Selenium nanomaterials improve the quality of lettuce (Lactuca sativa L.) by modulating root growth, nutrient availability, and photosynthesis

Selenium nanoparticles affected growth and secondary metabolism in chicory seedlings epigenetically by modifying DNA methylation and transcriptionally by upregulating DREB1A transcription factor and stimulating genes involved in phenylpropanoid metabolism

In this biosafety risk assessment project, the molecular and physiological responses of chicory seedlings to the introduction of selenate (0, 0.1, 0.5, 1, and 5 mgl-1) or nanoscale red elemental Se product (nSe) into the culture medium were investigated. The application of nSe at low concentrations improved the fresh weight of shoots and roots, while 5 mgl-1 nSe caused severe phytotoxicity. Molecular analysis confirmed partially different epigenetic responses to nSe and selenate. DNA hypomethylation is an important mechanism by which Se exerts its influence at the pre-transcriptional level. With increasing nSe concentration, the transcription factor DREB1A (dehydration-responsive element-binding) showed a linear upward trend. The use of nSe contributed to the transcriptional upregulation of the genes for phenylalanine ammonia-lyase (PAL), hydroxycinnamoyl-CoA: quinate-hydroxycinnamoyl transferases (HQT) and hydroxycinnamoyl-CoA: shikimate/quinate-hydroxycinnamoyl transferase (HCT). Proline concentrations were increased in both leaves and roots in response to the nano-supplement. Cytotoxicity of Se at toxic concentrations decreased protein levels, in contrast to the positive nSe treatments, 0.1 and 0.5. Notably, nSe supplementation acted as an efficient elicitor, stimulating the accumulation of phenylpropanoid derivatives, including caffeic acid, chlorogenic acid, and cichoric acid metabolites. The concentration of ascorbate and glutathione displayed a similar upward trend in response to the nSe supplementation. Further comprehensive comparative molecular studies in different stress-sensitive and tolerant species are necessary to gain a better understanding of the underlying mechanisms. This will allow for the optimization of functional protocols for nSe-based supplements to meet the expectations of sustainable agriculture.

Nanotechnology in Plant Nanobionics: Mechanisms, Applications, and Future Perspectives

Plants are vital to ecosystems and human survival, possessing intricate internal and inter-plant signaling networks that allow them to adapt quickly to changing environments and maintain ecological balance. The integration of engineered nanomaterials (ENMs) with plant systems has led to the emergence of plant nanobionics, a field that holds the potential to enhance plant capabilities significantly. This integration may result in improved photosynthesis, increased nutrient uptake, and accelerated growth and development. Plants treated with ENMs can be stress mitigators, pollutant detectors, environmental sensors, and even light emitters. This review explores recent advancements in plant nanobionics, focusing on nanoparticle (NP) synthesis, adhesion, uptake, transport, fate, and application in enhancing plant physiological functioning, stress mitigation, plant health monitoring, energy production, environmental sensing, and overall plant growth and productivity. Potential research directions and challenges in plant nanobionics are highlighted, and how material optimization and innovation are propelling the growth in the field of smart agriculture, pollution remediation, and energy/biomass production are discussed.

Selenium nanoparticles enhance metabolic and nutritional profile in Phaseolus vulgaris: comparative metabolomic and pathway analysis with selenium selenate

Selenium is a beneficial element in agriculture, particularly for its potential to improve plant growth and stress tolerance at suitable concentrations. In this study, Phaseolus vulgaris was foliar-sprayed with selenium selenate (Se) or selenium nanoparticles (SeNP) at different concentrations during the vegetative stage; afterward, the seed yield was analyzed for metabolomics using 1H, J-resolved and HSQC NMR data, and NMR databases. A total of 47 metabolites were identified with sugars being the major chemical class. In the control sample, the most abundant sugar was stachyose (14.6 ± 0.8 mM). Among the identified alkaloids, the concentration of trigonelline was the highest (0.6 ± 0.08 mM). Chemometric and cluster analyses distinctly differentiated the control from the Se and SeNP-treated samples. Treatments with SeNP resulted in elevated concentrations of sugars, carboxylic acids, and sulfur-containing amino acids compared to control and Se treated samples. Conversely, betaine levels were higher in Se samples. The presence of Se and SeNP significantly decreased the levels of several aliphatic amino acids, e.g. alanine. The addition of 50 µM SeNP upregulated the levels of trigonelline and syringate by 2-fold and 1.75-fold, respectively, relative to the control. Pathway analysis indicated the most significantly altered pathways due to SeNP addition were arginine biosynthesis and nitrogen metabolism. The pathways influenced by Se addition were glyoxylate and dicarboxylate metabolism as well as glycine-serine and threonine metabolism. This study proved that SeNP are more efficient than Se in enhancing the metabolic profile of Phaseolus vulgaris which will have implications for agricultural practices, focusing on the sustainability and nutritional enhancement of crops.

Pre-Grafting Exposure to Root-Promoting Compounds Improves Top-Grafting Performance of Citrus Trees

Top grafting is an efficient and practical technique for the renewal and rejuvenation of citrus trees in old orchards. However, root death after top grafting restricts plant growth and canopy reconstruction. Thus, applications of rooting promotion substances before citrus top grafting may increase the amount and activity of roots, thereby enhancing top-grafted plant performance. To test this assumption, four rooting promotion substances, i.e., rooting promotion powder, biochar, organic fertilizer, and potassium fulvic acid, were applied before top grafting, and the effects on biometric and physiological parameters were analyzed after top grafting. The results showed that the application of all rooting promotion substances before top grafting has a positive effect on growth and mineral nutrient acquisition, as well as on foliar C and N assimilates and the activity of anti-oxidative enzymes of top-grafted plants. Rooting promotion powder and biochar had the best effect on top-grafted tree performance in the short term. In conclusion, pre-grafting root promotion reduced root damage, enhanced nutrient acquisition, and improved the physiological performance of top-grafted plants. Therefore, this approach can play a crucial role in accelerating canopy reconstruction in old citrus orchards and in improving citrus plant development.

Unveiling influences of metal-based nanomaterials on wheat growth and physiology: From benefits to detriments

Metal-based nanomaterials (MNs) are widely used in agricultural production. However, our current understanding of the overall effects of MNs on crop health is insufficient. A global meta-analysis of 144 studies involving approximately 2000 paired observations was conducted to explore the impacts of MNs on wheat growth and physiology. Our analysis revealed that the MN type plays a key role in influencing wheat growth. Ag MNs had significant negative effects on wheat growth and physiology, whereas Fe, Ti, and Zn MNs significantly increased wheat biomass and photosynthesis. Our study also observed a clear dose-specific effect, with a decrease in wheat shoot biomass with increasing MN concentrations. Meanwhile, MNs with small sizes (<25 nm) have no significant impacts on wheat growth. Furthermore, both the root and foliar applications significantly improved wheat growth, with no considerable differences. Using a machine learning approach, we found that the MN type was the main driving factor affecting wheat shoot biomass, followed by MN dose and size. Overall, wheat growth and physiology can be negatively influenced by specific MNs, for which a high dose and small size should be avoided in practical applications. Therefore, our study can provide insights into the future design and safe use of MNs in agriculture and increase the public acceptance of nano-agriculture.

The application of organic selenium (SeMet) improve the photosynthetic characteristics, yield and quality of hybrid rice

Rice is an important food in the world, and selenium (Se) is a necessary trace element for the human. So the effects of selenomethionine (SeMet) on photosynthetic capacity, yield and quality of rice at different stages were studied. The results show that SeMet can increase the Ppotosynthetic capacity of rice leaves during each growth stage, the effect of 5 mg/L SeMet treatment was the most significant. At the mature stage of rice, SeMet significantly increased rice yield and total plant biomass, 7.5and 5 mg/L SeMet treatments had the most significant effects, respectively. In addition, SeMet significantly improved the content of Se and processing quality of rice, decreased chalkiness, inhibited amylose synthesis, and optimized flavor. The above indices showed the best results after treatment with 5 mg/L SeMet. It is hoped that this study will provide a theoretical basis for the application of organic selenium in rice production.

Selenium - An environmentally friendly micronutrient in agroecosystem in the modern era: An overview of 50-year findings

Agricultural productivity is constantly being forced to maintain yield stability to feed the enormously growing world population. However, shrinking arable and nutrient-deprived soil and abiotic and biotic stressor (s) in different magnitudes put additional challenges to achieving global food security. Though well-defined, the concept of macro, micronutrients, and beneficial elements is from a plant nutritional perspective. Among various micronutrients, selenium (Se) is essential in small amounts for the life cycle of organisms, including crops. Selenium has the potential to improve soil health, leading to the improvement of productivity and crop quality. However, Se possesses an immense encouraging phenomenon when supplied within the threshold limit, also having wide variations. The supplementation of Se has exhibited promising outcomes in lessening biotic and abiotic stress in various crops. Besides, bulk form, nano-Se, and biogenic-Se also revealed some merits and limitations. Literature suggests that the possibilities of biogenic-Se in stress alleviation and fortifying foods are encouraging. In this article, apart from adopting a combination of a conventional extensive review of the literature and bibliometric analysis, the authors have assessed the journey of Se in the "soil to spoon" perspective in a diverse agroecosystem to highlight the research gap area. There is no doubt that the time has come to seriously consider the tag of beneficial elements associated with Se, especially in the drastic global climate change era.

Speciation of Selenium Nanoparticles and Other Selenium Species in Soil: Simple Extraction Followed by Membrane Separation and ICP-MS Determination

The application of selenium nanoparticle (SeNP)-based fertilizers can cause SeNPs to enter the soil environment. Considering the possible transformation of SeNPs and the species-dependent toxicity of selenium (Se), accurate analysis of SeNPs and other Se species present in the soil would help rationally assess the potential hazards of SeNPs to soil organisms. Herein, a novel method for speciation of SeNPs and other Se species in soil was established. Under the optimized conditions, SeNPs, selenite, selenate, and seleno amino acid could be simultaneously extracted from the soil with mixtures of tetrasodium pyrophosphate (5 mM) and potassium dihydrogen phosphate (1.2 μM), while inert Se species (mainly metal selenide) remained in the soil. Then, extracted SeNPs can be effectively captured by a nylon membrane (0.45 μm) and quantified by inductively coupled plasma mass spectrometry (ICP-MS). Other extracted Se species can be separated and quantified by high-performance liquid chromatography coupled with ICP-MS. Based on the difference between the total Se contents and extracted Se contents, the amount of metal selenide can be calculated. The limits of detection of the method were 0.02 μg/g for SeNPs, 0.05 μg/g for selenite, selenate, and selenocystine, and 0.25 μg/g for selenomethionine, respectively. Spiking experiments also showed that our method was applicable to real soil sample analysis. The present method contributes to understanding the speciation of Se in the soil environment and further estimating the occurrence and application risks of SeNPs.

Biogenic Selenium Nanoparticles: Anticancer, Antimicrobial, Insecticidal Properties and Their Impact on Soybean (Glycine max L.) Seed Germination and Seedling Growth

Selenium nanoparticles (SeNPs) have demonstrated significant potential in a variety of disciplines, making them an extremely desirable subject of research. This study investigated the anticancer and antibacterial properties of my-co-fabricated selenium SeNPs, as well as their effects on soybean (Glycine max L.) seeds, seedling growth, cotton leafworm (Spodoptera littoralis) combat, and plant pathogenic fungi inhibition. SeNPs showed anticancer activity with an IC50 value of 1.95 µg/mL against MCF-7 breast adenocarcinoma cells. The myco-synthesized SeNPs exhibited an antibacterial effect against Proteus mirabilis and Klebsiella pneumoniae at 20 mg/mL. The use of 1 µM SeNPs improved soybean seed germination (93%), germination energy (76.5%), germination rate (19.0), and mean germination time (4.3 days). At 0.5 and 1.0 µM SeNPs, the growth parameters of seedlings improved. SeNPs increased the 4th instar larval mortality of cotton leafworm compared to control, with a median lethal concentration of 23.08 mg/mL. They inhibited the growth of Fusarium oxysporum, Rhizoctonia solani, and Fusarium solani. These findings demonstrate that biogenic SeNPs represent a promising approach to achieving sustainable progress in the fields of agriculture, cancer therapy, and infection control.

Application of Improved UNet and EnglightenGAN for Segmentation and Reconstruction of In Situ Roots

The root is an important organ for crops to absorb water and nutrients. Complete and accurate acquisition of root phenotype information is important in root phenomics research. The in situ root research method can obtain root images without destroying the roots. In the image, some of the roots are vulnerable to soil shading, which severely fractures the root system and diminishes its structural integrity. The methods of ensuring the integrity of in situ root identification and establishing in situ root image phenotypic restoration remain to be explored. Therefore, based on the in situ root image of cotton, this study proposes a root segmentation and reconstruction strategy, improves the UNet model, and achieves precise segmentation. It also adjusts the weight parameters of EnlightenGAN to achieve complete reconstruction and employs transfer learning to implement enhanced segmentation using the results of the former two. The research results show that the improved UNet model has an accuracy of 99.2%, mIOU of 87.03%, and F1 of 92.63%. The root reconstructed by EnlightenGAN after direct segmentation has an effective reconstruction ratio of 92.46%. This study enables a transition from supervised to unsupervised training of root system reconstruction by designing a combination strategy of segmentation and reconstruction network. It achieves the integrity restoration of in situ root system pictures and offers a fresh approach to studying the phenotypic of in situ root systems, also realizes the restoration of the integrity of the in situ root image, and provides a new method for in situ root phenotype study.

Opportunities for the use of selenium nanoparticles in agriculture

Due to the growing number of the world's population, there is an urgent need for high-quality food to meet global food security. Traditional fertilizers and pesticides face the problems of low utilization efficiency and possible hazards to non-target organisms. Selenium (Se) is an essential trace element for animals and humans. As a result, Se nanoparticles (SeNPs) have aroused intense interest and found opportunities in agricultural use. Herein, we summarized representative studies on the potential application of SeNPs in agriculture, including mitigating biotic and abiotic stresses in plants, promoting seed germination and plant growth, and improving Se contents and nutritional values in crops, and the underlying mechanisms were also discussed. Finally, future directions are highlighted to get a deep insight into this field.