Calcium-Mobilizing Properties of Salvia miltiorrhiza-Derived Carbon Dots Confer Enhanced Environmental Adaptability in Plants

Research Progress and Prospects of Nanozymes in Alleviating Abiotic Stress of Crops

The continuous destruction of the global ecological environment has led to increased natural disasters and adverse weather, severely affecting crop yields and quality, particularly due to abiotic stress. Nanase, a novel artificial enzyme, simulates various enzyme activities, is renewable, and shows significant potential in promoting crop growth and mitigating abiotic stress. This study reviews the classification of nanoenzymes into carbon-based, metal-based, metal oxide-based, and others based on synthesis materials. The catalytic mechanisms of these nanoenzymes are discussed, encompassing activities, such as oxidases, peroxidases, catalases, and superoxide dismutases. The catalytic mechanisms of nanoenzymes in alleviating salt, drought, high-temperature, low-temperature, heavy metal, and other abiotic stresses in crops are also highlighted. Furthermore, the challenges faced by nanoenzymes are discussed, especially in sustainable agricultural development. This review provides insights into applying nanoenzymes in sustainable agriculture and offers theoretical guidance for mitigating abiotic stress in crops.

Effects of Moringa oleifera leaf-derived carbon dots treatment on ROS metabolism regulation for postharvest flowering Chinese cabbage preservation

Postharvest flowering Chinese cabbage is prone to rapid senescence and quality deterioration during storage at room temperature. The imbalance of reactive oxygen species (ROS) metabolism is one of the critical factors leading to this process. In this study, we synthesized Moringa oleifera leaf-derived carbon dots (MoCDs) and investigated the effects of MoCDs treatment on ROS metabolism regulation for postharvest flowering Chinese cabbage preservation. The results showed that MoCDs exhibited more efficient antioxidant activity than M. oleifera extract, attributed to their abundant surface functional groups, including hydroxyl, carboxyl, and amino groups, and an extensive sp2-hybridized carbon network. Moreover, MoCDs treatment could reduce the accumulation of hydrogen peroxide and superoxide anion radical in postharvest flowering Chinese cabbage by generally enhancing the activities of a series of key antioxidant enzymes and increasing the contents of non-enzymatic antioxidants, which significantly delayed leaf senescence and deterioration of appearance and nutritional quality of postharvest flowering Chinese cabbage during storage. In summary, as an effective antioxidant, MoCDs entered leaf cells to scavenge excessive ROS directly; as an elicitor, MoCDs enhanced the ROS scavenging ability of the endogenous antioxidant defense system in postharvest flowering Chinese cabbage. These dual protective mechanisms synergistically regulated ROS metabolism, thus benefiting the postharvest preservation of flowering Chinese cabbage.

Modified carbon dot-mediated transient transformation for genomic and epigenomic studies in wheat

Genotype restriction poses a significant bottleneck to stable transformation in the vast majority of plant species, thereby severely impeding advancement in plant bioengineering, particularly for crops. Nanoparticles (NPs) can serve as effective carriers for the transient delivery of nucleic acids, facilitating gene overexpression or silencing in plants in a genotype-independent manner. However, the applications of NP-mediated transient systems in comprehensive genomic studies remained underexplored in plants, especially in crops that face challenges in genetic transformation. Consequently, there is an urgent need for efficient NP-mediated delivery systems capable of generating whole plants or seedlings with uniformly transformed nucleic acids. We have developed a straightforward and efficient modified carbon dot (MCD)-mediated transient transformation system for delivering DNA plasmids into the seeds of wheat, which is also applicable to other plant species. This system facilitates the generation of whole seedlings that contain the transferred DNA plasmids. Furthermore, our study demonstrates that this system serves as an excellent platform for conducting functional genomic studies in wheat, including the validation of gene functions, protein interactions and regulation, omics studies, and genome editing. This advancement significantly enhances functional genomic research for any plants or crops that face challenges in stable transformation. Thus, our study provides for the first time evidence of new applications for MCDs in functional genomics and epigenomic studies, and bioengineering potentially leading to the improvement of desirable agronomic traits in crops.

Genome-Wide Identification of the Cation/Proton Antiporter (CPA) Gene Family and Expression Pattern Analysis Under Salt Stress in Winter Rapeseed (Brassica rapa L.)

The CPA gene family regulates ionic balance and pH homeostasis in cells, significantly contributing to plant stress tolerance. In this study, a total of 63 BrCPA gene family members were identified in the whole genome of Brassica rapa L. (B. rapa), and the three subfamily members were BrNHX (9), BrKEA (15), and BrCHX (39), respectively. The members of the BrCPA gene family encoded 303-1259 amino acids, with molecular weights in the range of 32,860.39~139,884.73 kDa, distributed on 10 chromosomes, and contained 17 conserved motifs, BrNHX and BraKEA, and the BrCPA gene family members had the same molecular weights on 10 chromosomes and contain 17 conserved motifs. The BrNHX and BraKEA subfamilies have more exons than the BrCHX subfamily. An analysis of promoter cis-acting elements in the BrCPA gene showed that members of this gene family contain TC-rich, LTR, MBS, and ARE stress response elements. In addition, transcriptome analysis revealed the expression of CPA genes in B. rapa under salt stress. The selected genes were verified by RT-qPCR. By detecting the Na+ and K+ flow rates in the root and chloroplast cells of salt-tolerant and salt-sensitive varieties after salt treatment, it was found that the rate of Na+ and K+ efflux from the root and chloroplast cells of salt-sensitive varieties was significantly higher than that of salt-tolerant varieties. This investigation marks the first systematic identification of the CPA gene family in B. rapa. This study further explores its expression patterns and the efflux rates of Na+ and K+ across salt-tolerant varieties, providing a theoretical basis for understanding the role of the CPA gene family in the salt stress response of B. rapa.

Sunlight-sensitive carbon dots for plant immunity priming and pathogen defence

Global food production faces persistent threats from environmental challenges and pathogenic attacks, leading to significant yield losses. Conventional strategies to combat pathogens, such as fungicides and disease-resistant breeding, are limited by environmental contamination and emergence of pathogen resistance. Herein, we engineered sunlight-sensitive and biodegradable carbon dots (CDs) capable of generating reactive oxygen species (ROS), offering a novel and sustainable approach for plant protection. Our study demonstrates that CDs function as dual-purpose materials: priming plant immune responses and serving as broad-spectrum antifungal agents. Foliar application of CDs generated ROS under light, and the ROS could damage the plant cell wall and trigger cell wall-mediated immunity. Immune activation enhanced plant resistance against pathogens without compromising photosynthetic efficiency or yield. Specifically, spray treatment with CDs at 240 mg/L (2 mL per plant) reduced the incidence of grey mould in N. benthamiana and tomato leaves by 44% and 12%, respectively, and late blight in tomato leaves by 31%. Moreover, CDs (480 mg/L, 1 mL) combined with continuous sunlight irradiation (simulated by xenon lamp, 9.4 × 105 lux) showed a broad-spectrum antifungal activity. The inhibition ratios for mycelium growth were 66.5% for P. capsici, 8% for S. sclerotiorum and 100% for B. cinerea, respectively. Mechanistic studies revealed that CDs effectively inhibited mycelium growth by damaging hyphae and spore structures, thereby disrupting the propagation and vitality of pathogens. These findings suggest that CDs offer a promising, eco-friendly strategy for sustainable crop protection, with potential for practical agricultural applications that maintain crop yields and minimize environmental impact.

Spd-CDs-driven respiratory burst oxidase homolog/polyamine oxidase-dependent H2O2 signaling molecule engineering for salt tolerance in tomato

Carbon dots, are now considered safe, environment-friendly materials. Spermidine carbon dots (Spd-CDs) have been used as new agrochemicals for abiotic stress, but in-depth studies of salt stress remain scarce. Here, foliar application of Spd-CDs improved salt stress tolerance in tomatoes, and the beneficial effects were concentration-dependent. Tomato seedlings supplied with Spd-CDs (3.0 mg/L) had a greater height, a higher maximum quantum yield of PSII, and a higher net photosynthetic rate than controls after being exposed to 120 mM NaCl for 7 d. Molecular evidence showed that Spd-CDs promoted H2O2 molecule production by inducing the expression of respiratory burst oxidase homolog 1 (rboh1) and polyamine oxidase 5 (pao5), thus causing H2O2 molecule production and conferring resistance to salt stress. The role of RBOH1- and PAO5-dependent H2O2 molecule generation was evaluated by manipulating endogenous H2O2 levels and in rboh1 and pao5 mutants. Spd-CDs-meditated H2O2 regulation of salt tolerance could be articulated by reducing iron deficiency, maintaining ion homeostasis, and reducing root-to-shoot Na+ loading. Overall, the ROS signal molecule produced by RBOH1 and PAO5 protein was involved in the control of salt tolerance by Spd-CDs. These findings demonstrate that Spd-CDs are an effective and durable strategy to improve plant performance under salt stress, and to increase food security and quality.

Recent Advances of Carbon Dots: Synthesis, Plants Applications, Prospects, and Challenges

Nanomaterials and nanotechnology have garnered significant attention in the realm of agricultural production. Carbon dots (CDs), as a class of nanomaterials, play a crucial role in the field of plant growth due to their excellent properties. This review aims to summarize recent achievements on CDs, focusing on their methods of preparation and applications in plants systems. The effects of CDs on seed germination, growth, photosynthesis, nutritional quality, and stress resistance were studied. It has been demonstrated that CDs can promote seed germination and growth, as well as improve photosynthetic efficiency, ultimately leading to increase plants yield. The nutritional quality of the plants treated with CDs was significantly improved. Specifically, the levels of essential mineral elements, vitamins, amino acids, and other constituents that are beneficial to human health increased notably. Additionally, CDs show positive effects on augmenting plant resistance against environmental stresses, such as drought conditions, heavy metal toxicity, and high salinity. Finally, the prospects and challenges of the application of CDs in plant systems are also discussed, which provide a scientific basis for the future application of CDs in agricultural production.

Enhancing drought tolerance in blackgram (Vigna mungo L. Hepper) through physiological and biochemical modulation by peanut shell carbon dots

Among the abiotic factors that causes threat to crop production, drought is one of the foremost constraints in the changing climatic era. Hence, a study was conducted to mitigate the effect of drought stress in blackgram with the peanut shell carbon dots (PNS-CDs) as seed priming and foliar spray agent. Blackgram seeds were primed with PNS-CDs at 200 ppm for 3 h and plants were sprayed with PNS-CDs at 50 ppm on 30th and 45th DAS under drought stress conditions (30%, 50% and 75% WHC). The imposed treatments included dry seeds (control), water sprayed plants, seed priming with PNS-CDs, foliar spray with PNS-CDs and combination of both. The results demarcate the exemplary performance of plants when given with combined application of priming (200 ppm) and foliar spray (50 ppm) with PNS-CDs in terms of its growth and yield. Further, an increased activity of catalase (12%), peroxidase (12%), superoxide dismutase (22%), glutathione reductase (60%), ascorbate peroxidase (55%), H2O2 scavenging (32%) and proline (35%) were noticed over dry seeds, which confirmed the antioxidant defense mechanism offered by PNS-CDs. In addition, the percentage increase in photosynthetic parameters like total chlorophyll (44%), total soluble protein (54%), photosynthetic rate (89%), stomatal conductance (40%), internal CO2 concentration (74%) and chlorophyll stability index (51%) confirmed the role of PNS-CDs as photosynthesis enhancer under drought stress, which resulted in enhanced stress tolerance, plant growth and yield. Thus, it was found that priming blackgram seeds with 200 ppm PNS-CDs for 3 h followed by foliar spray with 50 ppm on 30 and 45th DAS could serve as a sustainable alternative to chemical inputs, ensuring better crop productivity and stress tolerance in water-limited environments. Further, future research could explore the molecular mechanisms underlying the stress tolerance offered by PNS-CDs. In addition, the application of PNS-CDs to different crops, biotic and abiotic stress conditions will also pave the way for broader agricultural sustainability in an eco-friendly approach.

Carbon dots based cascading nanozymes mitigate phytotoxicity in lettuces under imidacloprid stress

Improper pesticide use induces oxidative stress and disrupts detoxification systems in plants. We synthesized CDs with cascading nanozyme activities to mitigate phytotoxicity in lettuces under imidacloprid (IMI) stress. CDs exhibit superoxide dismutase-like (SOD-like) and peroxidase-like (POD-like) activities. Surface modifications and analysis of CDs, the SOD-like activity relies on the -NH2, -COOH, and -OH groups for binding superoxide anions (O2•-), while POD-like activity depends on -COOH and CO groups, also, CO group provides π-system and the electron-deficient structure for electron transfer. Practically, under IMI stress, CDs strengthen multiple defense systems in lettuces, reducing levels of reactive oxygen toxicity (O2•-, H2O2, and MDA, by 26.77 %, 48.52 %, and 13.10 %, respectively). Meanwhile, CDs upregulate detoxification gene expression, resulting in a 42.74 % reduction in IMI residue in lettuces. Moreover, the acceptable daily intake of IMI in lettuces treated with CDs was less than 18.0 % of the reference dose, even at high-concentration IMI.

Unlocking Photosynthetic Potential: Harnessing Rosa roxburghii Derived Carbon Dots as Nanofertilizers for Enhanced Plant Growth

The synthesis of nanomaterials from renewable resources has emerged as an environmentally friendly alternative. This approach helps to reduce the use of chemical fertilizers in agricultural production, further reducing the potential harm to the ecosystem and effectively reducing the burden on the environment. In this work, we synthesized Rosa roxburghii derived carbon dots (CDs) using the microwave hydrothermal method (RR-CDs) and the electrolytic oxidation method (GRR-CDs), and the results showed that RR-CDs had a wider ultraviolet absorption range and emitted blue fluorescence. These properties make RR-CDs more effective as light-harvesting materials in plants, thus promoting photosynthesis. In the cultivation of lettuce, RR-CDs significantly enhanced both the biomass and the quality of the lettuce. In addition, compared to the control group, the chlorophyll content of lettuce treated with RR-CDs increased by 31.83%, the net photosynthetic rate increased by 60.76%, and the electron transport rate of photosystem II increased by 38.72%. Therefore, we found that the microwave hydrothermal method could bring better benefits, with a yield of up to 40.20% after just 2 h of reaction. RR-CDs promote photosynthesis by promoting light conversion and improving nutrient efficiency while also boasting the dual advantages of low cost and easy large-scale production, thus opening up avenues for sustainable agricultural production.

Functional carbon nanodots enhance tomato tolerance to zinc deficient soils: Mechanisms and structure-function relationships

Zinc (Zn) deficiency is a global problem disorder affecting both crops and humans. Herein, modified functional carbon nanodots (MFCNs) with various structures and characteristics were developed to regulate tomato yields and Zn migration in plant-soil systems affected by Zn deficiency through structure-function relationships. Sulfur-doped FCNs (S-FCNs), nitrogen-doped FCNs (N-FCNs), and nitrogen‑sulfur co-doped FCNs (N,S-FCNs) were hydrothermally modified using FCNs as precursors. Their regulatory effects on tomatoes growing in Zn-deficient alkaline soils were studied in pot culture experiments. Specifically, 8 mg kg-1 of FCNs and S-FCNs improved tomato yields by 132 % and 108 %, respectively, compared with the control. However, N-FCNs and N,S-FCNs showed no significant effect on yield compared with the control (P < 0.05). Moreover, the application of FCNs or S-FCNs significantly improved fruit quality and nutritional value, including Zn content (by 26.3 % and 22.0 %, respectively) and naturally occurring antioxidants (by 3.37- and 2.08-fold for lycopene, 1.31- and 1.18-fold for flavonoids, and 2.28- and 1.89-fold for phenolics, respectively; P < 0.05). Although N-FCNs and N,S-FCNs increased Zn contents, they inhibited the synthesis of naturally occurring antioxidants in fruits. Zn bioaccessibility, uptake, and transportation in plant-soil systems were regulated by MFCNs through both direct and indirect mechanisms, including ionic reactions, plant physiology, and environmental effects. MFCNs regulated plant tolerance to Zn deficiency not only by affecting root activity, redox homeostasis, micronutrient balance, chelator synthesis, genetic expression, and plant photosynthesis but also by influencing rhizosphere soil properties and the microbial environment. Based on their dual role as "plant growth regulators" and "soil conditioners", MFCNs may have general applicability in agriculture. This study highlights the behavior of MFCNs in plant-soil systems, providing innovative nanotools for enhancing Zn availability, crop stress resistance and environmental preservation in sustainable agriculture.

Magnesium-Doped Carbon Quantum Dot Nanomaterials Alleviate Salt Stress in Rice by Scavenging Reactive Oxygen Species to Increase Photosynthesis

Salt stress has strongly impacted the long-term growth of eco-friendly farming worldwide. By targeting the oxidative stress induced by salt, the utilization of biomass-derived carbon dots (CDs) that possess high-efficiency antioxidant properties, are nontoxic, and have excellent biocompatibility represents a viable and effective approach for enhancing the salt tolerance of plants. In this study, we blended magnesium oxide nanoparticles with carbon sources derived from durian shells to construct Mg-doped carbon dots (Mg-CDs) through a hydrothermal reaction. We demonstrated that the foliar application of 150 μg/mL Mg-CDs to rice plants after treatment with 100 mM salt effectively increased the plant height (9.52%), fresh weight (22.41%), dry weight (33.33%), K+ content (21.46%), chlorophyll content (36.21%), and carotenoid content (16.21%); decreased the malondialdehyde (MDA) (9.43%), Na+ (25.75%), H2O2 (17.50%), and O2•- contents (37.99%); and promoted the photosynthetic system and antioxidant activity. Transcriptome analysis revealed that Mg-CD pretreatment triggered transcriptional reprogramming in rice seedlings. The enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes pathways based on trend groups of gene expression patterns of Profile 8 and Profile 15 indicated that priming with Mg-CDs activated stress signaling- and defense-related pathways, such as metabolic pathways, biosynthesis of secondary metabolites, and photosynthesis pathways. These activations subsequently prompted the expression of genes related to the mitogen-activated protein kinase signaling pathway, hormone signal transduction, the oxidative stress response, and the photosynthetic system. This study demonstrated that the use of Mg-CDs represents a potential strategy to increase plant salt tolerance, creating the possibility for the regulation of crop salinity stress and offering valuable advancements in sustainable agriculture.

Foliar application of carbon dots enhances nitrogen uptake and assimilation through CEPD1-dependent signaling in plants

The use of nitrogen (N) fertilizers increases crop yield, but the accumulation of residual N in agricultural soils poses significant environmental risks. Improving the N use efficiency (NUE) of crops can help reduce N pollution. While nanomaterials have been shown to enhance crop agronomic traits, more research is needed to clarify the regulatory mechanisms involved. In this study, foliar spraying of carbon dots (CDs, 1 mg mL-1) derived from Salvia miltiorrhiza increased the activity of plasma membrane H+-ATPase in Arabidopsis thaliana roots, promoting the uptake, transport, and assimilation of NO3- and NH4+. The upregulation of N metabolism-related genes, such as AtAMTs and AtNRTs, was also observed in A. thaliana roots. Transcriptome analysis suggested that this regulatory effect is mediated by the shoot-to-root mobile polypeptide CEPD1 (C-terminally encoded peptide DOWNSTREAM 1) signaling pathway. Additionally, foliar application of CDs increased the NUE of sweetpotato (Ipomoea batatas (L.) Lam.) from 2.5% to 8.1%. The upregulation of genes such as CEPD1 in leaves was observed following CDs application under different N conditions. Finally, foliar spraying of CDs significantly increased field yield and enhanced tolerance to low N stress in sweetpotato. Overall, this study demonstrated that foliar application of CDs improved NUE in plants through CEPD1-dependent signaling.

Carbohydrate-Derived Superhydrophilic Carbon Aerogels and Their Effects on Seedling Growth of Triticum aestivum

Synthesis methods of carbon nanomaterials have been developed vigorously in recent years, among which a simple, green, and mature approach is of more research significance. Carbon nanomaterials have depicted an impact on the growth and development of plants. In this study, a new type of carbon nanomaterial, superhydrophilic carbon aerogel (CA), was synthesized via a hydrothermal process using carbohydrates and water-soluble polymers as raw materials. Characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, and N2 adsorption analysis, the exemplified CA presented to have porous three-dimensional network structure composed of individual particles with diameters of 25 nm, with reactive surface, single composition, high specific surface area (89.94 m2·g-1), and wide range of density variation. The 9 mg·mL-1 CA suspension had a significant positive effect on the root growth of wheat seedlings, with promoted root elongation (about 67.17% longer) and root diameter (about 28.95% thicker) compared with those of the control group. The cytological results suggested that CA treatment triggered the propagation of meristematic cells, and the increased number of meristematic cells (65.79% more than the control group) led to enhanced root growth by upregulated expression of related phytohormone genes in wheat seedlings.

A new strategy of using low-dose caffeic acid carbon nanodots for high resistance to poorly differentiated human papillary thyroid cancer

Thyroid cancer is one of the most common endocrine malignancies in clinical practice. Traditional surgery and radioactive iodine ablation have poor treatment results for poorly differentiated thyroid cancer, and there is a risk of metastasis and recurrence. In this study, caffeic acid, a natural herbal extract with certain biological activity, has been as precursor to prepare new caffeic acid carbon nanodots via a one-step hydrothermal method. The caffeic acid carbon nanodots retains part of the structure and biological activity of caffeic acid, and have good biocompatibility, water solubility and stability. The construction of the carbon nanodots could effectively improve their bio-absorption rate and the efficacy. In vitro cell experiments showed that low-dose caffeic acid carbon nanodots had a significant inhibitory effect on poorly differentiated papillary thyroid carcinoma BCPAP cells. At low concentrations of 16 µg/mL, the inhibition rate of human thyroid cancer cells BCPAP was ~ 79%. The anti-tumor mechanism was predicted and verified by transcriptome, real-time quantitative PCR and western blot experiments. The caffeic acid carbon nanodots showed to simultaneously downregulate the expression of KRAS, p-BRAF, p-MEK1 and p-ERK1/2, the four continuous key proteins in a MAPK classical signaling pathway. In vivo experiments further confirmed the caffeic acid carbon nanodots could significantly inhibit the tumorigenicity of xenografts in papillary thyroid carcinoma at quite low doses. This piece of work provides a new nanomedicine and therapeutic strategy for highly resistant poorly differentiated papillary thyroid carcinoma.

Negatively Charged Carbon Dots Employed Symplastic and Apoplastic Pathways to Enable Better Plant Delivery than Positively Charged Carbon Dots

Efficient delivery of nanoparticles (NPs) to plants is important for agricultural application. However, to date, we still lack knowledge about how NPs' charge matters for its translocation pathway, i.e., symplastic and apoplastic pathways, in plants. In this study, we synthesized and used negatively charged citrate sourced carbon dots (C-CDs, -37.97 ± 1.89 mV), Cy5 coated C-CDs (Cy5-C-CDs, -41.90 ± 2.55 mV), positively charged PEI coated carbon dots (P-CDs, +43.03 ± 1.71 mV), and Cy5 coated P-CDs (Cy5-P-CDs, +48.80 ± 1.21 mV) to investigate the role of surface charges and coatings on the employed translocation pathways (symplastic and apoplastic pathways) of charged NPs in plants. Our results showed that, different from the higher fluorescence intensity of P-CDs and Cy5-P-CDs in extracellular than intracellular space, the fluorescence intensity of C-CDs and Cy5-C-CDs was similar between intracellular and extracellular space in cucumber and cotton roots. It suggests that the negatively charged CDs were translocated via both symplastic and apoplastic pathways, but the positively charged CDs were mainly translocated via the apoplastic pathway. Furthermore, our results showed that root applied negatively charged C-CDs demonstrated higher leaf fluorescence than did positively charged P-CDs in both cucumber (8.09 ± 0.99 vs 3.75 ± 0.23) and cotton (7.27 ± 1.06 vs 3.23 ± 0.22), indicating that negatively charged CDs have a higher translocation efficiency from root to leaf than do positively charged CDs. It should be noted that CDs do not affect root cell activities, ROS level, and photosynthetic performance in cucumber and cotton, showing its good biocompatibility. Overall, this study not only figured out that root applied negatively charged CDs employed both symplastic and apoplastic pathways to do the transportation in roots compared with mainly the employment of apoplastic pathway for positively charge CDs, but also found that negatively charge CDs could be more efficiently translocated from root to leaf than positively charged CDs, indicating that imparting negative charge to NPs, at least CDs, matters for its efficient delivery in crops.

Carbon Nanodot-Microbe-Plant Nexus in Agroecosystem and Antimicrobial Applications

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial-microbe-plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant organs, the nanotoxicity to soil microbes and plants, and different possible regulations. This review focuses on the challenges and prospects of the nanomaterial-microbe-plant nexus under agroecosystem conditions. The previous nano-forms were selected in this study because of the rare, published articles on such nanomaterials. Under the study's nexus, more insights on the carbon nanodot-microbe-plant nexus were discussed along with the role of the new frontier in nano-tellurium-microbe nexus. Transport of nanomaterials to different plant organs under possible applications, and translocation of these nanoparticles besides their expected nanotoxicity to soil microbes will be also reported in the current study. Nanotoxicity to soil microbes and plants was investigated by taking account of morpho-physiological, molecular, and biochemical concerns. This study highlights the regulations of nanotoxicity with a focus on risk and challenges at the ecological level and their risks to human health, along with the scientific and organizational levels. This study opens many windows in such studies nexus which are needed in the near future.

Peroxidase like Zn doped Prussian blue facilitates salinity tolerance in winter wheat through seed dressing

Salt stress severely limits the growth and yield of wheat in saline-alkali soil. While nanozymes have shown promise in mitigating abiotic stress by scavenging reactive oxygen species (ROS) in plants, their application in alleviating salt stress for wheat is still limited. This study synthesized a highly active nanozyme catalyst known as ZnPB (Zn-modified Prussian blue) to improve the yield and quality of wheat in saline soil. According to the Michaelis-Menten equation, ZnPB demonstrates exceptional peroxidase-like enzymatic activity, thereby mitigating oxidative damage caused by salt stress. Additionally, studies have shown that the ZnPB nanozyme is capable of regulating intracellular Na+ efflux and K+ retention in wheat, resulting in a decrease in proline and soluble protein levels while maintaining the integrity of macromolecules within the cell. Consequently, field experiments demonstrated that the ZnPB nanozyme increased winter wheat yield by 12.15 %, while also significantly enhancing its nutritional quality. This research offers a promising approach to improving the salinity tolerance of wheat, while also providing insights into its practical application.

Carbon Nanomaterials for Plant Priming through Mechanostimulation: Emphasizing the Role of Shape

The use of nanomaterials to improve plant immunity for sustainable agriculture is gaining increasing attention; yet, the mechanisms involved remain unclear. In contrast to metal-based counterparts, carbon-based nanomaterials do not release components. Determining how these carbon-based nanomaterials strengthen the resistance of plants to diseases is essential as well as whether shape influences this process. Our study compared single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) infiltration against the phytopathogen Pseudomonas syringae pv tomato DC3000. Compared with plants treated with GO, plants primed with SWNTs showed a 29% improvement in the pathogen resistance. Upon nanopriming, the plant displayed wound signaling with transcriptional regulation similar to that observed under brushing-induced mechanostimulation. Compared with GO, SWNTs penetrated more greatly into the leaf and improved transport, resulting in a heightened wound response; this effect resulted from the tubular structure of SWNTs, which differed from the planar form of GO. The shape effect was further demonstrated by wrapping SWNTs with bovine serum albumin, which masked the sharp edges of SWNTs and resulted in a significant decrease in the overall plant wound response. Finally, we clarified how the local wound response led to systemic immunity through increased calcium ion signaling in distant plant areas, which increased the antimicrobial efficacy. In summary, our systematic investigation established connections among carbon nanomaterial priming, mechanostimulation, and wound response, revealing recognition patterns in plant immunity. These findings promise to advance nanotechnology in sustainable agriculture by strengthening plant defenses, enhancing resilience, and reducing reliance on traditional chemicals.

Genome-Wide Identification and Expression Analysis of the DMP and MTL Genes in Sweetpotato (Ipomoea batatas L.)

Sweetpotato (Ipomoea batatas L.) is a strategic crop with both economic and energy value. However, improving sweetpotato varieties through traditional breeding approaches can be a time-consuming and labor-intensive process due to the complex genetic nature of sweetpotato as a hexaploid species (2n = 6x = 90). Double haploid (DH) breeding, based on in vivo haploid induction, provides a new approach for rapid breeding of crops. The success of haploid induction can be achieved by manipulating specific genes. Two of the most critical genes, DMP (DUF679 membrane proteins) and MTL (MATRILINEAL), have been shown to induce haploid production in several species. Here, we identified and characterized DMP and MTL genes in sweetpotato using gene family analysis. In this study, we identified 5 IbDMPs and 25 IbpPLAs. IbDMP5 and IbPLAIIs (IbPLAIIκ, IbPLAIIλ, and IbPLAIIμ) were identified as potential haploid induction (HI) genes in sweetpotato. These results provide valuable information for the identification and potential function of HI genes in sweetpotato and provide ideas for the breeding of DH lines.

Enhanced photosynthetic efficiency by nitrogen-doped carbon dots via plastoquinone-involved electron transfer in apple

Artificially enhancing photosynthesis is critical for improving crop yields and fruit qualities. Nanomaterials have demonstrated great potential to enhance photosynthetic efficiency; however, the mechanisms underlying their effects are poorly understood. This study revealed that the electron transfer pathway participated in nitrogen-doped carbon dots (N-CDs)-induced photosynthetic efficiency enhancement (24.29%), resulting in the improvements of apple fruit qualities (soluble sugar content: 11.43%) in the orchard. We also found that N-CDs alleviated mterf5 mutant-modulated photosystem II (PSII) defects, but not psa3 mutant-modulated photosystem I (PSI) defects, suggesting that the N-CDs-targeting sites were located between PSII and PSI. Measurements of chlorophyll fluorescence parameters suggested that plastoquinone (PQ), the mobile electron carrier in the photosynthesis electron transfer chain (PETC), was the photosynthesis component that N-CDs targeted. In vitro experiments demonstrated that plastoquinone-9 (PQ-9) could accept electrons from light-excited N-CDs to produce the reduced plastoquinone 9 (PQH2-9). These findings suggested that N-CDs, as electron donors, offer a PQ-9-involved complement of PETC to improve photosynthesis and thereby fruit quality. Our study uncovered a mechanism by which nanomaterials enhanced plant photosynthesis and provided some insights that will be useful in the design of efficient nanomaterials for agricultural/horticultural applications.

Nanoenabled Enhancement of Plant Tolerance to Heat and Drought Stress on Molecular Response

Global warming has posed significant pressure on agricultural productivity. The resulting abiotic stresses from high temperatures and drought have become serious threats to plants and subsequent global food security. Applying nanomaterials in agriculture can balance the plant's oxidant level and can also regulate phytohormone levels and thus maintain normal plant growth under heat and drought stresses. Nanomaterials can activate and regulate specific stress-related genes, which in turn increase the activity of heat shock protein and aquaporin to enable plants' resistance against abiotic stresses. This review aims to provide a current understanding of nanotechnology-enhanced plant tolerance to heat and drought stress. Molecular mechanisms are explored to see how nanomaterials can alleviate abiotic stresses on plants. In comparison with organic molecules, nanomaterials offer the advantages of targeted transportation and slow release. These advantages help the nanomaterials in mitigating drought and heat stress in plants.

Potential Efficacy of Herbal Medicine-Derived Carbon Dots in the Treatment of Diseases: From Mechanism to Clinic

Carbon dots (CDs), a crucial component of nanomaterials, are zero-dimensional nanomaterials with carbon as the backbone structure and smaller than 10 nm. Due to their beneficial characteristics, they are widely used in biomedical fields such as biosensors, drug delivery, bio-imaging, and interactions with DNA. Interestingly, a novel type of carbon dot, generated by using herbal medicines as synthetic raw materials, has emerged as the most recent incomer in the family of CDs with the extensive growth in the number of materials selected for carbon dots synthesis. Herbal medicine-derived carbon dots (HM-CDs) have been employed in the biomedical industry, and are rapidly emerging as "modern nanomaterials" due to their unique structures and exceptional capabilities. Emerging trends suggest that their specific properties can be used in bleeding disorders, gastrointestinal disorders, inflammation-related diseases, and other common intractable diseases including cancer, menopausal syndrome, central nervous system disorders, and pain of various forms and causes. In addition, HM-CDs have been found to have organ-protective and antioxidant properties, as evidenced by extensive studies. This research provides a more comprehensive understanding of the biomedical applications of HM-CDs for the aforementioned disorders and investigates the intrinsic pharmacological activities and mechanisms of these HM-CDs to further advance their clinical applications.

Machine-learning analysis to predict the fluorescence quantum yield of carbon quantum dots in biochar

Biochar nanoparticles have recently attracted attention, owing to their environmental behavior and ecological effects. However, biochar has not been shown to contain carbon quantum dots (< 10 nm) with unique photovoltaic properties. Therefore, this study utilized several characterization techniques to demonstrate the generation of carbon quantum dots in biochar produced from 10 types of farm waste. The generated carbon quantum dots had a quasi-spherical morphology and high-resolution lattice stripes with lattice spacings of 0.20-0.23 nm. Moreover, they contained functional groups with good hydrophilic properties, such as amino and hydroxyl groups, and elemental O, C, and N on the surface. A crucial determinant of the photoluminescence properties of carbon quantum dots is their fluorescence quantum yield. Therefore, the relationship between the biochar preparation parameters and the fluorescence quantum yield was investigated using six machine learning analytical models based on 480 samples. Among the models, the gradient-boosting decision-tree regression model exhibited the best predictive performance (R2 > 0.9, RMSE <0.02, and MAPE <3), and was used for the analysis of feature importance; compared to the properties of the raw material, the production parameters had a greater effect on the fluorescence quantum yield. Additionally, four key features were identified: pyrolysis temperature, residence time, N content, and C/N ratio, which were independent of farm waste type. These features can be used to accurately predict the fluorescence quantum yield of carbon quantum dots in biochar. The relative error range between the predicted and the experimental value of fluorescence quantum yield is 0.00-4.60 %. Thus, the prediction model has the potential to predict the fluorescence quantum yield of carbon quantum dots in other types of farm waste biochar, and provides fundamental information for the study of biochar nanoparticles.

Carbon Dots Derived from Traditional Chinese Medicines with Bioactivities: A Rising Star in Clinical Treatment

In the field of carbon nanomaterials, carbon dots (CDs) have become a preferable choice in biomedical applications. Based on the concept of green chemistry, CDs derived from traditional Chinese medicines (TCMs) have attracted extensive attention, including TCM charcoal drugs, TCM extracts, and TCM small molecules. The design and preparation of CDs from TCMs (TCMs-CDs) can improve the inherent characteristics of TCMs, such as solubility, particle size distribution, and so on. Compared with other precursor materials, TCMs-CDs have outstanding intrinsic bioactivities and potential pharmacological effects. However, the research of TCMs-CDs in biomedicine is not comprehensive, and their mechanisms have not been understood deeply either. In this review, we will provide concise insights into the recent development of TCMs-CDs, with a major focus on their preparation, formation, precursors, and bioactivities. Then we will discuss the perfect transformation from TCMs to TCMs-CDs. Finally, we discuss the opportunities and challenges for the application of TCMs-CDs in clinical treatment.

Physiological Functions of Carbon Dots and Their Applications in Agriculture: A Review

Carbon dots are carbon-based nanoparticles, which have the characteristics of a simple preparation process, photoluminescence, biocompatibility, an adjustable surface function, water solubility, and low-level toxicity. They are widely used in biological applications, such as imaging, biosensing, photocatalysis, and molecular transfer. They have also aroused great interest among researchers in agriculture, and there has been significant progress in improving crop growth and production. This review presents the physiological functions of carbon dots for crop growth and development, photosynthesis, water and nutrient absorption, and abiotic stress resistance and their applications in improving the ecological environment and agriculture as biosensors, and future application prospects and research directions of carbon dots in agriculture.

Role of Soil and Foliar-Applied Carbon Dots in Plant Iron Biofortification and Cadmium Mitigation by Triggering Opposite Iron Signaling in Roots

In China, iron (Fe) availability is low in most soils but cadmium (Cd) generally exceeds regulatory soil pollution limits. Thus, biofortification of Fe along with mitigation of Cd in edible plant parts is important for human nutrition and health. Carbon dots (CDs) are considered as potential nanomaterials for agricultural applications. Here, Salvia miltiorrhiza-derived CDs are an efficient modulator of Fe, manganese (Mn), zinc (Zn), and Cd accumulation in plants. CDs irrigation (1 mg mL-1 , performed every week starting at the jointing stage for 12 weeks) increased Fe content by 18% but mitigated Cd accumulation by 20% in wheat grains. This finding was associated with the Fe3+ -mobilizing properties of CDs from the soil and root cell wall, as well as endocytosis-dependent internalization in roots. The resulting excess Fe signaling mitigated Cd uptake via inhibiting TaNRAMP5 expression. Foliar spraying of CDs enhanced Fe (44%), Mn (30%), and Zn (19%) content with an unchanged Cd accumulation in wheat grains. This result is attributed to CDs-enhanced light signaling, which triggered shoot-to-root Fe deficiency response. This study not only reveals the molecular mechanism underlying CDs modulation of Fe signaling in plants but also provides useful strategies for concurrent Fe biofortification and Cd mitigation in plant-based foods.

Nitrogen-doped carbon dots enhanced seedling growth and salt tolerance with distinct requirements of excitation light

Numerous nanomaterials with optical properties have demonstrated excellent capacities to enhance plant growth and stress tolerance. However, the corresponding mechanisms have only been partially characterized, especially the excitation-light dependencies of different actions. Here, nitrogen-doped carbon dots (N-CDs) were developed to explore the excitation-light dependence in N-CD-induced growth enhancement and salt tolerance. Compared to the control, N-CDs induced significant enhancements in Arabidopsis thaliana growth under excitation light, including fresh/dry weight of shoot (21.07% and 16.87%), chlorophyll content (9.17%), soluble sugar content (23.41%), leaf area (28.68%), total root length (34.07%) and root tip number (46.69%). In the absence of excitation light, N-CD-treated seedlings exhibited little differences in these parameters, except the enhancements in root length (24.51%) and root tip number (10.24%). On the other hand, N-CD-treatment could improve seedling salt tolerance with or without excitation light. Under salt stress (150 mM NaCl), in the presence of excitation light, the N-CDs treatment significantly increased shoot/root fresh weight and chlorophyll content by 43.29%, 50.66% and 22.59%, and reduced malondialdehyde (MDA) content and relative conductivity by 17.59% and 32.58% compared to the control group. In the absence of excitation light, significant enhancements in shoot/root fresh weight (34.22%, 32.60%) and chlorophyll content (10.45%), and obvious decreases in MDA content (28.84%) and relative conductivity (16.13%) were also found. These results indicated that N-CDs only induced growth enhancement under excitation light, but they improved salt tolerance with and without excitation light, suggesting that the two effects occurred via distinct signaling pathways. This study revealed the excitation-light dependencies of nanomaterial-involved agriculture applications, providing insight into designing more efficient nanomaterials in the future.

Uptake of TiO2 Nanoparticles was Linked to Variation in net Cation flux in Wheat Seedlings

Titanium dioxide nanoparticles (TiO₂ NPs) are ubiquitous in the environment and enter the terrestrial food chain via plant uptake. However, plant uptake behaviors of TiO₂ NPs remain elusive. Here, the uptake kinetics of TiO₂ NPs by wheat (Triticum aestivum L.) seedlings and the effects on cation flux in roots were examined in a hydroponic system. Uptake rate of TiO₂ NPs ranged from 119.0 to 604.2 mg kg^- 1 h^- 1 within 8 h exposure. NP uptake decreased by 83% and 47%, respectively, in the presence of sodium azide (NaN₃) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), indicating an energy-dependent uptake of TiO₂ NPs. Moreover, accompanied with TiO₂ NP uptake, net influx of Cd²⁺ decreased by 81%, while Na⁺ flux shifted from inflow to outflow at the meristematic zone of root. These findings provide valuable information for understanding plant uptake of TiO₂ NPs.

Accumulation, translocation, and transformation of two CdSe/ZnS quantum dots in rice and pumpkin plants

As a widely applied semiconductor nanomaterial, quantum dots (QDs) have drawn considerable interest. In this study, pumpkin and rice seedlings were hydroponically exposed to two core/shell CdSe/ZnS QDs coated with cysteamine (CdSe/ZnS-CA) and polyethylene glycol-carboxy (CdSe/ZnS-PEG-COOH) for 10 days to analyze their time-varying uptake, translocation, and transformation behaviors in plants. Both QDs were mainly adsorbed/absorbed by the roots in the particulate state, and more CdSe/ZnS-CA accumulated than CdSe/ZnS-PEG-COOH. For CdSe/ZnS-CA-treated plants, the Se and Cd concentrations (CSe and CCd) associated with the roots were 561 ± 75 and 580 ± 73 μg/g (dw) for rice and 474 ± 49 and 546 ± 53 μg/g (dw) for pumpkin, respectively, on day 10. For CdSe/ZnS-PEG-COOH-treated plants, the concentrations of Se and Cd associated with roots were 392 ± 56 and 453 ± 56 μg/g (dw) for rice and 363 ± 52 and 417 ± 52 μg/g (dw) for pumpkin, respectively. The surface charges and coatings significantly affected the accumulation of QDs at the beginning of exposure; however, the impaction decreased with time. The ratios between the Cd and Se concentrations (CCd/CSe) in the stems and leaves varied from those of the QD standards, indicating the transformation of the QDs in the exposure system. Se and Cd were more likely to translocate in CdSe/ZnS-PEG-COOH-treated plants than in CdSe/ZnS-CA-treated plants. The vertical translocation of Se was greater than that of Cd. Rice showed greater abilities of accumulation and translocation of Se and Cd from both QDs than pumpkin. These findings improve our understanding of the interference of QDs with plants and their environmental fate.

Ultrasmall and highly biocompatible carbon dots derived from natural plant with amelioration against acute kidney injury

BACKGROUND

Acute kidney injury (AKI) refers to a tricky clinical disease, known by its high morbidity and mortality, with no real specific medicine for AKI. The carbonization product from Pollen Typhae (i.e., Pu-huang in China) has been extensively employed in clinic, and it is capable of relieving the renal damage and other diseases in China since acient times.

RESULTS

Inspired by the carbonization process of Traditional Chinese Medicine (TCM), a novel species of carbon dots derived from Pollen Typhae (PT-CDs) was separated and then collected using a one-pot pyrolysis method. The as-prepared PT-CDs (4.85 ± 2.06 nm) with negative charge and abundant oxygenated groups exhibited high solubility, and they were stable in water. Moreover, the rhabdomyolysis (RM)-induced AKI rat model was used, and it was first demonstrated that PT-CDs had significant activity in improving the level of BUN and CRE, urine volume and kidney index, and histopathological morphology in RM-induced AKI rats. It is noteworthy that interventions of PT-CDs significantly reduced degree of inflammatory reaction and oxidative stress, which may be correlated with the basial potential mechanism of anti-AKI activities. Furthermore, cytotoxicity assay and biosafety evaluation exhibited high biocompatibility of PT-CDs.

CONCLUSION

This study offers a novel relieving strategy for AKI based on PT-CDs and suggests its potential to be a related candidate for clinical applications.

Carbon dots promoted soybean photosynthesis and amino acid biosynthesis under drought stress: Reactive oxygen species scavenging and nitrogen metabolism

With global warming and water scarcity, improving the drought tolerance and quality of crops is critical for food security and human health. Here, foliar application of carbon dots (CDs, 5 mg·L^-1) could scavenge reactive oxygen species accumulation in soybean leaves under drought stress, thereby enhancing photosynthesis and carbohydrate transport. Moreover, CDs stimulated root secretion (e.g., amino acids, organic acids, and auxins) and recruited beneficial microorganisms (e.g., Actinobacteria, Ascomycota, Acidobacteria and Glomeromycota), which facilitate nitrogen (N) activation in the soil. Meanwhile, the expression of GmNRT, GmAMT, and GmAQP genes were up-regulated, indicating enhanced N and water uptake. The results demonstrated that CDs could promote nitrogen metabolism and enhance amino acid biosynthesis. Particularly, the N content in soybean shoots and roots increased significantly by 13.2 % and 30.5 %, respectively. The amino acids content in soybean shoots and roots increased by 257.5 % and 57.5 %, respectively. Consequently, soybean yields increased significantly by 21.5 %, and the protein content in soybean kernels improved by 3.7 %. Therefore, foliar application of CDs can support sustainable nano-enabled agriculture to combat climate change.

Glycine assists in efficient synthesis of herbal carbon dots with enhanced yield and performance

As a special type of biomass, herbal medicine often contains a variety of biologically active substances, and taking it as a carbon source, it is expected to produce various types of biologically functional carbon dots (CDs). However, there are few reports in this field, especially in achieving enhanced performance of CDs by improving the utilization efficiency of active substances in medicinal materials. In this work, by adding glycine as an auxiliary agent in the preparation of CDs from herbal medicine (Exocarpium Citri Grandis), the carboxyl and amino groups of the adjuvant provided more reactive sites, which greatly improved the yield of CDs (about 6 times). More importantly, the antioxidant and biological activities of herbal CDs were also improved. By controlling the functional groups of adjuvants, the effects of carboxyl and amino groups in adjuvants on the synthesis of herbal CDs were compared. The results reveal that both carboxyl and amino groups can react with the substances in the carbon source, and the influence of amino groups was greater. After adding glycine, the size of the CDs became larger, resulting from the more abundant functional groups on the carbon skeleton, which was the main reason for the improved performance of the CDs. Finally, the biological activity experiment demonstrated that CDs derived from Exocarpium Citri Grandis and glycine could greatly enhance the vitality of cells and activate immune cells, which are expected to be applied in the field of cell reproduction and biological immunity. The method proposed in this work provides a potential strategy for high-yield preparation of CDs from biomass.

Carbon Dots Improve Nitrogen Bioavailability to Promote the Growth and Nutritional Quality of Soybeans under Drought Stress

The inefficient utilization of nitrogen (N) in soil and drought stress seriously threatens agricultural and food production. Herein, soil application of carbon dots (CDs, 5 mg kg^-1) promoted the growth and nutritional quality of soybeans by improving N bioavailability, which was beneficial to alleviate the economic losses caused by drought stress. Soil application of CDs enhanced the N-fixing ability of nodules, regulated rhizosphere processes, and ultimately enhanced N and water uptake in soybeans under drought stress. Compared to control (drought stress), the application of CDs under drought stress enhanced soybean nitrogenase activity by 8.6% and increased N content in soybean shoots and roots by 18.5% and 14.8%, respectively. CDs in soil promoted the secretion of root exudates (e.g., organic acids, fatty acids, and polyketides) and regulated beneficial microbial communities (e.g., Proteobacteria, Acidobacteria, Gemmatimonadetes, and Actinobacteria), thus enhancing the N release from soil. Besides, compared to control, the expression of GmNRT, GmAMT, GmLB, and GmAQP genes in roots were upregulated by 1.2-, 1.8-, 2.7-, and 2.3-fold respectively, implying enhanced N transport and water uptake. Furthermore, the proteins, fatty acids, and amino acids in soybean grains were improved by 3.4%, 6.9%, and 17.3%, respectively, as a result of improved N bioavailability. Therefore, CD-enabled agriculture is promising for improving the drought tolerance and quality of soybeans, which is of significance for food security in facing the crisis of global climate change.

A Strategic Review on Carbon Quantum Dots for Cancer-Diagnostics and Treatment

The understanding of the genesis of life-threatening cancer and its invasion calls for urgent development of novel technologies for real-time observations, early diagnosis, and treatment. Quantum dots (QDs) grabbed the spotlight in oncology owing to their excellent photostability, bright fluorescence, high biocompatibility, good electrical and chemical stability with minimum invasiveness. Recently, carbon QDs (CQDs) have become popular over toxic inorganic QDs in the area of bioimaging, biosensing, and drug delivery. Further, CQDs derived from natural sources like biomolecules and medicinal plants have drawn attention because of their one-pot, low-cost and ease of synthesis, along with remarkable tunable optical properties and biocompatibility. This review introduces the synthesis and properties of CQDs derived from natural sources, focusing on the applicability of CQD-based technologies as nano-theranostics for the diagnosis and treatment of cancer. Furthermore, the current issues and future directions for the transformation of CQDs-based nanotechnologies to clinical applications are highlighted.