Low Cd Research Articles

Boron's Role in Diminishing Cadmium Concentrations in Rice (Oryza sativa L.): Insights into Absorption Inhibition and Ripening Promotion.

Boron, a crucial element for plant growth, has been demonstrated to mitigate cadmium (Cd) absorption in rice seedlings. However, its impact on Cd accumulation in rice grains and the underlying regulatory mechanisms remain poorly understood. The current study explored the roles of boron in reducing Cd accumulation and promoting ripening in rice through pot and hydroponic experiments. The results revealed that the basal boron application (1.5 mg kg-1) decreased grain Cd concentration by 61.1%, primarily due to the synergistic effects of inhibited Cd uptake and transport, along with increased maturation. Boron mitigated the root Cd2+ influx by 32.4% and transport factors by 36.0-47.3% primarily by downregulating the expression of OsNramp5, OsIRT1, and OsHMA2. Moreover, boron enhanced the activities of key sucrose-metabolizing enzymes and increased the relative expression levels of genes associated with sugar metabolism and transport, thereby shortening the rice growth period from 132 to 120 d. Field experiment confirmed that boron application decreased rice grain Cd concentration by 47.7% while promoting earlier maturation. This study elucidates the mechanism behind boron's ability to lower grain Cd levels and highlights its potential as an effective agronomic approach to mitigate food safety risks in rice grown on Cd-contaminated paddy soils.

Mechanistic Insights into the Effects of Aged Polystyrene Nanoplastics on the Toxicity of Cadmium to Triticum Aestivum.

The widespread concern over nanoplastics (NPs) has prompted extensive research into their environmental impact. Concurrently, the study examined the combined toxicity of PS NPs and cadmium (Cd) on wheat. As indicated by the results of in situ Micro-ATR/FTIR, the aging process of PS NPs (50nm) led to an increase in carbonyl and hydroxyl groups on their surface, enhancing hydrophilicity and consequently, the adsorption capacity for Cd. The toxicity assessment, measured by the impact on wheat leaf and root biomass after 7 d culture, revealed that pristine PS NPs with concentrations of 0-5000mg·kg⁻¹ had a negligible effect on Cd toxicity to wheat leaves. However, aged PS NPs significantly intensified the inhibitory effect on wheat root growth, particularly at low Cd concentrations (≤ 5.0mg·kg⁻¹). This synergistic toxicity between aged PS NPs and Cd is suspected to stem from the increased bioaccumulation of Cd in wheat, likely facilitated by the aged NPs. Thus, the study shed light on the aging behavior of soil surface NPs and its implications for environmental risk assessment.

Identification of Peanut Cultivars with Low Cadmium Contents and Their Rhizosphere Microbial Characteristics in Alkaline and Acidic Cadmium-Contaminated Fields

Employing crop cultivars with low cadmium (Cd) accumulation and high yield is an effective strategy for the sustainable and safe utilization of Cd-contaminated farmland. However, the current understanding of peanut cultivars, particularly under field conditions, is limited. This study identified low-Cd cultivars and their rhizosphere microbial characteristics in acidic and alkaline fields with moderate Cd contamination. The results indicated that cultivars LH11, FH1, LH14, and YH9414 exhibited low Cd accumulation and high yield, with kernel Cd content reduced by 27.27% to 47.28% and yield increased by 9.27% to 14.17% compared with cultivar SLH. Among them, FH1 was validated to achieve safe production in two fields. A unique microbial community was formed by the recruitment of diverse microbes, such as Alphaproteobacteria, Acidobacteria, Gemmatimonadetes, and Chloroflexi, to the rhizosphere soil of FH1, which might be associated with Cd immobilization and the promotion of plant growth. Functional predictions further validated these findings, revealing enhanced functional pathways in the FH1 rhizosphere related to microbial proliferation, Cd stabilization, and detoxification. This study provides valuable germplasm resources for safe agriculture of Cd-polluted soils and elucidates the rhizosphere microbial characteristics of different peanut cultivars under field conditions. These findings are important for the targeted management of contaminated farmland and ensuring safe food production.

Exploring the Design of Low Cd BEV by Comparing the Characteristic Parameters and Curves of the Li Auto Mega and ZEEKR 009

As the Battery Electric Vehicle (BEV) market expands, consumer expectations for BEV performance are rising rapidly, with range anxiety becoming a major concern. Merely increasing battery size isnt a long-term solution. Instead, optimizing key design parameters to enhance aerodynamic efficiency is crucial. This paper examines the evolution of Multi-Purpose Vehicles (MPVs) by comparing the traditional MPV designs with newer, low drag models. in terms of appearance parameters and explore the future development of MPVs appearance. Specifically, the Li Auto Mega and ZEEKR 009 are analyzed, highlighting the stark differences in their designs. The study finds that the more aggressive and innovative design elements of the Mega effectively reduce the drag coefficient (Cd), offering valuable insights for future MPV designs

Strategic Selenium Application Methods and Timing Enhance Grain Yield, Minimize Cadmium Bioaccumulation, and Optimize Selenium Fortification in Triticum aestivum L.

Based on previous research, we hypothesized that an SeVI and SeMet combined application at different growth stages could increase the yield and Se concentration and decrease Cd concentration in wheat grains. To verify this hypothesis, we designed a pot experiment throughout the wheat growth period and investigated the effects of SeIV, SeVI, and SeMet applied individually or in combination at different growth stages on yield traits; Cd absorption and transport; and Se content under Cd stress. The results indicated that grain yield was the highest under the SeVI individual application treatment and the SeVI (at the seedling, jointing, and heading stages) and SeMet (at the filling stage) combined application treatment (3 + 1 treatment), showing a more than 42% increase compared with the Cd-only control treatment (CK). Under the 5 mg/kg Cd stress, the grain Cd content in the 3 + 1 treatment was 34.1% lower than that in CK and over 14.1% lower than those in Se individual treatments. Furthermore, grain Se content was the highest under the 3 + 1 treatment, being 160.8%, 99.7%, and 39.5% higher than those in the SeIV, SeVI, and SeMet individual treatments under 5 mg/kg Cd stress. This may be attributed to early SeVI application in the 3 + 1 treatment, which enhanced yield traits and effectively promoted the retention of Cd in the middle and lower organs, reducing its transport to the grains. Furthermore, the SeMet application enhanced Se translocation to the grains, further reducing Cd content and increasing the Se concentration. In conclusion, the combined application of SeVI (at the seedling, jointing, and heading stages) and SeMet (at the filling stage) helped achieve the desired outcomes of high grain yield, low Cd content, and Se enrichment under Cd stress.

Lower Cadmium Bioavailability and Toxicity in Japonica Rice than in Indica Rice: Mechanisms and Health Implications.

Cadmium (Cd) is efficiently transferred from soil to food crops, notably rice. Research indicates that indica rice grains may accumulate more Cd than japonica cultivars; however, differences in Cd bioavailability (the fraction of ingested rice Cd absorbed into the systemic circulation) and toxicity remain unexplored, thus hindering a comprehensive understanding of exposure and health risks. To address this, a mouse bioassay was conducted to evaluate the relative bioavailability (RBA) of Cd in 35 samples each of japonica and indica rice, determining which type exhibits lower Cd bioavailability. The results revealed a significantly lower mean Cd-RBA in japonica rice (49.6 ± 7.8%) compared to indica rice (65.6 ± 12.2%). This disparity is attributed primarily to the 1.25- and 1.37-fold higher concentrations of calcium (Ca) and iron (Fe) in japonica rice, which enhanced Ca and Fe absorption from the intestine and reduced duodenal expression of Ca and Fe transporters by 1.8-5.9 times in mice consuming japonica rice, thereby decreasing Cd transcellular transport. Additionally, japonica rice consumption promoted beneficial gut probiotics (Bifidobacterium pseudolongum and Lactobacillus reuteri) and metabolites, particularly short-chain fatty acids and peptides, potentially increasing mineral absorption and reducing Cd uptake. Moreover, mice fed japonica rice exhibited 1.35-1.47 times higher gene expression of intestinal tight junctions, enhancing intestinal barrier function and reducing extracellular Cd transport. Consequently, consuming Cd-containing japonica rice was associated with lower oxidative stress, inflammation, and cancer risks in mice compared to indica rice consumption. This study significantly enhances our understanding on the health risks associated with Cd in different rice subspecies.

Evaluating a Soil Amendment for Cadmium Mitigation and Enhanced Nutritional Quality in Faba Bean Genotypes: Implications for Food Safety.

Soil amendments combined with low cadmium (Cd)-accumulating crops are commonly used for remediating Cd contamination and ensuring food safety. However, the combined effects of soil amendments and the cultivation of faba beans (Vicia faba L.)-known for their high nutritional quality and low Cd accumulation-in moderately Cd-contaminated soils remain underexplored. This study investigates the impact of a soil amendment (SA) on agronomic traits, seed nutrition, and Cd accumulation in 11 faba bean genotypes grown in acidic soil (1.3 mg·kg-1 Cd, pH 5.39). The SA treatment increased soil pH to 6.0 (an 11.31% increase) and reduced DTPA-Cd by 37.1%. Although the average yield of faba beans decreased marginally by 8.74%, it remained within the 10% national permissible limit. Notably, SA treatment reduced Cd concentration in seeds by 60% and significantly mitigated Mn and Al toxicity. Additionally, SA treatment enhanced levels of essential macronutrients (Ca, Mg, P, S) and micronutrients (Mo, Cu) while lowering Phytate (Phy)/Ca, Phy/Mg, and Phy/P ratios, thus improving mineral nutrient bioavailability. Among the genotypes, F3, F5, and F6 showed the most favorable balance of nutrient quality, and yield following SA application. This study provides valuable insights into the effectiveness of SA for nutrient fortification and Cd contamination mitigation in Cd-contaminated farmland.

Impact of Structural Subtleties on Chirality Induction and Amplification in Trizinc(II)Porphyrin Trimers.

Herein, we report the precise control of molecular to supramolecular chirality induction at the single-molecule level just upon subtle modification in an achiral 'nano-size' trizinc(II) porphyrin trimer. A slight variation in the projection of the substituent at the periphery of the central porphyrin unit in a porphyrin trimer (host) resulted in pronounced changes in the interchromophoric arrangement, leading to distinct 'open' and 'closed' conformations. While 'open' form generates 'monomeric' complex with low CD amplitude, 'closed' form produces exclusive 'polymer' with large, amplified CD signal with opposite sign due to stronger intermolecular excitonic coupling. Also, the sign of the CD couplets is just opposite between R and S substrates for both polymer and monomer which suggest that the chirality is predominantly governed by the stereogenic projection of the chiral center. X-ray structures of the host and polymer have been reported here. Crystallographic characterization offers a detailed perspective on the structural and geometrical transformations in the polymer, enabling a systematic understanding of its optical properties. DFT and TD-DFT calculations strongly corroborate with the experimental findings.

Adsorption Characteristics of Cadmium onto Calcite and Its Agricultural Environmental Relevance

Calcite (CaCO3), a common component of calcium-based fertilizers, has been recognized for its effectiveness as a cadmium (Cd) immobilization agent in the solidification/stabilization (S/S) method. This strategy is a widely used chemical remediation technique aimed at reducing the bioavailability and toxicity of Cd in contaminated soils. This study comprehensively evaluated the potential of calcite for Cd remediation through geochemical analyses, including adsorption isotherms, saturation index, ion concentration changes, and X-ray diffraction (XRD) analysis. Adsorption isotherm experiments indicated that Cd adsorption onto calcite aligns more closely with the Freundlich isotherm model, suggesting a heterogeneous surface with a maximum adsorption capacity of 1.56 mg g−1. Based on chemical states result, optimal conditions for CdCO3 precipitation with low Cd concentrations were identified at pH above 7.9. XRD analysis confirmed the formation of Ca0.67Cd0.33CO3 at higher Cd concentrations, indicating that chemisorption is the dominant immobilization mechanism. Additionally, variations in Ca2+ and CO32− concentrations supported the substitution of Cd for Ca on the calcite surface. These findings highlight calcite’s potential as an effective material for Cd immobilization, providing valuable insights for the developing more sustainable soil remediation strategies.

The cation/H+ exchanger OsCAX2 is involved in cadmium uptake and contributes to differential grain cadmium accumulation between Indica and Japonica rice.

Rice is a major source of dietary cadmium (Cd), a toxic heavy metal that poses serious threat to human health. How rice takes up and accumulates Cd is not fully understood. Here, we characterize the function of a cation/H+ exchanger, OsCAX2, in Cd uptake in roots and Cd accumulation in shoots and grains. OsCAX2 exhibited Cd and calcium (Ca) transport activities when was heterologously expressed in yeast. OsCAX2 was mainly expressed in roots, particularly in lateral roots, and in the exodermis and endodermis of primary roots. OsCAX2 is localized at the plasma membrane. Knockout of OsCAX2 significantly decreased Cd uptake in roots and Cd accumulation in shoots and grains. Knockout of OsCAX2 also decreased the Ca concentration in roots, but not in shoots or grains. Surprisingly, overexpression of OsCAX2 also resulted in a significant decrease in the Cd concentrations in roots and shoots. We further reveal that the variation in the coding sequence of OsCAX2 contributes to differential grain Cd accumulation between two major rice subspecies, Indica and Japonica. Our results demonstrate that OsCAX2 functions in Cd/Ca uptake in roots and could be a useful target for breeding or genetic engineering low Cd rice varieties.

Deciphering the mechanism of rhizosphere microecosystem in modulating rice cadmium accumulation via integrating metabolomics and metagenomics.

Cadmium (Cd) accumulation in rice poses significant risks to human health. The Cd accumulation levels vary widely among cultivars and are strongly associated with the rhizosphere microecosystem. However, the underlying mechanisms remain poorly understood. Here, we conducted a field experiment in Cd-contaminated areas with 24 popular regional cultivars. These cultivars were categorized into high Cd accumulation (HA) and low Cd accumulation (LA) groups based on their grain Cd content. Rhizosphere soil physicochemical properties were monitored, and key metabolites, microbiomes, and their interaction contributing to Cd accumulation were analyzed using omics-sequencing technologies and bioinformatics analysis. Metabolomic analysis identified distinct rhizosphere metabolite profiles between the HA and LA groups, with key metabolites showing strong correlations with Cd accumulation. Key metabolites in the LA group were linked to reduced Cd uptake and enhanced antioxidant defense mechanisms, while those in the HA group were associated with increased Cd mobility and uptake. Metagenomic analysis of the rhizosphere soil showed that the LA group harbored a more diverse and interconnected microbial community, with tax such as Syntrophaceae, Anaerolineae, Thermoflexales, and Syntrophales, along with metabolite such as disopyramide, playing central roles in Cd immobilization and detoxification. Additionally, the enhanced carbon, nitrogen, and phosphorus cycling in the LA group suggests a more robust nutrient assimilation process that supports plant growth and reduces Cd uptake. This study highlights the critical role of the rhizosphere microecosystem in regulating Cd accumulation and underscores the potential of selecting rice cultivars with favorable rhizosphere traits as a strategy for reducing Cd uptake.

Cadmium Reduces VE-Cadherin Expression in Endothelial Cells Through Activation of the Notch Signaling Pathway.

Cadmium (Cd) is a toxic heavy metal which induces vascular disorders. Previous studies suggest that Cd in the bloodstream affects vascular endothelial cells (ECs), potentially contributing to vascular-related diseases. However, the molecular mechanisms of effects of Cd on ECs remain poorly understood. Notch signaling pathway abnormalities have been implicated in ECs disruption. The present study aims to investigate the effect of low Cd concentrations on the Notch signaling pathway in ECs. Mice were treated with low concentration of Cd (2.28 mg/kg), and tissues were collected for examination of mRNA and protein levels of Notch pathway components and VE-cadherin, a major junctional protein in ECs. We found that Cd treatment increases expression of NICD1, Hes1, Hey1, Hey2 and decreases expression of VE-cadherin in brain and kidney tissues. In vitro, a low concentration of Cd (1 μM) also induces increase expression of NICD1, Hes1, Hey1, Hey2, and decrease expression of VE-cadherin in human umbilical vein endothelial cells (HUVECs). Low concentration of Cd increased the permeability of HUVECs. We also found that Notch signaling negatively regulates the expression of VE-cadherin. In addition, DAPT, a Notch pathway inhibitor, prevents Cd-induced reduction in VE-cadherin expression in HUVECs. In summary, these findings revealed that Cd exposure decreases VE-cadherin expression through activation of the Notch signaling pathway.

Remediation and environmental safety of paddy soil temporarily polluted by heavy metals from acid mine drainage

ABSTRACT This study examines the remediation of paddy soils briefly contaminated by acid mine drainage (AMD) using lime (LM) and steel slag (SS) amendments. The treatment not only boosted rice yields but also significantly lowered Cd and Cu levels in the rice. Additionally, it decreased net acid generation and increased acid neutralization capacity, reducing soil acidification risk, though reacidification potential remains high. Soil amendments improved pH, raising it to neutral, and enhanced cation exchange capacity from 4.35 to 9.23 cmol/kg. Enzymatic activities were also affected: dehydrogenase activity increased, urease decreased after LM and SS application, and sucrose activity varied with the type of amendment. The findings suggest that AMD-polluted paddy soils can be effectively remediated through soil amendments and rice cultivation, but continuous monitoring and further interventions are needed for sustained soil health.

γ-Aminobutyric Acid Alleviates Programmed Cell Death in Two Brassica Species Under Cadmium Stress

Previous studies have demonstrated that γ-Aminobutyric acid (GABA) effectively alleviates heavy metal stresses by maintaining the redox balance and reducing the accumulation of reactive oxygen species (ROS). However, little is known about the role of GABA on programmed cell death (PCD) under Cd treatments in plants. The present study investigated the effects of GABA on Cd-induced PCD in two Brassica species, oilseed rape (Brassica napus, Bn), and black mustard (Brassica juncea, Bj). We observed that GABA significantly alleviated Cd-induced PCD by enhancing antioxidant systems, inhibiting chromatin condensation in the nucleus, and reducing DNA fragmentation under Cd stress. Moreover, GABA may not only reduce caspase-3-like activity by repressing gene expression, but also regulate transcription of PCD-related genes. Bn showed lower Cd accumulation and lower tolerance, with more pronounced PCD, compared with Bj. Our results provide new insights into the mechanism that GABA enhances Cd tolerance in plants.

Multiple insights into differential Cd detoxification mechanisms in new germplasms of mung bean (Vigna radiata L.) and potential mitigation strategy.

Long-term cadmium (Cd) exposure inhibits plant growth and development, reduces crop yield and quality, and threatens food security. Exploring the Cd tolerance mechanisms and safe production of crops in Cd-contaminated environment has become a worldwide concern. In this study, mung bean (Vigna radiata L.) cultivar Sulu (SL) and its three mutant lines (20#, 09#, and 06#) were used to compare the difference in Cd absorption, accumulation, and tolerance through pot and field experiments. 20#, 09#, and 06# are Cd-tolerant germplasms of mung bean but exist in different Cd tolerance mechanisms, 20# exhibited the lowest Cd absorption capacity, 09# possessed lower Cd translocation capacity, while 06# accumulated more Cd in protoplasts. Mung bean germplasms with higher Cd tolerance generally showed lower absorption capacity and intracellular accumulation of Cd. Besides, Cd accumulation in mung bean seeds is mainly depended on the absorption and translocation of Cd in roots and the Cd concentration in leaves, exogenous Mn supply inhibited the Cd2+ net influx of roots and Cd accumulation in seeds, this trend was more pronounced in mung bean germplasms with higher Cd accumulation and absorption. Moreover, we characterized a Cd transporter gene VrNramp5, which was differentially expressed in different mung bean lines, overexpression of VrNramp5 increased Cd accumulation and was accompanied by Cd-sensitive phenotype in transgenic mung bean seedlings, and the Cd concentration of mung bean was significantly positively correlated with the expression levels of VrNramp5. Taken together, our findings demonstrated that different Cd tolerance mechanisms exist in mung bean. 20# is the new Cd-tolerant germplasm with low Cd absorption capacity and Cd accumulation in seeds, and has great potential for the safe production of mung bean in Cd-contaminated soils and the breeding of low Cd accumulation crop cultivars.

Wheat Tends to Accumulate Higher Levels of Cadmium in the Grains than Rice under a Wide Range of Soil pH and Cd Concentrations: A Field Study on Rice-Wheat Rotation Farmland.

Dietary intake is a predominant pathway of human exposure to environmental Cadmium (Cd), but wheat (Triticum aestivum L.) has not received enough concerns for its risk of Cd contamination. A field survey of Cd-contaminated rice-wheat rotation farmlands in China provided detailed comparison of Cd accumulation capacity by rice and wheat grains. The results indicated that Cd-BCF of wheat grains (median values 0.42) were obviously higher than those of rice grains (median values 0.12) under wide soil Cd levels and pH ranges. Soil Cd levels rather than pH played a vital role on Cd accumulation by wheat grains, and high wheat grain Cd concentrations (0.12-0.13 mg kg⁻1) were even observed in mildly alkaline soil that normally have low Cd mobility. Dietary Cd exposure risks were assessed by the crop Cd exposure models considering different soil Cd content, pH and dietary structures of residents. The results indicated that the intake of wheat grains contributed 56.1-86.5% of total crop Cd exposure, with an increase in its contribution with the increase of soil pH. Residents favoring wheat would have a significant Cd exposure risk if consuming crops from soils with Cd levels above 0.41 mg kg⁻1, which was considerably lower than the current soil Cd risk screening value for alkaline soils (0.6 mg kg-1). Our findings indicate a high Cd accumulation capacity of wheat grains and consequent risk of dietary Cd exposure, which deserves further exploration on the correlation among soil Cd screening value, grain Cd limit value and its dietary exposure risk.

Meta-Analysis of the Impacts of Applying Livestock and Poultry Manure on Cadmium Accumulation in Soil and Crops

The return of livestock and poultry manure (LPM) to fields is necessary for sustainable agricultural development, but it is also a primary source of heavy metal contamination in agricultural land, which potentially threatens soil and crops. Conflicting results have been reported in previous studies on the impacts of returning LPM to fields on cadmium (Cd) accumulation in the soil and crops. Herein, we investigated the impacts of applying such manure on Cd accumulation in the soil and crops through meta-analysis. We also explored the relationships of Cd content in the soil and crops with the soil properties, experimental conditions, and manure properties. Moreover, we evaluated the primary reasons for the differences in the results of different studies and the factors influencing them. Upon applying LPM, the contents of soil total Cd, soil available Cd, and crop grain Cd increased by 30.96%, 86.91%, and 20.43%, respectively, and the crop root Cd content decreased by 16.91%. Random forest analysis and decision tree analysis further quantified the importance of each influencing factor and identified the primary factors influencing soil available Cd and grain Cd contents. From the perspective of safe production, some suggestions were made for returning LPM to fields: (1) applying higher pH LPM or increasing the dosage in soils with low Cd content and pH of <5.7; (2) applying LPM to soils with Cd content of <1.8 mg/kg, pH of >5.7, and soil organic matter content of >19 g/kg, which was associated with a low risk of Cd accumulation in crop grains; and (3) applying LPM while planting low-Cd-accumulating crop varieties. This study provides scientific guidance for the safe use of such manure resources and helps to reduce the risk of cadmium accumulation.

Measures and effects on soil Cd remediation and safe rice production: a meta-analysis of 10-year Chinese patents

Rice is the staple food for 1/3 of the world’s population, but soil pollution with cadmium (Cd) is harmful to rice production and human health. Therefore, how to reduce the Cd content in rice grains is a hot topic worldwide. However, so far, little is known about Cd remediation technologies for paddy soils from the perspective of patents. Therefore, a meta-analysis was performed to assess the effects of measures based on 1402 observations from 336 patents from 2011 to 2021. The spatio-temporal analysis showed that the number of patents was positively related to the general economic development of the country, but hardly related to the regional economy or the level of provincal Cd pollution. The meta-analysis showed that the overall effect of Cd reduction was slightly higher for combined technologies (59%) than for single technologies (57%). Among all technology classifications, soil applications, which are mainly based on nutritional elements, were the most commonly used technology that could reduce the Cd content in rice grains by 57%. The plant biotechnology was the most effective and could reduce Cd content in rice grains by 76%. Further analysis showed that macronutrients (calcium, phosphorus, and sulfur) were preferred in soil amendments, while micronutrients (silicon, zinc, and selenium) were preferred in foliar amendments. NRAMP5 and HMA3 were the most important genes for manipulating Cd uptake in rice, while Bacillus and Pseudomonas were the most important bacterial taxa for bioremediation of Cd. Overall, this study compiled data on Cd remediation of paddy soil from 10 years of Chinese patents, providing a theoretical basis for better production of low Cd crops and protection of human health.

Energy metabolism, antioxidant defense system, metal transport, and ion homeostasis are key contributors to Cd tolerance in SSSL derived from wild rice.

Cadmium (Cd) toxicity poses major challenges to rice cultivation, affecting plant growth and development. Wild rice and nanoparticles offer promising strategies to enhance Cd tolerance, yet little is known about their combined effects. This study evaluates the single segment substitution line (SG004) from Oryza glumaepatula (wild rice) and its response to Cd stress compared to cultivated rice (HJX74). Both genotypes were also treated with calcium oxide nanoparticles (np-CaO). Results showed that Cd exposure disrupts reactive oxygen species (ROS) metabolism in both lines, such as malondialdehyde (MDA) increases by 57 % in HJX74 compared to SG004. Moreover, SG004 exhibited a 26 % reduction in shoot length compared to 41 % in HJX74 and a 42 % decline in chlorophyll ab content versus 53 % in HJX74. Antioxidant activity such as glutathione (GSH) decreased 25 % more in HJX74 than SG004 under Cd toxicity. Additionally, SG004 had lower Cd accumulation in roots (70 %) and shoots (85 %) than HJX74, indicating its enhanced tolerance to Cd toxicity. The root cell cytology reveals several deformations in different organelles of HJX74 but less in SG004. RNAseq analysis identifies key pathways, including energy metabolism, antioxidant defense, metal transport, and ion homeostasis, which may be critical for SG004 enhanced tolerance. Notably, two distinct metallothionein-like genes (BGIOSGA019338, BGIOSGA035982), a peroxidase (BGIOSGA019133), ammonium (BGIOSGA008640, BGIOSGA008641, and potassium transporters (BGIOSGA030867), NRAMP1 (BGIOSGA025476), and an aluminum-activated malate transporter (BGIOSGA014531), showed differential expressions in SG004 under Cd stress. Genes within the substituted fragment, including those for peroxidase 25 (BGIOSGA002866), metallothionein (BGIOSGA002389), and reductase (BGIOSGA002387), are also upregulated in SG004, reinforcing the role of antioxidant and ion homeostasis pathways. The utilization of np-CaO alleviates Cd-induced stress in both genotypes, hence reinforcing the application of wild rice and nanoparticles to improve Cd tolerance.

Tomato sprayed monocalcium phosphate had production-phytoremediation dual function with high soil Cd extraction and safer fruit production

In order to make use of the large biomass of tomato plant to fulfill the purpose of remediating-while-producing, two commercial tomato varieties, ‘Baiguoqiangfeng’ (BG) and ‘Ouguan’ (OG) were grown in Cd contaminated acidic soil to compare their performance on Cd phytoextraction, and monocalcium phosphate (Ca) was foliar applied to reduce their fruit Cd concentration. The results showed that the BG was a more Cd tolerant variety, comparing with OG, it suffered lighter tissue peroxidation and photosynthesis obstacle, owning weaker amino acid metabolism, secondary metabolism and stress signal transduction under Cd stress. The Ca application reduced its ABA level but increased the GSH, IAA, ZR and GA3 level, and enhanced its lysine degradation, tyrosine metabolism, alanine, asparagine and glutamate metabolism, plant hormone signal transduction and phenylpropanoid biosynthesis under Cd stress. With these metabolic regulations, the Ca application promoted its leaf biomass accumulation, guaranteeing the total Cd extraction amount (0.88 mg pot−1 as 0.20 mg kg −1), and reduced the fruit Cd partition, decreasing the fruit Cd concentration by 71.4% with higher yield. Meanwhile, the OG had lower Cd phytoextraction capacity than the BG, and Ca spray enhanced its cell energy generation, flavonoids biosynthesis and photosynthetic carbon fixation, but had no effect on fruit Cd concentration. The two tomato varieties had different responses to Ca application under Cd stress in their hormone signaling, energy metabolism, secondary metabolism and amino acids metabolism, which furtherly differed their Cd phytoextraction capacity and production safety. Therefore, the monocalcium phosphate spray combined ‘Baiguoqiangfeng’ tomato realized the dual function of production-phytoremediation, and the mechanism of plant Cd sensitivity adjustment through phenylpropanoid biosynthesis and amino acids metabolism deserved further study.