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Background Silver nanoparticles (AgNPs) are the most widely used nanomaterial in agricultural and environmental applications. In this study, the impact of AgNPs solutions at 20 mg/L, 40 mg/L, 80 mg/L, and 160 mg/L on cell ultrastructure have been examined in pea (Pisum sativum L) using a transmission electron microscope (TEM). The effect of AgNPs treatments on the α, β esterase (EST), and peroxidase (POX) enzymes expression as well as gain or loss of inter-simple sequence repeats (ISSRs) markers has been described. Results Different structural malformations in the cell wall and mitochondria, as well as plasmolysis and vacuolation were recorded in root cells. Damaged chloroplast and mitochondria were frequently observed in leaves and the osmiophilic plastoglobuli were more observed as AgNPs concentration increased. Starch grains increased by the treatment with 20 mg/L AgNPs. The expressions of α, β EST, and POX were slightly changed but considerable polymorphism in ISSR profiles, using 17 different primers, were scored indicating gain or loss of gene loci as a result of AgNPs treatments. This indicates considerable variations in genomic DNA and point mutations that may be induced by AgNPs as a genotoxic nanomaterial. Conclusion AgNPs may be used to induce genetic variation at low concentrations. However, considerations should be given to the uncontrolled use of nanoparticles and calls for evaluating their impact on plant growth and potential genotoxicity are justified.

Background In the present study, Allium test bioassay was utilized to evaluate the effects of mixed wastewater of agricultural and sewage effluents at Kitchener pool, Gharbia governate, Middle Delta region, North Egypt. Germination indices, mitotic index and aberrations, α, β-esterase isozymes and inter-simple sequence repeat (ISSR) fingerprinting were tested by different concentrations of the wastewater (tap water as control, 25%, 50% and 100% wastewater). Results Water analysis recorded high levels of electrical conductivity, cations and anions compared to control, but were in the permitted limits according to FAO (Food and Agricultural Organization) except Mg2+ and K1+ were above the limits. P, N and heavy metals as Pb, Mn and Ni were also higher than the control. Germination indices showed reduction for all parameters studied (root and shoot lengths, root and shoot fresh and dry weights, and tolerance index). Mitotic index decreased, and the percentage of mitotic aberrations increased as the concentration of treatments increased and the time prolonged. Different types of aberrations were recorded in all treatments and its percentage is time and dose independent. Goat cells are the most common type recorded after different times in all treatments. The expression of α, β-esterase enzymes showed variation in different treatments compared to control and ISSR profiles showed considerable polymorphism. Concentration of 25% mixed water induced different profiles for expression of both α- and β-esterase from other treatments, and the cluster analysis based on polymorphism in ISSR fingerprinting revealed the distinction of plants treated with this concentration and the control plants from those treated with high concentrations. Conclusion It was suggested that concentration of 25% mixed water may be suitable for growth and act as fertilizer. Mixed water from this pool may be genotoxic for Allium cepa plants at early growth if it is used for irrigation in its present form and usage of this wastewater for agricultural purposes may be harmful and must be partially treated and biologically tested before use.

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