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Wheat is a vital food crop that faces threats from various abiotic and biotic stresses. Understanding the molecular mechanism of cadmium (Cd) resistance can provide valuable insights into the tolerance of wheat. Plant proteins known as Topless/Topless-Related (TPL/TPR) play a role in growth, development, defense regulation, and stress response. In this study, we identified TaTPR2 as being induced by Cd stress treatment. Upon Cd treatment, wheat plants overexpressing TaTPR2 exhibited better growth compared to wild-type (WT) plants. Moreover, the transgenic lines showed reduced accumulation of reactive oxygen species (ROS), along with significantly higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) compared to WT plants. Additionally, the transgenic lines exhibited lower levels of malondialdehyde (MDA) and electrolyte leakage compared to WT plants. Further analysis revealed that TabHLH41 directly binds to the E-box motif of the TaTPR2 promoter and positively regulates its expression. Overall, the overexpression of TaTPR2 in transgenic wheat resulted in reduced accumulation of Cd and ROS. These findings highlight the significance of the TabHLH41-TaTPR2 pathway as a crucial response to Cd stress in wheat., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Recently, pollution caused by the heavy metal Cd has seriously affected the environment and agricultural crops. While Sinapis alba is known for its edible and medicinal value, its tolerance to Cd and molecular response mechanism remain unknown. This study aimed to analyze the tolerance of S. alba to Cd and investigate its molecular response mechanism through transcriptomic and physiological indicators. To achieve this, S. alba seedlings were treated with different concentrations of CdCl 2 (0.25 mmol/L, 0.5 mmol/L, and 1.0 mmol/L) for three days. Based on seedling performance, S. alba exhibited some tolerance to a low concentration of Cd stress (0.25 mmol/L CdCl 2 ) and a strong Cd accumulation ability in its roots. The activities and contents of several antioxidant enzymes generally exhibited an increase under the treatment of 0.25 mmol/L CdCl 2 but decreased under the treatment of higher CdCl 2 concentrations. In particular, the proline (Pro) content was extremely elevated under the 0.25 and 0.5 mmol/L CdCl 2 treatments but sharply declined under the 1.0 mmol/L CdCl 2 treatment, suggesting that Pro is involved in the tolerance of S. alba to low concentration of Cd stress. In addition, RNA sequencing was utilized to analyze the gene expression profiles of S. alba exposed to Cd (under the treatment of 0.25 mmol/L CdCl 2 ). The results indicate that roots were more susceptible to disturbance from Cd stress, as evidenced by the detection of 542 differentially expressed genes (DEGs) in roots compared to only 37 DEGs in leaves. GO and KEGG analyses found that the DEGs induced by Cd stress were primarily enriched in metabolic pathways, plant hormone signal transduction, and the biosynthesis of secondary metabolites. The key pathway hub genes were mainly associated with intracellular ion transport and cell wall synthesis. These findings suggest that S. alba is tolerant to a degree of Cd stress, but is also susceptible to the toxic effects of Cd. Furthermore, these results provide a theoretical basis for understanding Cd tolerance in S. alba .

In plants, expansin genes are responsive to heavy metal exposure. To study the bioremediary potential of this important gene family, we discovered a root-expressed expansin gene in sorghum, SbEXPA11 , which is notably upregulated following cadmium (Cd) exposure. However, the mechanism underlying the Cd detoxification and accumulation mediated by SbEXPA11 in sorghum remains unclear. We overexpressed SbEXPA11 in sorghum and compared wild-type (WT) and SbEXPA11 -overexpressing transgenic sorghum in terms of Cd accumulation and physiological indices following Cd. Compared with the WT, we found that SbEXPA11 mediates Cd tolerance by exerting reactive oxygen species (ROS)-scavenging effects through upregulating the expression of antioxidant enzymes. Moreover, the overexpression of SbEXPA11 rescued biomass production by increasing the photosynthetic efficiency of transgenic plants. In the pot experiment with a dosage of 10 mg/kg Cd, transgenic sorghum plants demonstrated higher efficacy in reducing the Cd content of the soil (8.62 mg/kg) compared to WT sorghum plants (9.51 mg/kg). Subsequent analysis revealed that the SbbHLH041 transcription factor has the ability to induce SbEXPA11 expression through interacting with the E-box located within the SbEXPA11 promoter. These findings suggest that the SbbHLH041- SbEXPA11 cascade module may be beneficial for the development of phytoremediary sorghum varieties.

Cadmium (Cd) is a heavy metal nonessential for plants; this toxic metal accumulation in crops has significant adverse effects on human health. The crosstalk between copper (Cu) and Cd has been reported; however, the molecular mechanisms remain unknown. The present study investigated the function of wheat Cu transporter 3D ( TaCOPT3D ) in Cd tolerance. The TaCOPT3D transcripts significantly accumulated in wheat roots under Cd stress. Furthermore, TaCOPT3D -overexpressing lines were compared to wildtype (WT) plants to test the role of TaCOPT3D in Cd stress response. Under 20 mM Cd treatment, TaCOPT3D -overexpressing lines exhibited more biomass and lower root, shoot, and grain Cd accumulation than the WT plants. In addition, overexpression of TaCOPT3D decreased the reactive oxygen species (ROS) levels and increased the active antioxidant enzymes under Cd conditions. Moreover, the transcription factor (TF) TaWRKY22 , which targeted the TaCOPT3D promoter, was identified in the regulatory pathway of TaCOPT3D under Cd stress. Taken together, these results show that TaCOPT3D plays an important role in regulating plant adaptation to cadmium stress through bound by TaWRKY22. These findings suggest that TaCOPT3D is a potential candidate for decreasing Cd accumulation in wheat through genetic engineering.

Arabis paniculata has been reported as a hyperaccumulator and functions in cadmium (Cd) tolerance and accumulation. However, the genes involved in Cd stress resistance in A. paniculata are still unknown. In this work, genes of the natural resistanceassociated macrophage proteins ( NRAMPs ) were characterized in A. paniculata , and their evolutionary relationship and expression patterns were analysed. Expression profiles indicated that ApNRAMPs showed large differences in response to Cd stress. It was highly induced by Cd in root and shoot tissues. To investigate the function of ApNRAMP4 under Cd stress, ApNRAMP4 was cloned and expressed in yeast and Arabidopsis . The results indicated that yeast and Arabidopsis expressing ApNRAMP4 showed normal growth under Cd stress. In addition, transgenic yeast and Arabidopsis showed the ability to concentrate Cd. Under 20 μM CdCl 2 , Cd concentrations in wild type (WT) and transgenic yeast were 3.11 and 5.92 mg/kg, respectively. Cd concentrations in root tissues of WTand transgenic Arabidopsis were 0.18 and 0.54 mg/kg, respectively. In shoot tissues of WT and transgenic Arabidopsis , Cd concentrations were 0.13 and 0.49 mg/kg, respectively. This report provides genomic information on hyperaccumulator A. paniculata . In addition, the present work identified key NRAMP genes that may serve as resources for heavy metal phytoremediation.

Cadmium (Cd) is a toxic heavy metal that accumulates in plants, negatively affecting their physiological processes, growth, and development, and poses a threat to human health through the food chain. 6-phosphogluconolactonase (PGL) is a key enzyme in the Oxidative Pentose Phosphate Pathway(OPPP) in plant cells, essential for cellular metabolism. The OPPP pathway provides energy and raw materials for organisms and is involved in antioxidant reactions, lipid metabolism, and DNA synthesis. This study describes the Cd responsive gene AetPGL from Aegilops tauschii. Overexpression of AetPGL under Cd stress increased main root length and germination rate in Arabidopsis. Transgenic lines showed higher antioxidant enzyme activities and lower malondialdehyde (MDA) content compared to the wild type. The transgenic Arabidopsis accumulated more Cd in the aboveground part but not in the underground part. Expression levels of AtHMA3, AtNRAMP5, and AtZIP1 in the roots of transgenic plants increased under Cd stress, suggesting AetPGL may enhance Cd transport from root to shoot. Transcriptome analysis revealed enrichment of differentially expressed genes (DEGs) in the plant hormone signal transduction pathway in AetPGL-overexpressing plants. Brassinosteroids (BR), Gibbenellin acid (GA), and Jasmonic acid (JA) contents significantly increased after Cd treatment. These results indicate that AetPGL may enhance Arabidopsis' tolerance to Cd by modulating plant hormone content. In conclusion, AetPGL plays a critical role in improving cadmium tolerance and accumulation and mitigating oxidative stress by regulating plant hormones, providing insights into the molecular mechanisms of plant Cd tolerance. [ABSTRACT FROM AUTHOR]

With the constant progress of urbanization and industrialization, cadmium (Cd) has emerged as one of the heavy metals that pollute soil and water. The presence of Cd has a substantial negative impact on the growth and development of both animals and plants. The allotetraploid Brasscia. carinata, an oil crop in the biofuel industry, is known to produce seeds with a high percentage of erucic acid; it is also known for its disease resistance and widespread adaptability. However, there is limited knowledge regarding the tolerance of B. carinata to Cd and its physiological responses and gene expressions under exposure to Cd. Here, we observed that the tested B. carinata exhibited a strong tolerance to Cd (1 mmol/L CdCl2 solution) and exhibited a significant ability to accumulate Cd, particularly in its roots, with concentrations reaching up to 3000 mg/kg. Additionally, we found that the total oil content of B. carinata seeds harvested from the Cd-contaminated soil did not show a significant change, but there were noticeable alterations in certain constituents. The activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX), were observed to significantly increase after treatment with different concentrations of CdCl2 solutions (0.25 mmol/L, 0.5 mmol/L, and 1 mmol/L CdCl2). This suggests that these antioxidant enzymes work together to enhance Cd tolerance. Comparative transcriptome analysis was conducted to identify differentially expressed genes (DEGs) in the shoots and roots of B. carinata when exposed to a 0.25 mmol/L CdCl2 solution for 7 days. A total of 631 DEGs were found in the shoots, while 271 DEGs were found in the roots. It was observed that these selected DEGs, which responded to Cd stress, also showed differential expression after exposure to PbCl2. This suggests that B. carinata may employ a similar molecular mechanism when tolerating these heavy metals. The functional annotation of the DEGs showed enrichment in the categories of 'inorganic ion transport and metabolism' and 'signal transduction mechanisms'. Additionally, the DEGs involved in 'tryptophan metabolism' and 'zeatin biosynthesis' pathways were found to be upregulated in both the shoots and roots of B. carinata, suggesting that the plant can enhance its tolerance to Cd by promoting the biosynthesis of plant hormones. These results highlight the strong Cd tolerance of B. carinata and its potential use as a Cd accumulator. Overall, our study provides valuable insights into the mechanisms underlying heavy metal tolerance in B. carinata. [ABSTRACT FROM AUTHOR]

Arabis paniculata is a newly discovered hyperaccumulator known for its ability to accumulate multiple metals. WRKY proteins play a significant role in plant responses to various stresses, including cadmium (Cd) stress. However, there is limited research on the molecular biology of Arabis paniculata, especially regarding the WRKY family. In this study, we conducted third-generation sequencing for functional annotation and structural analysis of Arabis paniculata. We obtained 41,196 high-quality isoforms from the full-length transcriptome, with an average length of 1043 bp. A total of 26,670 genes were predicted against NR, Swissprot, KOG, and KEGG databases. Functional comparison using the KOG database revealed excellent annotation in 25 functional categories, with general function prediction (1822 items) being the most predominant. MISA analysis identified 12,593 SSR loci, with single nucleotide repeats being the largest category (44.83% of the total). Moreover, our predictions provide insights into 20,022 coding sequences (CDS), 811 transcription factors, and 17,963 LncRNAs. In total, 34 WRKY gene sequences were identified in Arabis paniculata. Bioinformatics analysis revealed diverse numbers of amino acids in these WRKYs (113 to 545 aa), and a conserved WRKYGQK sequence within the N-terminus of the WRKY protein. Furthermore, all WRKYs were found to be localized in the nucleus. Phylogenetic analysis classified the WRKY genes into three categories: I (14 members), II (17 members), and III (3 members). Category II was subsequently divided into four sub-categories: II-a (8 members), II-b (1 member), II-c (1 member), and II-d (7 members). Our quantitative real-time polymerase chain reaction (qRT-PCR) experiments revealed that ApWRKY23 and ApWRKY34 exhibited the highest expression levels at the 24-h time point, suggesting their potential role as the candidate genes for Cd stress response. These findings contribute to our understanding of the genomic information of Arabis paniculata and provide a basis for the analysis of its genetic diversity. Additionally, this study paves the way for a comprehensive exploration of the molecular mechanisms underlying the WRKY genes in Arabis paniculata under Cd stress conditions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal that seriously affects metabolism after accumulation in plants, and it also causes adverse effects on humans through the food chain. The HIPP gene family has been shown to be highly tolerant to Cd stress due to its special domain and molecular structure. This study described the Cd-induced gene ApHIPP26 from the hyperaccumulator Arabis paniculata. Its subcellular localization showed that ApHIPP26 was located in the nucleus. Transgenic Arabidopsis overexpressing ApHIPP26 exhibited a significant increase in main root length and fresh weight under Cd stress. Compared with wild-type lines, Cd accumulated much more in transgenic Arabidopsis both aboveground and underground. Under Cd stress, the expression of genes related to the absorption and transport of heavy metals underwent different changes in parallel, which were involved in the accumulation and distribution of Cd in plants, such as AtNRAMP6 and AtNRAMP3. Under Cd stress, the activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) in the transgenic lines were higher than those in the wild type. The physiological and biochemical indices showed that the proline and chlorophyll contents in the transgenic lines increased significantly after Cd treatment, while the malondialdehyde (MDA) content decreased. In addition, the gene expression profile analysis showed that ApHIPP26 improved the tolerance of Arabidopsis to Cd by regulating the changes of related genes in plant hormone signal transduction pathway. In conclusion, ApHIPP26 plays an important role in cadmium tolerance by alleviating oxidative stress and regulating plant hormones, which provides a basis for understanding the molecular mechanism of cadmium tolerance in plants and provides new insights for phytoremediation in Cd-contaminated areas. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a highly toxic pollutant in soil and water that severely hampers the growth and reproduction of plants. Phytoremediation has been presented as a cost-effective and eco-friendly method for addressing heavy metal pollution. However, phytoremediation is restricted by the limited number of accumulators and the unknown mechanisms underlying heavy metal tolerance. In this study, we demonstrated that Erigeron canadensis (Asteraceae), with its strong adaptability, is tolerant to intense Cd stress (2 mmol/L CdCl2 solution). Moreover, E. canadensis exhibited a strong ability to accumulate Cd2+ when treated with CdCl2 solution. The activity of some antioxidant enzymes, as well as the malondialdehyde (MDA) level, was significantly increased when E. canadensis was treated with different CdCl2 solutions (0.5, 1, 2 mmol/L CdCl2). We found high levels of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities under 1 mmol/L CdCl2 treatment. Comparative transcriptomic analysis identified 5,284 differentially expressed genes (DEGs) in the roots and 3,815 DEGs in the shoots after E. canadensis plants were exposed to 0.5 mM Cd. Functional annotation of key DEGs indicated that signal transduction, hormone response, and reactive oxygen species (ROS) metabolism responded significantly to Cd. In particular, the DEGs involved in auxin (IAA) and ethylene (ETH) signal transduction were overrepresented in shoots, indicating that these genes are mainly involved in regulating plant growth and thus likely responsible for the Cd tolerance. Overall, these results not only determined that E. canadensis can be used as a potential accumulator of Cd but also provided some clues regarding the mechanisms underlying heavy metal tolerance. [ABSTRACT FROM AUTHOR]

The Cd tolerance protein SaCTP3, which responds to Cd stress, was identified in Sedum alfredii ; however, how to improve the efficiency of phytoremediation of Cd–contaminated soil using the CTP gene remains unknown. In this study, the phytoremediation potential of SaCTP3 of Sedum alfredii was identified. In the yeast Cd–sensitive strain Δycf1 overexpressing SaCTP3 , the accumulation of Cd was higher than that in the Δycf1 strain overexpressing an empty vector. Transgenic sorghum plants overexpression SaCTP3 were further constructed to verify the function of SaCTP3. Compared to wild–type plants, the SaCTP3 –overexpressing lines exhibited higher Cd accumulation under 500 μM Cd conditions. The average Cd content in SaCTP3 –overexpressing plants is more than four times higher than that of WT plants. This was accompanied by an enhanced ability to scavenge ROS, as evidenced by the significantly increased activities of peroxidase, catalase, and superoxide dismutase in response to Cd stress. Pot experiments further demonstrated that SaCTP3 overexpression resulted in improved soil Cd scavenging and photosynthetic abilities. After 20 days of growth, the average Cd content in the soil planted with SaCTP3 –overexpressing sorghum decreased by 19.4%, while the residual Cd content in the soil planted with wild–type plants was only reduced by 5.4%. This study elucidated the role of SaCTP3 from S.alfredii , highlighting its potential utility in genetically modifying sorghum for the effective phytoremediation of Cd. [Display omitted] • SaCTP3 overexpression increased Cd accumulation in transgenic sorghum. • Overexpression of SaCTP3 in sorghum increased photosynthesis efficiency. • SaCTP3 –overexpressing sorghum has the potential to effectively remove Cd from the soil. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal that is absorbed from the soil through roots and transmitted through the food chain, posing a serious threat to human health and food security. Exogenous NaCl can reduce the uptake of Cd by plants, but the underlying molecular mechanism is still unclear. In this study, we elucidated the molecular mechanism by which exogenous NaCl inhibited Cd absorption in wheat seedlings. Notably, 50 mM NaCl altered the wheat physiological response and reduce the Cd uptake by plants. Overexpression of the NaCl–responsive gene TaNHX2 increased the levels of chlorophyll and proline, enhanced antioxidant enzyme (CAT, POD, and SOD) activity, decreased the MDA content, and improved tolerance to Cd stress in transgenic wheat plants. We further found that TaWRKY13 binds directly to the TaNHX2 promoter to regulate its transcription. Subsequent research found that TaWRKY13 can also bind to the promoter of the heavy metal transporter gene TaHMA2 to activate its expression. TaNHX2 overexpression obviously downregulated the expression of TaHMA2 in the presence of both NaCl and Cd. In vivo and in vitro assays revealed that NaCl inhibited the binding of TaWRKY13 to the TaHMA2 promoter. This work reveals that NaCl and Cd antagonize uptake at the molecular level and provides new insights for future reductions in Cd accumulation in wheat. [Display omitted] • Exogenous NaCl can reduce the uptake of Cd by wheat plants. • Overexpression of TaNHX2 improved tolerance to Cd stress in wheat. • TaWRKY13 binds the promoters of TaNHX2 and TaHMA2. • NaCl promoted the binding of TaWRKY13 to the TaNHX2 promoter. • NaCl inhibited the binding of TaWRKY13 to the TaHMA2 promoter. [ABSTRACT FROM AUTHOR]

Sugar will eventually be exported transporter (SWEET) protein involved in various developmental and stress responses in plants. Here, we report the mechanisms and transcriptional regulatory pathway of the wheat TaSWEET14 in response to cadmium stress. Overexpression of TaSWEET14 improves cadmium stress tolerance and decreases cadmium accumulation in wheat grains. The overexpression of TaSWEET14 in wheat seedlings altered the expression pattern of the ion transporter genes NRAMP5 , LCT1 , HMA3 , and IRT1. These genes were remarkably down-regulated in shoot tissues of TaSWEET14 transgenic wheat lines under cadmium stress. However, there was no significant difference in their expression levels in roots between the wild type (WT) and transgenic plants. In addition, the transgenic plants had a strong ability to remove reactive oxygen species and showed increased activity of antioxidant enzymes. Notably, the transgenic lines had significantly lower cellulose content but higher lignin content than the WT under cadmium stress. The cell wall cadmium content was also significantly higher in the transgenic lines. Lastly, we revealed that TaMYB41 binds directly to the promoter of TaSWEET14 to activate its transcription. This study describes a novel cadmium-responsive regulatory pathway in wheat and demonstrates that TaSWEET14 directly controls wheat cadmium accumulation by altering lignin content. • Overexpression of wheat (Triticum aestivum) SWEET14 (TaSWEET14) significantly improves resistance to cadmium. • Overexpression of TaSWEET14 in wheat resulted in a change of the contents of lignin and cellulose. • Transcription factor TaMYB41 regulates TaSWEET14 gene transcription. [ABSTRACT FROM AUTHOR]

• TaHSP17.8 in response to Cd stress and enhances Cd tolerance of transgenic wheat. • TaHSP17.8 activates expression of TaJUB1D. • TaHSP17.8 binds to a CG-riched sequence of TaJUB1D promoter. In this work, the function of a wheat small heat shock protein TaHSP17.8 to respond to Cd stress was characterized. TaHSP17.8 is mainly expressed in root tissues and was found to be most highly expressed 4 h after Cd stress. The function of TaHSP17.8 in Cd stress response was investigated using transgenic wheat lines. Damage to both the root and shoot tissues of transgenic lines was reduced compared with the wild type (WT) plants. In addition, wheat lines overexpressing TaHSP17.8 showed higher Cd concentrations in root tissues than WT. However, Cd concentration in the shoots of transgenic lines was significantly lower than WT. Physiological and biochemical parameters indicated that proline, malonyldialdehyde (MDA), and H 2 O 2 contents were all substantially decreased in the transgenic lines after Cd treatment, while chlorophyll content was significantly higher. We therefore screened for transcription factors that interacted with TaHSP17.8, and identified TaJUB1D as a putative hit. Further analyses indicated that TaHSP17.8 binds directly to a region 1850–1900 bp upstream of the TaJUB1D open reading frame (ORF). This work confirms the function of TaHSP17.8 in response to Cd stress and identifies a novel pathway to regulate Cd stress in wheat. [ABSTRACT FROM AUTHOR]

• TaWRKY70 increased Cd tolerance of transgenic Arabidopsis. • Expression of TaWRKY70 in Arabidopsis suppress Cd transfer coefficient. • TaWRKY70 binds to the promoter of TaCAT5 as well as regulating the transcription of TaCAT5. The WRKY transcription factors (TFs) are involved in plant responses to multiple biotic and abiotic stressors; however, the role of WRKY TFs in the regulation of Cd stress in wheat remains unknown. In this study, we investigated the mechanism of the wheat TaWRKY70 TF in Cd stress. TaWRKY70 expression in Arabidopsis was used for the functional analysis. TaWRKY70 regulated Cd tolerance with Cd accumulating in roots but not in the leaf tissues of transgenic Arabidopsis. The net Cd2+ influx into Arabidopsis roots decreased when TaWRKY70 was expressed. The quantitative real-time-polymerase chain reaction (qRT-PCR) results showed that the expression levels of heavy metal ATPase (AtHMA3), natural resistance-associated macrophage protein (AtNRAMP5) , yellow stripe1-like (AtYSL3), and iron transport protein (AtIRT1) decreased under Cd-stress condition. Electrolyte leakage, as well as malondialdehyde and hydrogen peroxide contents, were lower in transgenic Arabidopsis than those in the wild-type (WT), whereas antioxidant enzyme activities were higher. Electrophoretic mobility shift assay (EMSA), yeast one-hybrid (Y1H) assay, and transient transactivation assay confrmed that TaWRKY70 could directly bind to the TaCAT5 promoter. Our findings provide a novel understanding of the WRKY TFs involved in the response to heavy metal stress. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), which is a nonessential heavy metal element for organisms, can have a severe impact on the growth and development of organisms that absorb excessive Cd. Studies have shown that Brassica carinata , a semiwild oil crop, has strong tolerance to various abiotic stresses, and RNA-seq has revealed that the B. carinata superoxide dismutase gene (BcaSOD1) likely responds to Cd stress. To elucidate the BcaSOD1 function involved in tolerance of Cd stress, we cloned the coding sequences of BcaSOD1 from a purple B. carinata accession and successfully transferred it into Arabidopsis thaliana. The subcellular localization results demonstrated that BcaSOD1 was primarily located in the plasma membrane, mitochondria and nucleus. Overexpression of BcaSOD1 in transgenic Arabidopsis (OE) effectively decreased the toxicity caused by Cd stress. Compared to the WT (wild type lines), the OE lines exhibited significantly increased activities of antioxidant enzymes (APX, CAT, POD, and SOD) after exposure to 2.5 mM CdCl 2. The Cd content of underground (root) in the OE line was dominantly higher than that in the WT; however, the Cd content of aboveground (shoot) was comparable between the OE and WT types. Moreover, the qRT‒PCR results showed that several heavy metal detoxification-related genes (AtIREG2, AtMTP3, AtHMA3, and AtNAS4) were significantly upregulated in the roots of OE lines under Cd treatment, suggesting that these genes are likely involved in Cd absorption in the roots of OE lines. In addition, both comparable transcriptome and qRT-PCR analyses revealed that exogenous BcaSOD1 noticeably facilitates detoxification by stimulating the expression of two arginine (Arg) biosynthesis genes (AtGDH1 and AtGDH2) while inhibiting the expression of AtARGAH1 , a negative regulator in biosynthesis of Arg. The Arg content was subsequently confirmed to be significantly enhanced in OE lines under Cd treatment, indicating that BcaSOD1 likely strengthened Cd tolerance by regulating the expression of Arg-related genes. This study demonstrates that BcaSOD1 can enhance Cd tolerance and reveals the molecular mechanism of this gene, providing valuable insights into the molecular mechanism of Cd tolerance in plants. • BcaSOD1 increased Cd tolerance of transgenic Arabidopsis. • Expression of BcaSOD1 in Arabidopsis up-regulates heavy metal detoxification-related genes. • BcaSOD1 affecting the arginine biosynthesis pathway under Cd stress. [ABSTRACT FROM AUTHOR]

In plants, high–affinity potassium transporters (HKTs) not only play a significant role in potassium transport but may also be important for the abiotic stress response. However, information regarding the response of HKTs to cadmium (Cd) stress is limited. Here, we focus on SbHKT2b , the expression of which is highly induced by Cd exposure. SbHKT2b overexpression reduced the accumulation of Cd and increased tolerance to Cd exposure, while SbHKT2b –RNA interference (RNAi) lines exhibited the opposite phenotype. In addition, the overexpression of SbHKT2b resulted in reduced reactive oxygen species (ROS) accumulation and enhanced ROS quenching capacity under Cd stress. Further analyses revealed that SbWRKY54 directly binds to the SbHKT2b promoter and upregulates its expression. Overall, the overexpression of SbWRKY54 decreased Cd and ROS accumulation in transgenic sorghum. Taken together, our results showed that SbWRKY54– SbHKT2b is an important Cd stress response pathway in sorghum. • SbHKT2b overexpression reduced the accumulation of Cd and increased tolerance to Cd exposure. • The overexpression of SbHKT2b resulted in reduced ROS accumulation and enhanced ROS quenching capacity under Cd stress. • SbWRKY54 directly binds to the SbHKT2b promoter and upregulates its expression. • SbWRKY54– SbHKT2b is an important Cd stress response pathway in sorghum. [ABSTRACT FROM AUTHOR]