Selenium distribution in the Chinese environment and its relationship with human health: A review

Research progress on environmental behavior of arsenic in Qinghai-Tibet Plateau soil

The Qinghai-Tibet Plateau, with its high altitude and cold climate, is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic (As) levels in the soil, largely due to its rich mineral and geothermal resources. This review provides a comprehensive analysis of As content, focusing on its distribution, environmental migration, and transformation behavior across the plateau. The review further evaluates the distribution of As in different functional areas, revealing that geothermal fields (107.2 mg/kg), mining areas (53.8 mg/kg), and croplands (39.3 mg/kg) have the highest As concentrations, followed by river and lake sediments and adjacent areas (33.1 mg/kg). These elevated levels are primarily attributed to the presence of As-rich minerals, such as arsenopyrite and pyrite. Additionally, human activities, including mining and geothermal energy production, exacerbate the release of As into the environment. The review also highlights the role of local microorganisms, particularly those from the phyla Proteobacteria and Actinobacteria, which possess As metabolic genes that facilitate As translocation. Given the unique climatic conditions of the plateau, conventional methods for As control may not be fully effective. However, the review identifies promising remediation strategies that are environmentally adaptable, such as the use of local microorganisms, specific adsorbents, and integrated technologies, which offer potential solutions for managing and utilizing As-contaminated soils on the plateau.

Bioavailability of selenium and the influence of trace elements in crops grown in selenium-rich areas

Trace elements in crops can affect the bioavailability of Se. To investigate the effect of trace element on Se bioavailability, trace element concentrations and Se bioavailability in crops from Se-rich area (Langao County, China) were analyzed using the physiologically-based extraction test (PBET) digestion model. Vegetables (rapes, radishes, and potatoes) had higher concentrations of total and bioavailable Se compared to grains (corn, rice, and sweet potatoes), suggesting they are more effective for Se supplementation. The bioavailability of Se was higher in the intestinal phase than in the gastric phase. Trace elements were positively correlated with the increased bioavailability of Se in corn, potato, and rape. Fe was a key element in increased bioavailability of Se in the gut model. Therefore, trace elements, particularly Fe, in crop can enhance Se bioavailability, suggesting their potential use in Se supplementation. The findings of this study provide valuable insights for dietary interventions to Se deficiencies.

Revealing the impact of organic selenium-enriched Lactiplantibacillus plantarum NML21 on yogurt quality through volatile flavor compounds and untargeted metabolomics

Effective selenium supplementation strategies are essential for alleviating global selenium deficiency. This study utilized the high‑selenium-tolerant strain Lactiplantibacillus plantarum NML21 to produce selenium-enriched yogurt, successfully converting inorganic Se(IV) into organic selenium, with selenoproteins accounting for 69.52 % of the total selenium content (995.19 ± 68.60 μg/g). Selenium-enriched yogurt exhibited excellent physicochemical properties and antioxidant activity. Volatile flavor analysis identified 36 compounds, with NML21 and SeNML21 significantly enhancing ketone flavors in yogurt, particularly increasing the contents of 2-heptanone and 2,3-pentanedione. Untargeted metabolomics identified 215 non-volatile metabolites, with NML21 and SeNML21 significantly regulating key metabolic pathways, including the phosphotransferase system, ABC transporters, and amino acid biosynthesis, promoting the accumulation of beneficial metabolites. Selenium specifically influenced the biosynthesis pathways of ABC transporters, phenylalanine, tyrosine, and tryptophan. This study demonstrates that NML21 is a promising strain for producing selenium-enriched functional yogurt, offering innovative perspectives for dietary selenium supplementation and functional food development.

Identification and functional characterization of a novel CaSrpA enzyme for selenite reduction and selenium nanoparticle formation

Selenite reductases are widely distributed across various oxidoreductase families (e.g., ThxR, OYE, and FccA enzymes) [1]. The ability of short-chain dehydrogenase/reductase (SDR) family enzymes for selenite reduction remains unknown. Using metagenomic and metatranscriptomic analyses, 40 putative selenite reductases were identified from selenium-rich regions based on catalytic domain homology and transcriptional upregulation. These enzymes mainly belong to the SDR family and metalloenzymes. Enzyme activity analysis indicated that CaSrpA possessed the ability (Vmax, 18.85 μM/min/g) to reduce selenite to selenium nanoparticles (SeNPs). Phylogenetic analysis showed that CaSrpA was clustered in the clade of SDR enzymes, with the typical Rossmann fold. CaSrpA also oxidized S-1-phenylethanol to phenylacetone (Vmax, 15.4 μM/min/mg), sharing 53 % sequence similarity with the alcohol dehydrogenase RasADH. Molecular docking and structural superposition identified sixteen key residues associated with CaSrpA activity. Site-directed mutagenesis revealed that over 14 mutants exhibited a 30-90 % reduction in relative activity. Mutant M206A enhanced catalytic efficiency towards selenite by 2.4-fold and S-1-phenylethanol by 5.4-fold via a lid-opening mechanism. Molecular dynamics simulation elucidated that the mutant M206A utilized lid opening mechanism to accommodate more substrate and co-factor for catalysis via altering the conformation of the α7-α8 loop. This study helps understand the intrinsic connection between the SDR family and selenite-reducing capability, broadening the repertoire of selenite reductases.

Systematic comparison of the effects of exogenous inorganic selenium and organic selenium on the quality and antioxidant capacity of Pleurotus eryngii

BACKGROUND

Pleurotus eryngii is an ideal food to improve the nutritional status of selenium (Se) in the human body. Besides Se accumulation and speciation, quality parameters and antioxidant capacity are key factors in determining the nutritional value of P. eryngii. However, the effects of exogenous inorganic Se (selenite and selenate) and organic Se (Se-enriched yeast) on the quality and antioxidant capacity of Se-enriched P. eryngii remain unclear. Therefore, this substrate cultivation experiment was carried out to analyze the concentrations of nutrient elements, quality parameters and antioxidant activity of P. eryngii cultivated with different forms of Se at varying concentrations.

RESULTS

All forms of exogenous Se increased crude protein content but decreased the contents of crude fiber and crude polysaccharide in P. eryngii, with the most significant promotion or inhibitory effects observed under Se-enriched yeast treatment. Compared to inorganic Se treatments, Se-enriched yeast more effectively enhanced nutrient element accumulation and antioxidant capacity of P. eryngii. The increased concentrations of zinc (Zn), magnesium (Mg), crude protein and phenolic compounds were identified as the primary factors improving the antioxidant activity of P. eryngii.

CONCLUSION

Compared to inorganic Se, Se-enriched yeast is the optimal Se source for enhancing the nutritional quality of P. eryngii, owing to its superior ability to increase crude protein content, nutrient element concentrations, and antioxidant capacity. © 2025 Society of Chemical Industry.

Impact of land use changes on selenium distribution and bioavailability in Mollisol of Sanjiang Plain

Recent changes in land use in the Mollisol region of the Sanjiang Plain have significantly impacted speciation and bioavailability of selenium (Se) in soils. This study examines Se species and distribution across various land use types, focusing on the interactions between iron oxides and organic matter in Se migration and transformation. The total Se content in woodland, dryland, and paddy soils is 0.79 mg/kg, 0.80 mg/kg, and 0.82 mg/kg, respectively, showing a uniform distribution. Soil organic carbon (SOC) is positively correlated with total Se, with complex effects on Se species. In paddy soils, SOC is positively associated with organic-bound Se and residual Se; Se content decreases with increasing soil depth in both profiles, following a typical surface accumulation pattern. Additionally, water management in paddy fields plays a critical role: prolonged water retention at the surface promotes Se enrichment in the topsoil and enhances dissolved Se leaching from deeper layers. This research indicated that coupling iron oxides and organic matter is crucial in Se fixation, particularly in paddy soils. Bioaccumulation factor (BCF) analysis shows a significant correlation between Se content in crops and soil Eh and pH, with higher Eh enhancing Se uptake. This study highlights the influence of land use and soil properties on Se bioavailability.

Effects of glomalin-related soil protein on soil selenium availability in farmland: a non-negligible component of organic matter

The selenium (Se) soil environmental behaviour directly regulates the Se enrichment effect of crops and the risk of Se ecotoxicity and is critically influenced by soil organic matter fractions. Recent studies have shown that glomalin-related soil protein (GRSP) plays an important role in regulating heavy metal transport transformation. However, there is still a lack of systematic knowledge of the effects of GRSP on the Se environmental behaviour in soil, which is a knowledge gap that might hinder the efficient and safe utilization of Se resources in farmland. This study combined field sampling across Se-rich and Se-toxicity farmlands with laboratory adsorption experiments to investigate the effects of GRSP on the soil Se availability. Field sampling revealed the impact of GRSP on soil Se availability in farmland cannot be ignored. Adsorption of Se by GRSP significant reduced soil Se availability in Se-rich farmland, but had a significant promoting effect in Se-toxicity farmland. This was related to the differential Se adsorption modes due to the adsorption saturation. Hydrogen bonding and ion exchange were the primary and secondary modes of Se adsorption by GRSP, respectively, demonstrated by laboratory results. The adsorption process of Se by GRSP started with Se reduction caused by carbonylation of hydroxyl groups on the surface. The Se adsorption was finally completed by abundant carbonyl and hydroxyl groups on GRSP surface through ion exchange generation and hydrogen bonding, respectively. This enhances our understanding of how organic matter, particularly GRSP, affects the environmental risk associated with Se in soil.

Chemical analysis and angiotensin I-converting enzyme inhibitory activity of enzymatic hydrolysates derived from meat of goat-kids with supplemental selenium

Background

The effects of selenium (Se) on animal health due to its antioxidant and immune system regulatory properties are very well-documented. However, there is still a lack of scientific evidence about the effect of Se on muscle tissue. Se supplementation in ruminants will enhance the antioxidant activity of myocytes and increase angiotensin-converting enzyme (ACE) inhibitory activity. Generating bioactive peptides derived from meat could prevent the production of angiotensin II, a key player in the development of cardiovascular diseases.

Methods

Forty-five suckling goat kids were randomized into one of three groups: (1) CG: group without Se supplemented in the diet; (2) GSS: group with a single injectable dose subcutaneously of sodium selenite (Na2SeO3) at a dose of 0.25 mg/kg of body weight; (3) GSM: group with an oral administration of selenomethionine (SeMe) at a dose of 0.3 mg/kg of body weight). The effect of both sources of Se was evaluated on the proximate composition of meat and liver and the angiotensin I-converting enzyme inhibitory activity of meat-derived enzymatic hydrolysates.

Results

The kids-goat meat from the GSM group had a higher protein content (p < 0.05). The fat content gradually increased over time in the treatment GSM, which increased ca. two-fold (from 1.77 to 3.68). The degree of hydrolysis of the meat samples decreased (p < 0.05) in the treatments supplemented with Se (GSS and GSM). The degree of hydrolysis increased significantly (p < 0.05) over time in treatments with Se (GSS and GSM). The electrophoretic patterns of the enzymatic hydrolysates at two h showed a molecular weight between 23.44 and 27.5 kDa, the bands with more intensity. At 21 d of slaughter, a major degree of hydrolysis was observed in the treatments supplemented with Se (GSS and GSM) compared to the CG. Meat protein content and rate of ACE inhibition after hydrolysis improved (50% and 2%, p < 0.05) with GSM at 7 d of slaughter. After hydrolysis, the IC50 of the selenium-supplemented groups decreased (p < 0.05) the amount of CAE and IC50 values.

Conclusion

This is the first report describing the ACE inhibitory activity of bioactive peptides derived from goat-kids meat with supplemental. These results indicate the presence of ACE in goat meat; however, the percentage of ACE inhibition after hydrolysis was only improved with selenomethionine dosing at 7 days of slaughter. The study's novelty indicates that supplemented selenium synergized with ACE in goat meat. It is necessary to continue these studies to identify specific bioactive peptides, antioxidant activities, and goat meat's biological and functional value, considering it a functional food that can prevent metabolic diseases and be a healthy alternative for the human population.

Molecular and physiological response of chives (Allium schoenoprasum) under different concentrations of selenium application by transcriptomic, metabolomic, and physiological approaches

Selenium (Se) is a vital trace element for human health, and its uneven distribution in soil triggers Se deficiencies in some regions. Se biofortification has been demonstrated to mitigate this issue by producing Se-enriched crops. Chives (Allium schoenoprasum cv. 'sijixiaoxiangcong'), a simple-to-cultivate and fast-growing vegetable, offers a promising Se-accumulation ability. However, the physiological and molecular mechanisms underlying Se responses in chives remain unclear. This study applied sodium selenite at various doses to chives via root irrigation, and integrated strategies including multi-omics were employed to unfold the response mechanism. (1) Physiological data reveal that sodium selenite irrigation adversely affects the height, shoot weight, chlorophyll, and soluble sugar content of chives' aerial parts. However, chives exhibit a remarkable ability to accumulate selenium, reaching up to 40.21 mg kg-1 DW under high Se exposure (160 mg L-1); (2) Transcriptomic analysis revealed significant enrichment of the phenylpropanoid biosynthesis and plant hormone signal transduction pathways under Se treatment. Key DEGs, such as MAPKKK17_18, JAZs, and PCL, were identified as Se response candidates. Our findings show that selenomethionine is the primary form of Se accumulation, and DEGs linked to antioxidant defense and phenylpropanoid biosynthesis are crucial for mitigating Se stress; (3) Importantly, plant hormone signaling plays a central role by regulating phenylpropanoid metabolism and enhancing the antioxidant enzyme system, highlighting its significance in chives' Se tolerance. These results clarify the Se response mechanisms in chives and enable Se-enriched chive cultivation.

Evaluation of yield, nutritional quality, and Se distribution in black-grained wheat and bioavailable Se concentrations in soil under irrigation and Se fertilizer application

In the future, ensuring the food and nutritional security of a rapidly growing population will pose an immense challenge in the future. To enhance crop nutrition and address this challenge, a two-year field experiment was conducted on selenium (Se)-deficient dryland soil; the effects of irrigation after Se ore powder (2160 g·ha-1) (Se2160) application on yield-related traits, nutritional quality, and Se uptake and accumulation in black-grained wheat (BGW) and soil Se availability in soil were investigated. This study aimed to determine whether the combination of Se ore powder application and irrigation enhanced yield-related factors and increased the related nutrient in wheat, thereby achieving biofortification. Irrigation had little effect on the grain protein, amylose, amylopectin, total starch, or soluble sugar content, copper concentration in grains, or the Se translocation factor from the root to grain following Se2160 application, but significantly increased the sucrose content and iron (Fe) concentration in grains. Se was readily taken up by roots of irrigated plants in Se2160-treated soils, resulting in leaf and grain Se concentrations that were 4-7 times higher than in control soils. Se fertigation increased the Se distribution in the leaves and grains of BGW due to its decline in the roots and spike-stalk + glume. Se2160 application significantly increased the grain yield and Fe, zinc, Se and manganese concentrations in grains under water regimes. Bioavailable Se concentrations in the 0-20-cm layer of Se2160-treated soil were significantly decreased by irrigation and increasing irrigation amount, but significantly higher than those of control soils, while those in the 20-40-cm layer were not affected. These findings indicate that Se fertigation enhances grain yield, sucrose content, Fe concentration, and Se accumulation in BGW as well as bioavailable Se concentrations in the 0-20-cm soil layer, effects that are conducive to Se-enriched agricultural production and human health improvement.

The effect of selenium biological enhancement on cucumber growth and powdery mildew control under greenhouse conditions

In this study, we clarified the effects of selenium fertilizer application on the growth of cucumber, explored the impact of exogenous selenium on the control of powdery mildew and its pathogens. Selenium-enriched ionic fertilizer and cucumber were selected as the test materials. A one-way, randomized design was adopted to set up four selenium solutions with concentrations of 0 mg/L, 3 mg/L, 6 mg/L, and 12 mg/L to investigate the effects of biofortification with different amounts of selenium concentrations on the growth of cucumber and the occurrence of powdery mildew in greenhouses. A leaf inoculation test was conducted by setting up three groups of treatments: water and fungicide (seedling fungicide) as the control groups, and 6 mg/L selenium-enriched ionic fertilizer as the treatment group. These treatments were selected to investigate the effect of selenium on the control of powdery mildew in greenhouse-grown cucumbers as well as the effect of selenium on the germination of powdery mildew pathogen spores. The results demonstrated that both the 6 mg/L and 12 mg/L selenium-enriched ionic fertilizer solutions had growth-promoting and yield-increasing effects on cucumber and that the difference in the growth-promoting effects of these treatments was insignificant. The 3 mg/L, 6 mg/L, and 12 mg/L treatments improved the nutritional quality of cucumber fruits, reducing the total acidity of the fruits and increasing the content of soluble proteins in the fruits; the 6 mg/L and 12 mg/L treatments increased the content of selenium in the fruits, and the difference in selenium enrichment between the two treatments was not significant. The 6 mg/L selenium solution had the greatest effectiveness in alleviating leaf photosynthesis inhibition by the powdery mildew fungus, in mitigating powdery mildew damage and in reducing the plant disease index. The results of the leaf inoculation trials revealed that at a concentration of 6 mg/L, the effects of the selenium-enriched ionic fertilizer were comparable to those of pharmaceutical treatments for powdery mildew disease. The activities of superoxide dismutase and peroxidase in all treatments tended to increase but then decreased within 72 h after pathogen inoculation. Nevertheless, selenium fertilizer treatment inhibited the germination of powdery mildew pathogen conidia, the number of conidial germination shoot tubes and mycelium formation.

Theoretical Study of the Reaction of Hydrogen Selenide with the Cl• Atom and the •OH Radical, and Differences with the Behavior of Other Hydrogen Chalcogenides

Hydrogen selenide, H2Se, is the third-row analog of hydrogen sulfide, H2S, and water, H2O. While there is ample thermochemical and kinetic information about the reactions of the latter two species, few experimental or theoretical data are available on H2Se. In this work, we use high-level post-Hartree-Fock methods to study the reaction of H2Se with two of the most abundant atmospheric radical species, the Cl• atom and the •OH radical, H2Se + Cl• → HSe• + HCl H2Se + •OH → HSe• + H2O We used the SVECV-f12 composite quantum chemical method to study the stability of adducts and transition states, as well as the barriers for the transformations. It was found that a correct representation of the barrierless adduct is crucial for a correct description of the reaction's kinetics, and we present in this paper the first theoretical determination of the reaction coefficient of H2Se with Cl• in the literature, obtaining a value of 5.7 × 10-10 cm3 molecule-1 s-1, in excellent agreement with the experimental determination of 5.5 × 10-10 cm3 molecule-1 s-1 at room temperature Additionally, using the same procedure, we obtained a value of 6.4 × 10-11 cm3 molecule-1 s-1 for the reaction with •OH, in this case slightly smaller than the only previous estimation of 7.2 × 10-11 cm3 molecule-1 s-1 obtained indirectly from similar reactions for sulfur compounds, in all cases at 298.15 K. Judging from the agreement of the theoretical and experimental rate coefficients in the case of the reaction with chlorine, we suggest that our value for the reaction with the hydroxyl radical is more accurate than the estimated one. A comparison of the dependence of the rate coefficients for H2S and H2Se as a function of the temperature shows some noticeable differences. A convex behavior of the T-dependence for the Cl• reaction at high temperatures was found, instead of the concave behavior found for sulfur. Nevertheless, this is not important in atmospheric chemistry conditions, and a sufficiently linear region was found with the expression, k(Cl•) = 1.6 × 10-10 exp (0.7/RT) cm3 molecule-1 s-1. The reaction with •OH is even more complicated, with nonlinear tail at high (combustion) and low (stratosphere) temperatures, while the region important in tropospheric chemistry could be fitted with the Arrhenius equation k(•OH) = 5.9 × 10-12 exp (1.4/RT) cm3 molecule-1 s-1. Using our theoretically determined kinetic data, we were also able to calculate the atmospheric lifetime of H2Se as 2.6 h, considerably shorter than that of H2S (12.2 h).

Enhanced leaf photosynthesis, grain yield, rice quality and aroma characteristics in rice grains (Oryza sativa L.) with foliar application of selenium nanoparticles

The potential of selenium nanoparticles application for rice with higher yield and quality, especially in great selenium bioavailability and rich aroma, is a crucial objective. In this study, a two-year field experiment was conducted to investigate the influence of selenium nanoparticles (Se NPs) foliar spraying on the grain yield, rice quality, selenium bioavailability and aroma formation. Our results demonstrated that Se NPs foliar application significantly increased the activities of peroxidase, superoxide dismutase and catalase (POD, SOD and CAT), and decreased the malondialdehyde (MDA) content to increase the SPAD value and net photosynthetic rate in flag leaves at 10-25 days after heading, which finally increased the grain yield by 1.3-3.7 % for improved grain filling, compared to CK. The increased grain filling also contributed to better rice quality, like higher taste value (2.4-6.9 %) and breakdown value (32.2-48.0 %), as well as lower amylose content (5.1-15.9 %), chalkiness grain rate (8.4-49.2 %) and degree (11.5-50.4 %). Meanwhile, Se NPs application improved the selenium bioavailability by increasing the selenium content and proportion in the rice edible parts. The further analysis indicated that the Se NPs application primarily enhanced the proline content and proline oxidase activity from heading to 10 days after heading, improving the initial synthesis of Δ1-pyrroline-5-carboxylic acid (P5C) for the vital 2-acetyl-1-pyrroline (2-AP) production during 10-25 days post-heading, which promoted the remarkable increase of the final 2-AP content (5.0-19.8 %). These findings showed that Se NPs can be practically applied as the foliar fertilizer for quality improvement, selenium bioavailability enhancement and aroma enrichment in rice grains.

Selenium Status Associates with Thyroid Hormone and Thyroid Dysfunction in Older Chinese Adults

Selenium (Se) is physiologically essential for thyroid function. However, epidemiological studies on the association between Se status and thyroid function are limited and the results are inconsistent. Therefore, we explored this association in an elderly Chinese population sample. Participants in the cross-sectional study were people aged 65 years or older who provided fingernail and whole blood samples. Hyperthyroidism and hypothyroidism were defined by serum thyroid hormones concentrations, including thyroid stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free thyroxine (FT3), and free thyrotropin (FT4). Significant positive association was observed between whole blood and fingernail Se concentrations (r = 0.672, P < 0.001). Compared with the lowest Se quartile (Q1), the other fingernail Se quartile groups had lower TSH, higher FT3 and FT4 levels, and Q2 had higher TT3 levels after adjusting for covariates; the other whole blood Se quartile groups had lower TSH levels, Q2 had higher FT3, FT4 and TT3 levels, Q3 had higher FT3 levels, and Q4 had higher FT4 levels after adjusting for covariates. Compared with Q1, the adjusted odds ratios (OR) and 95% confidence intervals (95%CIs) of hypothyroidism for Q4 of whole blood Se was 0.141 (0.029,0.675), and the adjusted OR (95%CIs) of hyperthyroidism for Q2 and Q3 of fingernail Se were 4.121 (1.233,13.733) and 3.614 (1.095,11.926). Higher Se levels were significantly associated with lower TSH levels and higher levels of TT3, FT3 and FT4. Meanwhile, higher Se levels were associated with lower risk of hypothyroidism and higher risk of hyperthyroidism.

Balancing application of plant growth-promoting bacteria and biochar in promoting selenium biofortification and remediating combined heavy metal pollution in paddy soil

Plant-growth-promoting bacteria (PGPB) and biochar have attracted increasing attention for remediating the combined pollution of arsenic (As) and cadmium (Cd) and promoting selenium (Se) biofortification. However, their differing effects on the bioavailability of As, Cd, and Se and their absorption by rice are still poorly understood. In this study, PGP Agrobacterium sp. T3F4 with Se- oxidizing capacity and corn straw biochar were applied to natively polluted paddy soil. Strain T3F4 reduced the bioavailability of As in soil but increased bioavailable Se, decreasing the As content in rice by 16.8% and improving the Se content of rice by 54.5% (p < .05). Application of 2.5% biochar stimulated iron (Fe) plaque formation of the root and immobilized As and Cd in the soil, decreasing the As and Cd absorption of rice by 14.7% and 40.3%, respectively (p < .05). Application of 5.0% biochar achieved similar mitigation effects for As and Cd but also decreased the Se content in rice by 60.6% by reducing bioavailability. This decrease in Se uptake was mitigated when 5.0% biochar was co-applied with strain T3F4. Notably, applying strain T3F4 also alleviated the oxidative stress on rice plants and enhanced soil enzyme activities, contributing to a substantial increase in grain yield in the polluted paddy soil. The adverse effects of 5.0% biochar on soil health and grain yield were mitigated by the co-application of strain T3F4. Our results provide new insights into applying PGPB and biochar for Se biofortification and As and Cd remediation in paddy soil.

Pyro-Thermolysis Pattern Analysis of Selenopeptide in Selenium-Enriched Rice Based on Two-Dimensional Dietary Kinetics Evolution

Selenopeptides can be ideal dietary selenium (Se) supplements for humans. Currently, rice is not used much as a source of selenopeptides. Here, we executed the selenopeptidomics analysis of selenium-enriched rice protein hydrolysates using the full MS-dd-MS2 acquisition method and identified selenopeptides, including L{Se-Met}AK and other selenopeptides. Specifically, selenomethionine (SeMet) replaced methionine (Met) in the rice protein-Oryzain alpha chain (EC: 3.4.22) and generated a selenopeptide L{Se-Met}AK (molecular formula: C20H38N5O5Se) during subsequent protein hydrolysis. This selenopeptide was in 425-428 amino acid residues of the Oryzain alpha chain. Thermal processing led to selenopeptide cleavage, which affected the efficient retention of selenopeptides. Activation energy (Ea) was used to locate the quality control markers in the thermal degradation of selenopeptides. Therefore, this study established the thermal degradation rate equation for the selenopeptide L{Se-Met}AK at 100 °C, 110 and 120 °C; and identified the pyrolysis products, including L{Se-Met}A, LMA, LMAK, K1, and K2, involving C-N cleavage on the amide bond of alanine and lysine, C-Se bond cleavage and C-N cleavage on the amide bond of alanine and Met; the fit coefficients of the thermal reaction models were ≥0.9248, which could accurately quantify the real-time pyrolysis kinetic process; and LMAK had a lower Ea of 88.20 kJ/mol, which made it easier to produce. In summary, LMAK can be used as a quality control marker in the pyrolysis process, providing technical support for the efficient retention of selenopeptides.

Nano-selenium strengthens potato resistance to potato scab induced by Streptomyces spp., increases yield, and elevates tuber quality by influencing rhizosphere microbiomes

Introduction

The application of selenium could directly or indirectly modulate the activity of antioxidant enzymes in crops, thereby mitigating the detrimental effects of abiotic and biotic stresses on crop health. However, there are few studies on the effects of nano-selenium fertilizer on potato scab caused by Streptomyces spp., potato yield and tuber quality.

Methods

We aimed to elucidate the impact of nano-selenium fertilizer on potato disease resistance, yield, tuber quality, antioxidant enzyme activity and rhizosphere soil bacterial communities, and to determine the optimal frequency and growth stages of nano-selenium fertilizer spraying.

Results and discussion

The application of nano-selenium fertilizer twice during the seedling stage significantly reduced the disease index of potato scab, enhanced potato yield, tuber quality (dry matter, Vitamin C, crude protein, and selenium content), and antioxidant enzyme activity (glutathione peroxidase, peroxidase, polyphenol oxidase, superoxide dismutase, and phenylalanine ammonia lyase). The diversity of the rhizosphere bacterial community of potatoes subjected to selenium fertilizer spraying at the seedling stage increased significantly, and concurrently, the symbiotic network of rhizosphere bacterial microbiome grew more complex. Beneficial microorganisms such as bacteria of the genus Bacillus were enriched in the rhizosphere soil. The current study provided theoretical support for the exploration of a potato selenium-enriched technology system and supplies scientific guidance for the utilization of nano-selenium.

Weighted Gene Correlation Network Analysis Reveals Key Regulatory Genes Influencing Selenium Enrichment and Yield with Exogenous Selenite in Tartary Buckwheat

Selenium (Se) is an essential trace element for human health, and dietary Se intake is an effective supplement. Rich in nutrients and functional components with potential for Se enrichment, Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) is a Se-biofortified cereal. To determine the optimal Se treatment concentration and fully understand its effects on Tartary buckwheat, sodium selenite (Na2SeO3) in different concentrations was sprayed onto leaves of Tartary buckwheat at the initial flowering stage. Agronomic and yield-related traits and Se enrichment were analyzed between CK and treatments. The results showed that Na2SeO3 concentrations of 3.0 and 6.0 mg/L significantly increased the contents of Se and starch in the grains, the 1000-grain weight, the number of grains per plant, and the yield. The 6.0 mg/L treatment had the best effect. Transcriptome and weighted gene co-expression network analyses showed that selenite promoted chlorophyll synthesis and photoelectron transport by upregulating chlorophyll synthase (CHLG) and protein CURVATURE THYLAKOID 1B (CURT1B) levels, improving photosynthesis, increasing sucrose synthesis and transport in leaves and starch synthesis and accumulation in grains, and promoting grain-filling and yield. These changes were regulated by genes related to photosynthesis, sucrose, and starch metabolism-related genes, including CAB3C, HPR3, SUS5, BAM9, SS3, SWEET1, and SWEET12. Selenite absorption in Tartary buckwheat was regulated by aquaporin genes NIP1-1 and PIP1-5. Selenite transport was regulated by the inorganic phosphate transporter gene PHT1-1, and organic Se transport was controlled by the proton-dependent oligopeptide transporters NPF3.1 and NPF4.6. Methionine gamma-lyase (MGL) was involved in selenocompound metabolism. This study identified the best spraying scheme for enhancing Se content in the grains. It also revealed the regulatory genes responding to selenite absorption, transport, and metabolism and the regulatory pathways promoting yield in Tartary buckwheat. These results provide technical guidance and theoretical support for producing high-yielding and Se-enriched Tartary buckwheat.

Associations of Serum Manganese, Zinc, Copper, and Selenium Concentrations With Autism Spectrum Disorders in Chinese Children: A Case-Control Study

Imbalances in several trace elements related to antioxidant function may lead to autism spectrum disorder (ASD)-related physiological dysfunction. Nonetheless, contradictory results have been found on the connection between these elements and ASD, and studies of their joint effects and interactions have been insufficient. We therefore designed a case-control study of 152 ASD children and 152 age- and sex-matched typically developing (TD) children to explore the individual and combined associations of manganese (Mn), zinc (Zn), copper (Cu), and selenium (Se) with ASD. Compared with TD, ASD has lower Zn and Se levels and higher Cu levels. The restricted cubic spline model showed J-shaped non-linearity, L-shaped non-linearity, and positive linearity correlations between Mn, Zn, Cu, and ASD. Zn and Cu were negatively and positively correlated with ASD symptoms, respectively. The superoxide dismutase (SOD) mediated 50.53% and 39.07% of the association between Zn, Se, and ASD, respectively. Bayesian kernel machine regression (BKMR) confirmed a U-shaped correlation between the element mixtures and ASD. Interactions of Mn with the other three elements and Cu with Zn were also observed. Our results confirm that the independent and combined exposure to the four trace elements was associated with ASD, with oxidative stress being an important mechanism. Due to the potential interactions between the elements, further research is needed to explore their involvement in the pathogenesis and progression of ASD from a combined perspective, as well as the beneficial and harmful concentration ranges.

Transcriptome and metabolome analyses reveal the promoting effects of arbuscular mycorrhizal fungi on selenium uptake in grapevines

To improve the selenium (Se) uptake in grapes, the effects of arbuscular mycorrhizal fungi (AMF) on the Se accumulation in grapevines were studied under a soil Se concentration of 5 mg/kg, and the transcriptome and metabolome sequencing were used to elucidate the regulatory mechanism of AMF on Se accumulation. AMF initially decreased the biomass of grapevines, but later increased the biomass. Moreover, AMF enhanced the activities of Se metabolism enzymes (adenosine triphosphate sulfurylase, adenosine 5'-phosphosulfate reductase, serine acetyltransferase, and cysteine methyltransferase) and the Se concentration in grapevines. Compared to Se treatment alone, AMF resulted in a 20% increase in root Se concentration and a 21% increase in shoot Se concentration 60 days after treatment. Transcriptome and metabolome analyses revealed that AMF up-regulated the expression levels of inorganic phosphate transporter proteins 1-11 and down-regulated the expression levels of ABC transporter family members, water channel proteins, and sulfur transporter proteins in grapevines. In addition, AMF elevated the levels of hesperidin, naringenin, apigenin, neohesperidin, pine sapogenin, and rutin in grapevines. Therefore, AMF can enhance Se accumulation in grapes by modulating the phosphate transport pathway and the biosynthesis of secondary metabolites involved in the phenylpropane biosynthesis pathway, flavonoid biosynthesis pathway, and flavonoid and flavonol biosynthesis pathway.

Thermophilic anaerobic ethane oxidation coupled with selenate and selenite reduction

Anaerobic microorganisms are critical in regulating ethane in geothermal environments, where selenate and selenite are common contaminants. Although coupling ethane oxidation with selenate reduction has been demonstrated as feasible, such processes remain poorly explored in geothermal environments. This study addressed this gap by successfully enriching thermophilic anaerobic cultures capable of coupling ethane oxidation with selenate/selenite reduction, achieving selenate and selenite removal rate of 2.7 mg Se/L/d and 2.1 mg Se/L/d, respectively. Metagenomic analysis revealed a novel genus 'Candidatus Ethanivorans selenatireducens', which accounted for 16.0 % and 32.6 % of microbial communities in selenate- and selenite-dependent systems, respectively. This microorganism encoded pathways for anaerobic ethane oxidation via fumarate addition and genes required for the sequential reduction of selenate to elemental selenium. These findings unveiled a novel microbial mechanism linking ethane oxidation and selenate reduction in geothermal systems, providing new insights into the biogeochemical interaction between carbon and selenium in thermophilic environments.

Temporal and spatial variations of soil Se in China over the past half century and its influencing factors

Soil serves as a significant reservoir of selenium (Se) and plays a crucial role for the entry of Se into the food chain. Therefore, it is of utmost importance to gain a deep understanding of the spatial and temporal variation of total soil Se content in China, as well as its influencing factors. This understanding is essential for the rational and efficient utilization of Se resources, the maintenance of ecological balance, and the preservation of human health in the future. Through a comprehensive literature search, relevant studies were identified, and information regarding soil total Se content, soil available Se content, soil pH, and soil organic matter (SOM) was extracted. The Mann-Kendall (M-K) test was employed to analyze the variation of total soil Se content, while Moran's I was used to examine the global and local spatial clustering characteristics of soil Se. The results indicate that the total Se content in China has shown an increase at different spatial and temporal scales, particularly in Central China. Furthermore, there is a significant difference in total Se content between cultivated soil and natural soil in Central China (P < 0.05). Additionally, soil physicochemical properties have been found to impact soil total Se content. Specifically, pH is negatively correlated with soil total Se content, while SOM is positively correlated with it (P < 0.05). Overall, the findings suggest that the total Se content in Chinese soil is increasing over time, and human agricultural activities and physicochemical properties of the soil, such as soil pH and SOM, likely influence the bioavailability of Se or the overall soil total Se content through their interaction with Se speciation in the soil to some extent. It is important to note that changes in environmental conditions may also have some degree of impact on the total Se content.

Climate and Soil Properties Drive the Distribution of Minor and Trace Elements in Forest Soils of the Winter Olympic Core Area

Minor and trace elements in soil play a crucial role in regulating ecological processes that sustain the functionality of forest ecosystems. In this study, we have selected three conifer forests (Pinus sylvestris, Picea asperata, Larix principis-rupprechtii), one broadleaf forest (Betula Platyfilla) and one mixed forest of Betula Platyfilla and Larix principis-rupprechtii in the Winter Olympic core area and determined the pattern of 12 typical elements (B, Fe, V, Cr, Ni, Co, Mn, As, Cu, Zn, Sn and Se) in soils and their main drivers in the three different soil layers (A, B and C horizon) in each soil profile. Our results showed that the concentrations of B, Fe, Cr, Cu, Ni and Sn were mainly enriched in the broadleaf forest and mixed broadleaf-conifer forest zones, and the average concentrations of Co, Mn, V, Zn, As and Se were mainly enriched in coniferous forest zones in contrast. We have observed that the mean concentrations of Fe, Cr, Ni, Zn, As, Sn and Co increase with soil depth in the BP forest. The concentrations of Se and Cu were higher in the A layer than the C layer. The piecewise structural equation modeling (piecewiseSEM) results visualized a direct and negative effect on B, Fe, V, Cr and Ni concentrations due to soil temperature, while the concentrations of Se is mainly influenced by soil temperature and soil properties.

Dietary Reference Intakes of Selenium for Chinese Residents

The plasma selenoprotein P (SELENOP) concentration leveling out was thought to represent saturation of the functional selenium body pool and an appropriate supply of selenium to all tissues, indicating that the necessary amount of selenium had been supplied. Based on the selenium intake when SELENOP reaches saturation, the estimated average requirement of selenium was set as 50 μg/d, and the recommended nutrient intake was 60 μg/d for Chinese general population. According to a recent study, "lactating Chinese women with the optimal daily selenium intake" was defined, and the adequate intake of 0‒6-mo-old infants was set as 15 μg/d, whereas 20 μg/d was calculated for 7‒12 mo old infants. Considering the negative health effects of intake of excessive nutrient levels of selenium, we recommend reducing the tolerable upper intake level (UL) for adults from 400 to 255 μg/d based on the results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT). The SELECT trial is a key basis for setting selenium's UL. It has a large sample size and long-term design. It rigorously measures selenium intake and monitors multiple health endpoints precisely. Also, with proper control groups, it effectively determines the threshold of adverse effects, enhancing the reliability of UL determination.

Spatial distribution and driving factors of soil selenium on the Leizhou Peninsula, southern China

Selenium (Se) is an essential element for humans, playing a critical role in the functioning of the immune system. The global prevalence of dietary Se deficiency is a significant public health concern, largely attributed to the low levels of Se present in crops. The sufficient Se in plants and humans is determined by the presence of stable Se sources in the soil. The Leizhou Peninsula is an important agricultural region in China, but the concentration and spatial distribution of Se in its soils remain unclear. To address this issue, we analyzed Se concentration data from 3333 soil samples collected at the depth of 0-20 cm from the Leizhou Peninsula, covering an area of 13,225 km2. The results indicate that the mean soil Se concentration was 0.50 mg kg-1, with Se-enriched soils being widely distributed. This provides prospects for the development of Se-enriched crops. Using random forest (RF) modeling and correlation analysis, the clay minerals (Fe-Al oxides), chemical index of alteration (CIA), and soil organic carbon (SOC) have been identified as the principal determinants of Se distribution in soil. During the weathering processes of the basalts, Fe-Al oxides serve as a crucial factor in Se accumulation in the red soils. Furthermore, the tropical climate further contributes to increasing the degree of weathering and the proportion of clay minerals and SOC in the soil. Atmospheric deposition derived from marine and precipitation is another important factor that promotes Se flux into soils. In conclusion, the distribution pattern of Se is jointly determined by the weathering process of basalt and climatic conditions. The results of the geographically weighted regression (GWR) analysis revealed that SOC, Al2O3, TFe2O3 and CIA change spatially and exhibit a spatial non-stationarity relationship with Se. This study offers a theoretical foundation and practical guidance for the sustainable development of Se-enriched agriculture and similar climate settings worldwide.

Effects of selenate on greenhouse gas release and microbial community variations during swine manure composting

Co-composting of livestock manure and selenate is an effective means to produce selenium-rich organic fertilizer. However the effect of selenate on greenhouse gas emission during composting is still unknown. To probe the influences of selenate on greenhouse gas and microbial community changes during swine manure composting. Various dose of selenate were added to the fresh swine manure and wheat straw for 80 days aerobic composting, sequentially labeled as T1 (control) to T6 (0, 1, 2, 3, 4 and 5 mg kg-1). Results indicated that selenate generally increased the nitrous oxide (N2O) and ammonia (NH3) emissions while presented varying impacts on methane (CH4) emissions. Compared with the control, adding 2 and 5 mg kg-1 selenate reduced the CH4 emission by 39.60% and 13.75%, respectively, while other concentrations presented opposite results. Meanwhile, adding 2 mg kg-1 selenate could reduce the global warming potential and improve the compost maturity. According to the microbial results, adding 2 mg kg-1 selenate enhanced the richness and variety of the microbes and might influence Proteobacteria, Chloroflexi, Actinobacteria and Methylococcaceae_unclassified to decrease the global warming potential.

A Multi-Channel Handheld Diagnostic Device Based on Green Biomimetic Material for Point-of-Care Testing of Vitamin C in Human Fluids

In the era of "Great Health", maintaining an appropriate level of vitamin C is crucial for human health as it directly impacts the proper functioning of the immune system. In this study, a handheld nonenzymatic electrochemical sensor based on biomimetic material prussian blue functionalized polydopamine is proposed for point-of-care testing (POCT) of vitamin C in human fluids. Particularly, Prussian blue, known as a bio-antidote, and polydopamine, a main component of cuttlefish ink, ensure the safety and reliability of home testing. The experimental results quantitatively demonstrate that this electrochemical POCT sensor enables rapid and accurate determination of vitamin C with a wide linear detection range from 0.2 to 200 µm, a low limit of detection at 0.03 µm, and high sensitivity at 0.33 µA µm-1 cm-2. More importantly, the performance evaluation using human urine and saliva samples confirms satisfactory accuracy and recovery rates for vitamin C determination by this electrochemical POCT sensor. Thus, the proposed handheld electrochemical POCT sensor holds potential utility as an affordable tool for VC determination and home-based healthcare.

Prediction and pathway models for assessing soil properties influencing soil selenium enrichment and bioavailability in Aksu Prefecture, northwest China

Selenium (Se) in soil is the primary source of human Se intake, and its content and bioavailability are influenced by soil physicochemical properties. However, the influence of soil physicochemical properties on Se enrichment and bioavailability in soil remains uncertain. Therefore, this study investigated 536 soil samples and their corresponding wheat grain samples collected from the oasis zone of Aksu Prefecture, located in northwest China. The Se content, spatial distribution, and bioaccumulation factor (BCF) in soil and wheat grains as well as soil Se fractions were examined, and the effects of soil physicochemical properties on Se enrichment and bioavailability were assessed. The results indicated that the mean Se content of soil (0.32 mg/kg) surpassed the national Se background level for Chinese soil by a factor of 1.10. The average Se content (0.13 mg/kg) in wheat grains met the national standard for Se-rich cereal products. The prediction model established using multiple linear regression showed that soil calcium carbonate (CaCO3), organic matter (OM), cation exchange capacity (CEC), and electrical conductivity (EC) were the main physicochemical factors influencing Se enrichment in soil, accounting for 29 % of the variation. The main physicochemical factors affecting Se bioavailability were CaCO3, OM, and iron, and the main Se fractions were the exchangeable and humic acid-bound Se fractions, which together explain 12 % of the variance. Additionally, a structural equation model was employed to analyze the pathways and interactions of soil factors on soil Se enrichment and bioavailability. The results indicated that soil CaCO3 and OM were the most critical factors affecting Se enrichment and bioavailability in soil. These findings can provide technical guidance for the cultivation and layout of Se-rich wheat in local and other similar regions around the world.

Volatile Substances, Quality and Non-Targeted Metabolomics Analysis of Commercially Available Selenium-Enriched Rice

Selenium is an essential trace element for the human body. However, its intake is usually low. Therefore, the production and utilization of selenium-enriched food are currently a research hotspot. Despite the remarkable scientific interest in this topic, only a few of the numerous studies focus on commercially available products. This study examined the nutritional quality, physical and chemical properties, cooking characteristics, and eating quality of four commercially available hot-selling rice types, both selenium-enriched and non-selenium-enriched, and discovered that selenium-enriched rice outperforms ordinary rice in terms of both nutritional quality and taste. In addition, we employed the gas chromatography-ion mobility spectrometry (GC-IMS) technique to evaluate the volatile chemicals of rice. Some of the chemicals that made selenium-rich rice taste different from regular rice were pentanal, (E)-2-Hexen-1-ol, ethyl-3-methyl butanoate, 2-furan methanol acetate, ethyl heptanoate, ethyl hexanoate, methyl hexanoate, isopentyl pentanoate, and ethyl butyrate. We looked into the metabolite profiles of rice using LC-MS-based untargeted metabolomics to obtain a better idea of the different metabolites that are found in selenium-enriched rice compared to regular rice. We identified a total of 522 metabolites and screened 182, 227, and 100 differential metabolites in selenium-enriched (A) vs. non-selenium-enriched rice (B/C/D) groups, respectively. This study revealed that selenium primarily influenced the metabolism of D-amino acids, starch, sucrose, and linoleic acid in rice. This study systematically analyzed the quality differences between selenium-enriched and non-selenium-enriched rice available on the market. For consumers, it is essential to understand the quality of selenium-rich rice on the market to guide the purchase of rice.

A nonlinear association between total selenium intake and blood selenium concentration: An analysis based on the National Health and Nutrition Examination Survey 2011-2018

Diets are the major sources of selenium (Se) and biomonitoring Se is used for the assessment of Se status. The present study explored the association between Se intake and blood Se concentration from the National Health and Nutrition Examination Survey 2011-2018 data for optimizing Se reference intakes among American adults and interpreted the data in the context of exposure guidance values. Weighted linear regression models were conducted to evaluate the association between Se intake and blood Se concentration. Restricted cubic spline models were employed to explore the dose-response association between total Se intake and blood Se concentration. Blood Se concentrations were compared to biomonitoring equivalents established for exposure guidance values. For gender, race, educational status, poverty income ratio, body mass index, smoking status, dietary Se intake, and total Se intake, significant differences were observed among quartiles of blood Se concentration. There was no significant difference for age and alcohol use. There was a positive association between dietary Se intake and blood Se concentration although the association was not statistically significant following the adjustments for covariates. When the associations between total Se intake and blood Se concentration were assessed, no statistically significant relationship was found. The restricted cubic spline supported a significant nonlinear association between total Se intake and blood Se concentration with/without the adjustments of covariates. The present work displayed a baseline for Se exposure among American adults. Considering the sex difference in dietary Se and blood Se concentration, it is necessary to establish gender-based Se reference intakes.

Estimated daily intake and health risk assessment of total and organic selenium in crops across areas with different selenium levels

BACKGROUND

The health risk of Se has gained significant attention. Previous studies mainly focused on the health risk of total Se in high-Se area. Less attention has been paid to the health risk of organic selenium in areas with varying selenium levels.

METHODS

A total number of 109 crop samples (edible parts) were collected in Langao County, Shannxi Province, China from 2018 to 2020, including 42 corn, 18 rice, 9 sweet potato, 25 potato, 12 radish, and 3 eggplant samples. The hydride generation atomic fluorescence spectrometry (HG-AFS) method was used to determine the total and organic Se contents.

RESULT AND CONCLUSION

(1) Corn (2.82 mg/kg), rice (0.44 mg/kg), potato (6.56 mg/kg), and eggplant (0.77 mg/kg) in high-Se area, as well as sweet potato (1.07 mg/kg) and radish (4.28 mg/kg) in medium-Se area, exhibited the highest total Se content among all crops in this county, and 5-328 times higher than the values of Se-enriched standard (2) The average daily intake of total/organic Se of residents in high-Se area reached 676/449 μg/day, which was 1-4 times higher than levels observed in medium-Se area (419/257 μg/day) and low-Se area (196/128 μg/day). The organic Se daily intakes from dietary combinations of rice + radish and rice + eggplant in high-Se area lower than 400 μg/day, which could be safely consumed. The organic Se daily intakes from dietary combinations of sweet potato + radish and sweet + eggplant in medium-Se area higher than 400 μg/day, which could not be safely consumed. The total / organic Se daily intakes of all dietary combinations in low-Se area lower than 400 μg/day, which could be safely consumed. (3) The health risk associated with crops might be overestimated due to the higher non-carcinogenic risk attributed to total Se compared to organic Se. The present study demonstrated that daily intake and health risk of total and organic Se in crops across areas with different Se levels varied significantly.

Effects of high-dose selenium-enriched Saccharomyces cerevisiae on growth performance, antioxidant status, tissue fat content and selenium concentration, and selenoenzyme mRNA expression in chicks

Selenium-enriched Saccharomyces cerevisiae (SSC) as organic selenium (Se) has been shown to have better advantages and is approved for use in animal feed rather than inorganic Se, however, there is little available data on the toxic effects of SSC on poultry. The present study was conducted to investigate the effects of high-dose SSC on growth performance, antioxidant status, tissue fat content and Se concentration, and selenoenzyme mRNA expression in chicks. A total of 500, 1-day-old SPF chicks were randomly divided into 5 groups with 10 replicates of 10 chicks each. Group 1 served as a control and was fed a basal diet supplemented with 0.15 mg/kg Se from sodium selenite (SS), group 2 was fed the basic diet supplemented with 1.5 mg/kg Se from SS, while groups 3, 4, and 5 were fed the basal diet supplemented with 1.5, 5 and 10 mg/kg Se from SSC, respectively. The results showed that SS and SSC supplementation significantly affected the average daily feed intake (ADFI), feed/gain ratio (FCR), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, total antioxidant capacity (T-AOC), malondialdehyde (MDA) content, tissue fat content and Se concentration, and GPx1 and GPx4 mRNA levels compared with the control group (P < 0.05). Compared with group 2, group 3 exhibited higher GPx and SOD activities, tissue Se concentration, and lower MDA content on d 30, and higher Se concentration, GPx1 mRNA levels in liver and breast muscle and GPx4 mRNA levels in liver and thigh muscle, and lower MDA content on d 60 (P < 0.05). The results of correlation analysis showed that high-dose SSC supplementation was positively correlated with AFDI, FCR, MDA content, and tissue Se concentration, and negatively correlated with GPx and SOD activities, T-AOC, GPx1 and GPx4 mRNA levels in tissues. In conclusion, up to 1.5 mg/kg Se from SSC in diet may be a safe concentration for chicks that exhibited better biological effects than SS, the toxic effects of high-dose SSC supplementation mainly exhibited growth decrease, peroxidation and lipid metabolism disturbance, and became stronger with the increase of dietary Se levels.

Overlapping Transcriptome Alterations Reveal the Mechanism of Interaction between Selenium and Zinc and Their Common Effect on Essential Nutrient Metabolism in Mung Bean (Vigna radiata L.)

Selenium (Se) and zinc (Zn) deficiencies have become serious global food security and public health problems. Biofortification through foliar fertilizer is a nonspecific, low-tech, and cost-effective strategy. Se and Zn have overlapping physiological roles and interacting relationships in plants. Mung bean is superior for Se enrichment and an excellent Zn carrier. However, the molecular mechanism underlying the interaction between Se and Zn in the mung bean remains unclear. Herein, Se and Zn accumulation, antioxidant activities, physiological determination, and transcriptomic analysis were performed under both Se and Zn treatments. Common essential roles of Se and Zn in mung bean were reflected by the comprehensively altered ten physiological indexes under both Se2 (24 g·ha-1) and Zn1 (1.2 kg·ha-1) treatments. Overlapping transcriptome changes and common DEGs in two compared groups revealed that the upregulated expression of sulfate transporters (SULTRs), phosphate transporters (PHTs), and Zinc-regulated/Iron-regulated-like protein (ZIP) family genes under Se and Zn treatments directly promoted both Se and Zn intakes. Furthermore, the altered Se/Sulfur, nitrogen, and carbohydrate metabolisms are closely interlinked with the uptake and assimilation of Se and Zn via the 20 key genes that we filtered through the protein-protein interaction (PPI) network analysis. Further analysis indicated that l-methionine γ-lyase (E 4.4.1.11) genes may play an important role in the transamination of selenomethionine and its derivatives; glutamine synthetase (GS), nitrate reductase (NR), and starch synthase (SS) genes may regulate the nitrogen assimilation and carbohydrate metabolism, which provide more carriers for Se and Zn; glutathione peroxidase (GPx), glutamate-cysteine ligase catalytic subunit (GCLC), and serine acetyltransferase (SAT) genes may accelerate the GSH-GSSH cycle and promote Se and Zn storages. This study provides new molecular insights into the comprehensive improvement of the nutritional quality of mung beans in Se and Zn biofortification productions.

Risk assessment and impact prediction of associated heavy metal pollution in selenium-rich farmland

Selenium (Se)-rich farmland is a valuable and nonrenewable resource for addressing the global challenge of Se deficiency. However, frequent warnings of heavy metal pollution have threatened the safety and legitimacy of Se-rich functional agriculture, eventually damaged public health security. Definitive and judgmental quantitative studies on this hazardous phenomenon are still missing. Relevant reviews published in the past have summarized textual descriptions of the problem, lacking the support of the necessary statistical analysis of the data. Based on the collected publications, the present study evaluated and analyzed the sources, risks and impacts of heavy metal pollution in Se-rich farmland. Concentrations of cadmium (Cd), arsenic, lead and zinc in Se-rich farmland were significantly higher than those in non-Se-rich farmland, especially Cd. Pollution source analyses indicated that Se enrichment and heavy metal pollution occurred simultaneously in farmland, related to Se-heavy metal homology in rocks. According to environmental risk assessment, both serious Cd pollution and the narrow Se concentration range of safety utilization limited the availability of Se-rich farmland. Pollution impact predictions showed that the pollution in Se-rich farmland would result in serious human health risks to consumers and economic losses of 4000 yuan/hm2 on production side. Tackling Cd pollution was anticipated to recover economic losses (81 %) while lowering the carcinogenic (60 %) and non-carcinogenic (10 %) health risks. Our study also provided recommendations to address heavy metal pollution in Se-rich farmland. The two criteria should be followed by pollution control strategies applied to Se-rich functional agriculture including (i) not affecting the original Se enrichment in plant and (ii) not being interfered by Se in soil-plant systems. This will provide valuable information for Se-rich functional agriculture and public health security.

Selenium dynamics in plants: Uptake, transport, toxicity, and sustainable management strategies

Selenium (Se) plays crucial roles in human, animal, and plant physiology, but its varied plant functions remain complex and not fully understood. While Se deficiency affects over a billion people worldwide, excessive Se levels can be toxic, presenting substantial risks to ecosystem health and public safety. The delicate balance between Se's beneficial and harmful effects necessitates a deeper understanding of its speciation dynamics and how different organisms within ecosystems respond to Se. Since humans primarily consume Se through Se-rich foods, exploring Se's behavior, uptake, and transport within agroecosystems is critical to creating effective management strategies. Traditional physicochemical methods for Se remediation are often expensive and potentially harmful to the environment, pushing the need for more sustainable solutions. In recent years, phytotechnologies have gained traction as a promising approach to Se management by harnessing plants' natural abilities to absorb, accumulate, metabolize, and volatilize Se. These strategies range from boosting Se uptake and tolerance in plants to releasing Se as less toxic volatile compounds or utilizing it as a biofortified supplement, opening up diverse possibilities for managing Se, offering sustainable pathways to improve crop nutritional quality, and protecting human health in different environmental contexts. However, closing the gaps in our understanding of Se dynamics within agricultural systems calls for a united front of interdisciplinary collaboration from biology to environmental science, agriculture, and public health, which has a crucial role to play. Phytotechnologies offer a sustainable bridge between Se deficiency and toxicity, but further research is needed to optimize these methods and explore their potential in various agricultural and environmental settings. By shedding light on Se's multifaceted roles and refining management strategies, this review contributes to developing cost-effective and eco-friendly approaches for Se management in agroecosystems. It aims to lead the way toward a healthier and more sustainable future by balancing the need to address Se deficiency and mitigate the risks of Se toxicity.

DGT and kinetic analyses differentiate Se and Cd bioavailability in naturally enriched paddy soils

Naturally selenium (Se)-rich soils often contain elevated cadmium (Cd) levels, complicating safe production of Se-enriched rice. This study employed diffusive gradients in thin-films (DGT) and DGT-induced fluxes in soils (DIFS) model to determine Se and Cd bioavailability in paddy soils. We investigated desorption kinetics and accumulation patterns in rice using paired rhizosphere and grain samples from 65 field sites in Guangxi, China, encompassing Se-enriched karst and non-karst soils. Despite greater total Se and Cd contents in karst soils, their elevated pH, along with greater soil organic matter and total Fe, Mn, and Ca contents, constrained Se and Cd bioavailability, resulting in similar accumulation levels in rice grains from both soil categories. DIFS-derived kinetic data revealed that Se was replenished 75.4 times faster than Cd, but Cd had an 83.2 times larger labile pool, leading to a stronger overall Cd resupply capacity. DGT-based labile Se:Cd molar ratios showed that rice Cd content declined sharply as the ratio increased from 0.7 to 4.0, stabilizing at its lowest level when exceeding 20. Moreover, DGT measurements demonstrated stronger correlations with grain Se and Cd concentrations compared to traditional methods. Our findings highlight the effectiveness of DGT and kinetic analyses in determining Se and Cd bioavailability in high-background paddy soils, offering insights for balancing Se fortification and Cd risk mitigation in rice production.

Effects of combined application of Se and ammonium fertilizers on the growth and nutritional quality of maize in Hg-polluted soil under two irrigation conditions and its health risk assessment

The interactive effects of Se (Na2SeO3) and ammonium fertilizers ((NH4)2SO4 and NH4Cl) on the growth and quality of maize (Zea mays L.) in mercury (Hg)-contaminated soil were studied under different water conditions. This study determined how two nutrient sources (Se and NH4+-N) interacted to improve the yield, quality, and safety of maize to ensure food security and quality assurance under the stress of heavy metal Hg. The experiment was conducted under two irrigation conditions: W1 (complete irrigation condition, 60-70% of water-holding capacity) and W2 (restricted irrigation condition, 40-50% of water-holding capacity). The combined treatment of Se and ammonium fertilizers significantly improved the growth of maize and the quality of grain in Hg-polluted soil. When Na2SeO3 and (NH4)2SO4 were combined, the growth and quality of maize increased the highest among all treatments. The interaction between Na2SeO3 and ammonium fertilizers significantly affected the available Hg/methylmercury (MeHg) content in soil and the Hg/MeHg concentration in maize. NH4Cl significantly increased the content of available Hg/MeHg in soil and increased the accumulation of Hg/MeHg in maize tissues due to Cl-. However, the treatments containing Na2SeO3 or (NH4)2SO4 significantly reduced the content of available Hg/MeHg in soil, reduced the accumulation of Hg/MeHg in maize tissues, and significantly reduced the possible health risks to human beings. The treatments containing Na2SeO3 or (NH4)2SO4 promoted maize growth by increasing the Se content in maize tissues and reducing the Hg/MeHg content, relieving the stress induced by Hg, and increasing the nutrient content. The combined treatment of Na2SeO3 and (NH4)2SO4 had the best effect in this experiment. This study also showed that this strategy is helpful in reducing the opportunities for consumers to accumulate Hg/MeHg by eating maize and its derivatives, thus ensuring food safety. Se and ammonium fertilizer can be used together to increase maize yield and develop agricultural production in Hg-polluted areas, which may have a significant impact on global food production. In addition, this simple method can help farmers manage soil affected by heavy metal pollution.

Legal Standards for Selenium Enriched Foods and Agricultural Products: Domestic and International Perspectives

Background/Objectives: Selenium is indispensable for human health, yet vast regions worldwide grapple with selenium-deficient soils, rendering dietary intake a critical avenue for supplementation. This narrative review aims to systematically examine and compare domestic and international regulations and standards related to selenium enrichment, providing insights to enhance regulatory frameworks and standardization within the selenium-enrichment industry. Methods: From June to September 2024, we conducted a comprehensive search of official websites belonging to international organizations (e.g., Codex Alimentarius Commission, European Union) and governmental agencies of countries such as China and the United States. Keywords, like "selenium enrichment", "selenium standards", and "selenium detection methods", were employed to identify pertinent regulations, standards, and guidelines encompassing intake benchmarks, detection methodologies, product specifications, technical guidelines for production, labeling requirements, and certification management norms. Results: Our analysis reveals several challenges within the current selenium-enriched regulatory and standardization systems, including inconsistent product determination criteria and limit settings, incomplete technical guidelines for selenium-enriched agricultural production, and a lack of unified regulations for labeling selenium-enriched agricultural products. Conclusions: These findings underscore the need for harmonization of standards and enhanced regulatory oversight. To address these issues, we recommend bolstering safety risk assessments for selenium-enriched agricultural products, establishing and refining a comprehensive standard system for selenium-enriched agriculture, and intensifying quality and safety supervision. This study offers a valuable reference for policymakers and stakeholders to promote the sustainable development of the selenium-enrichment industry.

Spatial distribution and enrichment characteristics of selenium in paddy soil and rice around the Dongting Lake

Selenium (Se) deficiency is a major global health issue. Given that the Dongting Lake region is a significant agricultural production area in China, its soil and geographical properties have a marked influence on Se accumulation in rice. Investigating these factors and their importance can provide technical guidance for the production of Se-rich rice locally and in other similar regions worldwide. Such studies can foster Se-enriched agricultural practices on a global scale, contributing to improved human health and environmental quality. Therefore, in this study, we investigated 15,403 paddy soil samples and their corresponding rice grains from the Dongting Lake area, by analyzing their Se content, spatial distribution, and bioaccumulation factor (BCF). The effects of parent materials, soil characteristics (physicochemical), and geographical factors on Se content in soil, rice grains, and BCF were also assessed. We found that the average Se content in the paddy soil of the Dongting Lake area was 0.43 mg/kg, which was 1.48 folds higher than the background Se content (0.29 mg/kg) in Chinese soil. The average Se content in rice grains was 0.059 mg/kg, surpassing the Chinese standard for Se-rich rice (0.04 mg/kg). Se distribution in the paddy soil and rice were the highest in the western and central regions and lowest in the eastern region. Se-enriched rice and Se-enriched rice fields are widely distributed in Dongting Lake area. Seven parent materials significantly influenced soil Se and BCF. Correlation analysis revealed positive correlations between soil Se and soil organic matter (SOM), zinc, altitude, and mean annual precipitation. BCF was positively correlated with pH and mean annual temperature. The Random Forest model highlighted that SOM played a pivotal role in soil Se enrichment, being the most influential factor for both soil and rice enrichment (RR type), whereas pH exerted the most significant influence on soil enrichment without rice enrichment (RN type).

Effect of Paenibacillus favisporus CHP14 inoculation on selenium accumulation and tolerance of Pakchoi (Brassica chinensis L.) under exogenous selenite treatments

The effects of Paenibacillus favisporus CHP14 inoculation on selenium (Se) accumulation and Se tolerance of Pakchoi were studied by a pot experiment conducted in greenhouse. The results revealed that the growth traits such as plant height, root length, and biomass were significantly elevated during CHP14 treatment at 0 ∼ 8.0 mg·kg-1 Se(IV) levels. CHP14-inoculated plants accumulated more Se in root and shoot, which were 24.1%∼57.3% and 7.5%∼50.9% higher than those of non-inoculated plants. The contents of leaf nitrogen (N), phosphorus (P), magnesium (Mg), and iron (Fe), as well as the ratio of indoleacetic acid and abscisic acid contents (IAA/ABA) were increased by CHP14 inoculation, and positively associated with photosynthetic pigment contents (p < 0.05). At ≥ 4.0 mg·kg-1 Se(IV) levels, superoxide dismutase, peroxidase, and glutathione peroxidase activities of Pakchoi roots were increased with CHP14 inoculation, by 9.9%∼17.1%, 28.4%∼40.7%, and 7.4%∼15.3%, respectively. Moreover, CHP14 inoculation enhanced ascorbate-glutathione (AsA-GSH) metabolism in roots by upregulating the related enzymes activities and antioxidant contents under excess Se(IV) stress. These findings suggest that CHP14 is beneficial to improve plant growth and enhance Se(IV) resistance of Pakchoi, and can be exploited as potential inoculants for phytoremediation process in Se contaminated soil.

Arbuscular Mycorrhizal Fungi Ameliorate Selenium Stress and Increase Antioxidant Potential of Zea mays in Seleniferous Soil

The indigenous arbuscular mycorrhizal fungi (AMF) spores were isolated from rhizosphere soil associated with maize plants grown in natural selenium-impacted agricultural soils present in north-eastern region of Punjab, India (32°46' N, 74°46' N), with selenium concentration ranging from 2.1 to 6.1 mg kg-1 dry weight, and their role in plant growth promotion, mitigation of selenium stress and phytochemical and antioxidant potential of host maize plants in natural seleniferous soil were examined. Soils with selenium content between 2 and 200 mg kg-1 and producing plants with 45 mg selenium kg-1 dry weight are considered seleniferous soils. AMF inoculum consisting of indigenous AMF spores multiplied in pot cultures were inoculated to maize seeds at the time of sowing alongside control maize seeds in a total of 12 plots (6 replicates) made in seleniferous agricultural fields and sampled at maturity, i.e. 3 months. A significant difference was observed in plant growth parameters between control and AMF-inoculated maize plants. AMF-inoculated plants had 24.0 cm and 101.1 cm higher root and shoot length along with 27.2 g, 119.4 g and 28.1 g higher root, shoot and maize cob biomass in comparison to control plants. Se uptake studies through measurement of the emission spectrum of piazselenol complex by fluorescence spectrometry revealed that AMF inoculation led to 6.3 µg g-1 more selenium accumulation in mycorrhizal maize roots in comparison to control roots but lesser translocation to shoots and seeds, i.e. 17.17 µg g-1 and 19.58 µg g-1 lesser. AMF increased total phenolic content by 13 µg GAE mg-1 and total flavonoid content by 13.4 µg QE mg-1 in inoculated maize plants when compared to control plants. Antioxidant studies revealed that AMF inoculation also led to significant rise in enzyme activities by a difference of 115 and 193 EU g-1 in catalase, 140 and 93 EU g-1 in superoxide dismutase, 15 and 37 EU g-1 in ascorbate peroxidase and 19.8 and 23.6% higher DPPH radical scavenging activities, respectively, in shoots and roots of plants with AMF inoculation. The findings of this study imply that AMF inoculated to maize plants in seleniferous field boost their plant growth and phytochemical and antioxidant properties, as well as minimize Se bioaccumulation in shoots and seeds of plants inoculated with AMF in comparison to control plants.

Effects and mechanisms of different exogenous organic matters on selenium and cadmium uptake by rice in natural selenium-cadmium-rich soil

Many natural selenium (Se)-rich rice plants are being polluted by cadmium (Cd). In this study, for reducing Cd concentrations in rice grains while maintaining Se concentrations, the effects of different exogenous organic matters (OMs), such as humic acid (HA), cow manure (CM), and vermicompost (VC), on Se and Cd uptake in rice growing in natural Se-Cd-rich paddy soils were investigated by pot experiments. The Se and Cd concentrations in the soil solution, their species in the soil, and their concentrations and translocations in rice tissues were determined. Results showed that different exogenous OMs exhibited distinct percentage changes in Se and Cd levels in rice grains with amplitudes of -19.42 % and -56.90 % (significant, p < 0.05) in the HA treatments, +10.79 % and -1.72 % in the CM treatments, and +15.83 % and -15.52 % in the VC treatments, respectively. Correlation analysis showed that the concentrations of Se and Cd in rice grains might be primarily influenced by their concentrations in the soil solution, rather than the Se/Cd molar ratios in the soil solution or their translocations in rice tissues. HA decreased Se and Cd bioavailability in soil by increasing HA-bound Se and residual Cd, respectively. Meanwhile, HA increased soil solution pH, which was negative for Cd bioavailability but positive for Se bioavailability. This additive effect made HA lowered Cd concentration more than Se concentration in both soil solution and grain. CM and VC did not have this additive effect and thus have limited effects on grain Se and Cd concentrations. In addition, according to grain Se and Cd concentrations, to prioritize reducing Cd in rice, use HA; to prioritize increasing Se in rice, use VC. This study enhances the understanding of Se and Cd uptake mechanisms in rice with the applications of various OMs and offers potential remediation methods for Se-Cd-rich paddy soils.

Bioreduction of Se(IV) by Lactiplantibacillus plantarum NML21 and synthesis of selenium nanospheres Se(0)

Selenium nanospheres (SeNPs) show less toxicity and greater bioavailability than selenite salts. This research demonstrated the substantial tolerance and efficient conversion of Se(IV) into SeNPs by Lactiplantibacillus plantarum NML21. The bioreduction process of Se(IV) and the properties of SeNPs, including their morphology, particle size, and stability, were investigated with techniques including SEM, EDX, TEM, XPS, FT-IR, dynamic light scattering, XRD, and Raman spectroscopy. Under high selenium stress, certain cells displayed significant deformation and rupture, and released SeNPs as the main product of the bioreduction of Se(IV). These SeNPs were red, amorphous, zero-valent, and spherical, with an average diameter of 160 nm. Spectroscopic analysis highlighted that the functional groups of CO and CO are key to the bioreduction of Se(IV). The study suggested preliminary mechanisms for the bioreduction of Se(IV) and the formation and release of SeNPs by lactic acid bacteria. NML21 may therefore be a promising candidate for SeNPs synthesis.

Influence of smoking status on the relationship between serum selenium and cause-specific mortality in US adults

Selenium, a crucial antioxidant in the body, has been linked to all-cause and cause-specific mortality. However, the relationship between selenium and mortality in the general population remains unclear. A total of 5449 participants in the National Health and Nutrition Examination Survey (NHANES) (2003-2004, 2011-2016) were analyzed to track participant mortality until December 31, 2019. The COX proportional hazard model, Kaplan‒Meier survival analysis and restricted cubic spline regression analysis were used to investigate the associations. Subgroup analysis was conducted on the basis of age (≤ 60, > 60), sex (male, female), and smoking status (nonsmoker, former smoker, and current smoker). The second quartile was associated with lower all-cause mortality and noncardiovascular mortality (HR and 95% CI 0.61,0.45-0.83;0.59,0.42-0.83, respectively). The third quartile was associated with lower cardiovascular-related mortality (HR and 95% CI 0.49, 0.32-0.76). Elevated serum selenium concentrations were associated with lower all-cause mortality, noncardiovascular mortality (range ≤ 129.82 μg/L), and cardiovascular mortality (range ≤ 129.08 μg/L). Subgroup analysis revealed a positive correlation between the serum selenium concentration (range ≥ 129.82 μg/L) and all-cause mortality among the subgroup of current smokers (p < 0.001). This study indicates that the protective effect of the serum selenium concentration on cause-specific mortality decreases beyond a certain range in the general population, potentially increasing the risk of death among current smokers.

Exogenous selenium promotes cadmium reduction and selenium enrichment in rice: Evidence, mechanisms, and perspectives

Cadmium (Cd) accumulation in rice, a global environmental issue, poses a significant threat to human health due to its widespread presence and potential transfer through the food chain. Selenium (Se), an essential micronutrient for humans and plants, can reduce Cd uptake in rice and alleviate Cd-induced toxicity. However, the effects and mechanisms of Se supplementation on rice performance in Cd-contaminated soil remain largely unknown. Here, a global meta-analysis was conducted to evaluate the existing knowledge on the effects and mechanisms by which Se supplementation impacts rice growth and Cd accumulation. The result showed that Se supplementation has a significant positive impact on rice growth in Cd-contaminated soil. Specifically, Se supplementation decreased Cd accumulation in rice roots by 16.3 % (11.8-20.6 %), shoots by 24.6 % (19.9-29.1 %), and grain by 37.3 % (33.4-40.9 %), respectively. The grain Cd reduction was associated with Se dose and soil Cd contamination level but not Se type or application method. Se influences Cd accumulation in rice by regulating the expression of Cd transporter genes (OSLCT1, OSHMA2, and OSHMA3), enhancing Cd sequestration in the cell walls, and reducing Cd bioavailability in the soil. Importantly, Se treatment promoted Se enrichment in rice and alleviated oxidative damage associated with Cd exposure by stimulating photosynthesis and activating antioxidant enzymes. Overall, Se treatment mitigated the health hazard associated with Cd in rice grains, particularly in lightly contaminated soil. These findings reveal that Se supplementation is a promising strategy for simultaneous Cd reduction and Se enrichment in rice.

Application of selenium to reduce heavy metal(loid)s in plants based on meta-analysis

Agricultural soils are currently at risk of pollution from toxic heavy metal(loid)s (HMs) due to human activities, resulting in the excessive accumulation of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), lead (Pb) and zinc (Zn) in food plants. This poses significant risks to human health. Exogenous selenium (Se) has been proposed as a potential solution to reduce HMs accumulation in plants. However, there is currently a lack of comprehensive quantitative overview regarding its influence on the accumulation of HMs in plants. This study utilized meta-analysis to consolidate the existing knowledge on the impact of Se amendments on plant HMs accumulation from contaminated soil media. The present study conducted a comprehensive meta-analysis on literature published prior to December 2023, investigating the effects of different factors on HMs accumulation by meta-subgroup analysis and meta-regression model. Se application showed an inhibitory effect on plant uptake of Hg (28.9%), Cr (25.5%), Cd (25.2%), Pb (22.0%), As (18.3%) and Cu (6.00%) concentration. There was a significant difference in the levels of HMs between treatments with Se application and those without Se application in various plant organs. The percentage changes in the HMs contents of the organs varied from -13.0% to -22.0%. Compared with alkaline soil (pH > 8), Se application can reduce more HMs contents in plants in acidic soil (pH < 5.5) and neutral soil (pH = 5.5-8). For daily food plants(e.g. rice, wheat and corn), Se application can reduce HMs contents in Oryza sp., Triticum sp. and Zea sp., ranging from 14.0-20.0%. Our study emphasizes that the impact of Se on reducing HMs depends on the single or combined effects of Se concentration, plant organs, plant genera and soil pH condition.

Study on Selenium Assimilation and Transformation in Radish Sprouts Cultivated Using Maillard Reaction Products

The organic selenium (Se), particularly in the form of selenoamino acids, in non-edible sections or by-products of Se-enriched plants, has the potential to generate Maillard reaction products (MRPs) during thermal treatment or fermentation. To elucidate the recycling process of organic selenium in foods and improve the utilization rate of Se, the biotransformation of organic selenium was studied by the cultivation of edible radish sprouts with Se-MPRs. Maillard reactions were simulated using selenoamino acids (SeAAs; selenomethionine and methylselenocysteine) and reducing sugars (glucose and fructose) for preparing Se-MRPs. The structures of the possible dehydrated Se-MRPs were analyzed using a HPLC-ESI-MS/MS system based on their fragmentation patterns and Se isotopic characteristics. Se absorption by the radish sprouts cultivated using Se-MRPs was estimated by the corresponding Se in the SeAAs and the total Se contents. The capabilities of SeAA transformation and total Se assimilation by the sprouts were related to the substrate composition during the Se-Maillard reaction. A particular Se-MRP (selenomethionine + fructose) increased SeAAs transformation by 33.8% compared to selenomethionine. However, glucose and fructose seemed to inhibit the transformation of the Se-MRPs to SeAAs by 10.0 to 59.1% compared to purified Se-MRPs. These results provide key references for the efficient utilization of organic Se in the cultivation of Se-enriched sprouts.

Transcriptome analysis reveals the promoting effects of exogenous melatonin on the selenium uptake in grape under selenium stress

Introduction

Exogenous melatonin (MT) can promote horticultural crops growth under stress conditions.

Methods

In this study, the effects of exogenous MT on the accumulation of selenium (Se) in grape were studied under Se stress.

Results and discussion

Under Se stress, exogenous MT increased the biomass, content of photosynthetic pigments and antioxidant enzyme activity of grapevines. Compared with Se treatment, MT increased the root biomass, shoot biomass, chlorophyll a content, chlorophyll b content, carotenoids, superoxide dismutase activity, and peroxidase activity by 18.11%, 7.71%, 25.70%, 25.00%, 25.93%, 5.73%, and 9.41%, respectively. Additionally, MT increased the contents of gibberellin, auxin, and MT in grapevines under Se stress, while it decreased the content of abscisic acid. MT increased the contents of total Se, organic Se and inorganic Se in grapevines. Compared with Se treatment, MT increased the contents of total Se in the roots and shoots by 48.82% and 135.66%, respectively. A transcriptome sequencing analysis revealed that MT primarily regulated the cellular, metabolic, and bioregulatory processes of grapevine under Se stress, and the differentially expressed genes (DEGs) were primarily enriched in pathways, such as aminoacyl-tRNA biosynthesis, spliceosome, and flavonoid biosynthesis. These involved nine DEGs and nine metabolic pathways in total. Moreover, a field experiment showed that MT increased the content of Se in grapes and improved their quality. Therefore, MT can alleviate the stress of Se in grapevines and promote their growth and the accumulation of Se.

Comprehensive evaluation of factors influencing selenium fertilization biofortification

BACKGROUND

Dietary selenium (Se) deficiency, stemming from low Se concentrations in agricultural products, threatens human health. While Se-containing fertilizers can enhance the Se content in crops, the key factors governing Se biofortification with Se fertilization remain unclear.

RESULTS

This study constructed a global meta-analysis dataset based on field experiments comprising 364 entries on Se content in agricultural products and 271 entries on their yield. Random forest models and mixed effects meta-analyses revealed that plant types (i.e., cereals, vegetables, legumes, and forages) primarily influenced Se biofortification, with Se fertilization rates being the next significant factor. The random forest model, which included variables like plant types, Se fertilization rates, methods and types of Se application, initial soil conditions (including Se content, organic carbon content, and pH), soil types, mean annual precipitation, and temperature, explained 82.14% of the variation in Se content and 48.42% of the yield variation in agricultural products. For the same agricultural products, the increase in Se content decreased with higher rates of Se fertilization. The increase in Se content in their edible parts will be negligible for cereals, forages, legumes, and vegetable crops, when Se fertilization rates were 164, 103, 144, and 147 g Se ha-1, respectively. Conversely, while low Se fertilization rates enhanced yields, high rates led to a yield reduction, particularly in cereals.

CONCLUSION

Our findings highlight the need for balanced and precise Se fertilization strategies to optimize Se biofortification benefits and minimize the risk of yield reduction. © 2024 Society of Chemical Industry.

Foliar application of sodium selenite affects the growth, antioxidant system, and fruit quality of strawberry

Introduction

Selenium (Se) plays a vital role in various physiological processes in plants and is regarded as an essential micronutrient for human health as well.

Methods

In this study, sodium selenite solution at 10, 40, 70, and 100 mg·L-1 concentrations was foliar sprayed, and the strawberry plant growth, antioxidant system, and fruit quality with an emphasis on sugar and acid content were assessed.

Results

The results showed that 10 mg·L-1 of sodium selenite treatment promoted plant growth, while all the treated concentrations could enhance photosynthesis, the antioxidant system in leaves, the content of Se, and ascorbic acid in fruits. More importantly, 40 mg·L-1 sodium selenite treatment significantly increased fruit weight, total soluble solid, total phenolic content, and anthocyanins, as well as improved the shape index. Furthermore, it decreased the total flavonoid and proanthocyanidin content. Particularly, sodium selenite treatment at 40 and 70 mg·L-1 largely increased the ratio of soluble sugars to titratable acid. The changes of predominant sugars and organic acids during fruit development were further investigated. The sucrose, fructose, and glucose content was upregulated by sodium selenite treatment through upregulating the activities of sucrose phosphate synthase (SPS) and acid invertase, as well as the FaSPS expression. In addition, sodium selenite treatment inhibited the activity of citrate synthase and phosphoenolpyruvate carboxylase, rather than modulating their transcript levels to reduce the citric acid content.

Conclusions

This work presented a potentially efficient approach to enhance plant growth and fruit quality and supplement Se in strawberry, providing insights into the mechanism of regulating sugar and acid metabolism by Se.