The effects of selenium biofortification on mercury bioavailability and toxicity in the lettuce-slug food chain

Efficient remediation of Hg in soils by iron-based materials: Environmental variable effect and regulatory mechanisms

The effectiveness of iron-based materials in soil remediation has gained significant attention. The mechanisms underlying the methylation and demethylation of mercury (Hg) by iron materials were still elusive. In this study, the effect of typical iron materials (pyrrhotite, hematite, and zero-valent iron (ZVI)) on the transformation of Hg were investigated. The supplementation of various iron-based material increased the THg removal efficiency in soil, particularly with ZVI, which was 5.6-14.2 % higher than that of the control. The iron-based materials also reduced the stress of Hg on plants and soil by decreasing the transformation and translocation of Hg and increasing oxidative enzyme activity of plants. The ZVI decreased the MeHg content in plants (0.1 mg/kg) compared to the control group (0.3 mg/kg). The relative abundances of genes that encoded Hg transportation (e.g. merA), glycolysis, TCA, and iron reduction were increased with the addition of iron materials. Iron-based materials also increased the complexity of the bacterial network, thereby enhancing the robustness of the microbial environmental systems that against Hg stress. The present study provided a comprehensive assessment of the efficacy of iron-based materials in remediating Hg-contaminated soils.

Effects of different crushing methods on the properties and flavor of selenium-enriched sweet potato leaves

In this study, the physical, chemical, structural, and antioxidant characteristics of selenium (Se)-enriched sweet potato leaves (SSPL) powder produced through shear breaking and superfine grinding were examined. The superfine grinding SSPL powder had a brighter color, smaller particle size, and spherical shape. The superfine grinding SSPL powder showed improved dispersibility and solubility but reduced liquidity. Superfine grinding destroyed the crystalline area and decreased the thermal stability, while Se application did not significantly change the ordered structure. Correlation analysis showed that superfine grinding could improve crude fiber, crude lipid, total flavonoids, total polyphenol, and significantly enhance the antioxidant activities compared to shear breaking. Se enrichment can enhance the content of the crude protein and the DPPH• scavenging activity and reducing power. The flavor characteristic was not altered with the different crushing methods and Se concentrations. SSPL powder could serve as a potential resource for a new solid beverage.

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.

Microgreens Biometric and Fluorescence Response to Iron (Fe) Biofortification

Microgreens are foods with high nutritional value, which can be further enhanced with biofortification. Crop biofortification involves increasing the accumulation of target nutrients in edible plant tissues through fertilization or other factors. The purpose of the present study was to evaluate the potential for biofortification of some vegetable microgreens through iron (Fe) enrichment. The effect of nutrient solution supplemented with iron chelate (1.5, 3.0 mg/L) on the plant's growth and mineral concentration of purple kohlrabi, radish, pea, and spinach microgreens was studied. Increasing the concentration of Fe in the medium increased the Fe content in the leaves of the species under study, except for radish. Significant interactions were observed between Fe and other microelements (Mn, Zn, and Cu) content in the shoots. With the increase in the intensity of supplementation with Fe, regardless of the species, the uptake of zinc and copper decreased. However, the species examined suggested that the response to Fe enrichment was species-specific. The application of Fe didn't influence plant height or fresh and dry weight. The chlorophyll content index (CCI) was different among species. With increasing fertilisation intensity, a reduction in CCI only in peas resulted. A higher dose of iron in the medium increased the fluorescence yield of spinach and pea microgreens. In conclusion, the tested species, especially spinach and pea, grown in soilless systems are good targets to produce high-quality Fe biofortified microgreens.

Effect of vanadium on Lactuca sativa L. growth and associated health risk for human due to consumption of the vegetable

Elevated vanadium in the environment adversely affects organisms, including plants, animals, and humans. Plants act as the main conduit for environmental vanadium to enter the food chain, and simultaneously their growth response characteristics reflect vanadium toxicity efficacy for plants. The aim of the present study is to investigate lettuce (Lactuca sativa L.) growth involving morphological change, physiological adjustment, vanadium accumulation under vanadium stress, and the potential health risk (expressed as health risk index (HRI)) of adults and children who consume it. Lettuce was grown in nutrient solution with 0, 0.1, 0.5, 2.0, and 4.0 mg L-1 of pentavalent vanadium [V(V)]. Results showed that 0.1 mg L-1 V did not significantly affect lettuce growth versus control, and marked depression arose at ≥ 0.5 mg L-1 V. Foliar proline increased rapidly at ≥ 0.5 mg L-1 V. No striking change emerged in leaf cell membrane permeability at all treatments. V(V) and total vanadium concentration in plant tissues were ordered as root > stem > leaf, while tetravalent vanadium [V(IV)] was leaf > root > stem. No health risk (HRI < 1) exists for adults and children who consume lettuce at control treatment. However, the health risk occurs (HRI ˃ 1) when they both ingest the seedlings exposed to ≥ 0.1 mg L-1 V, and the risk overall markedly increases with increasing vanadium. Therefore, enough attention needs to be paid to the human health associated with the ingestion of vegetables like lettuce grown in substrata contaminated by vanadium.

Biofortification of edible plants with selenium and iodine - A systematic literature review

Soil depletion with absorbed forms of microelements is a realistic problem leading to the formation of many human, plant, animal diseases related with micronutrient deficiencies. Searching for new ways to solve this problem is a crucial for the agro-chemical approach to food production. There are many research papers on plant micronutrient fertilization. However, there is still a lack of systematic review of the literature, which summarizes the most recent knowledge on biofortification of food of plant origin with microelements. This work is a systematic review which presents the various methodologies and compares the results of the applied doses and types of fertilizer formulation with the yield and micronutrient content of edible parts of plants. The PRISMA protocol-based review of the most recent literature data from the last 5 years (2015-2020) concerns enrichment of plants with selenium and iodine. These elements, in contrast to other microelements (zinc, manganese, iron, copper and others) are given to plants most often in anionic form: selenium - SeO₃^2- and SeO₄^2-, iodine - I^- and IO₃^-, making them a separate subgroup of microelements. The review focuses on original research papers (not reviews), collected in 3 popular scientific databases: Scopus, Web of Knowledge, PubMed. This study shows how to effectively cope with hidden hunger taking into account the significance of optimized fertilization. Based on the collected data, the best method of micronutrients administration an integrated fortification strategy for selected trace elements and prospects in research/action development was proposed. It was found that the best way to enrich plants with selenium is foliar fertilization with Se(VI), in increased doses. The effectiveness of fortification is supported by the balanced nutrients fertilization, the presence of microorganisms and selection of plant varieties. Foliar fertilization, in increased doses with iodide (I^-) is in turn an effective way to enrich plants with iodine.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.