Amassing of heavy metals in soils, vegetables and crop plants irrigated with wastewater: Health risk assessment of heavy metals in Dera Ghazi Khan, Punjab, Pakistan

Potentially toxic metals in Northeast Ethiopian agricultural soils: implications for Solanum lycopersicum (Tomato) production and human health

Exposure to heavy metal-contaminated vegetables, irrigation water and agricultural soil is one of the most challenging environmental issues worldwide. This study aimed to evaluate the health effects of potentially toxic metals (PTMs) including Cr, Cd, Fe, Pb, Cu, Zn, and Co from agricultural soil, irrigation water, and tomato plants collected from the Abuarie irrigation site, Northeast Ethiopia. The samples were digested using acid digestion method, and its concentration was quantified using Inductively Coupled Plasma-Optical Emission Spectroscopy. The concentrations of PTMs in the soil, tomato, and irrigation water samples ranged from 49,020 ± 275 (Fe) to 11.85 ± 0.44 (Cd), 170 ± 1.98 (Fe) to 0.29 ± 0.006 (Cd) mg kg-1, and 0.24 ± 0.003 (Fe) to 0.025 ± 0.005 (Ni) mg L-1 , respectively. The results revealed Zn, Ni, Cd and Cr in soil, all metals in tomato, and Cu, Ni, Cd and Pb in irrigation water sample were above the World Health Organization threshold values. Moreover, the separate and cumulative exposure to farm soil, irrigation water, and consumption of tomato were investigated using the hazard quotient (HQ) and hazard index (HI) values, respectively. The results revealed that individual exposure to each sample type did not have a significant impact on health (HQ < 1). However, simultaneous exposure to all of the sample types (soil, tomato and irrigation water) at the same time had a high likelihood of affecting health (HI > 1). The total carcinogenic concentrations of Cr, Cd, Ni, and Pb were greater than 1 × 10-4, revealing that farmers have a high probability of developing cancer during their lifetime. Minimizing simultaneous exposure to soil, tomato, and irrigated water for local people is highly recommended to prevent the risk of PTMs.

Toxicity and bioassimilation of lead and nickel in farm ruminants fed on diversified forage crops grown on contaminated soil

The cultivation of forage crops on wastewater-irrigated soils, while common in many developing countries, poses significant risks due to heavy metal pollution, particularly Lead (Pb) and Nickel (Ni). This practice, aimed at addressing water scarcity challenges and providing affordable irrigation, was investigated for its ecological and human health implications across three diverse sites (site A, site B, and site C). Our study unveiled increases in Pb concentrations in contaminated soil, cultivated with Sesbania bispinosa showing the highest Pb accumulation. The Ni concentrations ranged from 5.34 to 10.43 across all forage crop samples, with S. fruticosa from site C displaying the highest Ni concentration and S. bicolor from site A exhibiting the lowest. Trace element concentrations in the specimens were determined using an atomic absorption spectrophotometer. The Pb levels in the blood, hair, and feces of farm ruminants (cows, buffaloes, and sheep) varied across the sites, with buffaloes consistently displaying the highest Pb levels. Insights into daily Pb intake by ruminant's highlighted variations influenced by plant species, animal types, and sites, with site C, the cows exhibiting the highest Health Risk Index (HRI) associated with lead exposure from consuming forage crops. Soil and forage samples showed Pb concentrations ranging from 8.003 to 12.29 mg/kg and 6.69-10.52 mg/kg, respectively, emphasizing the severe health risks associated with continuous sewage usage. Variations in Ni concentrations across animal blood, hair, and feces samples underscored the importance of monitoring Ni exposure in livestock, with sheep at site B consistently showing the highest Ni levels. These findings highlight the necessity of vigilance in monitoring trace element (Pb and Ni) exposure in forage crops and livestock, to mitigate potential health risks associated with their consumption, with variations dependent on species, site, and trace element concentrations.

The Effect of Two Siderophore-Producing Bacillus Strains on the Growth Promotion of Perennial Ryegrass under Cadmium Stress

Cadmium (Cd) is a highly toxic and cumulative environmental pollutant. Siderophores are heavy metal chelators with high affinity to heavy metals, such as Cd. Ryegrass (Lolium perenne L.) has a potential remediation capacity for soils contaminated by heavy metals. Consequently, using ryegrass alongside beneficial soil microorganisms that produce siderophores may be an effective means to remediate soils contaminated with Cd. In this study, the Bacillus strains WL1210 and CD303, which were previously isolated from the rhizospheres of Nitraria tangutorum in Wulan and Peganum harmala L. in Dachaidan, Qinghai, China, respectively, both arid and sandy environments, were evaluated for heavy metal pollution mitigation. Our quantitative analyses have discerned that the two bacterial strains possess commendable attributes of phosphorus (P) solubilization and potassium (K) dissolution, coupled with the capacity to produce phytohormones. To assess the heavy metal stress resilience of these strains, they were subjected to a cadmium concentration gradient, revealing their incremental growth despite cadmium presence, indicative of a pronounced tolerance threshold. The subsequent phylogenetic analysis, bolstered by robust genomic data from conserved housekeeping genes, including 16S rDNA, gyr B gene sequencing, as well as dnaK and recA, delineated a species-level phylogenetic tree, thereby confirming the strains as Bacillus atrophaeus. Additionally, we identified the types of iron-carrier-producing strains as catechol (WL1210) and carboxylic acid ferrophilin (CD303). A genomic analysis uncovered functional genes in strain CD303 associated with plant growth and iron carrier biosynthesis, such as fnr and iscA. Ryegrass seed germination assays, alongside morphological and physiological evaluations under diverse heavy metal stress, underscored the strains' potential to enhance ryegrass growth under high cadmium stress when treated with bacterial suspensions. This insight probes the strains' utility in leveraging alpine microbial resources and promoting ryegrass proliferation.

Assessment of heavy metals and human health risk associated with the consumption of crops cultivated in industrial areas of Maputo, Mozambique

This study aimed to evaluate heavy metals concentrations in soils and vegetables (cabbage, lettuce, and cassava) cultivated at Matola and Beluluane Industrial Parks, and to assess health risks linked to their consumption through estimated daily intake, hazard index (HI), and incremental lifetime cancer risk. Concentrations of Al, As, Co, Cd, Cr, Ni, Pb, and Zn were determined in the two sites. Soil concentrations of As at Beluluane site and As, Cd, and Cr at Matola site exceeded reference limits of the Food and Agriculture Organization/World Health Organization, showing heavy metal contamination. At Beluluane site, all studied vegetables presented As and Pb levels higher than reference limits, Cd concentrations were higher than the reference limit in cabbage, lettuce, and cassava leaves. At Matola site crops concentrations of As, Cd, Cr, and Pb exceeded the reference limits. Zinc exceeded the reference limit in all crops except in cabbage. HIs for vegetables from Beluluane exceeded 1.0 in cabbage (2.66), lettuce (2.27), and cassava leaves (2.37). Likewise, at Matola, HIs exceeded 1.0 in lettuce (1.67), cassava leaves (1.65), and root tubers (13). We found that vegetables cultivated in industrial parks present high carcinogenic risk due to heavy metal contamination, rendering them unsuitable for human consumption.

Pervasive influence of heavy metals on metabolic pathways is potentially relieved by hesperidin to enhance the phytoremediation efficiency of Bassia scoparia

Hesperidin (HSP), a flavonoid, is a potent antioxidant, metal chelator, mediator of signaling pathways, and regulator of metal uptake in plants. The study examined the ameliorative effects of HSP (100 μM) on Bassia scoparia grown under excessive levels of heavy metals (zinc (500 mg kg-1), copper (400 mg kg-1), cadmium (100 mg kg-1), and chromium (100 mg kg-1)). The study clarifies the underlying mechanisms by which HSP lessens metabolic mayhem to enhance metal stress tolerance and phytoremediation efficiency of Bassia scoparia. Plants manifested diminished growth because of a drop in chlorophyll content and nutrient acquisition, along with exacerbated deterioration of cellular membranes reflected in elevated reactive oxygen species (ROS) production, lipid peroxidation, and relative membrane permeability. Besides the colossal production of cytotoxic methylglyoxal, the activity of lipoxygenase was also higher in plants under metal toxicity. Conversely, hesperidin suppressed the production of cytotoxic ROS and methylglyoxal. Hesperidin improved oxidative defense that protected membrane integrity. Hesperidin caused a more significant accumulation of osmolytes, non-protein thiols, and phytochelatins, thereby rendering metal ions non-toxic. Hydrogen sulfide and nitric oxide endogenous levels were intricately maintained higher in plants treated with HSP. Hesperidin increased metal accumulation in Bassia scoparia and thereby had the potential to promote the reclamation of metal-contaminated soils.

Metals in vegetables from markets in Zaria, Nigeria and risk assessment

This study, investigated the concentrations of cadmium, lead and arsenic in vegetables grown with irrigation and sold in Sabon gari and Samaru markets in Zaria, Nigeria. Cadmium was absent in amaranthus, pepper and tomatoes purchased from Samaru market. Nevertheless, amaranthus and lettuce had higher concentrations of these toxic metals than pepper. Total arsenic concentrations in the investigated vegetables were higher than the maximum levels set by the World Health Organization. Total daily intake of the metals was higher than the maximum levels for consuming vegetables from these markets. Therefore, individuals who consume these foods may be at risk. These results indicate the possibility of toxic metal contamination in vegetables purchased from Zaria markets.

Comparative Effects of Hydropriming and Iron Priming on Germination and Seedling Morphophysiological Attributes of Stay-Green Wheat

Seed priming is considered to play an essential role in the overall improvement of agricultural crops. The current research work was carried out in order to investigate the comparative effects of hydropriming and iron priming on the germination behavior and morphophysiological attributes of wheat seedlings. The experimental materials consisted of three wheat genotypes including a synthetically derived wheat line (SD-194), stay-green wheat genotype (Chirya-7), and conventional wheat variety (Chakwal-50). The treatments included hydro (distilled and tap water)- and iron priming (10 and 50 mM) of wheat seeds for 12 h duration. Results indicated that both priming treatment and wheat genotypes exhibited highly different germination and seedling characteristics. These included germination percentage, root volume, root surface, root length, relative water content, chlorophyll content, membrane stability index, and chlorophyll fluorescence attributes. Furthermore, the synthetically derived line (SD-194) was the most promising in majority of the studied attributes by exhibiting a high germination index (2.21%), root fresh weight (7.76%), shoot dry weight (3.36%), relative water content (19.9%), chlorophyll content (7.58%), and photochemical quenching coefficient (2.58%) when compared with stay-green wheat (Chirya-7). The study also found that hydropriming with tap water and priming wheat seeds with low concentrations of iron yielded better results when a comparison was made with wheat seeds primed at high concentrations of iron. Therefore, wheat seed priming with tap water and iron solution for 12 h is recommended for optimum wheat improvement. Furthermore, current findings suggest that seed priming may have the prospect of an innovative and user-friendly approach for wheat biofortification with the aim of enhanced iron acquisition and accumulation in grains.

Levels of heavy metal in soil and vegetable and associated health risk in peri-urban areas across China

Peri-urban vegetable field plays an essential role in providing vegetables for local residents. Because of its particularity, it is affected by both industrial and agricultural activities which have led to the accumulations of heavy metal in soil. So far, information on heavy metal pollution status, spatial features, and human health risks in peri-urban vegetable areas across China is still scarce. To fill this gap, we systematically compiled soil and vegetable data collected from 123 articles published between 2010 and 2022 at a national level. The pollution status of heavy metals (i.e., cadmium (Cd), mercury (Hg), arsenic (As), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn)) in peri-urban vegetable soils and vegetables were investigated. To evaluate the levels of heavy metal pollution in soil and human health risks, the geoaccumulation index (Igeo) and target hazard quotient (HQ) were calculated. The results showed that mean concentrations of Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn in peri-urban vegetable soils were 0.50, 0.53, 12.03, 41.97, 55.56, 37.69, 28.55, and 75.38 mg kg^-1, respectively. The main pollutants in peri-urban vegetable soil were Cd and Hg, and 85.25% and 92.86% of the soil samples had I_geo > 1, respectively. The mean I_geo values of this regions followed the order of northwest > central > south > north > east > southwest > northeast for Cd and northeast > northwest > north > southwest > east > central > south for Hg. The mean Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn concentrations in vegetables were 0.30, 0.26, 0.37, 0.54, 1.17, 6.17, 1.96, and 18.56 mg kg^-1, respectively. Approximately 87.01% (Cd), 71.43% (Hg), 20% (As), 65.15% (Pb), 27.08% (Cr) of the vegetable samples exceeded the safety requirement values. The vegetables grown in central, northwest, and northern China accumulated much more heavy metals than those grown in other regions. As the HQ values for adults, 53.25% (Cd), 71.43% (Hg), 84.00% (As), and 58.33% (Cr) of the sampled vegetables were higher than 1. For children, the HQ values were higher than 1 for 66.23% (Cd), 73.81% (Hg), 86.00% (As), and 87.50% (Cr) of the sampled vegetables. The findings of this study demonstrate that the situation of heavy metal pollution in peri-urban vegetable areas across China are not optimistic and residents who consume the vegetables are at high risk of health issues. To ensure soil quality and human health, strategies should be taken to guide vegetable production and remedy soil pollution in peri-urban areas with the rapidly urbanizing China.

Molecular Characterization of Germin-like Protein Genes in Zea mays (ZmGLPs) Using Various In Silico Approaches

Germin (GER) and germin-like proteins (GLPs) play an important role in various plant processes. Zea mays contains 26 germin-like protein genes (ZmGLPs) located on chromosomes 2, 4, and 10; most of which are functionally unexplored. The present study aimed to characterize all ZmGLPs using the latest computational tools. All of them were studied at a physicochemical, subcellular, structural, and functional level, and their expression was predicted in plant development, against biotic and abiotic stresses using various in silico approaches. Overall, ZmGLPs showed greater similarity in their physicochemical properties, domain architecture, and structure, mostly localized in the cytoplasmic or extracellular regions. Phylogenetically, they have a narrow genetic background with a recent history of gene duplication events on chromosome 4. Functional analysis revealed novel enzymatic activities of phosphoglycolate phosphatase, adenosylhomocysteinase, phosphoglycolate phosphatase-like, osmotin/thaumatin-like, and acetohydroxy acid isomeroreductase largely mediated by disulfide bonding. Expression analysis revealed their crucial role in the root, root tips, crown root, elongation and maturation zones, radicle, and cortex with the highest expression being observed during germination and at the maturity levels. Further, ZmGLPs showed strong expression against biotic (Aspergillus flavus, Colletotrichum graminicola, Cercospora zeina, Fusarium verticillioides, and Fusarium virguliforme) while limited expression was noted against abiotic stresses. Concisely, our results provide a platform for additional functional exploration of the ZmGLP genes against various environmental stresses.

An overview of genome engineering in plants, including its scope, technologies, progress and grand challenges

Genome editing is a useful, adaptable, and favored technique for both functional genomics and crop enhancement. Over the years, rapidly evolving genome editing technologies, including clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas), transcription activator-like effector nucleases (TALENs), and zinc finger nucleases (ZFNs), have shown broad application prospects in gene function research and improvement of critical agronomic traits in many crops. These technologies have also opened up opportunities for plant breeding. These techniques provide excellent chances for the quick modification of crops and the advancement of plant science in the future. The current review describes various genome editing techniques and how they function, particularly CRISPR/Cas9 systems, which can contribute significantly to the most accurate characterization of genomic rearrangement and plant gene functions as well as the enhancement of critical traits in field crops. To accelerate the use of gene-editing technologies for crop enhancement, the speed editing strategy of gene-family members was designed. As it permits genome editing in numerous biological systems, the CRISPR technology provides a valuable edge in this regard that particularly captures the attention of scientists.