Search Results (29)

Heavy metals in the soil inhibit plant growth, which significantly reduce the crop yield and quality. Natural Resistance-Associated Macrophage Proteins (NRAMP) are widely distributed on the plasma and vacuolar membranes of plant roots, stems, and leaves. The NRAMP gene family plays a crucial role in modulating plant heavy-metal uptake, sequestration, distribution, and translocation, while the molecular evolution and mechanisms underlying these processes remain unclear. Here, we reviewed recent progress on plant NRAMP genes, focusing on their structural characteristics and functions in the absorption, transport, accumulation, and detoxification of various heavy metals. Furthermore, we performed an evolutionary analysis of NRAMP in green plants, indicating expansion and tandem duplication in ferns. In addition, their key amino acid sequences and secondary structures were highly conserved across plant species. The expression of diverse tissue showed that NRAMP genes displayed distinct spatial regulation in the leaves and roots. We also explored the underlying molecular mechanisms and regulatory pathways by which NRAMP genes influence heavy metal uptake. Therefore, by integrating structural conservation, molecular evolution, tissue- and single-cell expression patterns, ion-stress-responsive expression, regulatory pathways, and the Cd–Mn nutrient–toxin trade-off, this review provides a framework for identifying unresolved NRAMP functions and for guiding future strategies in low-heavy-metal crop breeding, metal homeostasis engineering, and phytoremediation. Full article

While the molecular mechanisms of cadmium (Cd) uptake are well-studied in rice and tobacco, hexaploid wheat remains less explored. Elucidating the roles of transporter genes in Cd uptake and translocation in wheat is critical for minimizing Cd accumulation in grains. This study compared the differences in the expression levels of Cd transporter families (including the natural resistance-associated macrophage protein (NRAMP), heavy metal ATPase (HMA), zinc-regulated transporter/iron-regulated transporter (ZIP), and yellow stripe-like (YSL) families) between two high Cd-accumulating wheat varieties and two low Cd-accumulating wheat varieties using qPCR. We found that low Cd-accumulating wheat varieties had higher expression levels of TaNRAMP5 and TaHMA2 in roots and TaHMA3 in aboveground tissues, and lower expression levels of TaNRAMP6, TaZIP5, and TaYSL6 in both roots and aboveground tissues compared to the high Cd-accumulating wheat varieties. Mantel test analysis revealed that the root expression levels of TaNRAMP5 and TaNRAMP6 and aboveground expression levels of TaZIP6 and TaHMA2 were significantly correlated with the Cd content of wheat tissues. Furthermore, the expression levels of TaZIP5 in roots and TaZIP5 and TaHMA3 in aboveground tissues were significantly correlated with the Cd translocation factor from roots to aboveground tissues, suggesting that TaNRAMP5, TaNRAMP6, TaZIP6, and TaHMA2 played key roles in Cd uptake and accumulation in wheat, and TaZIP5 and TaHMA3 were closely associated with Cd translocation from roots to aboveground tissues. Compared to low Cd-accumulating varieties, high Cd-accumulating wheat varieties exhibit significantly elevated levels of thiol-containing compounds for Cd chelation, including glutathione (7.65%~75.5% higher), phytochelatins (2.35%~47.2% higher), and non-protein thiols (13.2%~37.1% higher). These findings deepen insights into wheat Cd absorption processes. The identified transporter genes could serve as foundational resources for future breeding strategies aimed at reducing Cd accumulation in wheat, pending further functional validation. Full article

The NRAMP (Natural Resistance-Associated Macrophage Protein) family plays a pivotal role as membrane transporters in plants’ responses to heavy metal stress. This study identified 12 NRAMP genes in Sorghum bicolor (sorghum) and performed a comprehensive bioinformatics analysis. The SbNRAMP genes are distributed across seven sorghum chromosomes. In-depth analyses of gene structure, conserved motifs, collinearity, and phylogeny indicated that the SbNRAMP family is divided into three subfamilies, each exhibiting unique structural and motif characteristics. Collinearity analysis suggested that large-fragment duplications, rather than tandem duplications, were responsible for the expansion of the SbNRAMP family, resulting in a greater number of genes compared to Arabidopsis thaliana and rice. Transcriptome analysis of the aboveground and underground parts of sorghum seedlings under saline–alkali stress revealed that SbNRAMP5 is a key hub gene exhibiting tissue-specific expression. Furthermore, qRT-PCR analysis following exposure to Cd, Mn, or Zn treatments revealed differential expression among the SbNRAMP genes. Subcellular localization predictions indicated that all twelve NRAMPs are primarily located in the plasma membrane, with nine to twelve transmembrane domains, consistent with their function in metal ion transport. Experimental evidence confirmed that SbNRAMP6 is localized in the plasma membrane. These findings establish a foundation for a deeper understanding of the structure and function of the sorghum NRAMP gene family. Full article

The natural resistance-associated macrophage proteins (NRAMPs) gene family represents a group of membrane transporter proteins with wide distribution in plants. This family of membrane transporters plays a pivotal role in mediating plant responses to metal stress by coordinating ion transport processes and maintaining cellular metal homeostasis, thereby effectively mitigating the detrimental effects of metal ion stress on plant growth and development. This study conducted a comprehensive genome-wide analysis of the NRAMP gene family in A. tauschii using integrated bioinformatics approaches, as well as the expression pattern when exposed to heavy metal-induced stress. By means of phylogenetic investigation, eleven AetNRAMP proteins were categorized into five distinct subgroups. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that the majority of NRAMP genes exhibited marked differential expression patterns under specific stress treatments. Subsequently, yeast cells were employed to validate the functions of AetNRAMP1 and AetNRAMP3. It was confirmed that AetNRAMP1 functioned in copper transport, and AetNRAMP3 showed an increase in its expression level under manganese stress. These findings establish a molecular foundation for elucidating the functional specialization of NRAMP gene family members in A. tauschii’s heavy metal detoxification pathways, providing critical genetic evidence for their stress-responsive regulatory networks. Nevertheless, significant knowledge gaps persist regarding its functions in A. tauschii. Research on metal stress resistance in this wheat progenitor species may establish a theoretical foundation for enhancing wheat tolerance and developing improved cultivars. Full article

Membrane transporters are vital for solute movement and localisation across cellular compartments, particularly in extremophilic organisms such as Galdieriales. These red algae thrive in geothermal and metal-rich environments, where adaptive transporter systems contribute to their metabolic flexibility. While inventories of transporter genes in the species Galdieria sulphuraria have previously been compiled, their phylogenetic origins remain incompletely resolved. Here, we conduct a comparative phylogenetic analysis of three transporter families—Major Facilitator Superfamily (MFS). Amino acid–Polyamine–Organocation (APC) and the natural resistance–associated macrophage protein (Nramp)—selected from overexpressed transcripts in G. sulphuraria strain SAG 107.79. Using sequences from six Galdieriales species and orthologs from diverse taxa, we reconstructed maximum likelihood trees to assess conservation and potential horizontal gene transfer (HGT). The MFS subfamilies revealed contrasting patterns: sugar porters (SPs) exhibited polyphyly and fungal affinity, suggesting multiple HGT events, while phosphate:H⁺ symporters (PHSs) formed a coherent monophyletic group. APC sequences were exclusive in G. sulphuraria and extremophilic prokaryotes, indicating a likely prokaryotic origin. In contrast, Nramp transporters were broadly conserved across eukaryotes and prokaryotes, showing no signs of recent HGT. Together, these findings highlight the mosaic evolutionary history of membrane transporters in Galdieriales, shaped by a combination of vertical inheritance and taxon-specific gene acquisition events, and provide new insight into the genomic strategies underpinning environmental resilience in red algae. Full article

Heavy metal pollution and soil salinization harm human health and the environment. Phytoremediation is a widely accepted soil decontamination method, with woody plants being particularly effective due to their large biomass and extensive root systems. In this study, we identified and cloned PsnMLP328 from Populus simonii × P. nigra and demonstrated its role in mitigating salt and cadmium stress. PsnMLP328 expression was up-regulated under both stress conditions, and its overexpression in tobacco enhanced resistance to these stresses, albeit through distinct mechanisms. Transgenic plants exhibited increased Cd²⁺ uptake and a higher biomass, alleviating Cd²⁺-induced growth inhibition. Additionally, PsnMLP328 boosted proline content, chlorophyll levels, and antioxidative enzyme activities (POD, SOD) under Cd²⁺ stress, likely by protecting cells from oxidative damage. Expression analysis revealed that PsnMLP328 down-regulated the cadmium transporter Nramp2 while up-regulating YSL2 (another cadmium transporter) and potassium channels (AKT1 and AKT2/3), suggesting its role in modulating K⁺ and Cd²⁺ homeostasis. These findings indicate that PsnMLP328 enhances tobacco resistance to salt and cadmium stress, particularly the latter. This study is the first to elucidate the function of poplar MLP family genes under salt and cadmium stress, advancing our understanding of MLP gene roles in heavy metal stress and offering new insights for remediating salinized and heavy metal-contaminated soils. Full article

Kenaf (Hibiscus cannabinu) is a grass bast fiber crop that has the ability to tolerate and accumulate heavy metals, and it has been considered as a potential heavy metal accumulator and remediation plant. Nramp is a natural resistance-related macrophage, which plays an important role in the transport of divalent metal ions, plant growth and development, and abiotic stress. In this study, the Nramp gene family of kenaf was analyzed at the whole genome level. A total of 15 HcNramp genes were identified. They are distributed unevenly on chromosomes. Phylogenetic analysis classified 15 HcNramp proteins into 3 different subfamilies. All proteins share specific motif 4 and motif 6, and the genes belonging to the same subfamily are similar in structure and motif. The promoters are rich in hormone response, meristem expression, and environmental stress response elements. Under different treatments, the expression levels of HcNramp genes vary in different tissues, and most of them are expressed in roots first. These findings can provide a basis for understanding the potential role of the Nramp gene family in kenaf in response to cadmium (Cd) stress, and are of great significance for screening related Cd tolerance genes in kenaf. Full article

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. Full article

The transport of metals such as iron (Fe), manganese (Mn), and cadmium (Cd) in rice is highly related. Although Fe and Mn are essential elements for plant growth, Cd is a toxic element for both plants and humans. OsNRAMP5—a member of the same family as the Fe, Mn, and Cd transporter OsNRAMP1—is responsible for the transport of Mn and Cd from soil in rice. Knockout of OsNRAMP5 markedly reduces both Cd and Mn absorption, and this OsNRAMP5 knockout is indispensable for the development of low-Cd rice. However, in low-Mn environments, such plants would exhibit Mn deficiency and suppressed growth. We generated random mutations in OsNRAMP5 via error-prone PCR, and used yeast to screen for the retention of Mn absorption and the inhibition of Cd absorption. The results showed that alanine 512th is the most important amino acid residue for Cd absorption and that its substitution resulted in the absorption of Mn but not Cd. Full article

The solute transport protein family 11 A1 (SLC11A1), also recognized as natural resistance-associated macrophage protein 1 (NRAMP1), represents a transmembrane protein encoded by the SLC11A1 gene. A variety of prior investigations have illuminated its involvement in conferring resistance or susceptibility to bacterial agents, positioning it as a promising candidate gene for breeding disease-resistant animals. Yaks (Bos grunniens), renowned inhabitants of the Qinghai-Tibet Plateau in China, stand as robust ruminants distinguished by their adaptability and formidable disease resistance. Notwithstanding these unique traits, there is scant literature on the SLC11A1 gene in the yak population. Our inquiry commences with the cloning of the 5′ regulatory region sequence of the Zhongdian yak SLC11A1 gene. We employ bioinformatics tools to identify transcription factor binding sites, delineating pivotal elements like enhancers and cis-acting elements. To ascertain the promoter activity of this region, we amplify four distinct promoter fragments within the 5′ regulatory region of the yak SLC11A1 gene. Subsequently, we design a luciferase reporter gene vector containing four site-specific deletion mutations and perform transient transfection experiments. Through these experiments, we measure and compare the activity of disparate gene fragments located within the 5′ regulatory region, revealing regions bearing promoter functionality and discerning key regulatory elements. Our findings validate the promoter functionality of the 5′ regulatory region, offering preliminary insights into the core and principal regulatory segments of this promoter. Notably, we identified single nucleotide polymorphisms (SNPs) that may be associated with important regulatory elements such as NF-1 and NF-1/L. This study provides a theoretical framework for in-depth research on the function and expression regulation mechanism of the yak SLC11A1 gene. Full article

Transmembrane carriers of the Slc11 family catalyze proton (H⁺)-dependent uptake of divalent metal ions (Me²⁺) such as manganese and iron—vital elements coveted during infection. The Slc11 mechanism of high-affinity Me²⁺ cell import is selective and conserved between prokaryotic (MntH) and eukaryotic (Nramp) homologs, though processes coupling the use of the proton motive force to Me²⁺ uptake evolved repeatedly. Adding bacterial piracy of Nramp genes spread in distinct environmental niches suggests selective gain of function that may benefit opportunistic pathogens. To better understand Slc11 evolution, Alphafold (AF2)/Colabfold (CF) 3D predictions for bacterial sequences from sister clades of eukaryotic descent (MCb and MCg) were compared using both native and mutant templates. AF2/CF model an array of native MCb intermediates spanning the transition from outwardly open (OO) to inwardly open (IO) carriers. In silico mutagenesis targeting (i) a set of (evolutionarily coupled) sites that may define Slc11 function (putative synapomorphy) and (ii) residues from networked communities evolving during MCb transition indicates that Slc11 synapomorphy primarily instructs a Me²⁺-selective conformation switch which unlocks carrier inner gate and contributes to Me²⁺ binding site occlusion and outer gate locking. Inner gate opening apparently proceeds from interaction between transmembrane helix (h) h5, h8 and h1a. MCg1 xenologs revealed marked differences in carrier shape and plasticity, owing partly to an altered intramolecular H⁺ network. Yet, targeting Slc11 synapomorphy also converted MCg1 IO models to an OO state, apparently mobilizing the same residues to control gates. But MCg1 response to mutagenesis differed, with extensive divergence within this clade correlating with MCb-like modeling properties. Notably, MCg1 divergent epistasis marks the emergence of the genus Bordetella-Achromobacter. Slc11 synapomorphy localizes to the 3D areas that deviate least among MCb and MCg1 models (either IO or OO) implying that it constitutes a 3D network of residues articulating a Me²⁺-selective carrier conformation switch which is maintained in fast-evolving clades at the cost of divergent epistatic interactions impacting carrier shape and dynamics. Full article

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. Full article

The excessive content of heavy metals and the deficiency of beneficial trace elements in cereals have threatened global food security and human health. As important metal transporters, Natural resistance-associated macrophage proteins (Nramps) are involved in the absorption and transport of various metal ions in plants, including beneficial elements and hazardous heavy metals, yet little is known about their roles in foxtail millet. In this study, 12 Nramps were identified in foxtail millet genome and divided into three clades. Expansion and functional differentiation of SiNramp gene family is evident in the high proportion of gene duplication as well as the diversity in protein structure and expression characteristics. The SiNramp genes exhibited different response patterns to Cd stress in different tissues. Based on the integration of ionome, RNA-seq and orthologous analysis, the association of SiNramp genes with the accumulation of different metal ions was investigated, and the possible functions of several SiNramp genes were predicted, such as SiNramp6 and SiNramp12. In general, this study provides a comprehensive theoretical framework for the study of Nramp genes in foxtail millet and other minor gramineous crops, which will lay a foundation for further research on the mechanism of metal transport and accumulation. Full article

Cadmium (Cd) is a toxic metal that threatens human health when enriched in crops. NRAMPs are a family of natural macrophage proteins reported to play a key role in Cd transport in plants. In order to explore the gene regulation mechanism of potato under Cd stress and the role of NRAMPs family in it, this study analyzed the gene expression differences of two different Cd accumulation levels in potato after 7 days of 50 mg/kg Cd stress and screened out the key genes that may play a major role in the differential accumulation of Cd in different varieties. Additionally, StNRAMP2 was selected for verification. Further verification showed that the StNRAMP2 gene plays an important role in the accumulation of Cd in potato. Interestingly, silencing StNRAMP2 increased Cd accumulation in tubers but significantly decreased Cd accumulation in other sites, suggesting a critical role of StNRAMP2 in Cd uptake and transport in potatoes. To further confirm this conclusion, we performed heterologous expression experiments in which overexpression of StNRAMP2 gene in tomato resulted in a threefold increase in Cd content, which further confirmed the important role of StNRAMP2 in the process of Cd accumulation compared with wild-type plants. In addition, we found that the addition of Cd to the soil increased the activity of the plant antioxidant enzyme system, and silencing StNRAMP2 partially reversed this effect. This suggests that the StNRAMP2 gene plays an important role in plant stress tolerance, and future studies could further explore the role of this gene in other environmental stresses. In conclusion, the results of this study improve the understanding of the mechanism of Cd accumulation in potato and provide experimental basis for remediation of Cd pollution. Full article

Cadmium (Cd) is a heavy metal that can cause damage to living organisms at different levels. Even at low concentrations, Cd can be toxic to plants, causing harm at multiple levels. As they are unable to move away from areas contaminated by Cd, plants have developed various defence mechanisms to protect themselves. Hyperaccumulators, which can accumulate and detoxify heavy metals more efficiently, are highly valued by scientists studying plant accumulation and detoxification mechanisms, as they provide a promising source of genes for developing plants suitable for phytoremediation techniques. So far, several genes have been identified as being upregulated when plants are exposed to Cd. These genes include genes encoding transcription factors such as iron-regulated transporter-like protein (ZIP), natural resistance associated macrophage protein (NRAMP) gene family, genes encoding phytochelatin synthases (PCs), superoxide dismutase (SOD) genes, heavy metal ATPase (HMA), cation diffusion facilitator gene family (CDF), Cd resistance gene family (PCR), ATP-binding cassette transporter gene family (ABC), the precursor 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and precursor 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) multigene family are also influenced. Thanks to advances in omics sciences and transcriptome analysis, we are gaining more insights into the genes involved in Cd stress response. Recent studies have also shown that Cd can affect the expression of genes related to antioxidant enzymes, hormonal pathways, and energy metabolism. Full article