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Panax notoginseng (Burk) F. H. Chen is a traditional medicinal herb in China. However, the high capacity of its roots to accumulate cadmium (Cd) poses a potential risk to human health. Although there is some evidence for the involvement of nitric oxide (NO) in mediating Cd toxicity, the origin of Cd-induced NO and its function in plant responses to Cd remain unknown. In this study, we examined NO synthesis and its role in Cd accumulation in P. notoginseng roots. Cd-induced NO production was significantly decreased by application of the nitrate reductase inhibitor tungstate but not the nitric oxide synthase inhibitor L-NAME (N G -methyl- l -arginine acetate), indicating that nitrate reductase is the major contributor to Cd-induced NO production in P. notoginseng roots. Under conditions of Cd stress, sodium nitroprusside (SNP, an NO donor) increased Cd accumulation in root cell walls but decreased Cd translocation to the shoot. In contrast, the NO scavenger cPTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and tungstate both significantly decreased NO-increased Cd retention in root cell walls. The amounts of hemicellulose 1 and pectin, together with pectin methylesterase activity, were increased with the addition of SNP but were decreased by cPTIO and tungstate. Furthermore, increases or decreases in hemicellulose 1 and pectin contents as well as pectin methylesterase activity fit well with the increased or decreased retention of Cd in the cell walls of P. notoginseng roots. The results suggest that nitrate reductase-mediated NO production enhances Cd retention in P. notoginseng roots by modulating the properties of the cell wall. [ABSTRACT FROM AUTHOR]

Maize ( Zea mays) has low Cd accumulation in grains and a high biomass compared to other crops. The capacities for Cd accumulation in different maize cultivars are, however, not fully understood. To reduce human health risk from maize grown in Cd-contaminated soil and to provide promising maize cultivars for the phytoremediation of Cd-polluted soil, a field experiment was conducted to screen low-Cd- and high-Cd-accumulation maize cultivars by evaluating the yield, Cd uptake, translocation, and accumulation differences among 19 maize cultivars. There were differences in straw dry weight (DW), root DW, and yield among the 19 cultivars. The cultivars Yudan19, Zhengda999, and Xianyu508 had a higher production compared to that of the other cultivars. The Cd concentrations in the roots were much higher than those in the straws and grains in all cultivars. The Cd accumulation factors (AF) decreased in the order of accumulation factors in root (AF) > accumulation factors in straw (AF) > accumulation factors in grain (AF). The Cd translocation factors (TFs) from root to straw (TF) were significantly ( p < 0.05) larger than those from straw to grain (TF) among all of the cultivars. The TF for all of the cultivars was less than 1, and the lowest TF (0.23) was found in cultivar Xiangyongdan3. The correlation analysis indicated that Cd concentrations in straws showed a significant ( p < 0.01) as well as positive correlation with TF while a negative correlation with TF ( p < 0.01). Moreover, Cd accumulation in different tissues decreased in the order straw > grain > root. Among the 19 maize cultivars, Jixiang2118 and Kangnong18 accumulated the highest Cd amount in the aboveground tissues, and the corresponding values were 7,206.51 and 6,598.68 mg hm, respectively. A hierarchical cluster analysis based on the Cd concentrations in grains and straws classified the 19 maize cultivars into four and two groups for a 0.4 minimum distance between clusters, respectively. Yudan19, Zhengda999, and Xianyu508 can be classified into one group in which low Cd in grains meeting the Cd tolerance limit in foods set by China National Standard, suggesting that those cultivars are safety for food and human health. However, Jixiang2118 and Kangnong18 can be classified as another group with potential application for phytoremediation in slightly or moderately Cd-polluted soil because of the high Cd accumulation in the aboveground tissues. [ABSTRACT FROM AUTHOR]

Metagenome research has brought much attention for the identification of important and novel genes of industrial and pharmaceutical value. Here, using a metagenome library constructed from bacteria associated with the marine sponge, Styllisa massa , a high-throughput screening technique using radioisotope was implemented to screen for cadmium (Cd) binding or accumulation genes. From a total of 3301 randomly selected clones, a clone 247-11C was identified as harboring an open reading frame (ORF) showing Cd accumulation characteristics. The ORF, termed as ORF5, was further analyzed by protein functional studies to reveal the presence of a protein, Cdae-1. Cdae-1, composed of a signal peptide and domain harboring an E(G/A)KCG pentapeptide motif, enhanced Cd accumulation when expressed in Escherichia coli . Although showing no direct binding to Cd in vitro, the presence of important amino acid residues related to Cd detoxification suggests that Cdae-1 may possess a different mechanism from known Cd binding proteins such as metallothioneins (MTs) and phytochelatins (PCs). In summary, using the advantage of bacterial metagenomes, our findings in this work suggest the first report on the identification of a unique protein involved in Cd accumulation from bacteria associated with a marine sponge. [ABSTRACT FROM AUTHOR]

The effect of cadmium (Cd) on mycorrhizal association and on shoot and root Cd concentration was investigated in jackbean plants under hydroponic conditions. The treatments consisted of the inoculation of three different species of arbuscular mycorrhizal fungi (AMF), Glomus etunicatum, G. intraradices and G. macrocarpum, and a non-inoculated control, two Cd (0 and 5 µmol L-1) and two P (1 and 10 mg L-1) levels in the nutrient solution. Mycorrhizal colonization, length of AMF extraradical mycelium, guaiacol peroxidase activity in roots, plant growth and root and shoot Cd and P concentrations were determined. Mycorrhizal status did not promote jackbean growth but in most of the cases mycorrhization increased root and shoot Cd concentrations. Cd ions were accumulated mainly in roots and only small amounts were translocated to the shoot. Cd addition did not affect root colonization by AMF but the AM extraradical mycelium (ERM) was sensitive to the added Cd. ERM length was reduced by 25% in the presence of Cd. This reduction was more pronounced under conditions of low P concentration. Also at this P concentration, Cd addition decreased guaiacol peroxidase activity in non-mycorrhizal roots and in roots colonized by G. macrocarpum. However, mycorrhizal roots maintained lower values of peroxidase activity. G. etunicatum showed the best performance when associated to jackbean plants and it could be a promising association for phytoremediation of Cd- contaminated soil.O efeito do cádmio na associação micorrízica e no teor e acúmulo de Cd na raiz e parte aérea de feijão de porco foi avaliado em condição de hidroponia. Os tratamentos consistiram da inoculação ou não de três espécies de fungos micorrízicos arbusculares (FMAs), Glomus etunicatum, G. intraradices e G. macrocarpum, e uma testemunha (ausência de FMA), duas concentrações de Cd ( 0 e 5 µmol L-1) e de P (1 e 10 mg L-1) na solução nutritiva. Foram determinados a colonização micorrízica, o comprimento do micélio extraradical, atividade da peroxidase nas raízes, crescimento das plantas e teor e acúmulo de Cd e P na raiz e na parte aérea das plantas. A associação micorrízica não promoveu crescimento das plantas mas aumentou a concentração foliar e radicular de Cd. O metal pesado foi acumulado principalmente nas raízes e somente uma pequena quantidade foi translocada para a parte aérea. A colonização micorrízica não foi influenciada pelo Cd adicionado, mas o micélio extrarradicular mostrou-se sensível ao metal, tendo sido reduzido em 25%, principalmente na menor concentração de P adicionado. Nesta mesma concentração de P, a adição de Cd reduziu a atividade da peroxidase nas raízes das plantas não colonizadas e nas colonizadas por G. macrocarpum. Entretanto, as raízes micorrizadas mostraram valores menores de atividade da enzima. Melhor desempenho da associação micorrízica foi constatado nas plantas colonizadas por G. etunicatum, o qual mostrou-se promissor na fitorremediação de solos contaminados por Cd quando em associação ao feijão de porco.

Many organic materials have been used to decrease heavy-metal bioavailability in soil via in-situ remediation due to its high efficiency and easy operation; meanwhile, cheap materials have also been pursued to decrease the cost of remediation. Agricultural wastes exhibit their potential in remediation materials due to their low cost; however, raw agricultural wastes have a low ability to immobilize heavy metals in soil. Attempts have been made to modify agricultural wastes to improve the efficiency of heavy-metal passivation. In this study, novel agricultural waste-based materials, raw sugarcane bagasse (SB), citric acid modified (SSB) and citric-acid/Fe 3 O 4 modified (MSB) sugarcane bagasse at 0.5% and 1% addition rates, were compared for their effectiveness in soil Cd passivation and Cd accumulations in pakchoi plants in a 30-day pot experiment. The addition of SB did not decrease soil bioavailable Cd effectively and slightly decreased Cd accumulation in plant roots and leaves. In comparison, SSB and MSB exhibited a great potential to decrease the transformation, translocation and accumulation of Cd with the decrease being greater at 1% than 0.5% rate in the soil-pakchoi system. For example, the addition of SSB and MSB at 0.5% decreased the concentration of Cd in leaves by 10%, and 16%, and at 1% decreased the concentration by 25% and 30%, respectively. High pH and abundant functional groups of three amendments played important roles in Cd immobilization. The enhanced microbial activities might also contribute to Cd passivation. However, plant growth was decreased in the amended treatments except SSB at 0.5% rate. The results suggest that citric-acid-modified sugarcane bagasse at addition rate of 0.5% has a potential to immobilize Cd in soil and decrease Cd accumulation in edible part of pakchoi effectively without decreasing vegetable growth. [Display omitted] • Sugarcane bagasse (SB) exhibited potential in passivating Cd in soil. • Citric-acid- and Fe 3 O 4 -modified SB decreased Cd bioavailability more than SB. • Passivation of Cd was greater at 1% than 0.5% addition rate of amendments. • Sugarcane bagasse at 0.5% showed the least effect on Cd bioavailability. • Citric-acid-modified SB at 0.5% decreased plant Cd accumulation but not growth. [ABSTRACT FROM AUTHOR]

Threats posed by Cd-contaminated arable soils to food security have attracted increasing attention. The combination of organic and inorganic amendments has been extensively applied to immobilize Cd in paddy soils. However, the regulatory mechanism of Cd fractionation under these combined amendments and the effect on wheat Cd accumulation remain unclear in upland soils. In this work, different combinations of organic and inorganic amendments were prepared with biochar, zeolite and humus, and the Cd-immobilization mechanism was also investigated in field experiments. The results demonstrated that the mixture of biochar, zeolite and humus had excellent Cd immobilization performance in highly Cd-contaminated (4.26 ± 1.25 mg kg−1) weakly alkaline soils, resulting in 76.5–84.8% decreases in soil available Cd. The contribution of single components to Cd immobilization in the combined amendment follows the order of humus > biochar > zeolite. The combined amendment converted the acid soluble Cd to the Cd bound to the reducible fraction with higher stability, thereby decreasing Cd bioavailability. The maximum Cd decrease rate in wheat roots, straw and grains could reach 68.2%, 45.0% and 59.3%, respectively, and the Cd content in grains (0.098 mg kg−1) was lower than the food security standards of China (0.1 mg kg−1). Wheat planting for two successive years in a large-scale field further verified the superior Cd immobilization performance and stability of the combined amendment in moderately to slightly Cd-contaminated soil. The present study provides references for the remediation of Cd-contaminated weakly alkaline upland soils and certain guidance for safe food production. [Display omitted] • Organic-inorganic combined amendment has excellent immobilization effect on soil Cd. • Cd content in wheat grains was decreased to below the food security standard of China. • The combined amendment converted acid soluble Cd to reducible Cd. • The combined amendment showed high stability for Cd immobilization. [ABSTRACT FROM AUTHOR]

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 Si-stimulated 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 (ethanol-extracted and deionized water-extracted) was changed to the extraction state of Cd with weak mobile activity (acetic acid-extracted and hydrochloric acid-extracted), 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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhao, Yu, Wang, Chen, Akhtar, Tang, Lu, He, Wen and He.)

This study offers new insight into the role of Na in Cu2ZnSnS4 (CZTS) thin film solar cells by studying samples with a spatially varying alkali distribution. This is achieved by omitting a diffusion barrier between the soda-lime glass substrate and the Mo back contact, where compositional variations of the glass inherently result in non-uniform alkali distributions in the CZTS. By correlating light beam induced current (LBIC) maps with secondary ion mass spectrometry composition maps, it is shown that samples containing regions of higher Na concentration ('hot spots') have corresponding LBIC hot spots on comparable length scales. Samples containing an alkali diffusion barrier have lower LBIC dispersion; thus, LBIC can be used to evaluate non-uniformity in CZTS devices, where a common cause is Na inhomogeneity. Moreover, it is shown that the Na hot spots are strongly correlated with other compositional variations in the device, including increased Cu in-diffusion with the underlying MoS2 layer and decreased diffusion of Cd to the back contact. Neither of these effects are well understood in CZTS devices, and neither have previously been correlated with the presence or absence of Na. [ABSTRACT FROM AUTHOR]

Environmental pollution by trace metal elements (TMEs) is a serious problem worldwide, increasing in parallel with the development of human technology. The present research aimed to examine the response of halophytic species Suaeda fruticosa to oxidative stress posed by combined abiotic stresses. Plants have been grown for 1 month with an irrigation solution supplemented with 200 mM NaCl and 400 μM Cd or 400 μM Cu. The level of glutathione (GSH), phytochelatins (PCs), and antioxidant enzyme activities [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] as well as lipid peroxidation was studied to see the stress exerted by the TME and the level of tolerance and detoxification strategy adopted by S. fruticosa. Relative growth rate (RGR) decreased under Cd stress in this species, whereas Cu did not have any impact on S. fruticosa performance. Cd or Cu enhanced malondialdehyde, suggesting reactive oxygen species-induced disruption of membrane integrity and oxidative stress in S. fruticosa. On the other hand, the activities of the antioxidant enzymes CAT, APX, and GPX diminished and mineral nutrition was disturbed by metal stress. S. fruticosa was able to synthesize PCs in response to TME toxicity. However, data indicate that GSH levels underwent a significant decrease in roots and leaves of S. fruticosa stressed by Cd or Cu. The GSH depletion accompanied by the increase of phytochelatin concentration suggests the involvement of GSH in the synthesis of phytochelatins. [ABSTRACT FROM AUTHOR]

The effects of three arbuscular mycorrhizal fungi isolates on Cd uptake and accumulation by maize ( Zea mays L.) were investigated in a planted pot experiment. Plants were inoculated with Glomus intraradices, Glomus constrictum and Glomus mosseae at three different Cd concentrations. The results showed that root colonization increased with Cd addition during a 6-week growth period, however, the fungal density on roots decreased after 9-week growth in the treatments with G. constrictum and G. mosseae isolates. The percentage of mycorrhizal colonization by the three arbuscular mycorrhizal fungi isolates ranged from 22.7 to 72.3 %. Arbuscular mycorrhizal fungi inoculations decreased maize biomass especially during the first 6-week growth before Cd addition, and this inhibitory effect was less significant with Cd addition and growth time. Cd concentrations and uptake in maize plants increased with arbuscular mycorrhizal fungi colonization at low Cd concentration (0.02 mM): nonetheless, it decreased at high Cd concentration (0.20 mM) after 6-week growth period. Inoculation with G. constrictum isolates enhanced the root Cd concentrations and uptake, but G. mosseae isolates showed the opposite results at high Cd concentration level after 9 week growth period, as compared to non-mycorrhizal plants. In conclusion, maize plants inoculated with arbuscular mycorrhizal fungi were less sensitive to Cd stress than uninoculated plants. G. constrictum isolates enhanced Cd phytostabilization and G. mosseae isolates reduced Cd uptake in maize ( Z. mays L.). [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a potentially hazardous element with substantial biological toxicity, adversely affecting plant growth and physiological metabolism. Therefore, it is necessary to explore practical and environment-friendly approaches to reduce toxicity. Jasmonic acid (JA) is an endogenous growth regulator which helps plants defend against biological and abiotic stresses. To determine how JA help relieve Cd toxicity in rice, both laboratory and field experiments were implemented. In the seedling stage, the role of JA in mediating rice Cd tolerance was investigated via a fluorescent probe in vivo localization, Fourier Transform Infrared Spectroscopy (FTIR), and colorimetry. At the mature growth stage of rice, field experiments were implemented to research the effects of JA on the Cd uptake and translocation in rice. In the seedling stage of rice, we found that JA application increased the cell wall compartmentalization of Cd by promoting the Cd combination on chelated-soluble pectin of rice roots and inhibited Cd movement into protoplasts, thereby reducing the Cd content in the roots by 30.5% and in the shoots by 53.3%, respectively. Application of JA reduced H 2 O 2 content and helped relieve Cd-induced peroxidation damage of membrane lipid by increasing the level of catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and glutathione (GSH), but had no significant effect on the superoxide dismutase (SOD) activity. Additionally, field experiments showed that foliar spraying of JA inhibited rice Cd transport from the stalk and root to the grain and reduced Cd concentration in grain by 29.7% in the high-Cd fields and 28.0% in the low-Cd fields. These results improve our understanding of how JA contributes to resistance against Cd toxicity in rice plants and reduces the accumulation of Cd in rice kernels. [Display omitted] • Jasmonic acid increased rice growth under Cd stress. • Jasmonic acid alleviated Cd toxicity by triggering antioxidant defense system. • Jasmonic acid enhanced Cd binding to the chelated-soluble pectin on the cell wall. • Foliar spray of jasmonic acid reduced Cd transport and accumulation in brown rice. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic, nonessential heavy metal; its accumulation in plants alters metabolism and limits productivity. Although various studies have addressed the Cd stress response in various species, the detailed molecular mechanisms remain unknown. Therefore, the present work investigated the influence of the TaMYC8 transcription factor (TF) on the Cd-induced stress response in wheat. The present study found that TaMYC8 is a nuclear protein highly induced in the roots under Cd stress. Overexpression of TaMYC8 in the wheat cultivar 'Bobwhite' increased sensitivity to Cd stress, probably due to the increased levels of superoxide (O 2 .-), malonaldehyde (MDA), jasmonic acid (JA), and Cd, and reduced the proline content and antioxidant enzyme activity. In contrast, silencing TaMYC8 via RNA interference (RNAi) significantly lowered Cd accumulation and improved Cd tolerance. Using the yeast one-hybrid assay (Y1H), chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP–qPCR), electrophoretic mobility shift assay (EMSA), and dual luciferase reporter assay, it was found that TaMYC8 could physically bind to the TaERF6 promoter and activate TaERF6 transcription. More importantly, knockdown of TaMYC8 by RNAi inhibited the activities of 1-aminocyclopropane-1-carboxylic (ACC) acid synthase (ACS) and ACC oxidase (ACO) of the ethylene biosynthetic pathway. In conclusion, TaMYC8 promotes TaERF6 transcription and affects the ethylene biosynthetic pathway. These findings provide a theoretical basis for breeding low-Cd-accumulating wheat cultivars. • TaMYC8 decreased Cd tolerance of transgenic wheat. • TaMYC8 binds to the promoter of TaERF6 as well as regulating the transcription of TaERF6. • TaMYC8 affects Cd tolerance of wheat by regulating ethylene synthesis. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in soil has become a serious problem, and cadmium (Cd) in particular is of increasing global concern due to its readily taken up by plants. The selection of plant genotypes with low Cd uptake in roots and its transport to edible parts is a realistic approach to alleviate adverse effects of Cd contamination. In view of these considerations, series of experiments were performed to identify the genotypic difference in physiological and biochemical characteristics of soybean genotypes by applying different Cd concentrations. Twenty three soybean genotypes were grown at 0 and 2.0 µmol L-1 Cd in nutrient solution to compare the difference in Cd tolerance. Biometric, physiological and biochemical parameters revealed better performance for S951-3 and high sensitivity of Q17-3 to Cd toxicity. S951-3 and Q17-3 were used in the succeeding experiment to investigate the mechanisms of Cd tolerance in soybean. The Cd (5.0 µmol L-1) reduced growth, chlorophyll content and photosynthetic rate in both genotypes, but the extent of reduction was different. Cadmium, MDA contents, and activity of antioxidant enzymes were significantly increased with Cd treatment, being higher in Q17-3. These data suggest S951-3 as more resistant genotype than Q17-3 to Cd stress. © 2014 Friends Science Publishers [ABSTRACT FROM AUTHOR]

The effects of zinc (Zn) at different spray concentrations (0, 500, and 1 000 μmol·L −1) on the plant growth, the activities of antioxidant enzymes chemical forms of cadmium (Cd), and the accumulation of Cd were studied and compared between two varieties, Shijichaotianjiao (SJCTJ) and Yanjiao425 (YJ425) of pepper ( Capsicum annuum L.) in Cd-contaminated soil (Cd 10 ·mg kg −1). The activities of catalase (CAT) and peroxidase (POD) were generally enhanced by Zn. However, superoxide dismutase (SOD) decreased. Addition of Zn decreased the ethanol-extractable Cd, NaCl-extractable Cd, and acetic acid-extractable Cd in the fruit by 34.6%–55.3%, 2.0%–17.7% and 0.4%–32.9%, and reduced the accumulation of Cd in fruit and plant total Cd by 12.8%–68.6% and 9.0%–29.3% in both varieties, respectively. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in paddy soil has become a worldwide problem for rice production. Foliar application has been reported as a practical approach to reducing Cd accumulation in rice. In the present study, we used mesoporous silica nanoparticles (MSN) and MSN-chitosan (MSN-CS) as carriers to deliver melatonin (MT) into rice plants through foliar spray. Both systems showed the potentials as controlled-release delivery vehicles, with MT@MSN-CS performing better in vitro. The hydroponic trial revealed that foliar spray of MT@MSN-CS could significantly reduce Cd concentration in rice leaves by 43.8%, which was better than those of MT and MT@MSN. The nano-delivery systems improved leaf photosynthesis efficiency, decreased malondialdehyde (MDA) content, enhanced the activity of antioxidative enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), as well as regulated the expression levels of Cd transport genes (OsNramp1 , OsNramp5 , OsHMA2 , OsHMA3 , OsLCD and OsPCR1). Our results also suggested that the use of stimuli-responsive carriers, MSN-CS, for example, as MT-delivery systems may be a feasible option for the reduction of heavy metal accumulation in plants and can be potentially implemented in soil remediation. [Display omitted] • MSN and MSN-CS were used as carriers to deliver melatonin into rice plants. • The foliar spray of MT@MSN-CS significantly reduced Cd concentration in rice leaves by 43.8%. • The nano-delivery systems improved photosynthesis efficiency and enhanced antioxidative enzyme activities. • The nano-delivery systems effectively regulated the expression levels of Cd transport genes. [ABSTRACT FROM AUTHOR]

A field experiment was carried out to assess the role of exogenously applied salicylic acid (SA) on radish (Raphanus staivus L.) plants grown in artificially cadmium (Cd)-contaminated soils. For this purpose, SA (300 mg L-1) was applied as foliar spray on control and Cd-stressed (0.5 mM and 1.0 mM CdCl2) plants at vegetative stage and its influence on Cd toxicity at vegetative and mature stages was examined. A progressive increase in the uptake of Cd and its accumulation in radish plant parts was observed with increase of CdCl2 concentration in the soil, which retarded root growth while stimulated the shoot growth. Reproductive stages like inflorescence raceme length, number of branches of inflorescence raceme and number of siliques per plant were enhanced due to presence of Cd in the soil. Foliar application of SA substantially retarded Cd uptake in radish plants thereby improved root vegetative characters resulting in amelioration of Cd-toxicity. Moreover, SA improved shoot characters, contributed to weight gain by mature siliques and positively influenced inflorescence and raceme characters. [ABSTRACT FROM AUTHOR]

A pot experiment was carried out by growing 29 different genotypes ( Amaranthus spp.) of vegetable amaranth under low- (0.12 mg·kg) and middle- (0.40 mg·kg) cadmium (Cd) exposure. The result showed that amaranth was vulnerable to cadmium (Cd) contamination in soil. Variations of Cd concentrations in both roots and edible parts among genotypes were significant ( P<0.001) in both treatments. Cd concentrations in edible parts of the tested genotypes grown under low- and middle-Cd levels were significantly correlated ( p<0.01), implying that Cdaccumulating property of amaranth is genotype-dependent. Differences in Cd chemical forms between cv. Nanxingdayemashixian (cv. Nan), a selected typical pollution-safe cultivar (Cd-PSC), and cv. Pennongjianyexian (cv. Pen), a selected typical non-Cd-PSC, under different Cd exposure conditions were compared. It was found that the alternation of Cd in F (Cd form extracted by 1 mol·L NaCl) may be a key factor in regulating Cd accumulation of different amaranth genotypes and that the protein-binding Cd is considered to be associated with Cd translocation. The results indicated that amaranth is capable of enduring high level of Cd pollution when grown as vegetable crop, and accordingly, consuming vegetable amaranth would bring high health risk. Therefore, adopting Cd-PSC strategy would help reducing the risk of Cd pollution in amaranth. In this study, cv. Nan was identified as a Cd-PSC and recommended to be applied production practice. [ABSTRACT FROM AUTHOR]

Abstract: A study quantifying the effect of NaCl on growth and Cd accumulation of Spartina alterniflora subjected to Cd stress was conducted. Seedlings were cultivated in the presence of 1 or 3mM Cd alone, or combined with NaCl (50 or 100mM). The results showed that NaCl magnified the phytotoxicity of moderate Cd stress (1mM Cd) on plants due to reduced levels of plant biomass, plant height, and chlorophyll a+b, while no synergistic effects were recorded under severe Cd stress (3mM Cd). Proline and Ca2+ accumulated along with additional NaCl under moderate Cd stress, instead of reduced or unchanged levels under severe Cd stress owing to different adoption strategies caused by NaCl under different Cd stresses. NaCl reduced the oxidative stress in Cd-treated plants through increasing levels of antioxidative enzymes (catalase (CAT) and peroxidase (POD)) under moderate Cd stress. With NaCl addition, Cd2+ contents in S. alterniflora increased and reduced under moderate and severe Cd stress, respectively. However, total Cd2+ amounts increased with increasing NaCl concentration due to biological dilution. NaCl improved the increase of Cd2+ translocation factor (TF) under moderate Cd stress, indicating that NaCl might improve Cd2+ uptake and translocation from roots to shoots, and enhance the phytoextraction of S. alterniflora on Cd; while phytostabilization of Cd under severe Cd stress may be possible due to the reduced TF. Thus, NaCl alleviated phytotoxicity caused by Cd stress through improved management of osmotic solutes and oxidative status, and affected Cd accumulations in S. alterniflora differently under moderate and severe Cd stresses. [Copyright &y& Elsevier]

Studying the chemical composition and characteristic differences of soil dissolved organic matter (DOM) is significant for understanding the mechanism of Cd immobilization by soil amendments. Soil amendments have been widely applied to contaminated farmlands to reduce the accumulation of heavy metals in crops, but the spectral characteristics of DOM in soils under amendment regulation have rarely been studied. Typical Cd-contaminated paddy soil from South China was collected, three categories of amendments (organic-based, inorganic-based, and lime-based, a total of 11 types) were applied, rice planting pot trials were done, and the effects of different amendments on soil DOM were investigated. The spectral characteristics of rhizosphere soil DOM under the regulation of different amendments were comparatively analyzed using UV-Vis spectroscopy, 3D fluorescence spectroscopy, and parallel factor analysis (PARAFAC). The results showed that the lime-based amendments increased the soil pH and promoted the dissolution of organic matter from the soil solid phase, resulting in a significant increase in soil DOM content. Compared with that of the control, organic-based amendments increased the relative molecular weight and recent autochthonous origin contribution of soil DOM, inorganic-based amendments increased the aromatic content and hydrophobic components of soil DOM, and lime-based amendments increased the chromogenic components and the degree of humification of soil DOM. Four fluorescence components, C1 (255/465), C2 (325/400), C3 (275/390), and C4 (240/460), were identified using PARAFAC and verified with the OpenFluor database, all of which were humic-like. Two types of spectra corroborated with each other, indicating that soil DOM dominated by humus-like matter originated from terrestrial source input. The correlation analysis showed that the fluorescent component C4 of soil DOM could be used to predict Cd accumulation in brown rice in the red limestone soil-rice system. These results will provide a reference for the selection of the appropriate soil amendments.

Although extensive studies of the effects of heavy metals on marine invertebrates have well documented their bioaccumulation and toxicity, less is known about the genotoxicity of trace metals. The aim of this investigation was to assess the DNA damaging potential of cadmium in a benthic marine bivalve mollusc Mizuhopecten yessoensis collected from coastal waters. A comet assay (alkaline single-cell gel electrophoresis) was used to evaluate the degree of DNA damage in scallop gill cells induced by Cd accumulation. The results of our experimental studies indicated that Cd accumulation is followed by alterations in essential trace element homoeostasis (Fe, Zn) and DNA integrity (DNA strand breaks) in the gill cells. Based on the criteria for quantifying DNA strand breaks (the percentage of DNA in the comet tail, the length of the comet tail and the tail moment) used in the comet assay, Cd was found to be genotoxic to the scallop gill cells under laboratory exposure conditions. The possible mechanisms of Cd-induced DNA damage are discussed. Our results provide the first description of the use of the comet assay to detect DNA damage induced by Cd in an important pollution indicator organism M yessoensis, which is common in coastal waters of the Sea of Japan. Thus, M yessoensis can be used as an in vivo model for ecogenotoxicity assessment using the Comet assay. [ABSTRACT FROM AUTHOR]

Translocation of cadmium (Cd) in the tissues of Vicia faba, the water content in biomass, the biomass production, and the glutathione and phytochelatin tissue concentrations were studied and correlated with the plant sensitivity and/or tolerance to Cd. The total concentrations of Cd were determined by inductively coupled plasma/mass spectrometry (ICP-MS), the concentrations of glutathione (GSH) and phytochelatins 2 and 3 (PC2 and PC3) were determined by on-line high performance liquid chromatography/electrospray-ionization tandem mass spectrometry (HPLC-ESI-MS-MS) in the roots and leaves of the sensitive and the tolerant cultivars of V. faba grown in Cd containing nutrient solutions (NS, 0-100 μmol l Cd). Both the cultivars of V. faba accumulate a major portion of Cd in the roots and only a minor part of ca. 4% in the leaves. The differences between the cultivars concerning Cd accumulation in leaves were apparent from higher Cd concentrations in NS and the Cd amount in the sensitive cultivar was approximately twice as high. In the roots, the differences between the cultivars in the Cd accumulation were only statistically significant with the highest Cd concentrations in NS, with the tolerant cultivar accumulating about 16% more of Cd compared to the sensitive one. The biomass production of the sensitive cultivar decreased approximately twice as fast with increasing Cd concentration in NS. The biomass water content decreased with increasing Cd concentration in NS in both the cultivars. In general, the GSH concentration did not linearly correlate with Cd accumulation, except for the roots of the sensitive cultivar where it was independent, and was higher in the sensitive cultivar than in the tolerant one in both the leaves and roots. The GSH concentration in leaves was approximately one order of magnitude higher than that in the roots for both the cultivars. The relationships between the PC and Cd concentrations in tissues were found nonlinear. At lower Cd accumulation levels, the PC concentrations followed an increase in the Cd accumulation in both the roots and leaves, whereas at higher Cd accumulations the relations differed between roots and leaves. In the roots, the PC concentrations decreased with increasing Cd accumulation, whereas the PC concentration in the leaves followed the decrease in the Cd accumulation. [ABSTRACT FROM AUTHOR]

Abstract: This study appraised cadmium (Cd) toxicity stress in wetland plant Juncus effusus, and explored its potential for Cd phytoextraction through chelators (citric acid and EDTA). Cadmium altered morphological and physiological attributes of J. effusus as reflected by growth retardation. Citric acid in the presence of 100μM Cd significantly countered Cd toxicity by improving plant growth. Elevated Cd concentrations reduced translocation factor that was increased under application of both chelators. Citric acid enhanced Cd accumulation, while EDTA reduced its uptake. Cadmium induced oxidative stress modified the antioxidative enzyme activity. Both levels of citric acid (2.5 and 5.0mM) and lower EDTA concentration (2.5mM) helped plants to overcome oxidative stress by enhancing their antioxidative enzyme activities. Cadmium damaged the root cells through cytoplasmic shrinkage and metal deposition. Citric acid restored structure and shape of root cells and eliminated plasmolysis; whereas, EDTA exhibited no positive effect on it. Shoot cells remained unaffected under Cd treatment alone or with citric acid except for chloroplast swelling. Only EDTA promoted starch accumulation in chloroplast reflecting its negative impact on cellular structure. It concludes that Cd and EDTA induce structural and morphological damage in J. effusus; while, citric acid ameliorates Cd toxicity stress. [Copyright &y& Elsevier]

Abstract: Hydroponic experiment was carried out to investigate the effect of cadmium (Cd) on growth, Cd accumulation, lipid peroxidation, antioxidative enzymes, leaf chlorophyll, root activity, protein content and Cd uptake kinetics of vetiver grass. The results showed that 1mg/L Cd in solution led to increased chlorophyll contents, root activity and enhanced the growth of vetiver grass after 15days, with 2.2% biomass increased compared to the control. Malondialdehyde (MDA) contents were significantly enhanced by all Cd supply levels. The development of toxic symptoms corresponded to a high accumulation of Cd and to the decrease of water content, chlorophyll, protein content and root activity, but to high increase in catalase and peroxidase activities in plants. Cd concentration in shoots and roots increased with increasing Cd supply levels, and reached a maximum of 93 and 2232mg/kg Cd dry weight at 30mg/L treatment, respectively. [Copyright &y& Elsevier]

Abstract: A study was undertaken to examine cadmium accumulation in freshwater biofilm, its effects on biofilm development and on diatom community structure in laboratory experimental conditions. A suspension of a biofilm originated from the Riou-Mort River (South West France) was inoculated into three experimental units containing clean glass substrates under laboratory conditions. Settling and already developed biofilms were exposed to a Cd concentration of 100µgL−1. Metal accumulation (total and intracellular metal content) in biofilms, dry weight and ash-free dry mass, diatom cell density and diatom community composition were analyzed. Both total and intracellular Cd accumulated by the biofilm throughout the experiment increased with duration of metal exposure. Biofilms in the course of maturation were showed higher Cd content and less effective development than settled biofilms. However diatom communities in younger biofilms exposed to Cd increased their tolerance to Cd by a highly significant development of Nitzschia palea. In contrast, Cd exposure had different effect in installed biofilm and taxonomic composition. These results indicate that mature biofilm may limit Cd accumulation into its architecture and protect diatom communities from the effects of metals. [Copyright &y& Elsevier]

Accumulation of Cd in rice grain is a serious concern of food safety since rice as a staple food is a major source of Cd intake in Asian countries. However, the mechanisms controlling Cd accumulation in rice are still poorly understood. Herein, we report both physiological and genetic analysis of two rice cultivars contrasting in Cd accumulation, which were screened from a core collection of rice cultivars. The cultivar Anjana Dhan (Indica) accumulated much higher levels of Cd than Nipponbare (Japonica) in the shoots and grains when grown in both soil and solution culture. A short-term uptake experiment (20 min) showed that Cd uptake by Nipponbare was higher than that by Anjana Dhan. However, the concentration of Cd in the shoot and xylem sap was much higher in Anjana Dhan than in Nipponbare. Of the Cd taken up by the roots, <4% was translocated to the shoots in Nipponbare, compared with 10–25% in Anjana Dhan, indicating a higher root-to-shoot translocation of Cd in the latter. A quantitative trait locus (QTL) analysis for Cd accumulation was performed using an F2 population derived from Anjana Dhan and Nipponbare. A QTL with large effect for Cd accumulation was detected on the short arm of chromosome 7, explaining 85.6% of the phenotypic variance in the shoot Cd concentration of the F2 population. High accumulation is likely to be controlled by a single recessive gene. A candidate genomic region was defined to <1.9 Mb by means of substitution mapping. [ABSTRACT FROM PUBLISHER]

In the northern hemisphere moose has been found to be suitable as a monitoring animal for the presence of cadmium in the environment. The metal accumulates mainly in the kidney and the liver, with the rate of accumulation dependent on age and possibly also on gender. Collection of tissue material often results in sample selections with disparate age and gender composition, which makes comparison between different regions and different studies difficult. A previous large scale investigation of metals in kidney and liver from moose in Sweden provided Cd data ( n = 3,817 and 3,802, respectively) to further explore the relation between Cd accumulation and age/gender. Based on local averages, the individual deviations were analysed with respect to the factors age and gender resulting in an ‘ageing function’ for each gender and organ. In addition, estimates of the pure individual variations were obtained; the standard deviations correspond to a factor 1.7–1.9 for the Cd concentration, which indicates that 25–30 samples are needed to give a representative mean value (with RSD ≈10%). In order to be able to compare results from different studies, all individual results can be transformed to represent a ‘standard moose’ with respect to age and gender. A comparison along these lines was undertaken between Cd levels in Alaska and Sweden. Finally, a relationship between the Cd levels in kidney and liver was derived, providing at least rough estimates for kidney from liver values (or vice versa). [ABSTRACT FROM AUTHOR]

As a pollutant, Cd causes severe impact to the environment and damages living organisms. It can be uptaken from the environment by the natural resistance-associated macrophage protein (Nramp) in plants. However, the ion absorption function of Nramp transporter genes in Spirodela polyrhiza has not been reported. In this study, SpNramp1 , SpNramp2 , and SpNramp3 from S. polyrhiza were cloned and their functions were analyzed in S. polyrhiza and yeast. Growth parameters and physicochemical indices of wild-type and transgenic lines were measured under Cd stress. Results revealed that SpNramp1 , SpNramp2 , and SpNramp3 were identified as plasma membrane-localized transporters, and their roles in transporting Cd were verified in yeast. In S. polyrhiza , SpNramp1 overexpression significantly increased the content of Cd, Fe, Mn, and fresh weight. SpNramp2 overexpression increased Mn and Cd. SpNramp3 overexpression increased Fe and Mn concentrations. These results indicate that SpNramp1 , SpNramp2 , and SpNramp3 had a different preference for ion absorption. Two S. polyrhiza transgenic lines (OE1 and OE3) were obtained. One of them (OE1) showed a stronger accumulation ability, and the other one (OE3) exhibited tolerance capacity to Cd. This study provides new insight into the functions of SpNramp1 , SpNramp2 , and SpNramp3 and obtains important enrichment lines (OE1) for manipulating Cd accumulation, phytoremediation, and ecological safety. [Display omitted] • SpNramp transporter genes were identified as plasma membrane-localized transporters. • SpNramp transporter genes showed a Cd transport activity in yeast. • SpNramp1 overexpression significantly increased Cd, Fe, and Mn contents in S. polyrhiza. • SpNramp2 and SpNramp3 overexpression significantly increased Mn content in S. polyrhiza. • The enrichment line for phytoremediation and manipulating Cd accumulation was obtained. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was conducted using twelve Japonica rice genotypes differing in grain Cd concentration, to study the genotypic difference in germination and early seedling growth in response to Cd stress and its relation to Cd accumulation. The results showed that under low Cd level (0.5 mM), germination was significantly enhanced for most rice genotypes, but higher Cd levels (2.5 and 10.0 mM) inhibited germination dramatically. When exposed to 10.0 mM Cd, a few genotypes could still germinate, but the seedlings of all genotypes would die in early stage. Shoot height and dry weight, and root length and dry weight of seedling were significantly inhibited at 0.5 and 2.5 mM Cd levels, irrespectively of genotypes, and the inhibition became more severe under higher Cd level. There was a significant genotypic difference in response of germination, early seedling growth and shoot Cd concentration to Cd stress. The difference was the largest for germination, followed by root growth, the least for shoot growth. A cluster analysis of tolerance indices, including germination rate, shoot height and weight, root length and weight of the plants exposed to 2.5 mM Cd level showed that 12 rice genotypes may be grouped into three clusters, i.e. high-, intermediate- and weak Cd-tolerance. No significant correlation was found between grain Cd concentration and Cd-tolerance in terms of germination and seedling growth, and shoot Cd concentrations, suggesting that it is possible to develop rice cultivars with high Cd-tolerance and low grain Cd accumulation. [ABSTRACT FROM AUTHOR]

Abstract: The effect of exposure to increasing cadmium concentrations was analyzed in rice seedlings (cv. Vialone nano). The highest Cd accumulation was found in roots, mostly in the apoplastic environment. Cd taken up in cells led to an increase in sulfhydryl groups, the appearance of phytochelatins, and formation of electron-dense vacuolar inclusions. The metal-exposure inhibited root growth and also interfered with correct root morphogenesis, causing disordered division and abnormal and forward enlargement of epidermal and cortical cell layers in the apical region. Cd accumulation in shoots was lower than in roots. In leaf cells, there was neither a substantial increase in sulfhydryl groups nor the appearance of phytochelatins. Shoot growth was reduced and, differently from in roots, leaf cell enlargement was inhibited. Chloroplasts had lowered contents of chlorophyll and a reduced number of thylakoids, but underwent structural alterations only at the highest Cd concentration tested (250μM). Photosynthetic activity was limited due to the curtailment of CO2 availability caused by the greater resistance of Cd-exposed leaves. The damage suffered by seedlings worsened with the increase in Cd concentration, but was already evident at the lowest concentration examined (50μM), showing that the cv. Vialone nano has a Cd-sensitivity higher than other rice cultivars. [Copyright &y& Elsevier]

One of the limits of Cd2+-phytoextraction is the high toxicity of this metal to plants. Growth restriction, chlorosis and necrosis are usually accompanied with a large disturbance of the uptake of essential elements. This work aims to study the effects of cadmium (Cd2+) on potassium (K+), calcium (Ca2+) and nitrogen (N) acquisition, and their consequences on growth in two halophytes species: Sesuvium portulacastrum and Mesembryanthemum crystallinum. Seedlings were grown for 30 days in split-root conditions. One half of the root system was immersed in complete nutrient solution (Basal medium (B)) supplemented with 100μM Cd2+, and the other half was immersed in a Cd2+-free medium, containing all nutrients (B/Cd plants) or deprived of potassium ((B-K)/Cd) or calcium ((B-Ca)/Cd) or nitrogen ((B-N)/Cd). Using this approach, we demonstrated that K+ and Ca2+ uptake was impaired in roots exposed to Cd2+. Concerning N, we noticed no indication of uptake inhibition by Cd2+. However, restriction of K+ uptake by roots was compensated by an increase in the K+-use efficiency, so that growth was not inhibited. Calcium uptake was strongly limited by Cd2+. This inhibition was accompanied by a reduction in growth of ((B-Ca)/Cd) plants. Thus, we conclude that Cd2+ limits growth of both halophytes through restriction imposed on Ca2+ uptake. We suggest that the increase of Ca2+ availability in soils could improve the growth of both species in the presence of Cd2+. This would be essential for improving their utility for extraction of this metal by from salty contaminated soils. [Copyright &y& Elsevier]

Abstract: Chlamydomonas acidophila KT-1 and Chlamydomonas acidophila DVB238 exhibit a strong heavy metal tolerance, but C. acidophila DVB238 can accumulate a much higher amount of Cadmium (Cd) than C. acidophila KT-1. Phytochelatins (PCs) are known to play an important role in the detoxification of several toxic heavy metals, but the relationship between PCs and Cd accumulation is not clear. PC metabolism and Cd accumulation were investigated by using three Chlamydomonas strains including Chlamydomonas reinhardtii C-9 as a standard alga. The results showed that the PC content did not correlate closely with the level of Cd accumulation, maintenance of a high GSH level seeming to be more important for Cd accumulation. The ultrastructure of C. acidophila KT-1 was extremely disrupted by a great increase in starch granules, which resulted in a moribund state, but hyper-accumulator C. acidophila DVB238 did not exhibit an increase in starch granules in its cells, in spite of Cd accumulation in its chloroplasts, cytosol and vacuoles. These results indicated that C. acidophila DVB238 probably has a developed detoxification system preventing such as destruction of the cells due to Cd toxicity. [Copyright &y& Elsevier]

Phytochelatins (PCs) are metal binding peptides involved in heavy metal detoxification. To assess whether enhanced phytochelatin synthesis would increase heavy metal tolerance and accumulation in plants, we overexpressed the Arabidopsis phytochelatin synthase gene ( AtPCS1) in the non-accumulator plant Nicotiana tabacum. Wild-type plants and plants harbouring the Agrobacterium rhizogenes rolB oncogene were transformed with a 35S AtPCS1 construct. Root cultures from rolB plants could be easily established and we demonstrated here that they represent a reliable system to study heavy metal tolerance. Cd2+ tolerance in cultured rolB roots was increased as a result of overexpression of AtPCS1, and further enhanced when reduced glutathione (GSH, the substrate of PCS1) was added to the culture medium. Accordingly, HPLC analysis showed that total PC production in PCS1-overexpressing rolB roots was higher than in rolB roots in the presence of GSH. Overexpression of AtPCS1 in whole seedlings led to a twofold increase in Cd2+ accumulation in the roots and shoots of both rolB and wild-type seedlings. Similarly, a significant increase in Cd2+ accumulation linked to a higher production of PCs in both roots and shoots was observed in adult plants. However, the percentage of Cd2+ translocated to the shoots of seedlings and adult overexpressing plants was unaffected. We conclude that the increase in Cd2+ tolerance and accumulation of PCS1 overexpressing plants is directly related to the availability of GSH, while overexpression of phytochelatin synthase does not enhance long distance root-to-shoot Cd2+ transport. [ABSTRACT FROM AUTHOR]

Summary: Growth, cadmium accumulation and potassium and calcium status were studied in two halophytes from Aizoaceae family: Sesuvium portulacastrum and Mesembryanthemum crystallinum. After multiplication, the seedlings were cultivated on nutrient solution supplemented with NaCl (100mM) and CdCl2 (0, 50, 100, 200 and 300μM). After 1 month of treatment, plants were harvested and the dry weight, as well as the Cd, K and Ca concentrations in tissues were determined. Results showed that S. portulacastrum, a perennial halophyte with slow growth, is significantly more tolerant to Cd than M. crystallinum, an annual plant. Cd severely inhibited Mesembryanthemum growth even at the lowest Cd concentration in culture medium (50μM), and did not modify significantly that of Sesuvium. For both halophytes, Cd accumulation was significantly higher in the roots than in the shoots. However, Cd concentration reached 350–700μgg−1 DM in the shoots, values characteristic of Cd hyperaccumulator plants. The addition of Cd in the culture medium led to a disturbance of Ca and especially K nutrition, suggesting the possibility to improve plant growth and Cd phytoextraction of both halophytes by increasing nutrient availability in the culture medium. [Copyright &y& Elsevier]

Cadmium (Cd) contamination in cropland poses a serious threat to food safety and human health. In this study we investigated the effects of grafting on Cd accumulation in the shoots of Solanum melongena (eggplant), Solanum lycopersicum (tomato) and Capsicum annuum L. (pepper) scion plants. The Cd mitigation effects were investigated in the un-grafted, self-grafted and grafted plants in both pot and field experiments. The results showed that grafting onto Solanum torvum rootstock can significantly decreased Cd accumulation in the shoots of eggplant, tomato and pepper scions by up to 85%. Moreover, our results demonstrated that the grafting operation did not significantly contribute to Cd accumulation in the scion plant shoots. However, using S. torvum as rootstock was significantly more effective in reducing Cd accumulation in tomato and pepper leaves as compared to using tomato cultivar Aimiao 2 or pepper cultivar Aimiao 1 as rootstocks. This suggests that the rootstock was responsible for lower Cd accumulation in the three scion plant shoots. Furthermore, there was a significant increase in yield and quality of plants grafted with S. torvum as rootstock. Overall, our finding suggests that grafting could be simultaneously used as a mitigation strategy to reduce Cd accumulation in the Solanaceae plant shoots and promote crop quality and yield. This study provides important insights for the safe use of low Cd-contaminated soils. [Display omitted] • Grafting greatly reduced Cd accumulation in eggplant, tomato and pepper shoots. • Rootstock was responsible for lower Cd accumulation in three scion plant shoots. • S. torvum was a good rootstock to reduce Cd accumulation in three plants in field. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), a toxic non-essential metal, is easily accumulated in cacao tissues. This represents a risk for cacao exportation, and consequently it affects the economic well-being of the resource-poor-small-producers in Latin America. A greenhouse experiment was conducted with 53 wild and domesticated cacao genotypes to determine their response to Cd in terms of growth and Cd and essential nutrients accumulation. Cacao seedlings were grown for 6 months in an acidic soil with or without added Cd. The total concentration of macro (Ca, K, Mg, N and P) and micronutrients (B, Cu, Fe, Mn and Zn) as well as Cd were measured in shoots along with growth (biometric) parameters after harvest. The results revealed that even if there was a wide range of Cd concentrations among genotypes, there was a reduction in the concentration of essential nutrients in genotypes grown in Cd spiked soils, however these concentrations were not significantly different from the control. In the case of growth parameters, the effects of Cd were diverse across all genotypes some of them being more tolerant to Cd stress than others. Thus, different growth responses to Cd stress are related to a genotype effect. Based on their lower Cd concentration, a total of 11 cacao genotypes (AYP-22, PAS-105, UGU-126, ICT-1026, ICT-1087, ICT-1189, ICT-1292, PH-17, CCN-51, ICS-39 and TSH-565) are proposed here as low Cd-accumulating genotypes. Therefore, these genotypes are potentially useful as rootstock to reduce uptake and transport of Cd, especially in economically important cacao cultivars. Unlabelled Image • Research with the higher quantity of genotypes assessed for Cd uptake in cacao • 53 genotypes assessed for Cd uptake in cacao from different origins • Growth parameters were related to genotype effect. • 11 cacao genotypes proposed as low Cd accumulators [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination, which poses a serious threat to human health, has been recognized as a major threat to the agricultural system and crop production. Salicylic acid (SA) is a signaling molecule that plays an important role in against Cd toxicity. Previously, we found that spraying rice with SA could reduce the Cd accumulation in rice grains grown in Cd-contaminated soil. In this study, we studied the specific mechanism of SA spray on reducing Cd accumulation in rice grain. The results showed that treatment with SA could alleviate Cd toxicity in rice by increasing the activities of antioxidant enzymes that reduce hydrogen peroxide (H 2 O 2) accumulation, but not by changing the pH, or total or available Cd of the soil. The key factor by which SA treatment reduced Cd accumulation in rice grains was by decreasing the Cd content in rice leaves at the flowering stage. This indicated that SA could modulate the Cd accumulation in shoots, reducing the Cd translocation to rice grains. Furthermore, SA could increase the H 2 O 2 content, activating the SA-signaling pathway and modulating the expression levels of Cd transporters (OsLCT1 and OsLCD) in rice leaves to increase Cd tolerance and reduce Cd accumulation in the rice grain. Thus, spraying rice with SA may be effective measure to cope with Cd contamination in paddy soils. Image 1 • SA spraying reduces Cd accumulation. • SA alleviates Cd toxicity. • SA activates SA-signaling pathway. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contaminated soil has threatened plant growth and human health. Rapeseed (Brassica napus L.), an ideal plant for phytoremediation, is an important source of edible vegetable oil, vegetable, animal fodder, green manure and biodiesel. For safe utilization of Cd polluted soil, physiological, biochemical, and molecular techniques have been used to understand mechanisms of Cd tolerance in B. napus. However, most of these researches have concentrated on vegetative and adult stages, just a few reports focus on the initial growth stage. Here, the partitioning of cadmium, gene expression level and activity of enzymatic antioxidants of H18 (tolerant genotype) and P9 (sensitive genotype) were investigated under 0 and 30 mg/L Cd stress at seedling establishment stage. Results shown that the radicle length of H18 and P9 under Cd stress were decreased by 30.33 (0.01 < P < 0.05) and 88.89% (P < 0.01) respectively. Cd concentration at cotyledon not radicle and hypocotyl in P9 was significantly higher than that in H18. The expression level of BnaHMA4c , which plays a key role in root-to-shoot translocation of Cd, was extremely higher in P9 than in H18 under both normal and Cd stress conditions. We also found that SOD, CAT and POD were more active in responding to Cd stress after 48 h, and the activity of SOD and CAT in H18 were higher than that in P9 at all observed time points. In conclusion, high activity of enzymatic antioxidants at initial Cd stress stage is the main detoxification mechanism in Cd-tolerant rapeseed, while the higher Cd transfer coefficient, driven by higher expression level of BnaHMA4c is the main mechanism for surviving radicle from initial Cd toxicity in Cd-sensitive rapeseed. • H18 performed higher Cd tolerance ability than P9 at seedling establishment stage. • High transfer coefficient is a mechanism for surviving radicle from Cd toxicity in P9. • BnaHMA4c plays a crucial role in Cd transfer from root to shoot in rapeseed. • SOD, CAT and POD were more active in respond to Cd stress after 36 h. • High activity of antioxidants can detoxify the initial Cd stress in tolerant rapeseed. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in paddy soils and the related pollution risk of rice grain have received increasing attention. Agronomic measures, such as the application of sulfur and changes in water regimes, were reported to mitigate the accumulation of Cd in rice. However, there is limited information on the combined effects of sulfur application and water regimes. Therefore, a pot experiment was conducted to investigate the effects of two sulfur forms, three water regimes and multiple sulfur application rates on Cd accumulation in rice. The sulfur was applied as SO 4 2− (SVI, replacing the traditional fertilizers by SO 4 2--containing fertilizers), and element S (S0) was applied at 0, 10, 20, 30 and 40 mg S kg−1 soil. The water regimes were continuous flooding (F), flooding-moist alternation (FM), and moist irrigation (M), for a total of 30 treatments. The results indicated that application of SVI exceeding 30 mg S kg−1 significantly reduced the Cd concentrations in brown rice by 31.1–56.3%, and the Cd concentrations decreased with increasing amount of irrigation water. Similar reductions in Cd concentrations in rice shoots and rice straw collected at tillering and maturity stages were observed after application of SVI. However, the effect of S0 application on Cd accumulation in grain was not significant under different water regimes. Furthermore, this study found that application of both SVI and S0 inhibited the transfer of Cd from rice roots to shoots in most cases. These findings indicate that replacing traditional fertilizers with SO 4 2--containing fertilizers, especially combined with increased irrigation, could be a potential approach to mitigate Cd accumulation in rice growing in Cd-contaminated acidic paddy soils. Image 1 • The effect of sulfur supply on the accumulation of Cd in rice under different water regimes was tested. • Reduction effect of SVI on rice grain Cd enhanced as irrigation water increased. • Application of S0 has a limited effect on the accumulation of Cd in rice. • Both forms of sulfur inhibited Cd transfer from roots to shoots in most cases. [ABSTRACT FROM AUTHOR]

Plants have evolved effective strategies to cope with heavy metals Cd toxicity, but the regulatory mechanism underlying Cd tolerance and accumulation are still poorly understood. miR156 has been shown to be the master regulator of development and stress response in plants. However, whether miR156 is also involved in plant Cd stress response remains unknown. Here, we show that plants overexpressing miR156 (miR156OE) accumulated significantly less Cd in the shoot, and conferred enhanced tolerance to Cd stress. Plants with a knocked-down level of miR156 (MIM156) were sensitive to Cd stress, and accumulated significantly higher Cd. Under Cd stress, miR156OE had significantly longer primary root length, higher biomass and chlorophyll content, increased activities of antioxidative enzymes and lower levels of endogenous reactive oxygen species (ROS), while MIM156 had the opposite phenotype. To investigate the underlying mechanism of miR156-mediated Cd stress response in Arabidopsis , we profiled the expression of several Cd transporter genes. The expression of Cd uptake transporter of AtZIP1 、 AtZIP2 and vacuole segregated transporter AtABCC1 was significantly elevated in miR156OE, whereas it was significantly reduced in MIM156. MIM156 also led to an elevated level of AtHMA4 responsible for transporting Cd from the root to the shoot. Our results indicate that miR156 acts as a positive regulator of plant tolerance to Cd stress by modulating ROS levels and Cd uptake/transport genes expression. Therefore, our study adds a new layer of regulatory mechanism for Cd transport and tolerance in plants, and provides a perspective to regulate Cd transport artificially by modulating plant vegetative growth and development using miR156. • Overexpressing miR156 (miR156OE) accumulated significantly less Cd in the shoot but higher in root. • miR156OE had significantly lower levels of endogenous reactive oxygen species (ROS) and conferred enhanced tolerance to Cd stress. • Modulation of miR156 synthetically affected the expression of Cd-related transporters. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted to investigate the growth response and Cd accumulation characteristics among different populations of Hylotelephium spectabile in Cd-contaminated cinnamon soil (2.22 mg·kg -1 ) with the addition of different concentrations of NaCl. Results showed that the biomasses and Cd concentrations of H. spectabile showed significant differences among different populations under Cd alone or Cd-salt combined stress. Moreover, salt stress aggravated the growth inhibition of H. spectabile and the Cd concentrations in different H. spectabile populations showed a declining trend, which may be related to the salt-derived pH increase leading to a decrease in Cd bioavailability. In addition, the growth and Cd absorption responses of H. spectabile under salt stress were significantly different in the different populations. The shoot biomasses of the LN population were significantly higher than in other populations under different treatment, and showed no significant decrease with the addition of 1% NaCl when compared with the control treatment and the tolerance index remained 0.91. At the same time, the shoot Cd concentration of the LN population was significantly higher than in other populations under different treatments. The result may be attributed to the Cd accumulation and detoxification mechanisms in LN are prior than other populations that may also have important physiological mechanisms for tolerance of salt stress. In summary, although Cd uptake in H. spectabile decreased with salt stress, there were significant differences among different populations. LN populations accumulated 84.4 μg·plant -1 Cd in shoots with 2% NaCl addition, which was 48.4%-89.3% higher than in other populations. Therefore, H. spectabile, especially LN populations, is a good candidate for phytoremediation of Cd-contaminated saline soil.