Risk assessment of heavy metal toxicity by sensitive biomarker δ-aminolevulinic acid dehydratase (ALA-D) for onion plants cultivated in polluted areas in Kosovo

Assessment of heavy metal stress in the adaptation strategies of Tulipa luanica growing on serpentine soil through some biomarkers in comparison to Tulipa kosovarica

The aim of this study was to gain a better understanding of how Tulipa luanica adapts to growth in soil with higher concentrations of heavy metals and to assess potential toxic effects using various biomarkers, in comparison to Tulipa kosovarica, a typical serpentine species. For this purpose, we analyzed the concentrations of Al, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn in the soil, as well as their accumulation in plants and their associated stress effects. The results indicate that, despite the presence of some metals in very high concentrations in the soil (Al, Fe, Mn, and Ni), they are translocated in minimal amounts within plant organs, particularly in T. luanica. Nearly all metals exhibited significantly higher concentrations in T. kosovarica when compared to T. luanica. Based on the analysis of biomarkers, it is apparent that T. luanica shows greater sensitivity to these conditions. This is evident through the decreased activity of δ-aminolevulinic acid dehydratase and levels of δ-aminolevulinic acid, malondialdehyde, and glutathione observed in T. luanica. It appears that T. luanica effectively restricts the absorption of metals in serpentine soils; however, it experiences oxidative stress induced by these metals, setting it apart from the more resilient T. kosovarica.

Stress induced by soil contamination with heavy metals and their effects on some biomarkers and DNA damage in maize plants at the vicinity of Ferronikel smelter in Drenas, Kosovo

The Ferronikel smelter in Drenas is one of the main industrial areas in the Kosovo and pollution by heavy metals causes serious threat for all living organisms on this area. The objective of this study was to determine the concentration of some heavy metals (Fe, Cu, Mn, Cr, Cd, Ni and Pb) in agricultural soils and in maize plants, and their potential toxic effects on this plant through some sensitive biochemical and molecular markers. Maize seedlings growth in nine soil samples from different locations of this area. The highest concentrations of heavy metals in soils and maize leaves were conducted close to the Ferronikel smelter, and in some locations, the nickel and chromium concertation in soils exceeded 800 mg kg-1. A significant effects of heavy metals induced toxicity resulted in the, build-up aminolevulinic acid and reduced activity of δ-aminolevulinic acid dehydratase, and chlorophyll content in the maize leaves. In general, maize seedlings growth in polluted locations showed an increase in nuclear DNA content and in G2M phase. We concluded that locations close to the smelter are affected by soil heavy metals pollution and these biochemical and molecular analysis would be a powerful ecotoxicological tool in biomonitoring of heavy metal pollution.

Risk assessment of heavy metals consumption through onion on human health in Iran

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Onions have medicational features such as anti-cancer, antimicrobial, antiviral, and antifungal.

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Onions are rich in edible flavonoids.

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Due to their physiology and ecosystem, onions have the property of accumulating heavy metals.

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Onion consumption per capita in Iran is higher than in neighboring countries.

Considering the importance of onions consumption in the household diet, controlling of heavy elements' concentration in foodstuffs is important to ensure the safety of an individual's health. This study aimed to evaluate the risk of heavy metals through onion consumption on human health. In this cross-sectional experimental study, 22 onion samples with varieties red, yellow, and white in the two autumn and winter seasons in 2020 were randomly collected from the different provinces of Kurdistan, Hamedan, and Kermanshah. The concentrations of heavy metals were evaluated with an atomic absorption spectrometer. The risks of human health were evaluated by the hazard quotient (HQ) and the obtained results were analyzed with one-way ANOVA and one sample t-test. The obtained findings demonstrated that all collected samples contained heavy metals. For example, the cadmium (Cd) concentration in onion samples in the province of West Azerbaijan, Kurdistan, Hormozgan, Isfahan, and Zanjan was 526.49, 274.49, 69.77, 67.39, 65.69 µg kg⁻¹, respectively. While the standard specified in Iran for the concentration of Cd in onions is 50 μg kg⁻¹. However, the rate of lead (Pb) contamination in samples collected from Isfahan, Hormozgan, Zanjan Khuzestan, Tehran (Varamin) was 296.50, 266.71, 261.49, 215.64, 106.19 µg kg⁻¹, respectively, which less than maximum allowable limit recommended by WHO-FAO (300 µg kg⁻¹). The HQ for non-cancerous diseases for Cd and Pb were 8.6 × 10⁻² and 1.6 × 10⁻¹, respectively, and the probability of carcinogenic risk for Pb (8.1 × 10⁻⁴) was at the level of acceptable. There is no concern about the non-carcinogenic diseases and carcinogenic risk of consuming heavy metals in onion. Therefore, for optimal management and prevention of further pollution, it is recommended to study the origin and determine the amounts of heavy metals for their potential contamination of foodstuffs from the region's soil, water, and dust.

Advances in "Omics" Approaches for Improving Toxic Metals/Metalloids Tolerance in Plants

Food safety has emerged as a high-urgency matter for sustainable agricultural production. Toxic metal contamination of soil and water significantly affects agricultural productivity, which is further aggravated by extreme anthropogenic activities and modern agricultural practices, leaving food safety and human health at risk. In addition to reducing crop production, increased metals/metalloids toxicity also disturbs plants' demand and supply equilibrium. Counterbalancing toxic metals/metalloids toxicity demands a better understanding of the complex mechanisms at physiological, biochemical, molecular, cellular, and plant level that may result in increased crop productivity. Consequently, plants have established different internal defense mechanisms to cope with the adverse effects of toxic metals/metalloids. Nevertheless, these internal defense mechanisms are not adequate to overwhelm the metals/metalloids toxicity. Plants produce several secondary messengers to trigger cell signaling, activating the numerous transcriptional responses correlated with plant defense. Therefore, the recent advances in omics approaches such as genomics, transcriptomics, proteomics, metabolomics, ionomics, miRNAomics, and phenomics have enabled the characterization of molecular regulators associated with toxic metal tolerance, which can be deployed for developing toxic metal tolerant plants. This review highlights various response strategies adopted by plants to tolerate toxic metals/metalloids toxicity, including physiological, biochemical, and molecular responses. A seven-(omics)-based design is summarized with scientific clues to reveal the stress-responsive genes, proteins, metabolites, miRNAs, trace elements, stress-inducible phenotypes, and metabolic pathways that could potentially help plants to cope up with metals/metalloids toxicity in the face of fluctuating environmental conditions. Finally, some bottlenecks and future directions have also been highlighted, which could enable sustainable agricultural production.

Recent Advances in Bioactive Compounds, Health Functions, and Safety Concerns of Onion (Allium cepa L.)

Onion (Allium cepa L.) is a common vegetable, widely consumed all over the world. Onion contains diverse phytochemicals, including organosulfur compounds, phenolic compounds, polysaccharides, and saponins. The phenolic and sulfur-containing compounds, including onionin A, cysteine sulfoxides, quercetin, and quercetin glucosides, are the major bioactive constituents of onion. Accumulated studies have revealed that onion and its bioactive compounds possess various health functions, such as antioxidant, antimicrobial, anti-inflammatory, anti-obesity, anti-diabetic, anticancer, cardiovascular protective, neuroprotective, hepatorenal protective, respiratory protective, digestive system protective, reproductive protective, and immunomodulatory properties. Herein, the main bioactive compounds in onion are summarized, followed by intensively discussing its major health functions as well as relevant molecular mechanisms. Moreover, the potential safety concerns about onion contamination and the ways to mitigate these issues are also discussed. We hope that this paper can attract broader attention to onion and its bioactive compounds, which are promising ingredients in the development of functional foods and nutraceuticals for preventing and managing certain chronic diseases.