Physiological and molecular mechanisms of medicinal plants in response to cadmium stress: Current status and future perspective

Smart reprogramming of plants against cadmium toxicity using membrane transporters and modern tools

Cadmium (Cd) in soil and water streams is now recognized as a significant environmental issue that harms plants and animals. Plants damaged by Cd toxicity experience various effects, from germination to yield reduction. Plant- and animal-based goods are allowing more Cd to enter our food chain, which could harm human health. Therefore, this urgent global concern must be addressed by implementing appropriate remedial measures. Plant-based phytoremediation is one safe, economical, and environmentally acceptable way to remove hazardous metals from the environment. Hyperaccumulator plants possess specialized transport proteins, such as metal transporters located in membranes of roots, as well as they facilitate Cd uptake from soil. This review outlines the latest findings about these membrane transporters. Moreover, we also discuss how innovative modern tools such as microbiomes, omics, nanotechnology, and genome editing have revealed molecular regulators connected to Cd tolerance, which may be employed to develop Cd-tolerant future plants. We can develop effective solutions to enhance tolerance of plant to Cd toxicity by leveraging membrane transporters and modern biotechnological tools. Additionally, implementing strategies to increase tolerance of Cd and restrict its bioavailability in plants' edible parts is crucial for improving food safety. These combined efforts will lead to the cultivation of safer food crops and support sustainable agricultural practices in contaminated environments.

Combined application of biochar and PGPB on crop growth and heavy metals accumulation: A meta-analysis

The combined application of biochar and plant growth-promoting bacteria (PGPB) has shown significant efficacy on alleviating plant heavy metals stress and remediating soil heavy metals pollution. Nevertheless, the underlying mechanism of the synergistic action of biochar and PGPB in the soil-plant system remain poorly understood. This investigation utilized a hierarchical meta-analysis approach to synthesize 237 datasets extracted from 59 studies, aiming to quantitatively evaluate the effectiveness of the co-application of biochar and PGPB in promoting plant growth and remediating soil heavy metals pollution. The combined treatment increased root and shoot biomass by 84% and 116%, respectively, while reducing heavy metal concentrations in roots (33%), shoots (45%), and soil (44%). This treatment markedly enhanced plant nutrient absorption and stimulated soil enzyme induction, optimizing metabolic functions in the rhizosphere. Through comprehensive analysis of diverse plant physiological parameters, it was determined that the biochar and Pseudomonas combination exhibited optimal performance in biomass enhancement, whereas the Proteobacteria and biochar consortium had the most significant effect on decreasing the content of heavy metals in the plant and soil. Furthermore, the biochar and PGPB co-application showed the best results in mitigating Pb pollution stress. This study provides subatantive scientific basis for remediation of soil heavy metals pollution and plant stress mitigation.

Ecotype-specific phenolic acid accumulation and root softness in Salvia miltiorrhiza are driven by environmental and genetic factors

Salvia miltiorrhiza Bunge, a renowned medicinal herb in traditional Chinese medicine, displays distinctive root texture and high phenolic acid content, traits influenced by genetic and environmental factors. However, the underlying regulatory networks remain unclear. Here, we performed multi-omics analyses on ecotypes from four major Chinese regions, focusing on environmental impacts on root structure, phenolic acid accumulation and lignin composition. Lower temperatures and increased UV-B radiation were associated with elevated rosmarinic acid (RA) and salvianolic acid B (SAB) levels, particularly in the Sichuan ecotype. Structural models indicated that the radial arrangement of xylem conduits contributes to greater root hardness. Genomic assembly and comparative analysis of the Sichuan ecotype revealed a unique phenolic acid metabolism gene cluster, including SmWRKY40, a WRKY transcription factor essential for RA and SAB biosynthesis. Overexpression of SmWRKY40 enhanced phenolic acid levels and lignin content, whereas its knockout reduced root hardness. Integrating high-throughput (DNA affinity purification sequencing) and point-to-point (Yeast One-Hybrid, Dual-Luciferase and Electrophoretic Mobility Shift Assay) protein-DNA interaction detection platform further identified SmWRKY40 binding sites across ecotypes, revealing specific regulatory networks. Our findings provide insights into the molecular basis of root texture and bioactive compound accumulation, advancing breeding strategies for quality improvement in S. miltiorrhiza.

Integration of lipidomics and widely targeted metabolomics provides a comprehensive metabolic landscape of Poa pratensis under cadmium stress

BACKGROUND

Soil cadmium (Cd) contamination poses significant environmental challenges globally. Kentucky bluegrass is considered a viable plant for remediating Cd-contaminated soils due to its high tolerance to Cd and accumulation capacity. Yet, the complete metabolic landscape underlying Cd detoxification mechanisms of Kentucky bluegrass remains incompletely understood.

RESULTS

Here, widely targeted metabolomics was used to identify key metabolites of Kentucky bluegrass that were responsive to Cd stress in comparisons between Cd-resistant (M) and sensitive (R) varieties. Moreover, lipidomics analyses were used to assess the content, composition, and saturation levels of lipid molecular species. The M variety exhibited higher levels of free amino acids, saccharides, and flavonoids (flavones, flavonols, isoflavones, and flavanones) after Cd stress that likely enhance its tolerance to Cd stress. Within the M variety, 183 lipid species (81%) were less abundant after Cd stress, representing a much larger number than the 81 lipid species (41.54%) similarly less abundant in the R variety. The lipid species with increased abundances primarily comprised diacylglycerols, monogalactosyldiacylglycerol, phosphatidylcholine, triacylglycerol, and lysophosphatidylcholine that exhibited higher saturation levels. Conversely, the lipid species with decreased abundances largely comprised those with shorter acyl chains including free fatty acids, phosphatidic acid, and lysophosphatidic acid, as well as those with higher unsaturation levels, including phosphatidylglycerol, diacylglycerol, triacylglycerol, phosphatidylcholine, and lysophosphatidylcholine. The elongation of these lipid acyl chains under Cd stress contributes to the increased membrane thickness and rigidity in Kentucky bluegrass, resulting from the dense packing of hydrophobic tails and enhanced lipid-lipid interactions. The changes in these metabolites and lipids may play a significant role in enhancing Cd tolerance, distribution, and accumulation in Kentucky bluegrass.

CONCLUSION

The results of this study provide a comprehensive metabolite profile for Kentucky bluegrass in response to Cd stress, elucidating the key metabolite characteristics essential for Cd detoxification under Cd-induced stress. Furthermore, the results provide insights into the metabolic regulation of metabolites and lipid homeostasis that contribute to enhanced Cd tolerance in Kentucky bluegrass.

Transcriptome and Physiological Analysis Reveals the Mechanism of Abscisic Acid in Regulating Cadmium Uptake and Accumulation in the Hyperaccumulator Phytolacca acinosa Roxb

Cadmium (Cd) is an extremely toxic heavy metal that can move from the soil to plants and enter the human body via the food chain, causing severe health issues for humans. Phytoremediation uses hyperaccumulators to extract heavy metals from polluted soil. Phytohormones, wildly used plant growth regulators, have been explored to improve phytoremediation efficiency. Abscisic acid (ABA) is also an essential regulator of plant tolerance to biotic and abiotic stresses, including heavy metal-induced toxicity. Previous research has revealed that Phytolacca acinosa Roxb. (P. acinosa) has a strong ability to enrich Cd and can be used as a Cd hyperaccumulator. In this study, physiological and biochemical analysis revealed that under Cd stress, exogenous ABA application alleviated oxidative stress, increased the Cd2+ concentration in P. acinosa, especially in the roots, and changed the phytohormone concentration in P. acinosa. Transcriptome analysis was conducted to explore the molecular mechanisms by which ABA regulates Cd uptake and accumulation in P. acinosa, and to further understand the regulatory role of ABA. The results show that ABA treatment affected gene expression in P. acinosa roots under Cd stress. This study identified 5788 differentially expressed genes (DEGs) (2541 up-regulated and 3247 down-regulated). Moreover, 96 metal transport-related DEGs, 54 phytohormone-related DEGs, 89 cell wall-related DEGs, 113 metal chelation-related DEGs, and 102 defense system-related DEGs cooperated more closely under exogenous ABA application to regulate Cd uptake and accumulation in P. acinosa under Cd stress. These results may help to elucidate the mechanisms by which ABA regulates Cd uptake and accumulation in plants, and provide a reference for developing a phytohormone-based strengthening strategy to improve the phytoremediation ability of other hyperaccumulators or accumulator species. The key genes involved in ABA's regulation of Cd uptake and accumulation in P. acinosa need to be further analyzed and functionally verified. This may expand our understanding of the molecular regulatory mechanisms underlying heavy metal uptake and accumulation in hyperaccumulators.

The Influence of Bisphenol A on Parsley: A Biochemical and Metabolomics Integrative Perspective

Bisphenol A (BPA), a widely used industrial chemical, poses environmental concerns due to its persistence and potential effects on plant systems. This study examines the impact of three BPA exposure levels on parsley plants, focusing on physiological, biochemical, and metabolomic responses. BPA exposure significantly shaped the plant's defense mechanisms, mainly through increased phenolic (up to 16.81%) and flavonoid (up to 37.94%) accumulation compared to the control group, which, in turn, enhanced antioxidant activity [up to 34% in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 51% in cupric reducing antioxidant capacity (CUPRAC)]. A moderate correlation between phenolic content and radical scavenging ability [R: 0.61 for DPPH and R: 0.44 for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)] highlights phenolics' role in mitigating BPA-induced oxidative stress. Low BPA concentrations stimulated gas exchange and photosynthesis, while higher levels (≥3 mg/L) disrupted these processes, causing physiological damage, especially in stomatal conductance (gs) and photochemical efficiency (Fv/Fo). Metabolomic profiling revealed concentration-dependent shifts in secondary metabolism, lipid biosynthesis, and stress-response pathways. At higher BPA levels, plants elicited defense mechanisms, such as flavonoids (rhamnetin, luteolin-7-O-β-D-glucronide, and quercetin-7-O-glucoside) and anthocyanin pathways, to tackle oxidative stress, though these systems became overwhelmed. Our findings show that while parsley can initially adapt to low BPA exposure, higher concentrations compromise its physiological and metabolic balance, threatening plant health and productivity.

Microrchidia OsMORC6 Positively Regulates Cadmium Tolerance and Uptake by Mediating DNA Methylation in Rice

Rice (Oryza sativa) is an extremely important global food crop. However, cadmium (Cd) contamination in paddy fields poses a serious threat to human health worldwide. To generate low-Cd or Cd-free rice germplasms, it is essential to understand the molecular mechanisms involved in Cd tolerance, uptake, and translocation from soil to plant. In this study, we identify three Microrchidia proteins, OsMORC6a, OsMORC6b, and OsMORC6c, that regulate Cd tolerance and accumulation, although they do not alter the translocation of Cd from roots to shoots. Knockout of all three genes results in reducing Cd accumulation and increasing sensitivity to Cd stress. Furthermore, transcriptome analysis reveals 1,127 differentially expressed genes (DEGs) in the morc6abc mutants, which are significantly enriched in 'plant-type cell wall' and 'oxidoreductase activity' pathways. Through an integrating DNA methylome and transcriptome data, we identify 247 hyper-DMR-associated DEGs and 325 hypo-DMR-associated DEGs in morc6abc mutants. Gene Ontology (Go) enrichment analysis reveals that OsMORC6 proteins positively regulate Cd tolerance and uptake by mediating DNA methylation, which regulates the proper expression of genes related to plant cell wall and oxidative stress under Cd stress. Taken together, our findings reveal novel genes that mediate Cd tolerance and accumulation by affecting DNA methylation, offering valuable resource for breeding low-Cd or Cd-free rice germplasms.

Elucidating the interaction and toxicity of cadmium and cerium on the growth of maize seedlings: Insights from morpho-physiological and biochemical analysis

The exploitation of rare earth elements (REEs) is often accompanied by heavy metal contamination. However, our understanding regarding the growth responses of plants to the co-existence of REEs and heavy metals (HMs), remains limited. In this study, cerium (Ce) and cadmium (Cd) were selected as representatives of REEs and HMs to investigate their interactive effects on maize growth through multiple model analyses. The results revealed that both Cd and Ce induce oxidative injuries by increasing reactive oxygen species (ROS) content in a dose-dependent manner. Ce can enhance chlorophyll content while reducing leaf yellowing induced by Cd. The addition of 10 and 100 mg· L-1 Ce significantly increased the Chla content in 50 μM Cd sets by 52.2 % and 50.2 % compared to Cd50Ce0 treatment, respectively. Evaluation of the physiological and biochemical effect level index (PBELI) showed that the primary interaction mode of Cd and Ce was antagonism. The co-existence of Cd (50 μM) and Ce (100 mg· L-1) poses a higher ecological risk than Ce alone. These results demonstrated that combined exposure to Cd and Ce exhibited diverse effects in mitigating the inhibition of maize growth, thereby improving our understanding of phytotoxicity resulting from metal mixtures in the environment.

Temperature-sensitive driving assembled fluorescence hydrogel based dual-mode sensor for adsorbing and detecting of heavy metal cadmium ions in food and water

The denatured bovine serum albumin (dBSA) is coupled with the CdTe/CdS quantum dot and the resulting CdTe/CdS@dBSA complex is assembled and retained in the poly(n-isopropyl acrylamide) (PNIPAM) hydrogel via regulating temperature and pH to form the CdTe/CdS@dBSA-PNIPAM fluorescence hydrogel substrate, which is able to adsorb and sense cadmium ions (Cd2+). Based on this fluorescence hydrogel, a fluorescence and colorimetric dual-mode detection system is established to quantitatively detect Cd2+ with a limit of detection (LOD) of 2.88 nM for fluorescence detection and 11.66 nM for colorimetric detection. Here, the fluorescence and colorimetric detection mode can obtain the dual test signal including the fluorescence signal and visual orange-red color signal. Therein, the utilization of smartphone can achieve the conversion of visual color signals into RGB digital signals, facilitating the interconnection of data among the communication devices. This research provides a novel and advanced strategy for the accurate and real-time detection of Cd2+.

Paraboremia selaginellae enhances Salvia miltiorrhiza growth and cadmium tolerance via modulating root architecture and cadmium speciation in contaminated environments

Introduction

Dark septate endophytes (DSEs) commonly colonize plant roots in heavy metal-polluted habitats, but little is known about the potential mechanisms driving medicinal plants to adapt to heavy metal-polluted environments. Here, we investigated the growth of Paraboeremia selaginellae strains and their enhancing of cadmium (Cd) tolerance and growth in Salvia miltiorrhiza in Cd-contaminated soil.

Methods

First, we tested the Cd resistance of P. selaginellae by in vitro culture. Then, we studied the performance of S. miltiorrhiza inoculated with P. selaginellae in Cd-contaminated soil.

Results

It was found that P. selaginellae possessed a capacity to accumulate Cd in its mycelium. The Cd-contaminated environment increased the content of melanin and osmotic substances and reduced the proportion of the highly toxic chemical form of Cd in the mycelium of P. selaginellae. In Cd-contaminated soil, P. selaginellae effectively colonized plant roots and improved soil nutrients and the growth of S. miltiorrhiza. The P. selaginellae-inoculated treatment significantly increased the contents of effective nitrogen (37.74%), urease (31.55%), and alkaline phosphatase (29.82%) in 10 mg Cd/kg soil, compared with the non-inoculated treatment. More importantly, P. selaginellae inoculation increased root biomass for 5 and 10 mg Cd/kg soil by 42.35% and 30.21%, respectively, in comparison to non-inoculated control. Inoculation with P. selaginellae reduced the proportion of the highly toxic chemical form of soil Cd, and reduced the accumulation of Cd in plants, especially in the roots.

Discussion

These results indicated that DSEs have a positive influence on the growth and Cd tolerance of S. miltiorrhiza, and reduce the biological toxicity of soil Cd. Therefore, exploitation and utilization of DSEs resources might be a new method for improving the cultivation of medicinal plants and soil microenvironment in heavy metal-contaminated areas.

Phytotoxicity of seven iron-based materials to mung bean seedlings

Due to the widespread application of various iron-based materials in environmental remediation and agricultural production, it is of significance to assess their environmental risks. Here, seven iron-based materials, including ionic FeCl3, micro- and nano-sized magnetite (i.e., mFe3O4 and nFe3O4), micro- and nano-sized zero-valent iron (i.e., mZVI and nZVI), and nZVI modified by starch and activated carbon (i.e., S-nZVI and A-nZVI), were targeted to compare their phytotoxicity in mung bean grown in the soil with different doses (0, 300, 600, and 1000 mg/kg) for 40 days. S-nZVI and A-nZVI severely inhibited plant growth, decreasing shoot and root dry weights by 45.1-79.2 and 26.0-82.3%, respectively, but other materials showed no or minimal effects on plant growth. All the materials decreased chlorophyll content and photosynthesis performance, with more pronounced inhibition from A-nZVI and S-nZVI, especially at 1000 mg/kg. The activities of superoxide dismutase (SOD) and peroxide dismutase (POD) in leaves were stimulated by all the materials, among which S-nZVI enhanced SOD activity by 206.9% at 300 mg/kg and POD activity by 541.1% at 1000 mg/kg. In most cases, Fe accumulation in the roots was increased by all materials, particularly by S-nZVI and A-nZVI. Fe concentrations in roots and shoots exposed to 1000 mg/kg S-nZVI and A-nZVI were 2-3 times higher than those in the control treatments. The disturbance in the homeostasis of minerals (Zn, Mn, Cu, and Mg) was induced by all iron-based materials. To conclude, the phytotoxicity of iron-based materials was dependent on their type and dosage, and stabilization was crucial for the phytotoxicity and bioaccumulation potential of nZVI in plants.

Cadmium accumulation potential and detoxication mechanism of Koenigia tortuosa: A novel extremely hardy plant from high altitude lead-zinc mine in Qinghai-Tibet Plateau

Hardy plants play a crucial role in restoring high-altitude tailings ponds, but the accumulation of potentially toxic elements (PTEs) and detoxification mechanisms in alpine plants are understudied. This study first investigated the cadmium (Cd) accumulation capacity and detoxification mechanisms by comparative transcriptomics with different Cd stress (0, 5, 10, 20 and 40 mg L-1 Cd2+) of Koenigia tortuosa from a lead-zinc mine (4950 m above sea level) in Qinghai-Tibet Plateau. The findings revealed that, despite elevated Cd concentrations suppressed the growth of Koenigia tortuosa, the plant retained a notable ability to accumulate Cd. The content of soluble protein and antioxidant enzyme activities increased with the concentration of Cd from 5 mg L-1 to 20 mg L-1, and then decreased when the concentration of Cd increased to 40 mg L-1. The maximum Cd accumulation in roots was 269.44 mg kg-1 at the 20 mg L-1 Cd concentration, with 61.83% of Cd extracted by NaCl. In addition, transcriptome analysis showed that differentially expressed genes (DEGs) were mainly distributed in the nucleotide metabolism, oxidative phosphorylation pathway, glutathione metabolism and plant signaling, which were significantly up-regulated in ribosomal protein genes, translational factor genes and glutathione-related genes. These results will contribute to revealing the physiological response and molecular mechanism of Cd tolerance in Koenigia tortuosa, supporting the ecological remediation of Cd contaminated sites in high-altitude mining areas.

RsWRKY75 promotes ROS scavenging and cadmium efflux via activating the transcription of RsAPX1 and RsPDR8 in radish (Raphanus sativus L.)

KEY MESSAGE

Acting as a nucleus-localized transcriptional activator, RsWRKY75 promotes ROS scavenging and Cd efflux by activating the transcription of RsAPX1 and RsPDR8 in radish. Radish (Raphanus sativus L.) is an important economical root vegetable crop worldwide. As a toxic heavy metal, cadmium (Cd) can dramatically hamper radish taproot quality as well as threaten human health. Although the WRKY transcription factors (TFs) play crucial roles in plant response to Cd stress, how WRKY TFs mediate Cd uptake and efflux remains elusive in radish. Herein, the RsWRKY75, belonging to the WRKY-IIc sub-group, displayed high expression in vascular cambium at the expanding stage, whose promoter activity and expression were obviously induced by Cd exposure at 24 h in radish root. RsWRKY75 was localized primarily to the nucleus and had transactivation activity in yeast and tobacco leaf cells. Transient transformation indicated that RsWRKY75 promoted Cd-induced ROS scavenging in radish cotyledons. Overexpression of RsWRKY75 led to increased root elongation but decreased Cd accumulation in Arabidopsis plants. Both in vitro and in vivo assays revealed that RsWRKY75 bound to the RsAPX1 promoter and activated its expression to eliminate excessive ROS accumulation. Moreover, RsWRKY75 activated RsPDR8 transcription by directly binding to its promoter, thereby promoting Cd efflux in the radish root. Collectively, we revealed a novel module of RsWRKY75-mediated ROS scavenging and Cd efflux in radish. These results would facilitate to establish genetic strategies to achieve RsWRKY75-dependent Cd extrusion and detoxification in radish.

Metabonomics reveals the mechanism of stress resistance in Vetiveria zizanioides inoculated with AMF under copper stress

Vetiveria zizanioides, renowned for its robust stability and exceptional capacity to sequester heavy metals, has garnered widespread application in tailings ecological restoration efforts. Arbuscular mycorrhizal fungi (AMF), which are capable of forming symbiotic relationships with more than 80% of terrestrial plant roots, play a pivotal role in enhancing plant nutrient uptake and bolstering resilience. In this study, we conducted a comprehensive investigation into the physiological and biochemical responses of Vetiveria zizanioides subjected to varying levels of copper stress (with copper concentrations ranging from 0 mg/kg to 400 mg/kg), with or without AMF inoculation. Additionally, we performed nontargeted metabonomic analyses to gain deeper insights into the metabolic changes that occur in vetiver grass under AMF inoculation and copper stress. Our findings revealed that Vetiveria zizanioides inoculated with AMF consistently demonstrated superior growth performance across all copper stress levels compared with noninoculated counterparts. Using nontargeted metabonomic analyses, inoculation with AMF affects the metabolism of phenylalanine and related pathways in vetiver as well as contributing to the promotion of the formation of phytochelatins (PCs) from glutamate, thereby alleviating copper stress. The results highlight the potential of AMF-inoculated Vetiveria zizanioides as a promising bioremediation tool capable of effectively mitigating the adverse effects of heavy metal pollution.

Exogenous selenium enhances cadmium stress tolerance by improving physiological characteristics of Artemisia argyi seedlings

The contamination of Chinese medicinal materials with cadmium (Cd) is a pressing global issue that poses significant risks to human health. The beneficial effects of selenium (Se) have been established in improving plant growth and reducing Cd accumulation in plant under Cd stress. This study employed soil cultivation experiments to investigate the remediation effects of exogenous Se (0, 0.5, 1, and 2 mg kg⁻1) under varying levels of Cd stress (0, 0.6 and 4 mg kg⁻1). The findings revealed that Cd stress markedly impaired seedling growth, biomass, and physiological characteristics in Artemisia argyi. Regardless of Cd levels, exogenous Se significantly enhanced seedling biomass, improved antioxidant enzyme activity, and increased the plant's antioxidant capacity, thereby mitigating Cd stress. Additionally, exogenous Se promoted A. argyi plant growth, decreased malondialdehyde (MDA) content in the shoots, and under two Cd stress environments of 0.6 and 4 mg kg⁻1, the application of 1 mg kg⁻1 Se reduced the Cd content in the aboveground parts of seedlings by 31.99 and 82.21%, respectively. We conclude 1 mg kg⁻1 Se could represent a promising strategy to contribute to the development and sustainability of crop production on soils contaminated with Cd at a concentration of up to 0.6 and 4 mg kg⁻1. These results indicate that exogenous Se activates physiological and biochemical defense mechanisms in A. argyi seedlings against Cd stress, offering a foundation for cultivating high-yield, high-quality A. argyi in Cd-contaminated soils.

Comparative Efficacy of Melatonin and Brassinolide in Mitigating the Adverse Effects of Cadmium on Wolffia arrhiza

Melatonin (MT) and brassinolide (BL) are phytohormones that regulate various physiological processes in plants. This study investigates their effects on Wolffia arrhiza when exposed to cadmium (Cd). Plant hormones were quantified using liquid chromatography-mass spectrometry, while photosynthetic pigments and phytochelatins (PCs) were analyzed through high-performance liquid chromatography. Protein, monosaccharide levels, and antioxidant activities were also spectrophotometrically measured. The findings reveal that MT and BL treatment decreased Cd accumulation in W. arrhiza compared to plants only exposed to Cd. MT was particularly effective in reversing Cd-induced growth inhibition and reducing stress markers more significantly than BL. It also enhanced antioxidant activity and maintained higher levels of photosynthetic pigments, proteins, and sugars. Although BL was less effective in these aspects, it promoted greater synthesis of glutathione and PCs in Cd-exposed duckweed. Overall, both MT and BL alleviate the negative impact of Cd on W. arrhiza, confirming their crucial role in supporting plant health under metal stress conditions.

NO and melatonin interplay augment Cd-tolerance mechanism in eggplants: ROS detoxification and regulation of gene expression

Global crop productivity is consistently threatened by cadmium (Cd) soil contamination. Crosstalk between nitric oxide (NO) and melatonin (MT) in enhancing crop resilience to heavy metal stress has gained significant attention. Here, we evaluated the joint effect of sodium nitroprusside (SNP; 200 μM as NO donor) and MT (100 μM) on Cd-stressed eggplant (Solanum melongena L.). Cd stress significantly reduced plant growth, biomass yield, leaf pigments, and biochemical properties. Conversely, SNP, MT, and particularly their combined (SNP + MT) application reduced Cd toxicity and enhanced growth and physio-biochemical traits of eggplants. For instance, at 50 mg Cd kg-1 soil, SNP, MT, and SNP + MT increased root biomass (41.6, 30, and 47%), total chlorophyll (30.7, 26.3, and 46%), soluble protein (20.5, 17.6 and 37%) and RLWC (23, 17.5, and 29%) over their respective control. Furthermore, SNP + MT significantly (p ≤ 0.05) reduced levels of EL, H2O2, proline, and MDA by 54.5, 66, 61 and 70%, respectively, in Cd-stressed eggplants. SNP + MT interplay enhanced antioxidant defense responses in leaf tissues under Cd stress. Besides, SNP and MT upregulated transcript levels of POD, SOD, CAT, and GPX genes in eggplants under Cd stress. SNP and MT applications improved essential nutrient cation homeostasis in Cd-stressed shoot tissues of eggplants. Moreover, SNP + MT lessens metal-induced toxicity by decreasing Cd uptake, translocation (TF) and bioconcentration (BCF) factors. Conclusively, these findings validated the beneficial defensive interaction between SNP and MT in regulating Cd tolerance in eggplants. However, further research is needed to uncover the underlying defensive mechanisms of these synergistic effects.

RsNRAMP5, a major metal transporter, promotes cadmium influx and ROS accumulation in radish (Raphanus sativus L.)

Arable soil contamination with heavy metals (HMs) poses a great potential threat to vegetable crops and human health. Radish (Raphanus sativus L.), an economical and popular root vegetable crop, is easily absorbed HMs by its taproot. Although the Natural Resistance-Associated Macrophage Proteins (NRAMPs) were participated in transporting a number of HMs in plants, whether and how the NRAMP genes involved in cadmium (Cd) uptake and transport remains elusive in radish. In this study, a total of nine RsNRAMP gene members were identified, which were classified into three subgroups and dispersed on six radish chromosomes. Three RsNRAMPs (RsNRAMP3, RsNRAMP4 and RsNRAMP5) displayed high expression in the vascular cambium, and they exhibited obviously Cd-induced expression, among which the expression of RsNRAMP4 and RsNRAMP5 reached to the highest level at 24h. Moreover, the RsNRAMP5 was localized to the plasma membrane and its promoter activity was dramatically induced by Cd exposure. Heterologous expression analysis indicated that over-expression of RsNRAMP5 significantly promoted the uptake of Cd, lead (Pb), iron (Fe) and manganese (Mn) in yeast cells. In addition, the transient over-expression of RsNRAMP5 promoted Cd uptake and enhanced ROS (reactive oxygen species) accumulation in radish cotyledons. These findings would expedite unraveling the molecular mechanism underlying RsNRAMP5-mediated Cd uptake and transport in radish.

Synergistic interplay between melatonin and hydrogen sulfide enhances cadmium-induced oxidative stress resistance in stock (Matthiola incana L.)

Ornamental crops particularly cut flowers are considered sensitive to heavy metals (HMs) induced oxidative stress condition. Melatonin (MLT) is a versatile phytohormone with the ability to mitigate abiotic stresses induced oxidative stress in plants. Similarly, signaling molecules such as hydrogen sulfide (H2S) have emerged as potential options for resolving HMs related problems in plants. The mechanisms underlying the combined application of MLT and H2S are not yet explored. Therefore, we evaluated the ability of individual and combined applications of MLT (100 μM) and H2S in the form of sodium hydrosulfide (NaHS), a donor of H2S, (1.5 mM) to alleviate cadmium (Cd) stress (50 mg L-1) in stock (Matthiola incana L.) plants by measuring various morpho-physiological and biochemical characteristics. The results depicted that Cd-stress inhibited growth, photosynthesis and induced Cd-associated oxidative stress as depicted by excessive ROS accumulation. Combined application of MLT and H2S efficiently recovered all these attributes. Furthermore, Cd stress-induced oxidative stress markers including electrolyte leakage, malondialdehyde, and hydrogen peroxide are partially reversed in Cd-stressed plants by MLT and H2S application. This might be attributed to MLT or H2S induced antioxidant plant defense activities, which effectively reduce the severity of oxidative stress indicators. Overall, MLT and H2S supplementation, favorably regulated Cd tolerance in stock; yet, the combined use had a greater effect on Cd tolerance than the independent application.

From stress to resilience: Unraveling the molecular mechanisms of cadmium toxicity, detoxification and tolerance in plants

Soil contamination with cadmium (Cd) has become a global issue due to increasing human activities. Cd contamination poses threats to plant growth as well as jeopardizing food safety and human health through the accumulation of Cd in edible parts of plants. Unraveling the Cd toxicity mechanisms and responses of plants to Cd stress is critical for promoting plant growth and ensuring food safety in Cd-contaminated soils. Toxicological research on plant responses to heavy metal stress has extensively studied Cd, as it can disrupt multiple physiological processes. In addition to morpho-anatomical, hormonal, and biochemical responses, plants rapidly initiate transcriptional modifications to combat Cd stress-induced oxidative and genotoxic damage. Various families of transcription factors play crucial roles in triggering such responses. Moreover, epigenetic modifications have been identified as essential players in maintaining plant genome stability under genotoxic stress. Plants have developed several detoxification strategies to mitigate Cd-induced toxicity, such as cell-wall binding, complexation, vacuolar sequestration, efflux, and translocation. This review provides a comprehensive update on understanding of molecular mechanisms involved in Cd uptake, transportation, and detoxification, with a particular emphasis on the signaling pathways that involve transcriptional and epigenetic responses in plants. This review highlights the innovative strategies for enhancing Cd tolerance and explores their potential application in various crops. Furthermore, this review offers strategies for increasing Cd tolerance and limiting Cd bioavailability in edible parts of plants, thereby improving the safety of food crops.

Earthworm mucus contributes significantly to the accumulation of soil cadmium in tomato seedlings

Whether earthworm mucus affects Cd transport behavior in soil-plant systems remains uncertain. Consequently, this study thoroughly assessed the impacts of earthworm mucus on plant growth and physiological responses, plant Cd accumulation, translocation, and distribution, as well as soil characteristics and Cd fractionation in a soil-plant (tomato seedling) system. Results demonstrated that the earthworm inoculation considerably enhanced plant Cd uptake and decreased plant Cd translocation, the effects of which were appreciably less significant than those of the earthworm mucus. This suggested that earthworm mucus may play a crucial role in the way earthworms influence plant Cd uptake and translocation. Moreover, the artificial mucus, which contained identical inorganic nitrogen contents to those in earthworm mucus, had no significant effect on plant Cd accumulation or translocation, implying that components other than inorganic nitrogen in the earthworm mucus may have contributed significantly to the overall effects of the mucus. Compared with the control, the earthworm mucus most substantially increased the root Cd content, the Cd accumulation amount of root and whole plant, and root Cd BCF by 93.7 %, 221.3 %, 72.2 %, and 93.7 %, respectively, while notably reducing the Cd TF by 48.2 %, which may be ascribed to the earthworm mucus's significant impacts on tomato seedling growth and physiological indicators, its considerable influences on the subcellular components and chemical species of root Cd, and its substantial effects on the soil characteristics and soil Cd fractionation, as revealed by correlation analysis. Redundancy analysis further suggested that the most prominent impacts of earthworm mucus may have been due to its considerable reduction of soil pH, improvement of soil DOC content, and enhancement of the exchangeable Cd fraction in soil. This work may help better understand how earthworm mucus influences the transport behavior of metals in soil-plant systems.

Effect of S-Allyl-L-Cysteine on Nitric Oxide and Cadmium Processes in Rice (Oryza sativa L. sp. Zhongzao35) Seedlings

Nitric oxide (NO) is an important signaling molecule involved in regulating plant processes to cope with abiotic stress. S-allyl-L-cysteine (SAC) is known to induce NO synthesis in animals. However, it is unknown whether SAC can trigger NO biosynthesis, regulate Cd transport, or alleviate Cd stress in plants. After being sprayed with 0.2 mM SAC, rice seedlings had a NO content that was 1.8 times higher than that of the control (ctrl) group at the ninth hour, which then gradually decreased. The expressions of Cd uptake and transport genes in the roots (including OsNRAMP5, OsNRAMP1, and OsHMA2) were markedly downregulated by 27.2%, 24.8%, and 49.1%, respectively, 72 h after SAC spraying treatment. The Cd content in seedling roots' cell wall (CW) components significantly increased by 43.5% compared to that of the ctrl group. The Cd content in the shoots and roots decreased by 49.0% and 29.8%, respectively. Cd stress in the seedlings was also substantially alleviated. In conclusion, spraying rice seedlings with SAC triggered an increase in NO synthesis, regulated the expression of genes related to Cd transport, increased Cd fixation in the root CW components, and reduced Cd accumulation in the roots and shoots.

Enhancing the Efficacy of Active Pharmaceutical Ingredients in Medicinal Plants through Nanoformulations: A Promising Field

This article explores the emerging field of nanomedicine as a drug delivery system, aimed at enhancing the therapeutic efficacy of active pharmaceutical ingredients in medicinal plants. The traditional methods of applying medicinal plants present several limitations, such as low bioavailability, poor solubility, challenges in accurately controlling drug dosage, and inadequate targeting. Nanoformulations represent an innovative approach in drug preparation that employs nanotechnology to produce nanoscale particles or carriers, which are designed to overcome these limitations. Nanoformulations offer distinct advantages, significantly enhancing the solubility and bioavailability of drugs, particularly for the poorly soluble components of medicinal plants. These formulations effectively enhance solubility, thereby facilitating better absorption and utilization by the human body, which in turn improves drug efficacy. Furthermore, nanomedicine enables targeted drug delivery, ensuring precise administration to the lesion site and minimizing side effects on healthy tissues. Additionally, nanoformulations can regulate drug release rates, extend the duration of therapeutic action, and enhance the stability of treatment effects. However, nanoformulations present certain limitations and potential risks; their stability and safety require further investigation, particularly regarding the potential toxicity with long-term use. Nevertheless, nanomaterials demonstrate substantial potential in augmenting the efficacy of active pharmaceutical ingredients in medicinal plants, offering novel approaches and methodologies for their development and application.

Isotope Evidence for Rice Accumulation of Newly Deposited and Soil Legacy Cadmium: A Three-Year Field Study

Biogeochemical processes of atmospherically deposited cadmium (Cd) in soils and accumulation in rice were investigated through a three-year fully factorial atmospheric exposure experiment using Cd stable isotopes and diffusive gradients in thin films (DGT). Our results showed that approximately 37-79% of Cd in rice grains was contributed by atmospheric deposition through root and foliar uptake during the rice growing season, while the deposited Cd accounted for a small proportion of the soil pools. The highly bioavailable metals in atmospheric deposition significantly increased the soil DGT-measured bioavailable fraction; yet, this fraction rapidly aged following a first-order exponential decay model, leading to similar percentages of the bioavailable fraction in soils exposed for 1-3 years. The enrichment of light Cd isotopes in the atmospheric deposition resulted in a significant shift toward lighter Cd isotopes in rice plants. Using a modified isotopic mass balance model, foliar and root uptake of deposited Cd accounted for 47-51% and 28-36% in leaves, 41-45% and 22-30% in stems, and 45-49% and 26-30% in grains, respectively. The implications of this study are that new atmospheric deposition disproportionately contributes to the uptake of Cd in rice, and managing emissions thus becomes very important versus remediation of impacted soils.

Identification and validation of reference genes for RT-qPCR analysis in Iris domestica under Cd stress

Iris domestica is a widely used ornamental garden and important medicinal plant. Our previous studies have shown that it exhibits significant uptake and translocation capacity under Cd stress compared to other Iris species. Gene expression is studied using RT-qPCR; however, there are no reference genes have been found for I. domestica under Cd stress. In this investigation, thirteen possible reference genes from previous studies and our transcriptome were screened using RT-qPCR in the leaves and roots of Cd-stressed plants. The findings revealed that UBC9 and ACT were the best reference genes for roots with and without Cd stress, whereas YLS8 and ACT7 were the best reference genes for leaves. Among the different tissues without Cd stress, UBC9 and UBC28 exhibited the best results, whereas PP2C06 and UBC9 exhibited the best results under Cd stress. The most stable reference genes in the leaves and roots were UBC9 and UBC28, respectively, under and without Cd stress, and GADPH was the most unstable. Finally, three metal ion response genes, NRAMP2, YSL9 and CYP81Q32 were detected using RT-qPCR and compared with the transcriptome data to further confirm the reliability of the chosen genes. This study identified suitable reference genes for I. domestica under Cd-stress conditions.

Transcriptome-wide m6A methylation profile reveals tissue specific regulatory networks in switchgrass (Panicum virgatum L.) under cadmium stress

The heavy metal cadmium (Cd), known for its high toxicity, poses a grave threat to human health through the food chain. N6-methyladenosine (m6A), the most abundant internal modification, regulates plant adaptation to various adversities, yet the panorama of m6A modifications in switchgrass under cadmium stress remains elusive. This study examines the physiological responses of switchgrass roots and shoots exposed to 50 μM CdCl2, alongside an overview of transcriptome-wide m6A methylation patterns. After cadmium treatment, methylation modifications are primarily enriched near stop codons and the 3'UTR region, with a negative correlation between m6A modification and gene expression levels. In shoots, approximately 58 % of DEGs with m6A modifications show upregulation in expression and decrease in m6A peaks, including zinc transporter 4-like (ZIP4). In roots, about 43 % of DEGs with m6A modifications exhibit downregulation in expression and increase in m6A peaks, such as the ABC transporter family member (ABCG25). We further validate the m6A enrichment, gene expression and mRNA stability of ZIP4 in response to Cd treatment. The results suggest that the negative correlation of m6A enrichment and gene expression is due to altered mRNA stability. Our study establishes an m6A regulatory network governing cadmium transport in switchgrass roots and shoots, offering new avenues for candidate gene manipulation in phytoremediation applications of heavy metal pollution.

Bio-pump cadmium phytoextraction efficiency promoted by phytohormones in Festuca arundinacea

The leaves of Festuca arundinacea can excrete cadmium (Cd) out onto the leaf surface, leading to a bio-pump phytoremediation strategy based on "root uptake-root-to-leaf translocation-leaf excretion". However, the bio-bump efficiency of soil Cd is a limiting factor for the implementation of this novel technology. Bio-bump remediation involves the bioprocess of plant root uptake from soil, root-to-leaf translocation, and leaf hydathode excretion. Here we show the significant effects of phytohormones in regulating the bio-pump phytoextraction efficiency. The results showed that salicylic acid and ethylene enhanced the whole process of Cd root uptake, root-to-leaf translocation, and leaf excretion, promoting the bio-pump phytoextraction efficiency by 63.6% and 73.8%, respectively. Gibberellin also greatly promoted Cd translocation, leaf excretion, and phytoextraction, but did not significantly impact Cd root uptake. Our results indicate that salicylic acid and ethylene could be recommended to promote bio-pump phytoextraction efficiency in F. arundinacea. Gibberellin might be used for a short-term promotion of the leaf Cd excretion.

In-situ remediation of cadmium contamination in paddy fields: from rhizosphere soil to rice kernel

Cadmium (Cd) has become an important heavy metal pollutant because of its strong migration and high toxicity. The industrial production process aggravated the Cd pollution in rice fields. Human exposure to Cd through rice can cause kidney damage, emphysema, and various cardiovascular and metabolic diseases, posing a grave threat to health. As modern technology develops, the Cd accumulation model in rice and in-situ remediation of Cd pollution in cornfields have been extensively studied and applied, so it is necessary to sort out and summarize them systematically. Therefore, this paper reviewed the primary in-situ methods for addressing heavy metal contamination in rice paddies, including chemical remediation (inorganic-organic fertilizer remediation, nanomaterials, and composite remediation), biological remediation (phytoremediation and microbial remediation), and crop management remediation technologies. The factors that affect Cd transformation in soil and Cd migration in crops, the advantages and disadvantages of remediation techniques, remediation mechanisms, and the long-term stability of remediation were discussed. The shortcomings and future research directions of in situ remediation strategies for heavily polluted paddy fields and genetic improvement strategies for low-cadmium rice varieties were critically proposed. To sum up, this review aims to enhance understanding and serve as a reference for the appropriate selection and advancement of remediation technologies for rice fields contaminated with heavy metals.

Enhancing the phytoremediation efficiency of Bacopa monnieri (L.) Wettst. using LED lights: a sustainable approach for heavy metal pollution control

In this study, the impacts of LEDs on the phytoremediation of arsenic (As) and mercury (Hg) by Bacopa monnieri (L.) Wettst. were investigated, along with the examination of the biochemical characteristics of plants exposed to metal-induced toxicity. In vitro multiple and rapid plant propagations were successfully achieved by adding 1.0 mg/L 6-Benzyl amino purine (BAP) to the Murashige and Skoog (MS) basal salt and vitamin culture medium. For plant-based remediation experiments, different concentrations of As (0-1.0 mg/L) and Hg (0-0.2 mg/L) were added to the water environment, and trials were conducted for four different application periods (1-21 days). White, red, and blue LEDs, as well as white fluorescent light, were preferred as the light environment. The results revealed that LED lights were more effective for heavy metal accumulation, with red LED light significantly enhancing the plant's phytoremediation capacity compared to other LED applications. Moreover, when examining biochemical stress parameters such as levels of photosynthetic pigments, protein concentrations, and lipid peroxidation, plants under red LED light showed better results. Generally, the lowest results were obtained under white fluorescent light. These findings contribute to phytoremediation studies by highlighting the integration of LED lights, thereby enabling the development of a more effective, cost-efficient, and environmentally sustainable remediation system compared to other treatment methods.

Genome-Wide Identification and Expression Analysis of SlNRAMP Genes in Tomato under Nutrient Deficiency and Cadmium Stress during Arbuscular Mycorrhizal Symbiosis

Arbuscular mycorrhizal (AM) fungi are well known for enhancing phosphorus uptake in plants; however, their regulating roles in cation transporting gene family, such as natural resistance-associated macrophage protein (NRAMP), are still limited. Here, we performed bioinformatics analysis and quantitative expression assays of tomato SlNRAMP 1 to 5 genes under nutrient deficiency and cadmium (Cd) stress in response to AM symbiosis. These five SlNRAMP members are mainly located in the plasma or vacuolar membrane and can be divided into two subfamilies. Cis-element analysis revealed several motifs involved in phytohormonal and abiotic regulation in their promoters. SlNRAMP2 was downregulated by iron deficiency, while SlNRAMP1, SlNRAMP3, SlNRAMP4, and SlNRAMP5 responded positively to copper-, zinc-, and manganese-deficient conditions. AM colonization reduced Cd accumulation and expression of SlNRAMP3 but enhanced SlNRAMP1, SlNRAMP2, and SlNRMAP4 in plants under Cd stress. These findings provide valuable genetic information for improving tomato resilience to nutrient deficiency and heavy metal stress by developing AM symbiosis.

Physiological, cytological and multi-omics analysis revealed the molecular response of Fritillaria cirrhosa to Cd toxicity in Qinghai-Tibet Plateau

Fritillaria cirrhosa, an endangered plant endemic to plateau regions, faces escalating cadmium (Cd) stress due to pollution in the Qinghai-Tibet Plateau. This study employed physiological, cytological, and multi-omics techniques to investigate the toxic effects of Cd stress and detoxification mechanisms of F. cirrhosa. The results demonstrated that Cd caused severe damage to cell membranes and organelles, leading to significant oxidative damage and reducing photosynthesis, alkaloid and nucleoside contents, and biomass. Cd application increased cell wall thickness by 167.89% in leaves and 445.78% in bulbs, leading to weight percentage of Cd increases of 76.00% and 257.14%, respectively. PER, CESA, PME, and SUS, genes responsible for cell wall thickening, were significantly upregulated. Additionally, the levels of metabolites participating in the scavenging of reactive oxygen species, including oxidized glutathione, D-proline, L-citrulline, and putrescine, were significantly increased under Cd stress. Combined multi-omics analyses revealed that glutathione metabolism and cell wall biosynthesis pathways jointly constituted the detoxification mechanism of F. cirrhosa in response to Cd stress. This study provides a theoretical basis for further screening of new cultivars for Cd tolerance and developing appropriate cultivation strategies to alleviate Cd toxicity.

NtGCN2 confers cadmium tolerance in Nicotiana tabacum L. by regulating cadmium uptake, efflux, and subcellular distribution

General control non-derepressible-2 (GCN2) is widely expressed in eukaryotes and responds to biotic and abiotic stressors. However, the precise function and mechanism of action of GCN2 in response to cadmium (Cd) stress in Nicotiana tabacum L. (tobacco) remains unclear. We investigated the role of NtGCN2 in Cd tolerance and explored the mechanism by which NtGCN2 responds to Cd stress in tobacco by exposing NtGCN2 transgenic tobacco lines to different concentrations of CdCl2. NtGCN2 was activated under 50 μmol·L-1 CdCl2 stress and enhanced the Cd tolerance and photosynthetic capacities of tobacco by increasing chlorophyll content and antioxidant capacity by upregulating NtSOD, NtPOD, and NtCAT expression and corresponding enzyme activities and decreasing malondialdehyde and O2·- contents. NtGCN2 enhanced the osmoregulatory capacity of tobacco by elevating proline (Pro) and soluble sugar contents and maintaining low levels of relative conductivity. Finally, NtGCN2 enhanced Cd tolerance in tobacco by reducing Cd uptake and translocation, promoting Cd efflux, and regulating Cd subcellular distribution. In conclusion, NtGCN2 improves the tolerance of tobacco to Cd through a series of mechanisms, namely, increasing antioxidant, photosynthetic, and osmoregulation capacities and regulating Cd uptake, translocation, efflux, and subcellular distribution. This study provides a scientific basis for further exploration of the role of NtGCN2 in plant responses to Cd stress and enhancement of the Cd stress signaling network in tobacco.

Silicon Dioxide Nanoparticles-Based Amelioration of Cd Toxicity by Regulating Antioxidant Activity and Photosynthetic Parameters in a Line Developed from Wild Rice

An extremely hazardous heavy metal called cadmium (Cd) is frequently released into the soil, causing a considerable reduction in plant productivity and safety. In an effort to reduce the toxicity of Cd, silicon dioxide nanoparticles were chosen because of their capability to react with metallic substances and decrease their adsorption. This study examines the processes that underlie the stress caused by Cd and how SiO2NPs may be able to lessen it through modifying antioxidant defense, oxidative stress, and photosynthesis. A 100 μM concentration of Cd stress was applied to the hydroponically grown wild rice line, and 50 μM of silicon dioxide nanoparticles (SiO2NPs) was given. The study depicted that when 50 μM SiO2NPs was applied, there was a significant decrease in Cd uptake in both roots and shoots by 30.2% and 15.8% under 100 μM Cd stress, respectively. The results illustrated that Cd had a detrimental effect on carotenoid and chlorophyll levels and other growth-related traits. Additionally, it increased the levels of ROS in plants, which reduced the antioxidant capability by 18.8% (SOD), 39.2% (POD), 32.6% (CAT), and 25.01% (GR) in wild rice. Nevertheless, the addition of silicon dioxide nanoparticles reduced oxidative damage and the overall amount of Cd uptake, which lessened the toxicity caused by Cd. Reduced formation of reactive oxygen species (ROS), including MDA and H2O2, and an increased defense system of antioxidants in the plants provided evidence for this. Moreover, SiO2NPs enhanced the Cd resistance, upregulated the genes related to antioxidants and silicon, and reduced metal transporters' expression levels.

Leveraging machine learning to unravel the impact of cadmium stress on goji berry micropropagation

This study investigates the influence of cadmium (Cd) stress on the micropropagation of Goji Berry (Lycium barbarum L.) across three distinct genotypes (ERU, NQ1, NQ7), employing an array of machine learning (ML) algorithms, including Multilayer Perceptron (MLP), Support Vector Machines (SVM), Random Forest (RF), Gaussian Process (GP), and Extreme Gradient Boosting (XGBoost). The primary motivation is to elucidate genotype-specific responses to Cd stress, which poses significant challenges to agricultural productivity and food safety due to its toxicity. By analyzing the impacts of varying Cd concentrations on plant growth parameters such as proliferation, shoot and root lengths, and root numbers, we aim to develop predictive models that can optimize plant growth under adverse conditions. The ML models revealed complex relationships between Cd exposure and plant physiological changes, with MLP and RF models showing remarkable prediction accuracy (R2 values up to 0.98). Our findings contribute to understanding plant responses to heavy metal stress and offer practical applications in mitigating such stress in plants, demonstrating the potential of ML approaches in advancing plant tissue culture research and sustainable agricultural practices.

Integrated physiological, transcriptomic and metabolomic analyses provide insights into phosphorus-mediated cadmium detoxification in Salix caprea roots

Phosphorus (P) plays a crucial role in facilitating plant adaptation to cadmium (Cd) stress. However, the molecular mechanisms underlying P-mediated responses to Cd stress in roots remain elusive. This study investigates the effects of P on the growth, physiology, transcriptome, and metabolome of Salix caprea under Cd stress. The results indicate that Cd significantly inhibits plant growth, while sufficient P alleviates this inhibition. Under Cd exposure, P sufficiency resulted in increased Cd accumulation in roots, along with reduced oxidative stress levels (superoxide anion and hydrogen peroxide contents were reduced by 16.8% and 30.1%, respectively). This phenomenon can be attributed to the enhanced activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), as well as increased levels of antioxidants including ascorbic acid (AsA) and flavonoids under sufficient P conditions. A total of 4208 differentially expressed genes (DEGs) and 552 differentially accumulated metabolites (DAMs) were identified in the transcriptomic and metabolomic analyses, with 2596 DEGs and 113 DAMs identified among treatments with different P levels under Cd stress, respectively. Further combined analyses reveal the potential roles of several pathways in P-mediated Cd detoxification, including flavonoid biosynthesis, ascorbate biosynthesis, and plant hormone signal transduction pathways. Notably, sufficient P upregulates the expression of genes including HMA, ZIP, NRAMP and CAX, all predicted to localize to the cell membrane. This may elucidate the heightened Cd accumulation under sufficient P conditions. These findings provide insights into the roles of P in enhancing plant resistance to Cd stress and improving of phytoremediation.

Melatonin-Regulated Chaperone Binding Protein Plays a Key Role in Cadmium Stress Tolerance in Rice, Revealed by the Functional Characterization of a Novel Serotonin N-Acetyltransferase 3 (SNAT3) in Rice

The study of the mechanisms by which melatonin protects against cadmium (Cd) toxicity in plants is still in its infancy, particularly at the molecular level. In this study, the gene encoding a novel serotonin N-acetyltransferase 3 (SNAT3) in rice, a pivotal enzyme in the melatonin biosynthetic pathway, was cloned. Rice (Oryza sativa) OsSNAT3 is the first identified plant ortholog of archaeon Thermoplasma volcanium SNAT. The purified recombinant OsSNAT3 catalyzed the conversion of serotonin and 5-methoxytryptamine to N-acetylserotonin and melatonin, respectively. The suppression of OsSNAT3 by RNAi led to a decline in endogenous melatonin levels followed by a reduction in Cd tolerance in transgenic RNAi rice lines. In addition, the expression levels of genes encoding the endoplasmic reticulum (ER) chaperones BiP3, BiP4, and BiP5 were much lower in RNAi lines than in the wild type. In transgenic rice plants overexpressing OsSNAT3 (SNAT3-OE), however, melatonin levels were higher than in wild-type plants. SNAT3-OE plants also tolerated Cd stress, as indicated by seedling growth, malondialdehyde, and chlorophyll levels. BiP4 expression was much higher in the SNAT3-OE lines than in the wild type. These results indicate that melatonin engineering could help crops withstand Cd stress, resulting in high yields in Cd-contaminated fields.

Physiological and molecular mechanisms of ZnO quantum dots mitigating cadmium stress in Salvia miltiorrhiza

This study delved into the physiological and molecular mechanisms underlying the mitigation of cadmium (Cd) stress in the model medicinal plant Salvia miltiorrhiza through the application of ZnO quantum dots (ZnO QDs, 3.84 nm). A pot experiment was conducted, wherein S. miltiorrhiza was subjected to Cd stress for six weeks with foliar application of 100 mg/L ZnO QDs. Physiological analyses demonstrated that compared to Cd stress alone, ZnO QDs improved biomass, reduced Cd accumulation, increased the content of photosynthetic pigments (chlorophyll and carotenoids), and enhanced the levels of essential nutrient elements (Ca, Mn, and Cu) under Cd stress. Furthermore, ZnO QDs significantly lowered Cd-induced reactive oxygen species (ROS) content, including H2O2, O2-, and MDA, while enhancing the activity of antioxidant enzymes (SOD, POD, APX, and GSH-PX). Additionally, ZnO QDs promoted the biosynthesis of primary and secondary metabolites, such as total protein, soluble sugars, terpenoids, and phenols, thereby mitigating Cd stress in S. miltiorrhiza. At the molecular level, ZnO QDs were found to activate the expression of stress signal transduction-related genes, subsequently regulating the expression of downstream target genes associated with metal transport, cell wall synthesis, and secondary metabolite synthesis via transcription factors. This activation mechanism contributed to enhancing Cd tolerance in S. miltiorrhiza. In summary, these findings shed light on the mechanisms underlying the mitigation of Cd stress by ZnO QDs, offering a potential nanomaterial-based strategy for enhancing Cd tolerance in medicinal plants.

Enhancing soil health to minimize cadmium accumulation in agro-products: the role of microorganisms, organic matter, and nutrients

Agro-products accumulate Cd from the soil and are the main source of Cd in humans. Their use must therefore be minimized using effective strategies. Large soil beds containing low-to-moderate Cd-contamination are used to produce agro-products in many developing countries to keep up with the demand of their large populations. Improving the health of Cd-contaminated soils could be a cost-effective method for minimizing Cd accumulation in crops. In this review, the latest knowledge on the physiological and molecular mechanisms of Cd uptake and translocation in crops is presented, providing a basis for developing advanced technologies for producing Cd-safe agro-products. Inoculation of plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi, application of organic matter, essential nutrients, beneficial elements, regulation of soil pH, and water management are efficient techniques used to decrease soil Cd bioavailability and inhibiting the uptake and accumulation of Cd in crops. In combination, these strategies for improving soil health are environmentally friendly and practical for reducing Cd accumulation in crops grown in lightly to moderately Cd-contaminated soil.

Integrated transcriptome and metabolome analysis provide insights into the mechanism of saponin biosynthesis and its role in alleviating cadmium-induced oxidative damage in Ophiopogon japonicum

Zhe-Maidong, a cultivar of Ophiopogon japonicus is a prominent traditional herbal medicine rich in saponins. This study explored the mechanism of saponin biosynthesis and its role in alleviating Cd-induced oxidative damage in the Zhe-Maidong cultivar using three experimental groups undergoing Cd stress. In the Cd-contaminated soil treatment, total saponins were 1.68 times higher than those in the control. The saponin content in the Cd-2 and Cd-3 treatments was approximately twice as high as that in the Cd-CK treatment. These findings revealed that Cd stress leads to total saponin accumulation. Metabolomic analysis identified the accumulated saponins, primarily several monoterpenoids, diterpenoids, and triterpenoids. The increased saponins exhibited an antioxidant ability to prevent the accumulation of Cd-induced reactive oxygen species (ROS). Subsequent saponin application experiments provided strong evidence that saponin played a crucial role in promoting superoxide dismutase (SOD) activity and reducing ROS accumulation. Transcriptome analysis revealed vital genes for saponin synthesis under Cd stress, including SE, two SSs, and six CYP450s, positively correlated with differentially expressed metabolite (DEM) levels in the saponin metabolic pathway. Additionally, the TF-gene regulatory network demonstrated that bHLH1, bHLH3, mTERF, and AUX/IAA transcript factors are crucial regulators of hub genes involved in saponin synthesis. These findings significantly contribute to our understanding of the regulatory network of saponin synthesis and its role in reducing oxidative damage in O. japonicum when exposed to Cd stress.

Identification and characterization of the critical genes encoding Cd-induced enhancement of SOD isozymes activities in Zhe-Maidong (Ophiopogon japonicus)

Superoxide dismutase (SOD) protects plants from abiotic stress-induced reactive oxygen species (ROS) damage. Here, the effects of cadmium (Cd) exposure on ROS accumulation and SOD isozymes, as well as the identification of significant SOD isozyme genes, were investigated under different Cd stress treatments to Zhe-Maidong (Ophiopogon japonicus). The exposure to Cd stress resulted in a notable elevation in the SOD activity in roots. Cu/ZnSODa and Cu/ZnSODb were the most critical SOD isozymes in response to Cd stress, as indicated by the detection results for SOD isozymes. A total of 22 OjSOD genes were identified and classified into three subgroups, including 10 OjCu/ZnSODs, 6 OjMnSODs, and 6 OjFeSODs, based on the analysis of conserved motif and phylogenetic tree. Cu/ZnSOD-15, Cu/ZnSOD-18, Cu/ZnSOD-20, and Cu/ZnSOD-22 were the main genes that control the increase in SOD activity under Cd stress, as revealed via quantitative PCR and transcriptome analysis. Additionally, under various heavy metal stress (Cu2+, Fe2+, Zn2+, Mn2+), Cu/ZnSOD-15, Cu/ZnSOD-18, and Cu/ZnSOD-22 gene expression were significantly upregulated, indicating that these three genes play a critical part in resisting heavy metal stress. The molecular docking experiments performed on the interaction between oxygen ion (O2•-) and OjSOD protein have revealed that the critical amino acid residues involved in the binding of Cu/ZnSOD-22 to the substrate were Pro135, Ile136, Ile140, and Arg144. Our findings provide a solid foundation for additional functional investigations on the OjSOD genes, as well as suggestions for improving genetic breeding and agricultural management strategies to increase Cd resistance in O. japonicus.

Impact of Heavy Metal Pollution in the Environment on the Metabolic Profile of Medicinal Plants and Their Therapeutic Potential

The paper provides a comprehensive examination of heavy metal stress on medicinal plants, focusing on its impact on antioxidant capacity and biosynthetic pathways critical to their therapeutic potential. It explores the complex relationship between heavy metals and the physiological and biochemical responses of medicinal plants, highlighting how metal stress disrupts biosynthetic pathways, altering concentrations of secondary metabolites. This disruption may compromise the overall quality and efficacy of medicinal plants, requiring a holistic understanding of its cumulative impacts. Furthermore, the study discusses the potential of targeted genetic editing to enhance plant resilience against heavy metal stress by manipulating genes associated with antioxidant defenses. This approach represents a promising frontier in safeguarding medicinal plants in metal-contaminated environments. Additionally, the research investigates the role of phytohormone signaling in plant adaptive mechanisms to heavy metal stress, revealing its influence on biochemical and physiological responses, thereby adding complexity to plant adaptation. The study underscores the importance of innovative technologies and global cooperation in protecting medicinal plants' therapeutic potential and highlights the need for mitigation strategies to address heavy metal contamination effectively.

The C2H2 family protein ZAT17 engages in the cadmium stress response by interacting with PRL1 in Arabidopsis

Cadmium (Cd) is a heavy metal and a toxic substance. Soil Cd pollution has emerged as a significant environmental issue that jeopardizes both the safety of agricultural products and human health. PLEIOTROPIC REGULATORY LOCUS 1 (PRL1) has been identified as a crucial factor in Cd stress and a series of defence mechanisms. However, the mechanism through which PRL1 mediates its downstream signalling has remained poorly understood. Here, we discovered a prl1-2 suppressor (sup8) for prl1-2 that complemented the defective development phenotype of prl1-2 under Cd stress. Gene cloning revealed a mutation in the C2H2 transcription factor ZAT17 as the basis for the sup8 phenotype. Genetic and biochemical studies indicated that ZAT17 acts as a negative regulator of Cd tolerance. Transcriptome analysis revealed that ZAT17 influences the alternative splicing (AS) process of multiple Cd-responsive genes by interacting with members of the MAC splicing complex, including PRL1 and CDC5. In conclusion, the identification of the novel gene ZAT17 enriches the understanding of the Cd stress response pathway and provides a valuable candidate locus for breeding Cd-resistant plant varieties.

Unlocking hormesis and toxic effects induced by cadmium in Polygonatum cyrtonema Hua based on morphology, physiology and metabolomics

Traditional Chinese medicine materials (TCMMs) are widely planted and used, while cadmium (Cd) is a widespread pollutant that poses a potential risk to plant growth and human health. However, studies on the influences of Cd on TCMMs have been limited. Our study aims to reveal the antioxidation-related detoxification mechanism of Polygonatum cyrtonema Hua under Cd stress based on physiology and metabolomics. The results showed that Cd0.5 (total Cd: 0.91 mg/kg; effective Cd: 0.45 mg/kg) induced hormesis on the biomass of roots, tubers and aboveground parts with increases of 22.88%, 27.12% and 17.02%, respectively, and significantly increased the flavonoids content by 57.45%. Additionally, the metabolism of caffeine, glutamine, arginine and purine was upregulated to induce hormesis in Cd0.5, which enhanced the synthesis of resistant substances such as spermidine, choline, IAA and saponins. Under Cd2 stress, choline and IAA decreased, and fatty acid metabolites (such as peanut acid and linoleic acid) and 8-hydroxyguanosine increased in response to oxidative damage, resulting in a significant biomass decrease. Our findings further reveal the metabolic process of detoxification by antioxidants and excessive Cd damage in TCMMs, deepen the understanding of detoxification mechanisms related to antioxidation, and enrich the relevant theories of hormesis induced by Cd.

Safe utilization evaluation of two typical traditional Chinese medicinal materials in Cd-contaminated soil based on the analysis of Cd transfer and AHP model

Due to the increasing scarcity of wild resources, most traditional Chinese medicinal materials (TCMMs) in the market are produced via artificial cultivation. The widespread pollution of cadmium (Cd) in soil limits the safe cultivation and use of TCMMs. This study investigated Cd accumulation, distribution, and the medicinal component content under simulated field conditions to clarify the differences in the Cd absorption, transfer and detoxification mechanisms of Polygonatum cyrtonema Hua and Bletilla striata, and provide the preliminary safe utilization conditions of TCMMs based on the analytic hierarchy process (AHP). The results showed that the Cd content of P. cyrtonema Hua was lower than the safety threshold under a high soil Cd concentration of 0.91 mg/kg (Cd-L), while B. striata was safe only at a low Cd concentration of 0.25 mg/kg (CK). Cd at 0.91 mg/kg induced hormesis affecting the net increase in biomass and medicinal component content for both TCMMs, while P. cyrtonema Hua showed better potential for safe utilization. Additionally, P. cyrtonema Hua had stronger resistance to Cd stress, exhibiting superior characteristics for synergistic absorption of Cd with mineral elements, transfer to nonmedical part and safer fixation forms in subcellular components. In contrast, B. striata showed insufficient Cd tolerance, and Cd was easily accumulated in organelles to inhibit plant growth. Our findings may attract more attention to the safe cultivation of TCMMs and provide insight into guidance for the safe utilization of slightly Cd-contaminated soil.

Comparative Analysis of the Effect of Gamma-, Electron, and Proton Irradiation on Transcriptomic Profile of Hordeum vulgare L. Seedlings: In Search for Molecular Contributors to Abiotic Stress Resilience

The development of adaptation strategies for crops under ever-changing climate conditions is a critically important food security issue. Studies of barley responses to ionising radiation showed that this evolutionarily ancient stress factor can be successfully used to identify molecular pathways involved in adaptation to a range of abiotic stressors. In order to identify potential molecular contributors to abiotic stress resilience, we examined the transcriptomic profiles of barley seedlings after exposure to γ-rays, electrons, and protons. A total of 553 unique differentially expressed genes with increased expression and 124 with decreased expression were detected. Among all types of radiation, the highest number of differentially expressed genes was observed in electron-irradiated samples (428 upregulated and 56 downregulated genes). Significant upregulation after exposure to the three types of radiation was shown by a set of ROS-responsive genes, genes involved in DNA repair, cell wall metabolism, auxin biosynthesis and signalling, as well as photosynthesis-related genes. Most of these genes are known to be involved in plant ROS-mediated responses to other abiotic stressors, especially with genotoxic components, such as heavy metals and drought. Ultimately, the modulation of molecular pathways of plant responses to ionising radiation may be a prospective tool for stress tolerance programmes.

Foliar spraying of lanthanum activates endocytosis in lettuce (Lactuca sativa L.) root cells, increasing Cd and Pb accumulation and their bioaccessibility

Cadmium (Cd) and lead (Pb) accumulate easily in leafy vegetables and can harm human health. Lanthanum (La) have been used to improve agricultural yield and quality, but the effect of La application on Cd/Pb enrichment in leafy vegetables remains incomplete currently. A previous study reported that the endocytosis in lettuce leaf cells can be activated by La, leading to an increase in Pb accumulation in lettuce leaves. However, it has not been investigated whether foliar application of La enhances root cellular endocytosis and promotes its uptake of Cd and Pb. In this study, the influence of La on the uptake of Cd and Pb, Cd bioaccessibility, and the safety risks of cultivating lettuce under Cd and Pb stress were explored. It was found that La increased Cd (16-30 % in shoot, 16-34 % in root) and Pb (25-29 % in shoot, 17-23 % in root) accumulation in lettuce. The increased accumulation of Cd and Pb could be attributed to La-enhanced endocytosis. Meanwhile, La enhanced the toxicity of both Cd and Pb, inhibited lettuce growth, and aggravated the damage to the photosynthetic and antioxidant systems. Finally, gastrointestinal simulation experiments showed that La increased the Cd bioaccessibility in both gastric and intestinal phase by 7-108 % and 9-87 %, respectively. These results offer valuable insights into the safety of REEs for agricultural applications.

Differential responses of chili varieties grown under cadmium stress

Heavy metal cadmium (Cd) naturally occurs in soil and is a hazardous trace contaminant for humans, animals, and plants. The main sources of Cd pollution in soil include overuse of phosphatic fertilizers, manure, sewage sludge, and aerial deposition. That's why an experiment was conducted to analyze the effect of Cd toxicity in Capsicum annuum L. by selecting its seven varieties: Hybrid, Desi, Sathra, G-916, BR-763, BG-912, and F1-9226. Cadmium was spiked in soil with four levels, i.e., (0, 3, 4, and 5 mg Cd kg- 1 of soil) for a week for homogeneous dispersion of heavy metal. Chili seeds were sown in compost-filled loamy soil, and 25-day-old seedlings were transplanted into Cd-spiked soil. Cadmium increasing concentration in soil decreased chili growth characteristics, total soluble sugars, total proteins, and amino acids. On the other hand, the activities of antioxidant enzymes were increased with the increasing concentration of Cd in almost all the varieties. Treatment 5 mg Cd/kg application caused - 197.39%, -138.78%, -60.77%, -17.84%, -16.34%, -11.82% and - 10.37% decrease of carotenoids level in chili V2 (Desi) followed by V4 (G-916), V1 (Hy7brid), V7 (F1-9226), V6 (BG-912), V5 (BR-763) and V3 (Sathra) as compared to their controls. The maximum flavonoids among varieties were in V5 (BR-763), followed by V6 (BG-912), V7 (F1-9226), V3 (Sathra) and V1 (Hybrid). Flavonoids content was decreased with - 37.63% (Sathra), -34.78% (Hybrid), -33.85% (G-916), -31.96% (F1-9226), -31.44% (Desi), -30.58% (BR-763), -22.88% (BG-912) as compared to their control at 5 mg Cd/kg soil stress. The maximum decrease in POD, SOD, and CAT was - 31.81%, -25.98%, -16.39% in chili variety V7 (F1-9226) at 5 mg Cd/kg stress compared to its control. At the same time, maximum APX content decrease was - 82.91%, followed by -80.16%, -65.19%, -40.31%, -30.14%, -10.34% and - 6.45% in V4 (G-916), V2 (Desi), V3 (Sathra), V6 (BG-912), V1 (Hybrid), V7 (F1-9226) and V5 (BR-763) at 5 mg Cd/kg treatment as compared to control chili plants. The highest CAT was found in 5 chili varieties except Desi and G-916. Desi and G-916 varieties. V5 (BR-763) and V6 (BG-912) were susceptible, while V1 (Hybrid), V3 (Sathra), and V7 (F1-9226) were with intermediate growth attributes against Cd stress. Our results suggest that Desi and G-916 chili varieties are Cd tolerant and can be grown on a large scale to mitigate Cd stress naturally.

Selenium improves the medicinal safety and quality of Bletilla striata by promoting the fixation of cadmium in root: Pot and field experiments

Soil cadmium (Cd) pollution poses a considerable threat to the safe production of traditional Chinese medicine (TCM) in China. The tubers of Bletilla striata, a precious TCM, are widely used to treat various ailments. However, the medicinal safety and quality of tubers are significantly affected by high Cd accumulation. While selenium (Se) is known to reduce Cd concentration in traditional crops, its impact on Cd content in medicinal parts and overall quality remains underexplored. To bridge the gap, a pot experiment and field validation were conducted to determine the effectiveness of foliar Se application. The results revealed that Se effectively counteracted Cd damage. Compared to Cd treatment alone, Se at 1.5 mg L-1 significantly decreased Cd content by 46.33 %, increased the biomass by 21.48 %, and raised the total phenolic, flavonoid, saponin, and polysaccharide contents by 46.31 %, 30.46 %, 27.08 %, and 29.01 %, respectively, in tubers. Furthermore, this study explored the mechanism of Se action. Se facilitated Cd accumulation in root cell walls and soluble fractions, enhanced the synthesis of phytochelatins (PC), and stored them in the form of PC-Cd complexes. These findings have profound implications for the cultivation of TCM, ensuring its safety, and promoting sustainable agricultural practices.

Transcriptomics combined with physiological analysis reveals the mechanism of cadmium uptake and tolerance in Ligusticum chuanxiong Hort. under cadmium treatment

Introduction

Ligusticum chuanxiong Hort. is a widely used medicinal plant, but its growth and quality can be negatively affected by contamination with the heavy metal cadmium (Cd). Despite the importance of understanding how L. chuanxiong responds to Cd stress, but little is currently known about the underlying mechanisms.

Methods

To address this gap, we conducted physiological and transcriptomic analyses on L. chuanxiong plants treated with different concentrations of Cd2+ (0 mg·L-1, 5 mg·L-1, 10 mg·L-1, 20 mg·L-1, and 40 mg·L-1).

Results

Our findings revealed that Cd stress inhibited biomass accumulation and root development while activating the antioxidant system in L. chuanxiong. Root tissues were the primary accumulation site for Cd in this plant species, with Cd being predominantly distributed in the soluble fraction and cell wall. Transcriptomic analysis demonstrated the downregulation of differential genes involved in photosynthetic pathways under Cd stress. Conversely, the plant hormone signaling pathway and the antioxidant system exhibited positive responses to Cd regulation. Additionally, the expression of differential genes related to cell wall modification was upregulated, indicating potential enhancements in the root cell wall's ability to sequester Cd. Several differential genes associated with metal transport proteins were also affected by Cd stress, with ATPases, MSR2, and HAM3 playing significant roles in Cd passage from the apoplast to the cell membrane. Furthermore, ABC transport proteins were found to be key players in the intravesicular compartmentalization and efflux of Cd.

Discussion

In conclusion, our study provides preliminary insights into the mechanisms underlying Cd accumulation and tolerance in L. chuanxiong, leveraging both physiological and transcriptomic approaches. The decrease in photosynthetic capacity and the regulation of plant hormone levels appear to be major factors contributing to growth inhibition in response to Cd stress. Moreover, the upregulation of differential genes involved in cell wall modification suggests a potential mechanism for enhancing root cell wall capabilities in isolating and sequestering Cd. The involvement of specific metal transport proteins further highlights their importance in Cd movement within the plant.

Comparative transcriptomic analysis provides key genetic resources in clove basil (Ocimum gratissimum) under cadmium stress

Planting aromatic plant might be a promising strategy for safely utilizing heavy metal (HM)-contaminated soils, as HMs in essential oil could be completely excluded using some special technologies with ease. Clove basil (Ocimum gratissimum L.) is an important aromatic plant used in essential oil production. Improving cadmium (Cd) tolerance in clove basil can increase its production and improve the utilization efficiency of Cd-contaminated soils. However, the lack of genomic information on clove basil greatly restricts molecular studies and applications in phytoremediation. In this study, we demonstrated that high levels of Cd treatments (0.8, 1.6 and 6.5 mg/L) significantly impacted the growth and physiological attributes of clove basil. Cd contents in clove basil tissues increased with treatment concentrations. To identify Cd stress-responsive genes, we conducted a comparative transcriptomic analysis using seedlings cultured in the Hoagland's solution without Cd ion (control) or containing 1.6 mg/L CdCl2 (a moderate concentration of Cd stress for clove basil seedlings). A total of 104.38 Gb clean data with high-quality were generated in clove basil under Cd stress through Illumina sequencing. More than 1,800 differential expressed genes (DEGs) were identified after Cd treatment. The reliability and reproducibility of the transcriptomic data were validated through qRT-PCR analysis and Sanger sequencing. KEGG classification analysis identified the "MAPK signaling pathway," "plant hormone signal transduction" and "plant-pathogen interaction" as the top three pathways. DEGs were divided into five clusters based on their expression patterns during Cd stress. The functional annotation of DEGs indicated that downregulated DEGs were mainly involved in the "photosynthesis system," whereas upregulated DEGs were significantly assigned to the "MAPK signaling pathway" and "plant-pathogen interaction pathway." Furthermore, we identified a total of 78 transcription factors (TFs), including members of bHLH, WRKY, AP2/ERF, and MYB family. The expression of six bHLH genes, one WRKY and one ERF genes were significantly induced by Cd stress, suggesting that these TFs might play essential roles in regulating Cd stress responses. Overall, our study provides key genetic resources and new insights into Cd adaption mechanisms in clove basil.