Role of SbNRT1.1B in cadmium accumulation is attributed to nitrate uptake and glutathione-dependent phytochelatins biosynthesis.

Phytoremediation of cadmium (Cd)-polluted soil by using sweet sorghum displays a tremendous potential as it is a fast-growing, high biomass and Cd tolerant energy plant. Previous study has demonstrated SbNRT1.1B expression change is in accordance with enhanced Cd accumulation by external nitrate supply in sweet sorghum. Nevertheless, underlying mechanism of SbNRT1.1B response to Cd stress is still elusive. SbNRT1.1B exhibited a positive response to Cd stress in sweet sorghum. Overexpressing SbNRT1.1B increased primary root length, shoot fresh weight, nitrate and chlorophyll concentrations compared with Col-0 under Cd stress, while complementary SbNRT1.1B rescued these decreased values in mutant chl1-5. Cd concentrations in overexpressing SbNRT1.1B, complementary SbNRT1.1B and Col-0 lines were 3.2-4.1, 2.5-3.1 and 1.2-2.1 folds of that in chl1-5. Consistent with Cd concentrations, non-protein thiol (NPT), reduced glutathione (GSH) and phytochelatins (PCs) concentrations as well as the related genes expression levels showed the same trends under Cd stress. GSH biosynthesis inhibitor failed to reverse the patterns of GSH-dependent PCs concentrations changes in different lines, suggesting that SbNRT1.1B plays an upstream role in GSH-dependent PCs biosynthesis under Cd treatment. Altogether, SbNRT1.1B enhances nitrate concentrations contributing to increased chlorophyll concentrations and GSH-dependent PCs metabolites biosynthesis, thereby improving growth and Cd concentrations in plants.

Effects of cadmium stress on the growth and physiological characteristics of sweet potato.

This study evaluated the responses of sweet potatoes to Cadmium (Cd) stress through pot experiments to theoretically substantiate their comprehensive applications in Cd-polluted agricultural land. The experiments included a CK treatment and three Cd stress treatments with 3, 30, and 150 mg/kg concentrations, respectively. We analyzed specified indicators of sweet potato at different growth periods, such as the individual plant growth, photosynthesis, antioxidant capacity, and carbohydrate Cd accumulation distribution. On this basis, the characteristics of the plant carbon metabolism in response to Cd stress throughout the growth cycle were explored. The results showed that T2 and T3 treatments inhibited the vine growth, leaf area expansion, stem diameter elongation, and tuberous root growth of sweet potato; notably, T3 treatment significantly increased the number of sweet potato branches. Under Cd stress, the synthesis of chlorophyll in sweet potato was significantly suppressed, and the Rubisco activity experienced significant reductions. With the increasing Cd concentration, the function of PS II was also affected. The soluble sugar content underwent no significant change in low Cd concentration treatments. In contrast, it decreased significantly under high Cd concentrations. Additionally, the tuberous root starch content decreased significantly with the increase in Cd concentration. Throughout the plant growth, the activity levels of catalase, peroxidase, and superoxide dismutase increased significantly in T2 and T3 treatments. By comparison, the superoxide dismutase activity in T1 treatment was significantly lower than that of CK. With the increasing application of Cd, its accumulation accordingly increased in various sweet potato organs. The the highest bioconcentration factor was detected in absorbing roots, while the tuberous roots had a lower bioconcentration factor and Cd accumulation. Moreover, the transfer factor from stem to petiole was the highest of the potato organs. These results demonstrated that sweet potatoes had a high Cd tolerance and a restoration potential for Cd-contaminated farmland.

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.

Phytotoxic responses of acrocarpous moss Campylopus schmidii as bioindicators in copper and cadmium contaminated environments: A comprehensive assessment.

Mosses play a vital role in environmental research as reliable biomonitoring tools. This study aims to understand the accumulation and distribution patterns of Cu and Cd in the acrocarpous moss [Campylopus schmidii (Müll. Hal.) A. Jaeger] (C.schmidii). In controlled in vitro experiments, C.schmidii cultures were exposed to varying concentrations of copper (Cu) and cadmium (Cd) stress (0, 10, 25, 50 µmol/L) in aquatic media. The study systematically evaluated the moss's response, including observing appearance features, oxidative traits, and accumulation characteristics. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analyses were employed. They aimed to characterize and determine the distribution of metal particles in different parts of the mosses under high concentration treatments (50 µmol/L Cd, 50 µmol/L Cu, 50 µmol/L Cu and Cd). Results indicated that C.schmidii exhibited greater tolerance to Cu compared to Cd, as evidenced by significantly higher soluble protein content and lipid peroxidation with increasing concentrations. However, Cd stress induced severe damage, including widespread chlorosis, reduced chlorophyll content, and surface fragmentation. Both Cu and Cd were found to stimulate antioxidant levels by increasing the activity of hydrogen peroxide and peroxidase, thus reducing the accumulation of free radicals in C.schmidii. Additionally, the results revealed differential metal distribution. Higher Cu (2.23%) and lower Cd (0.54%) accumulation were observed at the bottom of gametophores, with Cd content 180.46% higher than Cu at the top. This study provides valuable insights into the potential application of acrocarpous mosses for biomonitoring and phytoremediation. It suggests specific strategies for metal deposition and absorption, such as utilizing upper, younger parts for Cd absorption and lower parts for Cu remediation in soil.

Mechanisms of Cadmium stress response in watermelon: Insights from physiological, transcriptomic, and metabolic analyses.

Cadmium (Cd) contamination of soil may lead to Cd stress for plants, which significantly hinders plant growth and development, posing a risk to human health through the consumption of Cd-contaminated foods. Watermelon (Citrullus lanatus), a widely consumed fruit, is particularly affected by Cd stress globally, yet the mechanisms underlying its response are not well understood. Here, we subjected watermelon seedlings to simulated Cd stress treatment and explored the physiological, transcriptomic, and metabolic response. Our findings revealed that Cd stress treatment led to increased accumulation of reactive oxygen species (ROS) in watermelon leaves. Transcriptome sequencing unveiled a multitude of osmotic and oxidative stress-responsive genes, including peroxidase (POD), MYB, voltage-dependent anion channel (SLAC1), and ABC transporter. KEGG enrichment analysis highlighted the predominant enrichment of Cd stress-responsive genes in pathways such as glutathione (GSH) metabolism, MAPK signaling, and biosynthesis of secondary metabolites. Within the GSH metabolism pathway, several glutathione S-transferase (GST) genes were up-regulated, alongside phytochelatin synthetase (PCS) genes involved in phytochelatin synthesis. In the MAPK signaling pathway, genes associated with ABA and ethylene signal transduction showed up-regulation following Cd stress. Metabolomic analysis demonstrated that Cd stress enhanced the production of amino acids, phenolamines, and esters. Overall, our study elucidates that watermelon responds to Cd stress by activating its antioxidant system, GSH metabolism pathway, MAPK signal pathway, and biosynthesis of key metabolites. These findings offer valuable insights for the remediation of heavy metal pollution in soil affecting plant life.

Isolation and assessment of the beneficial effect of exopolysaccharide-producing PGPR in Triticum aestivum (L.) plants grown under NaCl and Cd -stressed conditions.

Exopolysaccharide (EPS)-producing beneficial bacteria play a multifaceted role in improving plant growth and adaptive responses against different stressors. In this study, we isolated 25 bacterial strains from pea nodules and were further studied for their sodium chloride (NaCl) and cadmium (Cd) stress tolerance. Based on our results, Rhizobium fabae SR-22 (NCBI Accession number: MG063739.1) showed better tolerance toward salinity and Cd stress and produced a wide range of plant growth-promoting compounds. However, the amount of EPS varies during NaCl and Cd stress. It was important to note that NaCl and Cd beyond the tolerant level, affected the morphology and cellular viability of R. fabae. Interestingly, plant growth-promoting (PGP) substances (indole-3-acetic acid, ammonia, siderophore, and ACC deaminase) released by R. fabae were increased with increasing NaCl concentrations. In contrast, PGP substances were greatly decreased by increasing Cd dosages. Further, the beneficial effect of EPS-producing R. fabae in Triticum aestivum grown in soil treated with different levels of NaCl and Cd was assessed. Inoculation of R. fabae in wheat seedlings grown under higher NaCl and Cd concentrations showed improved growth compared to non-inoculated plants. R. fabae exhibited maximum effect in wheat plants grown under 2% NaCl and increased seed germination (8%), root length (13%), vigor indices (19%), root biomass (20%), chlorophyll-a (31%), total chlorophyll (27%) and carotenoid content. Additionally, R. fabae increased Cd and NaCl tolerance in wheat seedlings and improved their antioxidative responses. Conclusively, this work demonstrated that EPS-producing R. fabae showed a promising role in mitigating salinity and Cd-stress in wheat possibly by reducing salt and HM stress-induced abrasions and growth promotion via inorganic phosphate solubilization, and increased nutrient absorption. In the future, R. fabae equipped with these distinguishing characteristics may be used as effective bio-inoculants/bio-formulations in agriculture to address salinity and HM stress issues.

Corrigendum: BrMYB116 transcription factor enhances Cd stress tolerance by activating FIT3 in yeast and Chinese cabbage.

[This corrects the article DOI: 10.3389/fpls.2024.1388924.].

Integrated physiological and metabolomic responses reveal mechanisms of Cd tolerance and detoxification in kenaf (Hibiscus cannabinus L.) under Cd stress.

Introduction: Cadmium (Cd) is a highly toxic trace element that occurs in large quantities in agricultural soils. The cultivation of industrial crops with high phytoremediation potential, such as kenaf, could effectively reduce soil Cd contamination, but the mechanisms of toxicity, tolerance, and detoxification remain unclear. Methods: In this study, the effects of different Cd concentrations (0, 100, 250, and 400 µM) on growth, biomass, Cd uptake, physiological parameters, metabolites and gene expression response of kenaf were investigated in a hydroponic experiment. Results and discussion: The results showed that Cd stress significantly altered the ability of kenaf to accumulate and transport Cd; increased the activity of hydrogen peroxide (H2O2), superoxide anion (O2 -), and malondialdehyde (MDA); reduced the activities of superoxide dismutase (SOD) and catalase (CAT); and decreased the content of photosynthetic pigments, resulting in significant changes in growth and biomass production. Exposure to Cd was found to have a detrimental effect on the ascorbate-glutathione (AsA-GSH) cycle in the roots, whereas it resulted in an elevation in AsA levels and a reduction in GSH levels in the leaves. The increased content of cell wall polysaccharides under Cd stress could contribute to Cd retention in roots and limited Cd transport to above-ground plant tissues. Metabolomic analyses revealed that alanine, aspartate, and glutamate metabolism, oxidative phosphorylation, ABC transporter, and carbon metabolism were the major metabolic pathways associated with Cd stress tolerance. Cd stress increased gene expression of IRT1 and MTP1 in roots, which resulted in kenaf roots accumulating high Cd concentrations. This study extends our knowledge of the factors regulating the response of kenaf to Cd stress. This work provided a physiological and metabolomic perspective on the mechanism controlling the response of kenaf to Cd stress.

Defense of cabbages against herbivore cutworm Spodoptera litura under Cd stress and insect herbivory stress simultaneously.

Biotic (e.g., heavy metal) and abiotic stress (e.g., insect attack) can affect plant chemical defense, but little is known about the changes in plant defense when they occur concurrently. Herein, the impacts of heavy metal cadmium (Cd) stress and insect herbivory stress on the direct and indirect defense of two cultivar cabbages of Brassica campestris, the low-Cd cultivar Lvbao701 and the high-Cd cultivar Chicaixin No.4, against the herbivore cutworm Spodoptera litura were investigated. Although 10 mg kg-1 Cd stress alone inhibited leaf secondary metabolites (total phenolics, flavonoids), it reduced the feeding rate and odor selection of S. litura towards both cultivar cabbages, especially for Lvbao701, by increasing leaf Cd content and repellent volatile organic compounds (VOCs) (6-methyl-5-hepten-2-one, 7,9-di-tert-butyl-1-oxaspiro (4,5)deca-6,9-diene-2,8-dione), and reducing soluble sugar and attractive VOCs (3-methyl-3-pentanol, 2,5-hexanedione, tetradecanal). Under 2.5 mg kg-1 Cd and herbivory stress, although leaf total phenolics and flavonoids increased significantly, the feeding rate and odor selection of S. litura towards both cultivar cabbages increased, especially for Chicaixin No.4, indicating that the chemical defense of cabbages was depressed. Therefore, Cd stress alone improved the insect resistance of cabbages, whereas herbivory stress weakened the enhanced cabbages defence by Cd stress. The low-Cd cultivar Lvbao701 presented stronger insect resistance than Chicaixin No.4, suggesting that Lvbao701 application in Cd-polluted soil can not only decrease Cd transmission to higher levels in the food chain but also reduce pest occurrence.

SpSIZ1 from hyperaccumulator Sedum plumbizincicola orchestrates SpABI5 to fine-tune cadmium tolerance.

Sedum plumbizincicola is a renowned hyperaccumulator of cadmium (Cd), possesses significant potential for eco-friendly phytoremediation of soil contaminated with Cd. Nevertheless, comprehension of the mechanisms underpinning its Cd stress response remains constrained, primarily due to the absence of a comprehensive genome sequence and an established genetic transformation system. In this study, we successfully identified a novel protein that specifically responds to Cd stress through early comparative iTRAQ proteome and transcriptome analyses under Cd stress conditions. To further investigate its structure, we employed AlphaFold, a powerful tool for protein structure prediction, and found that this newly identified protein shares a similar structure with Arabidopsis AtSIZ1. Therefore, we named it Sedum plumbizincicola SIZ1 (SpSIZ1). Our study revealed that SpSIZ1 plays a crucial role in positively regulating Cd tolerance through its coordination with SpABI5. Overexpression of SpSIZ1 significantly enhanced plant resistance to Cd stress and reduced Cd accumulation. Expression pattern analysis revealed higher levels of SpSIZ1 expression in roots compared to stems and leaves, with up-regulation under Cd stress induction. Importantly, overexpressing SpSIZ1 resulted in lower Cd translocation factors (Tfs) but maintained relatively constant Cd levels in roots under Cd stress, leading to enhanced Cd stress resistance in plants. Protein interaction analysis revealed that SpSIZ1 interacts with SpABI5, and the expression of genes responsive to abscisic acid (ABA) through SpABI5-dependent signaling was significantly up-regulated in SpSIZ1-overexpressing plants with Cd stress treatment. Collectively, our results illustrate that SpSIZ1 interacts with SpABI5, enhancing the expression of ABA downstream stress-related genes through SpABI5, thereby increasing Cd tolerance in plants.

Integrative physiological, transcriptomic, and metabolomic analysis of Abelmoschus manihot in response to Cd toxicity.

Rapid industrialization and urbanization have caused severe soil contamination with cadmium (Cd) necessitating effective remediation strategies. Phytoremediation is a widely adopted technology for remediating Cd-contaminated soil. Previous studies have shown that Abelmoschus manihot has a high Cd accumulation capacity and tolerance indicating its potential for Cd soil remediation. However, the mechanisms underlying its response to Cd stress remain unclear. In this study, physiological, transcriptomic, and metabolomic analyses were conducted to explore the response of A. manihot roots to Cd stress at different time points. The results revealed that Cd stress significantly increased malondialdehyde (MDA) levels in A. manihot, which simultaneously activated its antioxidant defense system, enhancing the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) by 19.73%-50%, 22.87%-38.89%, and 32.31%-45.40% at 12 h, 36 h, 72 h, and 7 days, respectively, compared with those in the control (CK). Moreover, transcriptomic and metabolomic analyses revealed 245, 5,708, 9,834, and 2,323 differentially expressed genes (DEGs), along with 66, 62, 156, and 90 differentially expressed metabolites (DEMs) at 12 h, 36 h, 72 h, and 7 days, respectively. Through weighted gene coexpression network analysis (WGCNA) of physiological indicators and transcript expression, eight hub genes involved in phenylpropanoid biosynthesis, signal transduction, and metal transport were identified. In addition, integrative analyses of metabolomic and transcriptomic data highlighted the activation of lipid metabolism and phenylpropanoid biosynthesis pathways under Cd stress suggesting that these pathways play crucial roles in the detoxification process and in enhancing Cd tolerance in A. manihot. This comprehensive study provides detailed insights into the response mechanisms of A. manihot to Cd toxicity.

[Effect of Exogenous Chitosan on Physiological Properties, Antioxidant Activity, and Cadmium Uptake of Wheat (Triticum aestivum L.) Seedlings Under Cadmium Stress].

This research aimed to clarify the effects of exogenously applied chitosan on the physiological characteristics, antioxidant activities, and Cd accumulation of wheat (Triticum aestivum L.) seedlings under cadmium (Cd) stress and to identify the key indicators based on the partial least squares model. The wheat variety studied was Bainong207 (BN207), and Cd-stress was achieved by growing seedlings in a hydroponic culture experiment with 10 and 25 µmol·L-1 Cd2+ added to the culture solution. It was found that both Cd-stress at 10 and 25 µmol·L-1 significantly inhibited the chlorophyll content, photosynthesis, and biomass accumulation of wheat seedlings. Seedling roots became shorter and thicker, and the lateral roots decreased under Cd-stress. The Cd-stress also increased H2O2 and MDA accumulation and the degree of cell membrane lipid peroxidation and affected the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). Under Cd stress, exogenous chitosan decreased the Cd content in the aboveground and underground parts of wheat by 13.22 %-21.63 % and 7.92 %-28.32 % and reduced Cd accumulation in the aboveground and underground parts by 5.37 %-6.71 % and 1.91 %-4.09 %, respectively. Whereas exogenous chitosan application significantly reduced the content of H2O2 in roots and aboveground parts of wheat by 38.21 %-47.46 % and 45.81 %-55.73 % and MDA content by 37.65 %-48.12 % and 29.87 %-32.51 %, it increased the activities of SOD and POD in roots by 2.78 %-5.61 % and 13.81 %-18.33 %, respectively. In summary, exogenous chitosan can improve the photosynthetic characteristics and antioxidant enzyme activities of wheat seedlings under Cd stress, reduce the content and accumulation of Cd in the root and aboveground parts of wheat, and alleviate the damage of lipid peroxidation to the cell membrane. All of these results provide the basal data for the application of exogenous chitosan to alleviate Cd toxicity to wheat seedlings.

Effect of exogenous γ-aminobutyric acid on physiological property, antioxidant activity, and cadmium uptake of quinoa seedlings under cadmium stress.

Increasing cadmium (Cd) pollution has negative effects on quinoa growth and production. Gamma-aminobutyric acid (GABA) confers plants with stress resistance to heavy metals; however, the mechanism remains unclear. We explored the effects of exogenous GABA on the physiological characteristics, antioxidant capacity, and Cd accumulation of quinoa seedlings under Cd stress using hydroponic experiments. Partial least-squares regression was used to identify key physical and chemical indices of seedlings affecting Cd accumulation. Compared with those of the CK group, exposure to 10 and 25 µmol·L-1 Cd significantly reduced the photosynthetic pigment contents, photosynthesis, and biomass accumulation of quinoa seedlings; resulted in shorter and thicker roots; decreased the length of the lateral roots; decreased the activities of superoxide dismutase (SOD) and peroxide (POD); and increased H2O2 and malondialdehyde (MDA) contents. Exogenous GABA reduced the Cd content in the stem/leaves and roots of quinoa seedlings under Cd stress by 13.22-21.63% and 7.92-28.32%, decreased Cd accumulation by 5.37-6.71% and 1.91-4.09%, decreased the H2O2 content by 38.21-47.46% and 45.81-55.73%, and decreased the MDA content by 37.65-48.12% and 29.87-32.51%, respectively. GABA addition increased the SOD and POD activities in the roots by 2.78-5.61% and 13.81-18.33%, respectively, under Cd stress. Thus, exogenous GABA can reduce the content and accumulation of Cd in quinoa seedlings by improving the photosynthetic characteristics and antioxidant enzyme activity and reducing the degree of lipid peroxidation in the cell membrane to alleviate the toxic effect of Cd stress on seedling growth.

BrMYB116 transcription factor enhances Cd stress tolerance by activating FIT3 in yeast and Chinese cabbage.

Cd (cadmium) is a highly toxic heavy metal pollutant often present in soil and detrimentally impacting the production and quality of horticultural crops. Cd affects various physiological and biochemical processes in plants, including chlorophyll synthesis, photosynthesis, mineral uptake and accumulation, and hormonal imbalance, leading to cell death. The MYB family of transcription factors plays a significant role in plant response to environmental influences. However, the role of MYB116 in abiotic stress tolerance remains unclear. In this study, we reported that Chinese cabbage transcription factor BrMYB116 enhanced Cd stress tolerance in yeast. The expression level of BrMYB116 was increased by Cd stress in Chinese cabbage. Additionally, yeast cells overexpressing BrMYB116 showed improved Cd stress tolerance and reduced Cd accumulation. Moreover, we found that BrMYB116 interacted with facilitator of iron transport (FIT3) to enhance Cd stress tolerance. ChIP-qPCR results showed that ScFIT3 was activated through specific binding to its promoter. Additionally, the overexpression of ScFIT3 induced Cd stress tolerance and reduced Cd accumulation in yeast and Chinese cabbage. These results suggest new avenues for plant genomic modification to mitigate Cd toxicity and enhance the safety of vegetable production.

The ethylene response factor gene, ThDRE1A, is involved in abscisic acid- and ethylene-mediated cadmium accumulation in Tamarix hispida.

Tamarix hispida is highly tolerant to salt, drought and heavy metal stress and is a potential material for the remediation of cadmium (Cd)-contaminated soil under harsh conditions. In this study, T. hispida growth and chlorophyll content decreased, whereas flavonoid and carotenoid contents increased under long-term Cd stress (25 d). The aboveground components of T. hispida were collected for RNA-seq to investigate the mechanism of Cd accumulation. GO and KEGG enrichment analyses revealed that the differentially expressed genes (DEGs) were significantly enriched in plant hormone-related pathways. Exogenous hormone treatment and determination of Cd2+ levels showed that ethylene (ETH) and abscisic acid (ABA) antagonists regulate Cd accumulation in T. hispida. Twenty-five transcription factors were identified as upstream regulators of hormone-related pathways. ThDRE1A, which was previously identified as an important regulatory factor, was selected for further analysis. The results indicated that ThABAH2.5 and ThACCO3.1 were direct target genes of ThDRE1A. The determination of Cd2+, ABA, and ETH levels indicated that ThDRE1A plays an important role in Cd accumulation through the antagonistic regulation of ABA and ETH. In conclusion, these results reveal the molecular mechanism underlying Cd accumulation in plants and identify candidate genes for further research.

Genome-wide identification of bHLH gene family and its response to cadmium stress in Populus × canescens.

The basic helix-loop-helix (bHLH) gene family is integral to various aspects of plant development and the orchestration of stress response. This study focuses on the bHLH genes within Populus × canescens, a poplar species noted for its significant tolerance to cadmium (Cd) stress. Through our comprehensive genomic analysis, we have identified and characterized 170 bHLH genes within the P. canescens genome. These genes have been systematically classified into 22 distant subfamilies based on their evolutionary relationships. A notable conservation in gene structure and motif compositions were conserved across these subfamilies. Further analysis of the promoter regions of these genes revealed an abundance of essential cis-acting element, which are associated with plant hormonal regulation, development processes, and stress response pathway. Utilizing quantitative PCR (qPCR), we have documented the differential regulation of PcbHLHs in response to elevated Cd concentrations, with distinct expression patterns observed across various tissues. This study is poised to unravel the molecular mechanism underpinning Cd tolerance in P. canescens, offering valuable insights for the development of new cultivars with enhanced Cd accumulation capacity and tolerance. Such advancements are crucial for implementing effective phytoremediation strategies to mitigate soil pollution caused by Cd.

Oceanobacillus picturae alleviates cadmium stress and promotes growth in soybean seedlings.

Cadmium (Cd) is a heavy metal that significantly impacts human health and the environment. Microorganisms play a crucial role in reducing heavy metal stress in plants; however, the mechanisms by which microorganisms enhance plant tolerance to Cd stress and the interplay between plants and microorganisms under such stress remain unclear. In this study, Oceanobacillus picturae (O. picturae) was isolated for interaction with soybean seedlings under Cd stress. Results indicated that Cd treatment alone markedly inhibited soybean seedling growth. Conversely, inoculation with O. picturae significantly improved growth indices such as plant height, root length, and fresh weight, while also promoting recovery in soil physiological indicators and pH. Metabolomic and transcriptomic analyses identified 157 genes related to aspartic acid, cysteine, and flavonoid biosynthesis pathways. Sixty-three microbial species were significantly associated with metabolites in these pathways, including pathogenic, adversity-resistant, and bioconductive bacteria. This research experimentally demonstrates, for the first time, the growth-promoting effect of the O. picturae strain on soybean seedlings under non-stress conditions. It also highlights its role in enhancing root growth and reducing Cd accumulation in the roots under Cd stress. Additionally, through the utilization of untargeted metabolomics, metagenomics, and transcriptomics for a multi-omics analysis, we investigated the impact of O. picturae on the soil microbiome and its correlation with differential gene expression in plants. This innovative approach unveils the molecular mechanisms underlying O. picturae's promotion of root growth and adaptation to Cd stress.

Omics analysis of 'Shine Muscat' grape grafted on different rootstocks in response to cadmium stress.

Cadmium (Cd) is detrimental to grape growth, development, and fruit quality. Grafting is considered to be a useful method to improve plant adaptability to Cd stress in grape production. However, little information is available on how Cd stress affects grafted grapes. In this study, the effects of Cd on Shine Muscat grapes (Vitis vinifera L. cv. 'Shine Muscat') were studied under different "Cd treatments" concentrations (0, 0.2, 0.4, 0.8, 1.6, 3.2 mg kg-1) and "rootstock treatments" (SO4, 5BB, and 3309C). The results showed that low levels of Cd had hormesis effect and activated the grape antioxidant system to eliminate the ROS induced by Cd stress. The antioxidant capacity of the SM/3309C rootstock combination was stronger than that of the other two groups under low-concentration Cd stress. Moreover, the rootstock effectively sequestered a substantial amount of Cd, consequently mitigating the upward translocation of Cd to the aboveground portions. Transcriptomic and metabolomic analysis revealed several important pathways enriched in ABC transporters, flavonoid biosynthesis, Plant hormone signal transduction, phenylpropanoid biosynthesis, and glutathione metabolism under Cd stress. WGCNA analysis identified a hub gene, R2R3-MYB15, which could promote the expression of several genes (PAL, 4CL, CYP73A, ST, CHS, and COMT), and alleviate the damage caused by Cd toxicity. These findings might shed light on the mechanism of hormesis triggered by low Cd stress in grapes at the transcriptional and metabolic levels.

Physiological response and molecular mechanism of Quercus variabilis under cadmium stress.

Heavy metal pollution is a global environmental problem, and Quercus variabilis has a stronger tolerance to Cd stress than do other species. We aimed to explore the physiological response and molecular mechanisms of Q. variabilis to Cd stress. In this study, the antioxidant enzyme activities of leaves were determined, while the photosynthetic parameters of leaves were measured using Handy PEA, and ion fluxes and DEGs in the roots were investigated using noninvasive microtest technology (NMT) and RNA sequencing techniques, respectively. Cd stress at different concentrations and for different durations affected the uptake patterns of Cd2+ and H+ by Q. variabilis and affected the photosynthetic efficiency of leaves. Moreover, there was a positive relationship between antioxidant enzyme (CAT and POD) activity and Cd concentration. Transcriptome analysis revealed that many genes, including genes related to the cell wall, glutathione metabolism, ion uptake and transport, were significantly upregulated in response to cadmium stress in Q. variabilis roots. WGCNA showed that these DEGs could be divided into eight modules. The turquoise and blue modules exhibited the strongest correlations, and the most significantly enriched pathways were the phytohormone signaling pathway and the phenylpropanoid biosynthesis pathway, respectively. These findings suggest that Q. variabilis can bolster plant tolerance by modulating signal transduction and increasing the synthesis of compounds, such as lignin, under Cd stress. In summary, Q. variabilis can adapt to Cd stress by increasing the activity of antioxidant enzymes, and regulating the fluxes of Cd2+ and H+ ions and the expression of Cd stress-related genes.

The role and transcriptomic mechanism of cell wall in the mutual antagonized effects between selenium nanoparticles and cadmium in wheat.

Selenium nanoparticles (SeNPs) has been reported as a beneficial role in alleviating cadmium (Cd) toxicity in plant. However, underlying molecular mechanisms about SeNPs reducing Cd accumulation and alleviating Cd toxicity in wheat are not well understood. A hydroponic culture was performed to evaluate Cd and Se accumulation, cell wall components, oxidative stress and antioxidative system, and transcriptomic response of wheat seedlings after SeNPs addition under Cd stress. Results showed that SeNPs application notably reduced Cd concentration in root and in shoot by 56.9% and 37.3%, respectively. Additionally, SeNPs prompted Cd distribution in root cell wall by 54.7%, and increased lignin, pectin and hemicellulose contents by regulating cell wall biosynthesis and metabolism-related genes. Further, SeNPs alleviated oxidative stress caused by Cd in wheat through signal transduction pathways. We also observed that Cd addition reduced Se accumulation by downregulating the expression level of aquaporin 7. These results indicated that SeNPs alleviated Cd toxicity and reduced Cd accumulation in wheat, which were associated with the synergetic regulation of cell wall biosynthesis pathway, uptake transporters, and antioxidative system via signaling pathways.