Cadmium Uptake Research Articles

Kadmiyum stresi altında yetiştirilen Brassica rapa’da bazı metal taşıyıcı ATPaz’ların anlatımı

Cadmium (Cd) is one of the toxic heavy metals not essential for the growth and development of plants and other organisms. Brassica rapa accumulates several heavy metals in its leaves and is reportedly suitable for phytoremediation. In this study, Cd uptake and accumulation in the leaves of B. rapa exposed to different cadmium levels (0, 5, 10, 20, 50, 100 μM CdSO4) were analyzed, as well as the effect of Cd stress on HMA2 and HMA4 genes expression were investigated. The qRT-PCR results showed that HMA2 and HMA4 play a vital role in cadmium uptake and translocation in B. rapa at low Cd levels (5-20 μM). However, exposure to high Cd levels (50 and 100 μM) significantly reduced the growth and biomass of B. rapa. Furthermore, high levels of Cd inhibit the expression of HMA2 and HMA4 genes in B. rapa. Our data show a multigenetic (co-acting of many transporter gene clusters) response in the signaling pathway associated with Cd accumulation and tolerance mechanism in B. rapa.

The Effect of Ca-Bentonite Aplication on Cadmium Uptake and Shoot Dry Matter of Bread Wheat

Cadmium(Cd) is a non-essential heavy metal that is highly toxic even at very low concentrations. Although Cd is a non-essential trace metal, when reached to high levels in agricultural soils, it can be easily absorbed by plants. Cadmium accumulation in wheat (Triticum aestivum L.) and its subsequent transfer to food chain is an important problem worldwide. Bentonite is a material essentially composed by montmorillonite and related clay minerals of the smectite group. The purpose of this study was to investigate the effects of bentonite (0, 3, 6 and 12%) application on Cd uptake of bread wheat growing in high Cd (0, 5 and 10 mg/kg soil) application. Plants were grown under greenhouse conditions acid soil. The experiment was conducted randomized block design with three replicates. The results revealed that shoot dry weight of bread was significantly increased with increasing doses of bentonite applications. While the dry weight of shoot without bentonite application was 480 mg/plant, it increased approximately 2 fold with 12% bentonite application. Cadmium concentration with the bentonite of control application decreased 4 times from 20.74 ppm to 5.07 ppm with application of 12% bentonite. The results show that Cd toxicity in the shoot was alleviated by bentonite treatment.

Cadmium Uptake From Soil by Ornamental Metallophytes: A Meta-analytical Approach.

Soil pollution by cadmium (Cd) is a serious issue worldwide affecting environmental and human health. Conventional chemical and physical methods of treating contaminated soil are costly, time-consuming, and less effective. Phytoremediation using ornamental plants is a safe and effective method for the treatment of heavy metal-polluted soil due to their rapid growth and accumulation of biomass, high heavy metal tolerance, and non-edible nature. The present study is the first attempt for the meta-analysis of existing literature on Cd accumulation and translocation by ornamental plants. The uptake and transfer capacity of ornamental plants was measured using the bio-concentration factor (BCF) and translocation factor (TF). The results indicate that ornamental plants have varying Cd-absorption capacities. Among the 49 plant species identified from 31 articles, Helianthus annuus (BCF = 5.785), Impatiens glandulifera (BCF = 4.722), and Crassocephalum crepidioides (BCF = 3.623) represented higher accumulation capacity, whereas Rorippa globosa (TF = 1.653) and Sedum spectabile Boreau (TF = 1.579) represented significantly higher translocation capacity for Cd. The contribution of various environmental factors in influencing BCF was obtained through multiple linear regression analysis. Results showed that soil pH was the major factor influencing the BCF. To further explain the influence of four main factors that are soil pH, soil organic matter (SOM), cation exchange capacity (CEC), and soil Cd concentration on the accumulation efficiency of ornamental plants, a subgroup meta-analysis was performed. Results of the subgroup meta-analysis revealed that the BCF is negatively correlated with the soil pH and SOM, while the estimated limit of soil Cd concentration for growing ornamental plants was up to 50 mg/kg. Results of this study indicate that choosing a native hyperaccumulator is not the sole key to the success of a phytoremediation design, rather the conditions of the pedosphere will determine the regulating factor for efficient removal. In order to overcome the issue of recirculation and gradual release in the rhizosphere, it is important to match the type of hyperaccumulators to the soil environment (pH, CEC, SOM, etc.) to achieve maximum translocation and desired removal. This study will help researchers to pair the right plant with environmental conditions and customize more efficient phytoremediation systems.

Combined effects of zinc oxide nanoparticles and melatonin on wheat growth, chlorophyll contents, cadmium (Cd) and zinc uptake under Cd stress

Zinc oxide nanoparticles (ZnONPs) and melatonin (MT) have been known to regulate heavy metal toxicities in plants in some studies, the effect of their combined use on cadmium (Cd) uptake by wheat (Triticum aestivum L.) and underlying mechanisms is largely unknown. Thus, plant growth, uptake and translocation of Cd mediated by soil applied ZnONPs and foliar applied MT were investigated in wheat grown in Cd polluted soil under ambient conditions. The results depicted that ZnONPs stimulated the growth, chlorophyll contents, and yield of wheat in a dose additive way and this effect was further increased with foliar application of MT. 100 mg/kg of ZnONPs alone enhanced the grain yield by 60.5 % and this increase was about 177.5 % under combined ZnONPs and 100 μM MT treatment. ZnONPs treatments decreased Cd concentration whereas increased zinc (Zn) concentrations in shoots, roots, husks and grains and the effect was further increased with exogenous MT combined with NPs in a dose-additive way. 50 and 100 mg/kg ZnONPs treatments alone decreased grain Cd by 6.5 %, and 20 % and increased the Zn concentration by 20.1 % and 24 % than control. 100 mg/kg ZnONPs +100 μM MT treatment decreased the grain Cd by 63.5 % and increased grain Zn by 51 % than control treatment. Total Cd uptake (tissues biomass × Cd concentration in respective tissues) in shoots, roots, husks and grains increased with ZnONPs alone or combined with MT than control whereas soil post-harvest bioavailable Cd concentration decreased with treatments than control. The Cd reduction in grains was due to increase in biomass and Zn concentration thereby decreasing bioavailable Cd in soil and its accumulation in plants. This study suggested that combined use of ZnONPs and MT may provide new approaches for minimizing Cd and biofortification of Zn in edible parts of plants.

Inhibition mechanisms of urea combined with nitrification on cadmium uptake by rice (Oryza sativa L.) seedlings

Inhibition mechanisms of urea combined with nitrification on cadmium uptake by rice (Oryza sativa L.) seedlings

Comparative genomic analysis of Citrobacter sp. XT1-2-2 reveals insights into the molecular mechanism of microbial immobilization of heavy metals

BackgroundIn our previous study, Citrobacter sp. XT1-2-2 was isolated from high cadmium-contaminated soils, and demonstrated an excellent ability to decrease the bioavailability of cadmium in the soil and inhibit cadmium uptake in rice. In addition, the strain XT1-2-2 could significantly promote rice growth and increase rice biomass. Therefore, the strain XT1-2-2 shows great potential for remediation of cadmium -contaminated soils. However, the genome sequence of this organism has not been reported so far. ResultsHere the basic characteristics and genetic diversity of the strain XT1-2-2 were described, together with the draft genome and comparative genomic results. The strain XT1-2-2 is 5040459 bp long with an average G + C content of 52.09%, and contains a total of 4801 genes. Putative genomic islands were predicted in the genome of Citrobacter sp. XT1-2-2. All genes of a complete set of sulfate reduction pathway and various putative heavy metal resistance genes in the genome were identified and analyzed.ConclusionsThese analytical results provide insights into the genomic basis of microbial immobilization of heavy metals.

Cultivar-specific response of rhizosphere bacterial community to uptake of cadmium and mineral elements in rice (Oryza sativa L.)

Toxic metal-contaminated farmland from Cadmium (Cd) can enhance the accumulation of Cd and impair the absorption of mineral elements in brown rice. Although several studies have been conducted on Cd exposure on rice, little has been reported on the relationship between Cd and mineral elements in brown rice and the regulatory mechanism of rhizosphere microorganisms during element uptake. Thus, a field study was undertaken to screen japonica rice cultivars with low Cd and high mineral elements levels, analyze the quantitative relationship between Cd and seven mineral elements, and investigate the cultivar-specific response of rice rhizosphere bacterial communities to differences in Cd and mineral uptake in japonica rice. Results showed that Huaidao-9 and Xudao-7 had low Cd absorption and high amounts of mineral nutrient elements (Fe, Zn, Mg, and Ca, LCHM group), whereas Zhongdao-1 and Xinkedao-31 showed opposite accumulation characteristics (HCLM group). Stepwise regression analysis showed that zinc, iron, and potassium are the key minerals that affect Cd accumulation in japonica rice and zinc was the most important factor, accounting for 68.99 %. The accumulation of Cd and mineral elements is potentially associated with rhizosphere soil bacteria. Taxa enriched in the LCHM rhizosphere (phyla Acidobacteriota and MBNT15) indicated the high nutrient characteristics of the soil and reduced activity of Cd in soil. The HCLM rhizosphere was highly colonized by metal-activating bacteria (Actinobacteria), lignin-degrading bacteria (Actinobacteria and Chlorofexi), and bacteria scavenging nutrients and trace elements (Anaerolinea and Ketobacter). Moreover, the differences in the uptake of Cd and mineral elements affected predicted functions of microbial communities, including sulfur oxidation and sulfur derivative formation, human or plant pathogen, and functions related to the iron oxidation and nitrate reduction. The results indicate a potential association of Cd and mineral elements uptake and accumulation with rhizosphere bacteria in rice, thus providing theoretical basis and a new perspective on the maintenance of rice security and high quality simultaneously.

Integration of Transcriptome and Metabolome Analyses Reveals the Mechanistic Basis for Cadmium Accumulation in Maize.

Cadmium (Cd) pollution in soil has become a major environmental issue worldwide. However, the underlying molecular mechanism of low grain-Cd accumulation (GCA) in maize is still largely unknown. Herein, we report the mechanistic basis for low GCA in maize by a multiomics approach. The low GCA genotype L63 showed normal vacuolar formation and a lower capacity of xylem loading of Cd than the high-accumulator L42 under Cd stress. Transcriptomic sequencing identified 84 low-GCA-associated genes which are mainly involved in the S-adenosylmethionine (SAM) cycle, metal transport, and vacuolar sequestration. A metabolome analysis revealed that L63 plants had a more active SAM cycle and a greater capacity for terpenoid synthesis and phenylalanine metabolism than L42. Combining the analysis of transcriptome and metabolome characterized several genes as key genes involved in the determination of Cd accumulation. Our study identifies a mechanistic basis for low Cd accumulation in maize grains and provides candidate genes for genetic improvement of crops.

Photosynthetic response, antioxidase activity, and cadmium uptake and translocation in Monochoria korsakowii with cadmium exposure.

To identify the tolerance mechanisms of wetland plants exposed to heavy metal, a hydroponic experiment was used to investigate variations in photosynthetically physiological parameters and antioxidant enzyme activities in leaves of Monochoria korsakowii exposed to 0.05, 0.15, 0.30, and 0.45 mM Cd2+ for 7 d. The Cd2+ concentrations in the plant roots, stems, and leaves were also investigated. Cd2+ exposure significantly decreased the total chlorophyll content, net photosynthetic rate, intercellular carbon dioxide concentration, and stomatal conductance, while stomatal limitation value had the opposite trend (P < 0.05). During Cd2+ stress, ascorbate peroxidase activity significantly increased (P < 0.05). The translocation factor for Cd2+ was significantly lower than that of the control, and both were less than 1 (P < 0.05). Cd2+ stress damaged the photosynthetic apparatus in the leaves. During Cd2+ stress, M. korsakowii alleviated oxidative stress by increasing the activities of antioxidant enzymes, such as APX. Under 0.45 mM Cd2+ stress, increased heat dissipation was responsible for alleviating the photooxidative damage to photosynthetic organs in the leaves. Meanwhile, the majority of Cd2+ was immobilized in the roots, thus alleviating excessive Cd2+ phytotoxicity in the aboveground parts. Generally, M. korsakowii has potential application in the phytoremediation of low-cadmium-polluted water.

OsNRAMP5 Is a Major Transporter for Lead Uptake in Rice.

Lead (Pb) is one of the most toxic metals affecting human health globally. Food is an important source of chronic Pb exposure in humans. How Pb is taken up by rice, a staple food for over half of the global population, remains unknown. In the present study, we investigated the role of OsNRAMP5, a member of the NRAMP (Natural Resistance-Associated Macrophage Protein) transporter family, in Pb uptake by rice roots. Heterologous expression of OsNRAMP5 in yeast increased Pb uptake and sensitivity toward Pb. Knockout of OsNRAMP5 in rice by CRISPR/Cas9 gene editing resulted in significant decreases in root uptake of Pb and accumulation in rice shoots. The maximum influx velocity (Vmax) for Pb uptake of the knockout mutants was 70% lower than that of wild-type plants. When grown in Pb-contaminated paddy soil, OsNRAMP5 knockout mutants accumulated approximately 50 and 70% lower Pb concentrations in the grain and straw, respectively, than the wild type. OsNRAMP5 expression in rice roots was not affected by Pb exposure. These results indicate that OsNRAMP5 is a major transporter for Pb uptake in rice, in addition to its role in the uptake of manganese and cadmium. This study provides a mechanistic understanding of Pb uptake in rice plants and a potential strategy to limit Pb accumulation in rice grains.

Effects of Biochar on Purslane-Mediated Transfer and Uptake of Soil Bioavailable Cadmium

Effects of Biochar on Purslane-Mediated Transfer and Uptake of Soil Bioavailable Cadmium

WGCNA Analysis Revealed the Hub Genes Related to Soil Cadmium Stress in Maize Kernel (Zea mays L.).

Soil contamination by heavy metals has become a prevalent topic due to their widespread release from industry, agriculture, and other human activities. Great progress has been made in elucidating the uptake and translocation of cadmium (Cd) accumulation in rice. However, there is still little known about corresponding progress in maize. In the current study, we performed a comparative RNA-Seq-based approach to identify differentially expressed genes (DEGs) of maize immature kernel related to Cd stress. In total, 55, 92, 22, and 542 DEGs responsive to high cadmium concentration soil were identified between XNY22-CHS-8 vs. XNY22-YA-8, XNY22-CHS-24 vs. XNY22-YA-24, XNY27-CHS-8 vs. XNY27-YA-8, and XNY27-CHS-24 vs. XNY27-YA-24, respectively. The weighted gene co-expression network analysis (WGCNA) categorized the 9599 Cd stress-responsive hub genes into 37 different gene network modules. Combining the hub genes and DEGs, we obtained 71 candidate genes. Gene Ontology (GO) enrichment analysis of genes in the greenyellow module in XNY27-YA-24 and connectivity genes of these 71 candidate hub genes showed that the responses to metal ion, inorganic substance, abiotic stimulus, hydrogen peroxide, oxidative stress, stimulus, and other processes were enrichment. Moreover, five candidate genes that were responsive to Cd stress in maize kernel were detected. These results provided the putative key genes and pathways to response to Cd stress in maize kernel, and a useful dataset for unraveling the underlying mechanism of Cd accumulation in maize kernel.

The ameliorative effect of hydrogen sulfide on cadmium toxicity and oxidative stress damage in garlic (Allium sativum) seedlings

• H 2 S reduces the uptake and accumulation of cadmium in garlic plants. • H 2 S reducing Cd oxidative damages by adjusting antioxidant enzyme system. • H 2 S considerably balanced Fe and Na in garlic seedlings. • H 2 S ameliorator improved the photosynthetic rate of garlic seedlings. Hydrogen sulfide (H 2 S) was identified as a novel signaling molecule that plays roles in plant growth and responses to abiotic stresses. However, information regarding its role in cadmium (Cd) detoxification and possible beneficial effects against oxidative damage in garlic plants is lacking. In this study, garlic ( Allium sativum ) seedlings were grown hydroponically at 0, 10 −4 , 10 −3 and 10 −2 M of cadmium chloride (CdCl 2 ) and 0, 200 µM concentrations of sodium hydrosulfide (NaHS). Cadmium stress caused growth inhibition and biomass reduction, which was related to high accumulation of cadmium in roots and shoots, depletion of chlorophyll contents, decrease of photosynthetic parameters and imbalanced in essential elements. These changes were accompanied by increasing activities of superoxide dismutase and ascorbate peroxidase enzymes while catalase enzyme activity decreased. The treatment with H 2 S ameliorator reduced Cd accumulation in seedling and improved photosynthetic rate of plants. This conclusion was supported by the increase of superoxide dismutase and ascorbate peroxidase activities as well as the balanced to mineral element uptake. Based on the results, it can be concluded that exogenous H 2 S has a positive effect on reducing Cd oxidative damages by adjusting antioxidant enzyme system and balances in nutrient element uptake, thus proposing H 2 S as a candidate for managing toxicity of cadmium in garlic plants.

Selection of rice and maize varieties with low cadmium accumulation and derivation of soil environmental thresholds in karst

Cadmium (Cd) is considered the primary dietary toxic element. Previous studies have demonstrated significant differences in heavy metal accumulation among crop species. However, this information in karst areas with low heavy metal activity is missing. In this study, the uptake and accumulation characteristics of cadmium in soil–crop samples of group 504 in the core karst region of East Asia were analyzed. Cadmium low-accumulating maize and rice were screened using cluster and Pareto analytic methods. In addition, a new method, the species–sensitive distribution model (SSD), was proposed, which could be used to estimate the environmental threshold for cadmium in regional cropland. The results showed that both maize and rice soils in the research area were contaminated with varying degrees of cadmium. The total concentrations of cadmium ω(T–Cd) in maize and rice fields are 0.18–1.32 and 0.20–4.42 mg kg–1, respectively. The ω(T–Cd) of heavy metals in maize kernels and rice grains is 0.002–0.429 and 0.003–0.393 mg kg–1, respectively. The bioaccumulation factor (BCF) of cadmium in maize ranged from 0.0079 to 0.9701, with a coefficient of variation of 1.71; the BCF of cadmium in rice ranged from 0.0074 to 0.1345, with a coefficient of variation of 0.99. According to cluster and Pareto analyses, the maize crop varieties with low cadmium accumulation suitable for local cultivation were screened as JHY809, JDY808, AD778, SN3H and SY13, and the rice varieties were DMY6188, GY725, NY6368, SY451 and DX4103. In addition, the environmental cadmium threshold ranges of 0.30–10.05 mg kg–1 and 0.89–24.39 mg kg–1 for maize and rice soils, respectively, were deduced in this study. This threshold will ensure that 5–95% of maize and rice will not be contaminated with cadmium in the soil.

Exopolysaccharides from Lactobacillus plantarum reduces cadmium uptake and mitigates cadmium toxicity in rice seedlings.

Exopolysaccharides (EPSs) can be used as effective exogenous substances to alleviate the toxic effect of cadmium (Cd) on rice and other crops, thus improving plant growth characteristics under stress conditions, and reducing the accumulation of Cd in grains, but the underlying mechanism is still unclear. In the present work, the effects of EPSs from Lactobacillus plantarum on the efficiency of Cd absorption and distribution in rice seedlings under Cd stress were investigated. The results revealed that growth of rice seedlings was severely inhibited by exposure to Cd, resulting in the decrease of plant height, leaf length and biomass. This inhibition phenomenon was alleviated by the addition of EPSs from L. plantarum LPC-1. The underlying mechanism might be that EPSs could facilitate the accumulation efficiency of Cd in rice roots and reduce the transportation rate of Cd from root to leaves, therefore decreasing the Cd content in leaves. Further research showed that Cd contents in the cell wall fraction of the rice seedling root were increased by the addition of EPSs, while the proportions of Cd in the cell organelle and cell soluble component were reduced. Application of EPSs promotes the proportion of pectate- and protein- integrated Cd in rice roots. While the content of water-soluble Cd, which is more toxic to plants, decreased continuously both in roots and leaves. Our study clearly confirmed the positive effects of EPSs on alleviating Cd toxicity and decreasing Cd translocation in rice above-ground parts. Furthermore, the subcellular distribution and chemical forms of Cd in different rice seedlings parts were also affected by the addition of EPSs, which might be an important potential mechanism for EPSs in respect of alleviating Cd toxicity for rice. These findings provided a foundation for the application of exogenous substances on improving the growth performance of crops under heavy metal stress.

Use of Parthenium hysterophorus with synthetic chelator for enhanced uptake of cadmium and lead from contaminated soils-a step toward better public health.

Parthenium hysterophorus L. is a vigorous plant species with cosmopolitan distribution. It can uptake considerable quantities of heavy metals from the soil and accrue these metals in its different tissue. The use of chelating agent i.e., Ethylenediaminetetraacetic acid (EDTA) can boost up metal uptake capacity. Pot experiment was performed to evaluate phytoextraction potential of P. hysterophorus for lead (Pb) and cadmium (Cd) with and without the aid of EDTA chelator. Shoot length, weight of root and shoot (both fresh and dry), leaves number, and chlorophyll contents of P. hysterophorus got reduced with an increase in metal uptake. The results revealed the highest concentration of Cd in shoot without and with EDTA was 283.6 and 300.1 mg kg−1, correspondingly. Increase in Pb concentration was also boosted up by the EDTA from its maximum concentration in shoot 4.30–9.56 mg kg−1. Generally, Pb and Cd concentrations were greater in shoots of P. hysterophorus than the roots regardless of EDTA in the treatments. EDTA also impacted positively the accumulation of essential ions K+, Na+, and Ca+2 in P. hysterophorus. The capacity of P. hysterophorus to accumulate Pb and Cd found to be increased with EDTA in the soil. Bringing metals level in the soil in accordance to the WHO standards can improve the ecosystem as well as public health.

Calcium Carbonate Crystallization on a Microalgal Matrix: The Effects of Heavy Metal Presence

Microalgae and other microorganisms often play a significant role in the transportation of heavy metal ions in the environment, while at the same time they are closely related to the formation of minerals in aquatic systems, especially with the formation of calcium carbonate (CaCO3). The biomineralization of calcite was investigated in aqueous solutions, supersaturated with respect to calcium carbonate (7.94 &lt; SRcalcite &lt; 31.36) in the presence of heavy metals (Zn, Cd, Ni, Cu) and of colonies of Acutodesmus obliquus (A. obliquus). The presence of metals tested in the supersaturated solutions, at concentration levels below the threshold of precipitation of the respective hydroxides, reduced the rate of calcium carbonate precipitation by 40 to 90% depending on the solution supersaturation. The presence of A. obliquus culture increased the rates of calcium carbonate precipitation by 80%. The presence of the test metals inhibited the growth of A. obliquus, especially the presence of Cd. The uptake of the test metals on calcite fitted Langmuir adsorption isotherm. Cadmium uptake onto calcite reached 85% of the total amount in the solutions. Charged ion pairs of test metals play an important role in their activity with respect to calcium carbonate precipitation and algal growth.

Phytoremediation Process of Water Spinach (Ipomoea aquatica) in Absorbing Heavy Metal Concentration in Wastewater

Heavy metals have become one of the environmental pollutants in water. To overcome this problem, the phytoremediation process was used as the method to cleanse polluted media. The objectives of the study are to determine the heavy metal accumulation by water spinach (Ipomea aquatica) in different types of heavy metal and to determine the level of heavy metal reduction in contaminated water. Ipomea aquatica was placed in containers that had solutions of different heavy metal concentrations. The selected heavy metals are cadmium (Cd), zinc (Zn), and copper (Cu), with a concentration of 5 ppm, 10 ppm, and 15 ppm, respectively. This study lasted about 20 days. Every four days, plant and water samples are collected. The plant samples were dried, digested, and analyzed by using ICP-OES. The two-way ANOVA statistical test was used to measure the differences in the amounts of the heavy metals accumulated in the plant and water. The accumulation of elements in plants shows a gradual increase in the uptake of cadmium, Cu, and Zn. Ipomea aquatica is suitable to take up cadmium, where the highest level of cadmium found was 13.99 mg/kg. On day 8, the level of heavy metals in the water gradually decreases for Cu and Zn. The presence of heavy metals in the water had decreased by 82.20 % on the last day of treatment. Ipomea aquatica accumulated more heavy metals while the number of heavy metals in the water decreased over a period of days. For all heavy metal types, significant differences in heavy metal concentration were obtained at p&lt;0.05, showing that Ipomea aquatica can be used in the phytoremediation approach to remove heavy metals from wastewater.

The rhizosphere microbiome improves the adaptive capabilities of plants under high soil cadmium conditions.

Cadmium (Cd) contamination of agricultural soils poses a potential public health issue for humans. Phytoremediation-based accumulating plants are an effective and sustainable technology for Cadmium remediation of contaminated agricultural soil. The rhizosphere microbiome can promote the growth and Cadmium accumulation in hyperaccumulators, but its taxonomic and functional traits remain elusive. The present study used two ecotypes of Sedum alfredii, an accumulating ecotype (AE) and a non-accumulating ecotype (NAE), as model plants to investigate the rhizosphere microbiome assemblages and influence on plant growth under high cadmium conditions. Our results showed that distinct root microbiomes assembled in association with both ecotypes of S. alfredii and that the assemblages were based largely on the lifestyles of the two ecotypes. In addition, we demonstrated that the functions of the microbes inhabiting the rhizosphere soils were closely associated with root-microbe interactions in both ecotypes of S. alfredii. Importantly, our results also demonstrated that the rhizosphere microbiome assembled in the AE rhizosphere soils contributed to plant growth and cadmium uptake under high cadmium conditions through functions such as nitrogen fixation, phosphorus solubilization, indole acetic acid (IAA) synthesis, and siderophore metabolism. However, this phenomenon was not clearly observed in the NAE. Our results suggest that the rhizosphere microbiome plays important roles in biogeochemical nutrient and metal cycling that can contribute to host plant fitness.

Intercropping with the potential cadmium hyperaccumulator Solanum photeinocarpum, and its post‐grafting generations, decrease cadmium uptake and promote growth of cherry

AbstractCadmium (Cd)‐contaminated soil has affected the fruit production safety. To decrease the Cd accumulation in the fruits, the effects of intercropping with the potential Cd‐hyperaccumulator Solanum photeinocarpum and its post‐grafting generations on the Cd uptake in cherry (Cerasus pseudocerasus) were studied by the pot experiments. Intercropping increased the biomass of cherry seedlings to some extent, and decreased the biomass of S. photeinocarpum and its post‐grafting generations. Intercropping decreased the Cd contents in cherry seedlings, and increased the Cd contents in S. photeinocarpum and its post‐grafting generations. Compared with their respective monoculture, intercropping decreased the shoot Cd content in cherry seedlings by 31.37%–60.70%, and increased the shoot Cd contents in S. photeinocarpum its post‐grafting generations by 18.50%–28.76%. In addition, intercropping also decreased the root‐to‐shoot Cd translocations in both plant species, and decreased the Cd content in the branches and fruits of fruiting cherry trees and the Cd extractions of S. photeinocarpum and its post‐grafting generations. Therefore, intercropping with S. photeinocarpum and its post‐grafting generations can be used to reduce Cd accumulation in cherry for fruit production safety.