformation of Cd in soil-rice systems is essential for the rational application of pesticides and the effective mitigation of soil heavy metal pollution. In this paper, we explained the effect of Cl- on the environmental behavior of Cd in the soil-rice system in terms of growth traits, Cd uptake and accumulation by rice, and Cd solid-solution phase interface behavior through pot experiments and sand culture experiments. The results showed that Cd concentrations in all parts of the rice treated with CaCl2 during the filling period were lower than those in the Ca(NO3)2-treated group, with Cd accumulation diminishing as Cl- concentration increased. This suggests that the filling period is critical for Cd uptake and accumulation in rice. Unlike the accompanying anion NO3 -, exogenous Cl- reduced Cd concentrations in the soil solution but increased them in rice. Notably, when the Cd/Cl ratio ranged from 0.625 to 2.5, Cl- formed predominantly CdCl+-complexes with free Cd2+ in the soil solution, enhancing the mobilization of Cd bound to soil particles and its subsequent absorption by rice. This study aims to assess Cl-'s effect on Cd migration and transformation in soil-rice systems, providing insights for safe rice production on Cd-contaminated soils and rational use of chlorine-containing pesticides. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), which accumulates in tobacco leaves, enters the human body through inhalation of smoke, causing harmful effects on health. Therefore, identifying the pivotal factors that govern the absorption and resistance of Cd in tobacco is crucial for mitigating the harmful impact of Cd. In the present study, four different Cd-sensitive varieties, namely, ZhongChuan208 (ZC) with resistance, ZhongYan100 (ZY), K326 with moderate resistance, and YunYan87 (YY) with sensitivity, were cultivated in hydroponic with different Cd concentrations (20 µM, 40 µM, 60 µM and 80 µM). The results indicated that plant growth was significantly decreased by Cd. Irrespective of the Cd concentration, ZC exhibited the highest biomass, while YY had the lowest biomass; ZY and K326 showed intermediate levels. Enzymatic (APX, CAT, POD) and nonenzymatic antioxidant (Pro, GSH) systems showed notable variations among varieties. The multifactor analysis suggested that the ZC and ZY varieties, with higher levels of Pro and GSH content, contribute to a decrease in the levels of MDA and ROS. Among all the Cd concentrations, ZC exhibited the lowest Cd accumulation, while YY showed the highest. Additionally, there were significant differences observed in Cd distribution and translocation factors among the four different varieties. In terms of Cd distribution, cell wall Cd accounted for the highest proportion of total Cd, and organelles had the lowest proportion. Among the varieties, ZC showed lower Cd levels in the cell wall, soluble fraction, and organelles. Conversely, YY exhibited the highest Cd accumulation in all tissues; K326 and ZY had intermediate levels. Translocation factors (TF) varied among the varieties under Cd stress, with ZC and ZY showing lower TF compared to YY and K326. This phenomenon mainly attributed to regulation of the NtNramp3 and NtNramp5 genes, which are responsible for the absorption and transport of Cd. This study provides a theoretical foundation for the selection and breeding of tobacco varieties that are resistant to or accumulate less Cd.

Introduction: Cadmium (Cd) is a highly toxic heavy metal which contaminates agricultural soils and is easily absorbed by plants. Brassica rapa L. is one of the most popular vegetables in China and is known to accumulate Cd in its roots and aerial tissues. Methods: A highly Cd-resistant bacterium (‘CD2’) was isolated and identified. Its ability to immobilize Cd(II) in medium was studied. Strain CD2 were added into Cd-polluted soil to ameliorate Cd accumulation in B. rapa. The underlying mechanisms of ‘CD2’ to reduce Cd accumulation in B. rapa. were analyzed by transcriptomics. Results and discussion: Strain CD2 was classified as belonging to the genus Stenotrophomonas. Strain CD2 was found to be able to remove 0.1 mmol/L Cd(II) after 36 h by intracellular sequestration and by producing biofilm, exopolysaccharide, and H2S. When applied to Cd-contaminated soil, ‘CD2’ significantly increased the content of nonbioavailable Cd by 212.70%. Furthermore, ‘CD2’-inoculated B. rapa exhibited a 51.16% decrease in the Cd content of roots and a 55.56% decrease in the Cd content of aerial tissues. Transcriptome analysis identified 424 differentially expressed genes (DEGs) in the roots and 501 DEGs in the aerial tissues of uninoculated Cd-exposed plants. By comparison, 1107 DEGs were identified in the roots and 1721 DEGs were identified in the aerial tissues of ‘CD2’-inoculated Cd-exposed plants. In both treatment groups, genes related to vacuolar sequestration were upregulated, resulting in inhibited Cd transport. In addition, both catalase and glutathione transferase were induced in uninoculated plants, while the oxidative stressrelated genes CPK and RBOH belonged to ‘plant-pathogen interactions’ were upregulated in ‘CD2’-inoculated plants. Moreover, inoculation with ‘CD2’ resulted in the enrichment of phenylpropane metabolism; cutin, suberine, and wax biosynthesis; and the AP2, Dof, WOX, Trihelix, B3, EIL, and M-type_MADS transcription factors; as well as the downregulation of zinc transporters and blue copper proteins. All of these changes likely contributed to the reduced Cd accumulation in ‘CD2’-inoculated B. rapa. The results of this study suggest that Stenotrophomonas sp. CD2 may prove to be a useful inoculant to prevent Cd accumulation in B. rapa. [ABSTRACT FROM AUTHOR]

【Objective】The study aimed to explore the effects of biochar combined with nitrogen on morphological characteristics, root morphology, antioxidant activity, photosynthetic characteristics and Cd accumulation, accumulation and transport of Paulownia fortunei seedlings under Cd stress. 【Method】Taking ‘Paulownia fortunei 1201’ seedlings as materials, a combination of tissue culture and hydroculture tests was set up. The growth index, root parameters, photosynthetic gas parameters, antioxidant enzyme activity, MDA content, Cd accumulation, enrichment coefficient and transport coefficient of seedlings were measured by biochar and nitrogen single treatment and biochar combined with nitrogen treatment. 【Result】 (i) Under Cd stress, application of biochar and nitrogen could significantly increase plant height, biomass and root parameters, and their combination could achieve the optimal effect. (ii) SOD and CAT activities increased and MDA activities decreased in leaves and roots of Paulownia fortunei seedlings, POD activity decreased with increasing concentration under single application of biochar and nitrogen, and slightly increased with increasing concentration under combined application of biochar and nitrogen. (iii) Chla, Chlb and Chl (a+b) increased significantly, but Chl (a/b) had no significant change; Photosynthetic gas parameters (Pn, Tr, Ci, Gs) increased, WUE was the highest, and Ls decreased significantly. (iv) With the application of biochar or nitrogen, the Cd content and enrichment coefficient of Paulownia fortunei seedlings decreased, while the transport coefficient and Cd accumulation increased. (v) According to the correlation and PCA analysis of each index of seedlings, it was found that there was correlation among each index, and the overall promoting effect was biochar combined with nitrogen ＞ biochar ＞ nitrogen.【Conclusion】The application of biochar and nitrogen can improve the photosynthetic capacity of Paulownia fortunei seedlings, reduce the absorption of Cd, alleviate the toxicity of Cd, and then increase the biomass and promote the accumulation of Cd in various organs. [ABSTRACT FROM AUTHOR]

The utilization of the thin film gradient diffusion technique has been on the rise for appraising the efficacy of soil cadmium (Cd). Nonetheless, in contrast to conventional methodologies employed to gauge the efficacy of soil Cd, there exists a dearth of adequate research concerning whether the technique of diffusive gradients in thin films (DGT) can furnish a more precise and all-encompassing evaluation of soil Cd effectiveness in soil passivation and remediation procedures. Herein, this study selects four popular amendments (i.e. oyster shells, red mud, hydroxyapatite and biochar) and analyses the correlations among soil Cd availability, Cd uptake amount and spinach biomass. Results showed that the following concentration ranges: DGT-Cd (1.78-21.1 µg L-1), HAc-Cd (1.84-2.22 mg kg-1), DTPA-Cd (0.62-1.22 mg kg-1) and CaCl2-Cd (0.0489-0.103 mg kg-1). Among the methods, CaCl2 extraction had a lower capacity to extract soil Cd compared with the other methods. These amendments improved soil environment, promoted spinach growth and decreased plant Cd concentrations. Oyster shells and red mud treatments significantly reduced DGT-Cd levels (by 90.4% and 82.2%, respectively), which led to a reduction in plant Cd concentrations (by 77.1% and 72.4%) and bioconcentration factor (by 75.8% and 68.8%). Furthermore, oyster shells were found to be most effective in reducing soil-available Cd and inhibiting Cd uptake by spinach. Based on correlation analysis, the DGT method showed the largest measurement range and provided the best prediction of Cd accumulation in spinach compared with chemical extraction methods (R2 = .88, p <.001). Overall, the use of DGT in combination with plant uptake and chemical extraction data can provide a comprehensive assessment of soil Cd bioavailability. These findings facilitate an accurate and comprehensive evaluation of the bioavailability of Cd after applying amendments. These results also showed that oyster shells can be regarded as a promising eco-friendly and low-cost amendment for large-scale immobilizing Cd and producing plants with lesser Cd concentrations. [ABSTRACT FROM AUTHOR]

In plants, expansin genes are responsive to heavy metal exposure. To study the bioremediary potential of this important gene family, we discovered a root-expressed expansin gene in sorghum, SbEXPA11, which is notably upregulated following cadmium (Cd) exposure. However, the mechanism underlying the Cd detoxification and accumulation mediated by SbEXPA11 in sorghum remains unclear. We overexpressed SbEXPA11 in sorghum and compared wild-type (WT) and SbEXPA11-overexpressing transgenic sorghum in terms of Cd accumulation and physiological indices following Cd. Compared with the WT, we found that SbEXPA11 mediates Cd tolerance by exerting reactive oxygen species (ROS)-scavenging effects through upregulating the expression of antioxidant enzymes. Moreover, the overexpression of SbEXPA11 rescued biomass production by increasing the photosynthetic efficiency of transgenic plants. In the pot experiment with a dosage of 10 mg/kg Cd, transgenic sorghum plants demonstrated higher efficacy in reducing the Cd content of the soil (8.62 mg/kg) compared to WT sorghum plants (9.51 mg/kg). Subsequent analysis revealed that the SbbHLH041 transcription factor has the ability to induce SbEXPA11 expression through interacting with the E-box located within the SbEXPA11 promoter. These findings suggest that the SbbHLH041–SbEXPA11 cascade module may be beneficial for the development of phytoremediary sorghum varieties. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) pollution threatens food security and the environment. Willow species (Salix, Salicaceae) exhibit a remarkable potential to restore Cd-polluted sites due to their high biomass production and high Cd accumulation capacities. This study examined the Cd accumulation and tolerance in 31 genotypes of shrub willow in hydroponic conditions at varying Cd levels (0 μM Cd, 5 μM Cd, and 20 μM Cd). The root, stem, and leaf biomass of 31 shrub willow genotypes showed significant differences to Cd exposure. Among 31 willow genotypes, four patterns of biomass variation response to Cd were identified: insensitive to Cd; growth inhibition due to excessive Cd supply (high Cd inhibition); low Cd causing inhibited growth, whereas high Cd leading to increased biomass (U-shape); and growth increment with excessive Cd exposure (high Cd induction). The genotypes belonging to the "insensitive to Cd" and/or "high Cd induction" were candidates for the utilization of phytoremediation. Based on the analysis of Cd accumulation of 31 shrub willow genotypes at high and low Cd levels, genotypes 2372, 51–3, and 1052 obtained from a cross between S. albertii and S. argyracea grew well and accumulated relatively more Cd levels than other genotypes. In addition, for Cd-treated seedlings, root Cd accumulation was positively correlated with shoot Cd accumulation and total Cd uptake, demonstrating that Cd accumulation in roots could serve as a biomarker for evaluating the Cd extraction capacity of willows, especially in hydroponics screening. The results of this study screened out willow genotypes with high Cd uptake and translocation capacities, which will provide valuable approaches for restoring Cd-contaminated soils with willows. [ABSTRACT FROM AUTHOR]

Heavy metal ions, in particular cadmium (Cd), have a negative impact on the growth and productivity of major crops, including wheat. The use of environmentally friendly approaches, in particular, bacteria that have a growth-stimulating and protective effect, can increase the resistance of plants. The effects of the pre-sowing seed treatment with the plant growth-promoting endophyte Bacillus subtilis 10-4 (BS) on cadmium acetate (Cd)-stressed Triticum aestivum L. (wheat) growth, photosynthetic pigments, oxidative stress parameters, roots' lignin content, and Cd ions accumulation in plants were analyzed. The results showed that the tested Cd-tolerant BS improved the ability of wheat seeds to germinate in the presence of different Cd concentrations (0, 0.1, 0.5, and 1 mM). In addition, the bacterial treatment significantly decreased the damaging effects of Cd stress (1 mM) on seedlings' linear dimensions (lengths of roots and shoots), biomass, as well as on the integrity and permeability of the cell walls (i.e., lipid peroxidation and electrolyte leakage) and resulted in reduced H2O2 generation. The pretreatment with BS prevented the Cd-induced degradation of the leaf photosynthetic pigments chlorophyll (Chl) a, Chl b, and carotenoids. Moreover, the bacterial treatment intensified the lignin deposition in the roots under normal and, especially, Cd stress conditions, thereby enhancing the barrier properties of the cell wall. This manifested in a reduced Cd ions accumulation in the roots and in the restriction of its translocation to the aboveground parts (shoots) of the bacterized plants under Cd stress in comparison with non-bacterized controls. Thus, the pre-sowing seed treatment with the endophyte BS may serve as an eco-friendly approach to improve wheat production in Cd-contaminated areas. [ABSTRACT FROM AUTHOR]

Screening high-tolerant microorganisms to cadmium (Cd) and revealing their bio-obstruction mechanism could be significant for Cd regulation from farmland to the food chain. We examined the tolerance and bio-removal efficiency of Cd ions of two bacterial strains, Pseudomonas putida 23483 and Bacillus sp. GY16, and measured the accumulation of Cd ions in rice tissues and its different chemical forms in soil. The results showed that the two strains had high tolerance to Cd, but the removal efficiency was decreased successively with increasing Cd concentrations (0.05 to 5mg kg-1). Cell-sorption accounted for the major proportion of Cd removal compared with excreta binding in both strains, which was conformed to the pseudo-second-order kinetics. At the subcellular level, Cd was mostly taken up by the cell mantle and cell wall, and only a small amount entered into the cytomembrane and cytoplasmic with time progressed (0 to 24 h) in each concentration. The cell mantle and cell wall sorption decreased with increasing Cd concentration, especially in the cytomembrane and cytoplasmic. The scanning electron microscope (SEM) and energy dispersive X-ray (EDS) analysis verified that Cd ions were attached to the cell surface, and the functional groups of C-H, C-N, C=O, N-H, and O-H in the cell surface may participate in cell-sorption process tested by the FTIR analysis. Furthermore, inoculation of the two strains significantly decreased Cd accumulation in rice straw and grain but increased in the root, increased Cd enrichment ratio in root from soil, decreased Cd translocation ratio from root to straw and grain, and increased the Cd concentrations of Fe--Mn binding form and residual form in rhizosphere soil. This study highlights that the two strains mainly removed Cd ions in solution through biosorption and passivated soil Cd as Fe--Mn combined form ascribe to its characteristics of manganese-oxidizing, eventually achieving bio-obstruction of Cd from soil to rice grain. [ABSTRACT FROM AUTHOR]

The effect of sodium chloride (NaCl) on cadmium (Cd) tolerance, uptake, translocation, and compartmentation was investigated in 3 barley genotypes. Seedlings were cultivated hydroponically in the absence of NaCl and Cd (control), in the presence of 50 mM NaCl alone, in the presence of 10 µM Cd alone, and in the combined addition of NaCl (50 mM) and Cd (10 µM). Plants were cultivated during one month under 16 h light period at a minimal light intensity of 250 µmol m−2 s−1, a temperature of 25 ± 3 °C, and 70–80% of relative humidity. Results showed that NaCl alone did not significantly affect plant development and biomass production; however, Cd alone reduced plant development rate leading to a decline in biomass production in Raihane and Giza 127 but did not affect that in Amalou. NaCl addition in Cd-treated plants accentuated the Cd effect on plant growth. NaCl limited Cd accumulation in the roots and in the shoots in all tested barley varieties by reducing Cd-absorption efficiency and the translocation of Cd from the root to the shoot. In all Cd-treated plants, cell Cd compartmentalization showed the following gradient: organelles < cell wall < vacuole. NaCl in the medium increased Cd accumulation in the soluble fraction and reduced that in organelle and cell wall fractions. Globally our results showed that, although NaCl reduces Cd accumulation in barley, it accentuates the Cd toxic effects, hence limiting the plant yield. We advise farmers to avoid barley cultivation near mine sites and its irrigation with moderately salty water, although this plant is considered as salt tolerant. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cadmium (Cd) contamination in farmland is a serious environmental and safety issue affecting plant growth, crop productivity, and human health. This study aimed to investigate genotypic variation in root morphology and Cd accumulations under moderate Cd stress among diverse maize genotypes. Twenty maize genotypes with contrasting root systems were assessed for Cd tolerance 39 days after transplanting (V6, six‐leaf stage) under 20 μmol L−1 CdCl2 using a semi‐hydroponic phenotyping platform in a glasshouse. RESULTS: Cadmium stress significantly inhibited plant growth across all genotypes. Genotypic variation in response to Cd toxicity was apparent: shoot dry weight varied from 0.13 (genotype NS2020) to 0.35 g plant−1 (Dongke301) with deductions up to 63% compared with non‐Cd treatment (CK). Root dry weight of 20 genotypes ranged from 0.06 (NS2020) to 0.18 g plant−1 (Dongke301) with a deduction up to 56%. Root length ranged from 2.21 (NS590b) to 9.22 m (Dongke301) with a maximal decline of 76%. Cadmium‐treated genotypes generally had thicker roots and average diameter increased by 34% compared with CK. Genotypes had up to 3.25 and 3.50 times differences in shoot and root Cd concentrations, respectively. Principal component and cluster analyses assigned the 20 genotypes into Cd‐tolerant (five genotypes) and Cd‐sensitive (15 genotypes) groups. CONCLUSIONS: Maize genotypes varied significantly in response to moderate Cd stress. Cadmium‐tolerant genotypes optimized root morphology and Cd accumulation and distribution. This study could assist in the selection and breeding of new cultivars with improved adaptation to Cd‐contaminated soil for food and feed or land remediation purposes. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) pollution and uptake into the grains of developing rice plants represent a major threat to human health. Studies of specific genes can offer new insights into the functional roles of particular genes, highlighting candidate alleles that can be leveraged as DNA markers. Accordingly, the identification of novel Cd-related traits and sequence variants can provide new molecular markers for Cd resistance in rice. In the present study, a genetic diversity analysis was carried out on 85 rice varieties exhibiting varied Cd accumulation, and 436 single polymorphic sites (SNP) corresponding to 43 haplotypes were detected across 12 Cd-associated genes (CAL1, OsCADT1, Oscd1, OsHMA4, OsHMA9, OsNRAMP1, OsNRAMP2, OsNRAMP5, OsHMA2, OsHSMA3, OsPCR1, and OsABCG43). By utilizing the information of the SNPs, 85 rice varieties was classified the into 2 clusters with different source categories and Cd contents. Among the variants, 45 sites in 5 genes were significantly associated with the Cd content in rice grains, of which 8 alleles in OsPCR1, CAL1, and Oscd1 were negatively correlated with Cd accumulation. The results of haplotype aggregation analysis for OsPCR1, Oscd1, and CAL1 showed that 85 rice varieties were divided into 5 clusters. Interestingly, most of the varieties in Cluster A belonged to tropical type, which contained the aggregation of three favorable alleles, whereas the temperate varieties constituted the majority of Cluster B lacking favorable alleles. This observation suggests that the allelic combination found in tropical rice varieties may hold promise for reducing Cd accumulation levels in rice grains. The Cd-associated alleles identified in the present study can not only be used to check the Cd tolerance of rice varieties, but also serve as functional molecular markers to differentiate the source of the rice varieties, which provides a better understanding of the relationship between the sequence variation in Cd-related genes and Cd accumulation in rice. [ABSTRACT FROM AUTHOR]

High levels of cadmium (Cd) in soil can cause crop yield reduction or death. Cadmium accumulation in crops affects human and animal health as it passes through the food chain. Therefore, a strategy is needed to enhance the tolerance of crops to this heavy metal or reduce its accumulation in crops. Abscisic acid (ABA) plays an active role in plants' response to abiotic stress. The application of exogenous ABA can reduce Cd accumulation in shoots of some plants and enhance the tolerance of plants to Cd; therefore, ABA may have good application prospects. In this paper, we reviewed the synthesis and decomposition of ABA, ABA-mediated signal transduction, and ABA-mediated regulation of Cd-responsive genes in plants. We also introduced physiological mechanism underlying Cd tolerance because of ABA. Specifically, ABA affects metal ion uptake and transport by influencing transpiration and antioxidant systems, as well as by affecting the expression of metal transporter and metal chelator protein genes. This study may provide a reference for further research on the physiological mechanism of heavy metal tolerance in plants. [ABSTRACT FROM AUTHOR]

In this study, acrylic acid and acrylamide were used as synthetic monomers, N, N′ methylene bisacrylamide was used as a crosslinking agent to synthesize a functional superabsorbent polymer (SAP). The effects of SAP on available Cd, soil quality, growth, and Cd accumulation of pakchoi plants were investigated. Soil incubation experiment showed that adding 0.3% SAP had better effect in decreasing bioavailable Cd in soil than other applied dosage, and the content of available Cd in acid soil and alkaline soil decreased by 28.13–40.88% and 27.92–50.20%, respectively. Meanwhile, addition of SAP increased the pH of both soils. The pot experiment indicated that the content of available N, P, and K in acid soil and available N in alkaline soil was elevated, the content of water stable macro-aggregates was enriched, and soil urease, catalase, and sucrase activity was improved, indicating a better soil quality achieved upon SAP application. Besides, SAP addition improved the dry mass of the root and shoot of pakchoi plants by 35.29% and 14.41%, and 33.06% and 9.23%, in acidic and alkaline soils, respectively. Meanwhile, Cd in the edible part of pakchoi grown in acid soil and alkaline soil decreased by 20.53% and 31.38%, respectively. Taken together, application of SAP not only reduces the content of available Cd in soil and decreases Cd accumulation in plants, but also improves soil fertility and soil structure, which thus could be used for Cd remediation and soil quality improvement. [ABSTRACT FROM AUTHOR]

Selection of sunflower varieties with greater cadmium (Cd) tolerance and detecting physiological variation under different Cd concentrations are important to study the potential of sunflower (Helianthus annuus L.) in the phytoremediation of Cd. The aim of this study was to investigate the variation in the Cd tolerance among four sunflower varieties (79−79, 363, 8361, ADT). Photosynthesis was determined using a Li−6400 XT portable photosynthesis system. Inductively coupled plasma mass spectrometry was used to detect the accumulation of Cd in different plant parts (leaf, stem and root). Subsequently, the Cd amount per plant, bio−concentration factor (BCF), and translocation factor (TF) were calculated. Cd exposure caused a decline in photosynthesis in four sunflower varieties. The 79−79 species displayed the highest Cd concentrations in tissues and 363 displayed a higher BCF in aerial parts under Cd exposure among the four species. Under Cd stress, the total soluble sugars in roots remained unaffected in 363. Based on the results of this experiment, the cultivar of 79−79 and 363 were more tolerant to Cd when compared to the other sunflower cultivars ADT and 8361. The present investigation results indicate that 79−79 and 363 can be further applied in the field trials of phytoremediation practices in contaminated soil. [ABSTRACT FROM AUTHOR]

Biochar has been widely applied to remediate heavy metal-contaminated soils, but the environmental risk of the endogenous pollutants in biochar remains unclear. Two biochars with different endogenous cadmium (Cd) concentrations were prepared from background soil (BCB) and contaminated soil (BCC), respectively. We studied the effects of simulated acid rain (SAR) on the activation mechanism of endogenous Cd in biochar and Cd uptake of Cd by lettuce from the biochar-amended soils. SAR aging significantly increased Cd bioavailability by 27.5 % and 53.9 % in BCB and BCC, respectively. The activation of Cd from biochar may be due to the decrease of biochar pH and persistent free radicals (PFRs) and the increase of specific surface area (SSA) and O-contained functional groups in biochars. Two biochars at dosages of 2 % and 5 % rates did not change soil pore water Cd, but BCB and BCC at 10 % increased pore water Cd by 17.3 % and 219 %, respectively after SAR aging. SAR aging significantly increased the bioavailability of Cd in BCB and BCC treated soils than those before SAR aging. BCB application enhanced the biomass of lettuce (Lactuca sativa L.) and decreased the uptake of Cd. However, BCC addition at 10 % decreased the biomass of lettuce and increased the accumulation of Cd. In summary, endogenous Cd in biochar from contaminated soils has a potential environmental risk to plants and human health and the negative effects of endogenous pollutants from the biochars should be further investigated.

Most studies have shown that foliar silicon (Si) spraying can reduce the risk of rice quality safety caused by cadmium (Cd) contamination. However, it has recently been found that different rice varieties have different responses to Si. Therefore, we selected six rice varieties (YHSM, YXY1179, YXYLS, JLK1377, MXZ2, and YLY900) to compare the differences in the effects of leaf spray on Cd accumulation among different varieties. According to the change in Cd content in brown rice after Si application, the six rice varieties were divided into two types: Si-inhibited varieties (JLY1377, MXZ2, LY900, and YXYLS) and Sistimulated varieties (WY1179 and YHSM). For Si-inhibited varieties, the Cd content of rice was reduced by 13.5%–65.7% after Si application. At the same time, the Cd content of the root, stem, leaf, panicle, and glume decreased to different degrees, the Cd content of the cell wall component increased by 2.2%–37.6%, the extraction state of Cd with strong mobile activity (ethanolextracted and deionized water-extracted) was changed to the extraction state of Cd with weak mobile activity (acetic acid-extracted and hydrochloric acidextracted), and the upward transport coefficient of different parts was reduced. For Si-stimulated varieties, Si application increased the Cd content of rice by 15.7%–24.1%. At the same time, the cell soluble component Cd content significantly increased by 68.4%–252.4% and changed the weakly mobile extraction state Cd to the strong mobile extraction state, increasing the upward transport coefficient of different sites. In conclusion, different rice varieties have different responses to Si. Foliar Si spraying inhibits the upward migration of Cd of Si-inhibited varieties, thereby reducing the Cd content of rice, but it has the opposite effect on Si-stimulated varieties. This result reminds us that we need to consider the difference in the effect of varieties in the implementation of foliar Si spraying in remediation of Cd-contaminated paddy fields. [ABSTRACT FROM AUTHOR]

Soybean is an important source of plant protein used in human diets. Cadmium (Cd) from agricultural soil is a toxic metal for plants, including soybean. Furthermore, the cadmium is taken up to seeds of soybean and becomes a risk for animals and human by feed and food chain. A method to avoid this risk is represented by the selection and breeding soybean lines/cultivars with genetic potential to minimized cadmium accumulation. This work reports an approach assisted by DNA-markers for selection of soybean cultivars with low Cd-accumulation. In this study, we screened the alleles of Cda1 gene, in 22 soybean cultivars, using three DNA markers (SSR-Sack149, Gm-dCAPS-HMA1 and Cda1-KASP). The results showed that 11 genotypes carried the allele for low cadmium accumulation, 8 genotypes had the allele for high cadmium accumulation and three genotypes were heterozygous/heterogenous. All three markers classified the soybean genotypes in the same manner but KASP marker is more efficient in marker-assisted selection/breeding for Cda1. This study offers valuable information to breeders and other researches regarding the selection of soybean germplasm with low cadmium accumulation in the pursuit of reducing the Cd-accumulation and assuring the food safety worldwide. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a highly toxic heavy metal that readily enters cereals, such as wheat, via the roots and is translocated to the shoots and grains, thereby posing high risks to human health. However, the vast and complex genome of allohexaploid wheat makes it challenging to understand Cd resistance and accumulation. In this study, a Cd-resistant cultivar of wheat, 'ZM1860', and a Cd-sensitive cultivar, 'ZM32', selected from a panel of 442 accessions, exhibited significantly different plant resistance and grain accumulation. We performed an integrated comparative analysis of the morpho-physiological traits, ionomic and phytohormone profiles, genomic variations, transcriptomic landscapes, and gene functionality in order to identify the mechanisms underlying these differences. Under Cd toxicity, 'ZM1860' outperformed 'ZM32', which showed more severe leaf chlorosis, poorer root architecture, higher accumulation of reactive oxygen species, and disordered phytohormone homeostasis. Ionomics showed that 'ZM32' had a higher root-to-shoot translocation coefficient of Cd and accumulated more Cd in the grains than 'ZM1860'. Whole-genome re-sequencing (WGS) and transcriptome sequencing identified numerous DNA variants and differentially expressed genes involved in abiotic stress responses and ion transport between the two genotypes. Combined ionomics, transcriptomics, and functional gene analysis identified the plasma membrane-localized heavy metal ATPase TaHMA2b-7A as a crucial Cd exporter regulating long-distance Cd translocation in wheat. WGS- and PCR-based analysis of sequence polymorphisms revealed a 25-bp InDel site in the promoter region of TaHMA2b-7A , and this was probably responsible for the differential expression. Our multiomics approach thus enabled the identification of a core transporter involved in long-distance Cd translocation in wheat, and it may provide an elite genetic resource for improving plant Cd resistance and reducing grain Cd accumulation in wheat and other cereal crops. [ABSTRACT FROM AUTHOR]

Zinc (Zn)-regulated and iron (Fe)-regulated transporter-like proteins (ZIP) are key players involved in the accumulation of cadmium (Cd) and Zn in plants. Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (S. plumbizincicola) is a Crassulaceae Cd/Zn hyperaccumulator found in China, but the role of ZIPs in S. plumbizincicola remains largely unexplored. Here, we identified 12 members of ZIP family genes by transcriptome analysis in S. plumbizincicola and cloned the SpZIP2 gene with functional analysis. The expression of SpZIP2 in roots was higher than that in the shoots, and Cd stress significantly decreased its expression in the roots but increased its expression in leaves. Protein sequence characteristics and structural analysis showed that the content of alanine and leucine residues in the SpZIP2 sequence was higher than other residues, and several serine, threonine and tyrosine sites can be phosphorylated. Transmembrane domain analysis showed that SpZIP2 has the classic eight transmembrane regions. The evolutionary analysis found that SpZIP2 is closely related to OsZIP2, followed by AtZIP11, OsZIP1 and AtZIP2. Sequence alignment showed that most of the conserved sequences among these members were located in the transmembrane regions. A further metal sensitivity assay using yeast mutant Δyap1 showed that the expression of SpZIP2 increased the sensitivity of the transformants to Cd but failed to change the resistance to Zn. The subsequent ion content determination showed that the expression of SpZIP2 increased the accumulation of Cd in yeast. Subcellular localization showed that SpZIP2 was localized to membrane systems, including the plasma membrane and endoplasmic reticulum. The above results indicate that ZIP member SpZIP2 participates in the uptake and accumulation of Cd into cells and might contribute to Cd hyperaccumulation in S. plumbizincicola. [ABSTRACT FROM AUTHOR]

SUMMARY: Genetic variation is an important determinant of gene transcription, which in turn contributes to functional and phenotypic diversity. Identification of the genetic variants controlling gene expression and alternative splicing in crops responding to cadmium (Cd), an important issue for food safety and human health, is of great value to improve our understanding of Cd accumulation‐related genes. Here we report an in‐depth survey of population‐level transcriptome variation of barley (Hordeum vulgare) core accessions under Cd exposure. We reveal marked transcriptomic changes in response to Cd exposure, and these are largely independent of tissues. A genome‐wide association study (GWAS) revealed 59 498 expression quantitative trait loci (eQTLs) and 23 854 splicing quantitative trait loci (sQTLs), leading to a complex network that covers 66.6% of the expressed genes, including 68 metal transporter genes. On average, 41.0% of sQTLs overlapped with eQTLs across different tissues, indicating that these two dimensions of transcript variation are largely independent. Moreover, we found that 34.5% of GWAS QTLs that underlie 10 Cd accumulation traits in barley are co‐localized with eQTLs and sQTLs, which could imply a mechanistic role of different genetic variants affecting gene expression and alternative splicing in these traits. This study highlights the role of distal and proximal genetic effects on gene expression, splicing, and phenotypic plasticity. We anticipate that our results on the genetic control of expression and splicing underlying Cd accumulation provide a bridge to better understand genetic variation and phenotypic diversity to elucidate the mechanisms underlying Cd accumulation in plants. Significance Statement: An in‐depth survey of population‐level transcriptome variation was conducted in 100 barley (Hordeum vulgare) core accessions under Cd exposure. We found that 34.5% of GWAS QTLs that underlie 10 Cd‐related traits in barley are co‐localized with eQTLs and sQTLs, which could imply a mechanistic role of gene expression and alternative splicing in these traits. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is toxic for humans, but its effects on the yield and quality of rice under contaminated irrigation conditions remain uncertain. In this study, paddy soils in the Red River Delta (Vietnam) were selected for experiments with the purpose of understanding the effects of Cd contaminated irrigation water on growth, yields, and grain Cd accumulation. In addition, biochar was produced from rice husk (BRH) and rice straw for preventing Cd infiltration into rice was also studied in this experiment. A field experiment was established with applicated BRH and straw into polluted paddy soil, as a result the Cd content in grains reduced significantly. The Cd contaminated soil was added to the BRH and rice straw (RS) with six ratios, including: (1) RS 2.5%, (2) BRH 2.5%, (3) RS-BRH: 1.25%-1.25%, (4) RS 5.0%, (5) BRH 5.0%, (6) RS-BRH: 2.5%-2.5%, (w:w). Besides, three content levels 0.01 - 0.05 - 0.5 mg/L of Cd in irrigation water were applied throughout crop season. The results showed that the Cd accumulation in rice was in the following order: roots > stems > seeds. With 3 contaminated irrigation levels which were applied, the Cd concentrations of 0.05 mg/L and 0.5 mg/L affected plant height and yield. However, the Cd content in grains under contaminated soil condition can be controlled from 82.47 – 83.94% by applying a BRH ratio from 2.5 - 5% (w:w).

Abstract Background Lentinula edodes (Berk.) is the second most productive mushroom in the world. It contains compounds effective for antiviral, antitumor, antioxidant and immune regulation. Although genomes have previously been reported for this species, a high-quality chromosome-level reference for L. edodes is unavailable. This hinders detailed investigation of population genetics, breeding history of strains and genes related to environmental stress responses. Results A high-quality chromosome-level genome was constructed. We separated a monokaryon from protoplasts of the commercial L. edodes strain L808 and assembled the genome of L. edodes using PacBio long-read and Illumina short-read sequencing, along with the high-throughput chromatin conformation capture (Hi-C) technique. We assembled a 45.87 Mb genome, and 99% of the sequences were anchored onto 10 chromosomes. The contig and scaffold N50 length were 2.17 and 4.94 Mb, respectively. Over 96% of the complete Benchmarking Universal Single-Copy Orthologs (BUSCO) were identified, and 9853 protein-coding genes were predicted. We performed population genome resequencing using 34 wild strains and 65 commercial cultivars of L. edodes originating from China, Japan, the United States and Australia. Based on whole-genome variants, we showed substantial differences in the Chinese wild population, which divided into different branches according to the main areas of their geographical distribution. We also determined the breeding history of L. edodes at the molecular level, and demonstrated that the cultivated strains in China mainly originated from wild strains from China and Northeast Asia. Phenotypic analysis showed that 99 strains exhibited differences on the Cd accumulation. Three significant loci in the of L. edodes genome were identified using the genome-wide association study (GWAS) of Cd accumulation traits. Functional genes associated with Cd accumulation traits were related to DNA ligase and aminoacyl tRNA synthetase, indicating that DNA damage repair and in vivo protein translation may be responses to Cd stress. Conclusions A high-quality chromosome-level genome and population genetic data of L. edodes provide genetic resources for functional genomic, evolutionary and artificial breeding studies for L. edodes.

Cadmium (Cd), which accumulates in tobacco leaves, enters the human body through inhalation of smoke, causing harmful effects on health. Therefore, identifying the pivotal factors that govern the absorption and resistance of Cd in tobacco is crucial for mitigating the harmful impact of Cd. In the present study, four different Cd-sensitive varieties, namely, ZhongChuan208 (ZC) with resistance, ZhongYan100 (ZY), K326 with moderate resistance, and YunYan87 (YY) with sensitivity, were cultivated in hydroponic with different Cd concentrations (20 µM, 40 µM, 60 µM and 80 µM). The results indicated that plant growth was significantly decreased by Cd. Irrespective of the Cd concentration, ZC exhibited the highest biomass, while YY had the lowest biomass; ZY and K326 showed intermediate levels. Enzymatic (APX, CAT, POD) and nonenzymatic antioxidant (Pro, GSH) systems showed notable variations among varieties. The multifactor analysis suggested that the ZC and ZY varieties, with higher levels of Pro and GSH content, contribute to a decrease in the levels of MDA and ROS. Among all the Cd concentrations, ZC exhibited the lowest Cd accumulation, while YY showed the highest. Additionally, there were significant differences observed in Cd distribution and translocation factors among the four different varieties. In terms of Cd distribution, cell wall Cd accounted for the highest proportion of total Cd, and organelles had the lowest proportion. Among the varieties, ZC showed lower Cd levels in the cell wall, soluble fraction, and organelles. Conversely, YY exhibited the highest Cd accumulation in all tissues; K326 and ZY had intermediate levels. Translocation factors (TF) varied among the varieties under Cd stress, with ZC and ZY showing lower TF compared to YY and K326. This phenomenon mainly attributed to regulation of the NtNramp3 and NtNramp5 genes, which are responsible for the absorption and transport of Cd. This study provides a theoretical foundation for the selection and breeding of tobacco varieties that are resistant to or accumulate less Cd. [Display omitted] • At any given cadmium concentration, the cadmium accumulation in highly resistant varieties (ZC) is lower compared to that in sensitive varieties (YY). • High Pro and GSH content in resistant varieties (ZC) mitigated the damage caused by ROS. • NtNramp3 and NtNramp5 genes were the key factors to regulate cadmium accumulation in tobacco. [ABSTRACT FROM AUTHOR]

In plants, expansin genes are responsive to heavy metal exposure. To study the bioremediary potential of this important gene family, we discovered a root-expressed expansin gene in sorghum, SbEXPA11, which is notably upregulated following cadmium (Cd) exposure. However, the mechanism underlying the Cd detoxification and accumulation mediated by SbEXPA11 in sorghum remains unclear. We overexpressed SbEXPA11 in sorghum and compared wild-type (WT) and SbEXPA11-overexpressing transgenic sorghum in terms of Cd accumulation and physiological indices following Cd. Compared with the WT, we found that SbEXPA11 mediates Cd tolerance by exerting reactive oxygen species (ROS)-scavenging effects through upregulating the expression of antioxidant enzymes. Moreover, the overexpression of SbEXPA11 rescued biomass production by increasing the photosynthetic efficiency of transgenic plants. In the pot experiment with a dosage of 10 mg/kg Cd, transgenic sorghum plants demonstrated higher efficacy in reducing the Cd content of the soil (8.62 mg/kg) compared to WT sorghum plants (9.51 mg/kg). Subsequent analysis revealed that the SbbHLH041 transcription factor has the ability to induce SbEXPA11 expression through interacting with the E-box located within the SbEXPA11 promoter. These findings suggest that the SbbHLH041–SbEXPA11 cascade module may be beneficial for the development of phytoremediary sorghum varieties.

Paddy fields contaminated with cadmium (Cd) present decreased grain yield and produce Cd-contaminated grains. Screening for low-Cd-accumulating cultivars is a useful method to reduce the amount of Cd in the grains. The present study aimed to examine the roles of the root morphology and anatomy in Cd translocation and accumulation in rice plants. Twenty-two rice cultivars were used in the first experiment, after which two cultivars [Zixiangnuo (ZXN) and Jinyou T36 (JYT36)] were selected and used in subsequent experiments under hydroponic conditions. The results showed that there were significant differences in Cd concentrations in the shoots (ranging from 4 to 100 mg/kg) and the Cd translocation rates (shoot/root) (from 7% to 102%) among the 22 cultivars, and the shoot Cd concentration was significantly correlated with the Cd translocation rate of the 22 cultivars under 0.1 mg/L Cd treatment. Compared with cultivar ZXN, JYT36 had greater root Cd uptake and accumulation but lower shoot Cd accumulation and Cd translocation rate. The number of root tips per surface area of cultivar ZXN was greater than that of JYT36, while the average root diameter was lower than that of JYT36. Compared with ZXN, JYT36 had stronger apoplastic barriers, and the Casparian bands and suberin lamellae in the root endodermis and exodermis were closer to the root apex in both the control and Cd treatments, especially for suberin lamellae in the root exodermis with Cd treatments, with a difference of 25 mm. The results also showed that, compared with ZXN, JYT36 had greater percentages of Cd bound in cell walls and intracellular Cd but lower Cd concentrations in the apoplastic fluid under the Cd treatment. The results suggested that Cd translocation, rather than root Cd uptake, is a key process that determines Cd accumulation in the rice shoots. The root morphological and anatomical characteristics evidently affect Cd accumulation in the shoots by inhibiting Cd translocation, especially via the apoplastic pathway. It was possible to pre-screen low-Cd-accumulating rice cultivars on the basis of their root morphology, anatomical characteristics and Cd translocation rate at the seedling stage.

Recently, there has been increasing concern about the health hazards of heavy metal-polluted farmlands. Recent findings suggest that intercropping could be effective remediation strategy for agricultural soils without affecting crop biomass yield. However, there are concerns on the heavy metal accumulation in plant organs in phytoremediation, emphasizing the need to develop an effective intercropping remediation model. In this study, we evaluated the effects of intercropping rape and wheat with different accumulation characteristics of cadmium (Cd), and crop growth and physiological characteristics. Intercropping significantly reduced the Cd content of rape shoot and root, with the rape–low Cd-accumulating wheat intercropping system yielding the best results. However, intercropping had no significant effect on Cd accumulation in wheat. Additionally, intercropping affected the root system configuration and structure, photosynthetic indicators, chlorophyll content, crop enzyme content, and rhizosphere enzyme activity of both species, but did not significantly affect the biomass of wheat and rape. Overall, our findings showed that intercropping rape with a low Cd-accumulating wheat variety could be an effective model for safe production of wheat and rape in weak alkaline soils without compromising biomass yield. The study demonstrates that similar innovative, effective, and judicious intercropping strategy can enrich the theory of contaminated soil remediation.

This study aimed to investigate the possibility of eliminating cadmium (Cd) from contaminated agricultural soil using a combination of microbial inoculants of Penicillium chrysogenum fungus and Bacillus licheniformis with Limnocharis flava plants. Limnocharis flava (L. flava) and microbial inoculants with four Cd levels, including 2.05 (T1 control), 5 (T2), 10 (T3), and 20 mg/kg (T4), respectively, were tested in green house conditions. Cd accumulation was evaluated to assess the safety limit of the Cd concentration in the edible parts of L. flava. The results showed that the application of the microbial inoculants facilitated the stress tolerance of the plants caused by a Cd accumulation in the soil matrix. The use of Penicillium chrysogenum and Bacillus licheniform in combination with L. flava increased the Cd accumulation in plant biomass. The total Cd after the experiment varied between 4.86 and 18.44 mg/kg in dry, clean soil, equivalent to reduction rates of 2.80, 4.40, and 7.80%, respectively. Meanwhile, the availability of Cd in soil was significantly reduced by 12.50, 13.04, 13.33, and 13.93%, respectively. Consequently, the microbial inoculants helped the plants to grow healthily, increased the yield, and reduced the total and available Cd content of contaminated agricultural land up to a concentration level of 5 mg/kg. [ABSTRACT FROM AUTHOR]

The application of biodegradable chelating agents to enhance phytoremediation is a low-cost and promising method to improve the remediation efficiency of heavy metal–contaminated soil. The effects of N, N-bis glutamic acid (GLDA) on the growth and heavy metal absorption of Solanum nigrum were studied by pot experiment. The addition of chelate on the 20th day after sowing can improve the bioavailability of cadmium (Cd) in the soil. The results showed that the addition of chelating agents effectively improved the migration rate of the target heavy metal Cd in the soil, and significantly increased the accumulation of heavy metal in the roots, stems, and leaves of plants. The results showed that compared with the control group, the chelating agent could increase the extraction rate of total Cd by 28.65–68.74%. The application of GLDA significantly increased the accumulation of Cd (20 mg kg−1 and 40 mg kg−1), reaching 24.28–40.30 and 25.71–33.16 μg of pot−1 DW, respectively. At the same time, GLDA increased Cd stress by decreasing plant biomass, inhibiting photosynthetic pigment synthesis and increasing MDA levels. These results indicated that GLDA could improve the absorption of Cd by S. nigrum, which provided a new idea for its practical application in the remediation of Cd-contaminated soil. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal with no known biological function in plants and one of the most toxic substances released into the environment. Crops, such as rice, maize, wheat and tobacco are the major sources of Cd for humans. Cd toxicity inhibits crop growth and development by affecting many central physiological and biochemical processes, and finally it affects human health via the food chain. To adapt to Cd toxicity, crops have evolved a series of detoxification mechanisms. Immediate responses include rapid changes at the transcriptional level with simultaneous changes at the physiological and metabolic levels. However, the long-term responses involve genetic modifications and epigenetic changes. During the last decade, many genes involved in Cd uptake and translocation have been identified, and many of them are transporters. To decrease the accumulation of Cd in cereal grains and tobacco leaves, a number of approaches have been proposed, including physical and chemical methods, developing and planting low accumulation genotypes using transgenic strategies or marker–trait association breeding. In this review, we describe the toxicity of Cd to crops and human body, advances in the molecular mechanisms of Cd accumulation in cereal crops and tobacco, and approaches to decrease Cd accumulation. [ABSTRACT FROM AUTHOR]

Environmental contamination by cadmium (Cd), a highly toxic heavy metal, poses significant health risks to plants and humans. Biochar has been effectively used to promote plant growth and productivity under Cd stress. This study presents an innovative application of biochar derived from the invasive weed Parthenium hysterophorus to promote plant growth and productivity under Cd stress. Our study includes detailed soil and plant analyses, providing a holistic perspective on how biochar and urea amendments influence soil properties, nutrient availability, and plant physiological responses. To address these, we established seven treatments: the control, Cd alone (5 mg kg -1 ), biochar alone (5 %), urea alone (3 g kg -1 ), biochar with Cd, urea with Cd, and a combination of biochar and urea with Cd. Cd stress alone significantly reduced plant growth indicators such as shoot and root length, fresh and dry biomass, chlorophyll content, and grain yield. However, the supplementation of biochar, urea, or their combination significantly increased shoot length (by 48%, 34%, and 65%), root length (by 73%, 46%, and 70%), and fresh shoot biomass (by 4%, 31%, and 4%), respectively. This improvement is attributed to enhanced soil properties and improved nutrient absorption. The biochar-urea combination also enhanced Cd tolerance by improving total chlorophyll content by 14 %, 13 %, and 16 % compared to the control, respectively. Similaly, these treatments significantly (p < 0.05) boosted the activity of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase by 51 %, 30 %, and 51 %, respectively, thereby mitigating oxidative stress as a defensive mechanism. The Cd tolerance was improved by biochar, urea, and their combinations, which reduced Cd content in the shoots (by 60.5 %, 38.9 %, and 51.3 %), roots (by 47.5 %, 23.9 %, and 57.6 %), and grains (by 58.1 %, 30.2 %, and 38.3 %) relative to Cd stress alone, respectively. The synergistic effects of biochar and urea are achieved through improved soil properties, nutrient availability, activating antioxidant defense mechanisms, and minimizing the accumulation of metal ions in plant tissues, thereby enhancing plant defenses against Cd stress. Conclusively, converting invasive Parthenium weed into biochar and combining it with urea offers an environmentally friendly solution to manage its spreading while effectively mitigating Cd stress in crops., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

MicroRNAs (miRNAs) play important roles in plant response to Cd stress. In our previous study, we observed significant differences in the expression levels of IamiR-4-3p between high-Cd and low-Cd cultivars of water spinach. The function of IamiR-4-3p was investigated by using wild type Arabidopsis (WT), Arabidopsis transfected with empty vector pCambia1302 (CK), and Arabidopsis transfected with IamiR-4-3p + vector pCambia1302 (p35S::miR-4-3p) in this study. In p35S::miR-4-3p Arabidopsis, the expression levels of GST3 and AWPM19-like were reduced by 20% and 24%. Under Cd treatment, higher root and shoot Cd concentrations were detected in the transgenic p35S::miR-4-3p Arabidopsis. MDA and H2O2 concentrations were positively correlated with the Cd concentrations in all Arabidopsis. The elevated GSH pool in p35S::miR-4-3p Arabidopsis should compensate for its restricted GST3 expression in response to Cd-induced oxidative stress. Lower F1 (cell wall) and higher F2 (organelle) and F3 (soluble fraction) Cd concentrations were observed along with the reduced ABA level in p35S::miR-4-3p Arabidopsis, which could induce a weakened apoplastic barrier and higher Cd accumulation and translocation in roots. It is suggested that IamiR-4-3p is able to reduce the expression levels of GST3 and AWPM19-like, resulting in higher Cd uptake and translocation in Arabidopsis. [ABSTRACT FROM AUTHOR]

The association between the rhizospheric microbial community and Cd accumulation in rice is poorly understood. A field trial was conducted to investigate the different rhizobacterial communities of two rice cultivars with high Cd accumulation (HA) and low Cd accumulation (LA) at four growth stages. Results showed that the Cd content in the roots of the HA cultivar was 1.23 - 27.53 higher than that of the LA cultivar (0.08 - 10.5 µg/plant) at four stages. The LA cultivar had a significantly lower Cd availability in rhizosphere and a higher quantity of iron plaque (IP) on the root surface than the HA cultivar at four stages. This resulted in the reduction of Cd concentration in IPs and Cd translocation from IP-to-root. Microbial analysis indicated that the LA cultivar formed a distinct rhizobacterial community from the HA cultivar and had less α-diversity. The rhizosphere of the LA cultivar was enriched in specific bacterial taxa (e.g., Massilia and Bacillus) involved in Cd immobilization by phosphate precipitation and IP formation by iron oxidization. However, the rhizosphere in the HA cultivar assembled abundant sulfur-oxidizing bacteria (e.g., Sulfuricurvum) and iron reduction bacteria (Geobacter). They promoted Cd mobilization and reduced IP formation via the metal redox process. This study reveals a potential approach in which specific rhizobacteria decrease or increase Cd accumulation in rice on contaminated soil and provides a new perspective for secure rice production. [Display omitted] [ABSTRACT FROM AUTHOR]

The oligopeptide transporter (OPT) family is a group of proton-coupled symporters that play diverse roles, including metal homeostasis. However, little is known about this family of peanuts. To reveal the potential roles of AhOPT genes in Fe/Cd interactions, peanut AhOPT genes were genome-widely identified, and the relationships between gene expression and Cd accumulation were detected in two contrasting peanut cultivars (Fenghua 1 and Silihong) under Fe-sufficient or Fe-deficient conditions. A total of 40 AhOPT genes were identified in peanuts, which were divided into two subfamilies (PT and YS). Most AhOPT genes underwent gene duplication events predominated by whole-genome duplication. Clustered members generally have similar protein structures. However, gene structural divergences occurred in most of the duplicated genes. Transcription analysis revealed that AhOPT3.2 / 3.4 and AhYSL3.1 / 3.2 might be responsible for Fe deficiency tolerance, while AhOPT3.1 / 3.4, AhOPT7.1 / 7.2 , and AhYSL1.1 be involved in Fe/Cd interactions. These genes might be regulated by transcription factors, including ATHB-12, ATHB-6, DIVARICATA, MYB30, NAC02, DOF3.4, IDD7 , and LUX. Reduced expressions of AhYSL3.1 / 3.2 and higher expressions of AhOPT3.4 might contribute to higher Fe-deficiency tolerance in Silihong. Higher expression of AhOPT7.3 and AhOPT6.1 might be responsible for low Cd accumulation in Fenghua 1. Our results confirmed that AhOPT3 / 6 / 7 and AhYSL1 / 3 might be involved in the transport of Fe and/or Cd in peanuts and provided new clues to understanding potential mechanisms of Fe/Cd interactions. [ABSTRACT FROM AUTHOR]

The oligopeptide transporter (OPT) family is a group of proton-coupled symporters that play diverse roles, including metal homeostasis. However, little is known about this family of peanuts. To reveal the potential roles of AhOPT genes in Fe/Cd interactions, peanut AhOPT genes were genome-widely identified, and the relationships between gene expression and Cd accumulation were detected in two contrasting peanut cultivars (Fenghua 1 and Silihong) under Fe-sufficient or Fe-deficient conditions. A total of 40 AhOPT genes were identified in peanuts, which were divided into two subfamilies (PT and YS). Most AhOPT genes underwent gene duplication events predominated by whole-genome duplication. Clustered members generally have similar protein structures. However, gene structural divergences occurred in most of the duplicated genes. Transcription analysis revealed that AhOPT3.2/3.4 and AhYSL3.1/3.2 might be responsible for Fe deficiency tolerance, while AhOPT3.1/3.4, AhOPT7.1/7.2, and AhYSL1.1 be involved in Fe/Cd interactions. These genes might be regulated by transcription factors, including ATHB-12, ATHB-6, DIVARICATA, MYB30, NAC02, DOF3.4, IDD7, and LUX. Reduced expressions of AhYSL3.1/3.2 and higher expressions of AhOPT3.4 might contribute to higher Fe-deficiency tolerance in Silihong. Higher expression of AhOPT7.3 and AhOPT6.1 might be responsible for low Cd accumulation in Fenghua 1. Our results confirmed that AhOPT3/6/7 and AhYSL1/3 might be involved in the transport of Fe and/or Cd in peanuts and provided new clues to understanding potential mechanisms of Fe/Cd interactions.

Selection of sunflower varieties with greater cadmium (Cd) tolerance and detecting physiological variation under different Cd concentrations are important to study the potential of sunflower (Helianthus annuus L.) in the phytoremediation of Cd. The aim of this study was to investigate the variation in the Cd tolerance among four sunflower varieties (79−79, 363, 8361, ADT). Photosynthesis was determined using a Li−6400 XT portable photosynthesis system. Inductively coupled plasma mass spectrometry was used to detect the accumulation of Cd in different plant parts (leaf, stem and root). Subsequently, the Cd amount per plant, bio−concentration factor (BCF), and translocation factor (TF) were calculated. Cd exposure caused a decline in photosynthesis in four sunflower varieties. The 79−79 species displayed the highest Cd concentrations in tissues and 363 displayed a higher BCF in aerial parts under Cd exposure among the four species. Under Cd stress, the total soluble sugars in roots remained unaffected in 363. Based on the results of this experiment, the cultivar of 79−79 and 363 were more tolerant to Cd when compared to the other sunflower cultivars ADT and 8361. The present investigation results indicate that 79−79 and 363 can be further applied in the field trials of phytoremediation practices in contaminated soil.

Cadmium (Cd) pollution and uptake into the grains of developing rice plants represent a major threat to human health. Studies of specific genes can offer new insights into the functional roles of particular genes, highlighting candidate alleles that can be leveraged as DNA markers. Accordingly, the identification of novel Cd-related traits and sequence variants can provide new molecular markers for Cd resistance in rice. In the present study, a genetic diversity analysis was carried out on 85 rice varieties exhibiting varied Cd accumulation, and 436 single polymorphic sites (SNP) corresponding to 43 haplotypes were detected across 12 Cd-associated genes (CAL1, OsCADT1, Oscd1, OsHMA4, OsHMA9, OsNRAMP1, OsNRAMP2, OsNRAMP5, OsHMA2, OsHSMA3, OsPCR1, and OsABCG43). By utilizing the information of the SNPs, 85 rice varieties was classified the into 2 clusters with different source categories and Cd contents. Among the variants, 45 sites in 5 genes were significantly associated with the Cd content in rice grains, of which 8 alleles in OsPCR1, CAL1, and Oscd1 were negatively correlated with Cd accumulation. The results of haplotype aggregation analysis for OsPCR1, Oscd1, and CAL1 showed that 85 rice varieties were divided into 5 clusters. Interestingly, most of the varieties in Cluster A belonged to tropical type, which contained the aggregation of three favorable alleles, whereas the temperate varieties constituted the majority of Cluster B lacking favorable alleles. This observation suggests that the allelic combination found in tropical rice varieties may hold promise for reducing Cd accumulation levels in rice grains. The Cd-associated alleles identified in the present study can not only be used to check the Cd tolerance of rice varieties, but also serve as functional molecular markers to differentiate the source of the rice varieties, which provides a better understanding of the relationship between the sequence variation in Cd-related genes and Cd accumulation in rice.

High levels of cadmium (Cd) in soil can cause crop yield reduction or death. Cadmium accumulation in crops affects human and animal health as it passes through the food chain. Therefore, a strategy is needed to enhance the tolerance of crops to this heavy metal or reduce its accumulation in crops. Abscisic acid (ABA) plays an active role in plants’ response to abiotic stress. The application of exogenous ABA can reduce Cd accumulation in shoots of some plants and enhance the tolerance of plants to Cd; therefore, ABA may have good application prospects. In this paper, we reviewed the synthesis and decomposition of ABA, ABA-mediated signal transduction, and ABA-mediated regulation of Cd-responsive genes in plants. We also introduced physiological mechanism underlying Cd tolerance because of ABA. Specifically, ABA affects metal ion uptake and transport by influencing transpiration and antioxidant systems, as well as by affecting the expression of metal transporter and metal chelator protein genes. This study may provide a reference for further research on the physiological mechanism of heavy metal tolerance in plants.

It has been established that wheat (Triticum aestivum L.) has a higher Cd absorption capacity than other cereal crops causing an excess daily Cd intake and a huge threat for public health. Therefore, the reduction of Cd accumulation in wheat from the soil is a crucial food-security issue. A pot trial was performed on Cd-stressed wheat seedlings to evaluate the morphological and physio-biochemical responses via foliage spray of two different bio-stimulants, i.e., ascorbic acid (AsA) and moringa leaf extract (MLE). Two wheat cultivars (Fsd-08 and Glxy-13) were exposed to cadmium (CdCl2.5H2O) stress (0, 500, and 1,000 μM), along with foliar spray of AsA (0 and 50 mM) and MLE (0 and 3%). The most observable growth reduction was documented in plants that are exposed to a higher Cd concentration (1,000 μM), followed by the lower Cd level (500 μM). The wheat growth attributes, such as number of leaves per plant, number of tillers per plant, biomass yield, shoot/root length, and leaf area, were greatly depressed under the Cd stress, irrespective of the cultivar. Under the increasing Cd stress, a significant diminution was observed in maximum photochemical efficiency (Fv/Fm), photochemical quenching (qP), and electron transport rate (ETR) accompanied with reduced gas exchange attributes. However, Cd-induced phytotoxicity enhanced the non-photochemical quenching (NPQ) and internal carbon dioxide concentration (Ci), which was confirmed by their significant positive correlation with Cd contents in shoot and root tissues of both cultivars. The contents of proline, AsA, glycine betaine (GB), tocopherol, total free amino acid (TFAA), and total soluble sugar (TSS) were greatly decreased with Cd stress (1,000 μM), while MLE and AsA significantly enhanced the osmolytes accumulation under both Cd levels (especially 500 μM level). The Cd accumulation was predominantly found in the root as compared to shoots in both cultivars, which has declined after the application of MLE and AsA. Conclusively, MLE was found to be more effective to mitigate Cd-induced phytotoxicity up to 500 μM Cd concentration, compared with the AsA amendment. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), a toxic heavy metal, affects the yield and quality of crops. Wheat (Triticum aestivum L.) can accumulate high Cd content in the grain, which poses a major worldwide hazard to human health. Advances in our understanding of Cd toxicity for plants and humans, different parameters influencing Cd uptake and accumulation, as well as phytoremediation technologies to relieve Cd pollution in wheat have been made very recently. In particular, the molecular mechanisms of wheat under Cd stress have been increasingly recognized. In this review, we focus on the recently described omics and functional genes uncovering Cd stress, as well as different mitigation strategies to reduce Cd toxicity in wheat. [ABSTRACT FROM AUTHOR]

Globally, plants face large amounts of environmental stresses, which can inhibit their growth rate and element uptake capacity. Droughts are a critical limitation to plant growth in arid and semi-arid areas. Effects of drought stress and post-drought rewatering on the compensatory growth and Cd phytoremediation efficiency of Arabidopsis thaliana were estimated using slight and moderate drought conditions. Results showed compensatory growth can be induced by post-drought rewatering, as manifested by the increased dry weight and photosynthetic efficiency of the species under drought stress (particularly slight stress) as compared to those of the control. Slight stress increased concentrations of Cd in roots and leaves of A. thaliana by elevating its transpiration rate, whereas moderate stress induced the opposite effect. When the species was subjected to slight stress, Cd concentrations in plant tissues surpassed those in the control after rewatering, indicating that post-drought rewatering can compensate for the detrimental impacts caused by slight drought in A. thaliana. At the end of the experiment, slight and moderate drought stresses increased the Cd extraction ability of the species by 48.9% and 12.7%, respectively, compared to the control. This study demonstrates compensatory effects of post-drought rewatering on the Cd phytoextraction capacity of A. thaliana and suggests that suitable water deficit irrigation practices can enhance soil remediation efficiency and simultaneously save water in the field. [ABSTRACT FROM AUTHOR]

Background: Lentinula edodes (Berk.) is the second most productive mushroom in the world. It contains compounds effective for antiviral, antitumor, antioxidant and immune regulation. Although genomes have previously been reported for this species, a high-quality chromosome-level reference for L. edodes is unavailable. This hinders detailed investigation of population genetics, breeding history of strains and genes related to environmental stress responses. Results: A high-quality chromosome-level genome was constructed. We separated a monokaryon from protoplasts of the commercial L. edodes strain L808 and assembled the genome of L. edodes using PacBio long-read and Illumina short-read sequencing, along with the high-throughput chromatin conformation capture (Hi-C) technique. We assembled a 45.87 Mb genome, and 99% of the sequences were anchored onto 10 chromosomes. The contig and scaffold N50 length were 2.17 and 4.94 Mb, respectively. Over 96% of the complete Benchmarking Universal Single-Copy Orthologs (BUSCO) were identified, and 9853 protein-coding genes were predicted. We performed population genome resequencing using 34 wild strains and 65 commercial cultivars of L. edodes originating from China, Japan, the United States and Australia. Based on whole-genome variants, we showed substantial differences in the Chinese wild population, which divided into different branches according to the main areas of their geographical distribution. We also determined the breeding history of L. edodes at the molecular level, and demonstrated that the cultivated strains in China mainly originated from wild strains from China and Northeast Asia. Phenotypic analysis showed that 99 strains exhibited differences on the Cd accumulation. Three significant loci in the of L. edodes genome were identified using the genome-wide association study (GWAS) of Cd accumulation traits. Functional genes associated with Cd accumulation traits were related to DNA ligase and aminoacyl tRNA synthetase, indicating that DNA damage repair and in vivo protein translation may be responses to Cd stress. Conclusions: A high-quality chromosome-level genome and population genetic data of L. edodes provide genetic resources for functional genomic, evolutionary and artificial breeding studies for L. edodes. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to explore the effects of microbial agents combined with leaf barrier on the translocation and accumulation of Cd in rice, and provided important reference for the safe production of moderate and mild Cd contaminated farmland. [Method] The field experiment was adopted, organosilicon and chelated iron were selected as foliar control agents, combined with microbial agents, and a total of 6 treatments were set up in the field: conventional planting pattern ( CK), spraying on the leaf with organosilicone and EDD HA-Fe ( Y), microbial agents derived from Bacillus amyloliquefaciens and Enterobacter ludwigii as base fertilizer applied separately to soil ( Dl and D2), microbial agents derived from B. amyloliquefaciens and E. ludwigii applied separately to soil, meanwhile spraying on the leaf with organosilicone and EDDHA-Fe ( D1 + Y and D2 + Y) . [Result] ( i) Leaf spraying with organosilicone and EDDHA-Fe significantly reduced the content of Cd in leaves, decreased TF roct-maw , and increased the proportion of Cd in roots by 38. 3%, compared with the control. Foliar fertilizer could effectively prevent the translocation and accumulation of Cd to the shoot of rice. (ii) The two formulations of basal application of microbial agents had different effects on Cd accumulation in rice. Compared with the control, the content of Cd in different parts of rice was decreased by basal application of B. amyloliquefaciens, and t he variation of Cd proportion was small. Applying with E. ludu!igii, Cd content in leaves of rice decreased, and Cd content in stems and grains increased significantly, which were 2. 06 and 1. 17 times higher than those in control, respectively. Meanwhile, the accumulation of Cd in whole plant was increased by 9 . 8 % . ( iii) The accumulation of Cd in rice plants decreased and the distribution of Cd in different parts of rice was significantly changed by basal application of microbial agents combined with foliar fertilizer. When treated with Dl + Y, the proportion of Cd in grains was 1. 68 times higher than that in the control, and the proportion of Cd in roots was 63. 5 % equivalent to the control. The combination of microbial agent in B. amyloliquefaciens and foliar fertilizer could accelerate the translocation of Cd to the shoot and grains of rice. Wben treated with D2 + Y, the TF,root-straw of Cd decreased by 64. 5 % compared with CK, the root Cd content was 1. 57 times higher than that of the control, and the proportion of Cd in the root increased by 57 . 7 % . Cd was restricted to the root by the combination of the basal application of E. ludwigii and foliar fertilizer, so that limited Cd was transferred to the shoot of rice. [Conclusion] The application of B. amyloliquefaciens agents, combined with leaf spraying of organosilicone and EDD HA-Fe can reduce the accumulation of Cd in the root and increase the transfer of Cd to the shoot of rice. Combined application of E. ludwigii and foliar fertilizer can effectively reduce the accumulation of Cd in the straw and grain of rice, which is one of the important measures for the safety production of medium and mild Cd contaminated farmland. [ABSTRACT FROM AUTHOR]

It has been established that wheat (Triticum aestivum L.) has a higher Cd absorption capacity than other cereal crops causing an excess daily Cd intake and a huge threat for public health. Therefore, the reduction of Cd accumulation in wheat from the soil is a crucial food-security issue. A pot trial was performed on Cd-stressed wheat seedlings to evaluate the morphological and physio-biochemical responses via foliage spray of two different bio-stimulants, i.e., ascorbic acid (AsA) and moringa leaf extract (MLE). Two wheat cultivars (Fsd-08 and Glxy-13) were exposed to cadmium (CdCl2.5H2O) stress (0, 500, and 1,000 μM), along with foliar spray of AsA (0 and 50 mM) and MLE (0 and 3%). The most observable growth reduction was documented in plants that are exposed to a higher Cd concentration (1,000 μM), followed by the lower Cd level (500 μM). The wheat growth attributes, such as number of leaves per plant, number of tillers per plant, biomass yield, shoot/root length, and leaf area, were greatly depressed under the Cd stress, irrespective of the cultivar. Under the increasing Cd stress, a significant diminution was observed in maximum photochemical efficiency (Fv/Fm), photochemical quenching (qP), and electron transport rate (ETR) accompanied with reduced gas exchange attributes. However, Cd-induced phytotoxicity enhanced the non-photochemical quenching (NPQ) and internal carbon dioxide concentration (Ci), which was confirmed by their significant positive correlation with Cd contents in shoot and root tissues of both cultivars. The contents of proline, AsA, glycine betaine (GB), tocopherol, total free amino acid (TFAA), and total soluble sugar (TSS) were greatly decreased with Cd stress (1,000 μM), while MLE and AsA significantly enhanced the osmolytes accumulation under both Cd levels (especially 500 μM level). The Cd accumulation was predominantly found in the root as compared to shoots in both cultivars, which has declined after the application of MLE and AsA. Conclusively, MLE was found to be more effective to mitigate Cd-induced phytotoxicity up to 500 μM Cd concentration, compared with the AsA amendment.

Paddy fields contaminated with cadmium (Cd) present decreased grain yield and produce Cd-contaminated grains. Screening for low-Cd-accumulating cultivars is a useful method to reduce the amount of Cd in the grains. The present study aimed to examine the roles of the root morphology and anatomy in Cd translocation and accumulation in rice plants. Twenty-two rice cultivars were used in the first experiment, after which two cultivars [Zixiangnuo (ZXN) and Jinyou T36 (JYT36)] were selected and used in subsequent experiments under hydroponic conditions. The results showed that there were significant differences in Cd concentrations in the shoots (ranging from 4 to 100 mg/kg) and the Cd translocation rates (shoot/root) (from 7% to 102%) among the 22 cultivars, and the shoot Cd concentration was significantly correlated with the Cd translocation rate of the 22 cultivars under 0.1 mg/L Cd treatment. Compared with cultivar ZXN, JYT36 had greater root Cd uptake and accumulation but lower shoot Cd accumulation and Cd translocation rate. The number of root tips per surface area of cultivar ZXN was greater than that of JYT36, while the average root diameter was lower than that of JYT36. Compared with ZXN, JYT36 had stronger apoplastic barriers, and the Casparian bands and suberin lamellae in the root endodermis and exodermis were closer to the root apex in both the control and Cd treatments, especially for suberin lamellae in the root exodermis with Cd treatments, with a difference of 25 mm. The results also showed that, compared with ZXN, JYT36 had greater percentages of Cd bound in cell walls and intracellular Cd but lower Cd concentrations in the apoplastic fluid under the Cd treatment. The results suggested that Cd translocation, rather than root Cd uptake, is a key process that determines Cd accumulation in the rice shoots. The root morphological and anatomical characteristics evidently affect Cd accumulation in the shoots by inhibiting Cd translocation, especially via the apoplastic pathway. It was possible to pre-screen low-Cd-accumulating rice cultivars on the basis of their root morphology, anatomical characteristics and Cd translocation rate at the seedling stage. [ABSTRACT FROM AUTHOR]

Excessive accumulation of cadmium (Cd) in vegetables poses a serious threat to human health; therefore, it is urgent to screen and cultivate vegetable cultivars with low Cd accumulation in the edible parts. Eggplant has a high tendency for Cd accumulation, but research on its low Cd accumulation cultivars is still rare. In this study, to screen low-Cd cultivars, 30 eggplant cultivars were screened using soils containing 0.22 mg/kg, 2.9 mg/kg (low-Cd), and 4.7 mg/kg of Cd (high-Cd). MYCQ and ZGQ were confirmed as low-Cd cultivars, BXGZ and WCCQ were confirmed as high-Cd cultivars, and a 2.52–3.88-fold difference in Cd concentration was observed in their fruits. The subcellular distribution revealed that the root cell wall and vacuole Cd concentrations of a typical low-Cd cultivar (MYCQ) were significantly higher than those of a typical high-Cd cultivar (BXGZ); however, the Cd concentrations in the cell wall and vacuole in fruits, leaves, and stems were significantly lower in MYCQ than in BXGZ. These results indicated that the low-Cd cultivars of eggplant could lessen Cd toxicity through the elevated Cd retention and sequestration levels of root cell walls and vacuoles, thus reducing Cd transport from roots to aboveground tissues, leading to low Cd accumulation. The findings of this study can provide a physiological and biochemical foundation for the screening and breeding of low-Cd cultivars of fruit vegetables and demonstrates that the application of low-Cd cultivars is necessary for food safety in humans. [ABSTRACT FROM AUTHOR]