Aerially applied zinc oxide nanoparticle affects reproductive components and seed quality in fully grown bean plants ( Phaseolus vulgaris L.)

The development of reproductive components in plant species is susceptible to environmental stresses. The extensive application of zinc oxide nanoparticles (nZnO) in various agro-industrial processes has jeopardized the performance and functionality of plants. To understand the response of the developmental (gametogenesis and sporogenesis) processes to nanoparticles (NPs) exposure, the aerial application of nZnO and their ionic counterpart of ZnSO4 at four different levels were examined on bean plants (Phaseolus vulgaris) before the flowering stage. To evaluate the mentioned processes, briefly, flowers in multiple sizes were fixed in paraffin, followed by sectioning and optical analysis. The possibility of alteration in reproductive cells was thoroughly analyzed using both light and electron microscopes. Overall, our results revealed the histological defects in male and female reproductive systems of mature plants depend on NPs levels. Furthermore, NPs caused tapetum abnormalities, aberrations in carbohydrate accumulation, and apoptosis. The nZnO induced abnormal alterations right after meiosis and partly hindered the microspore development, leading to infertile pollens. The seed yield and dry weight were reduced to 70 and 82% at 2,000 mg L-1 nZnO foliar exposure, respectively. The sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis pattern showed the increased expression of two proteins at the molecular weight of 28 and 42 kDa at various concentrations of nZnO and ZnSO4. Overall, our results provided novel insights into the negative effect of nano-scaled Zn on the differential mechanism involved in the reproductive stage of the plants compared with salt form

Exogenous application of ZnO nanoparticles and ZnSO4 distinctly influence the metabolic response in Phaseolus vulgaris L

Nanomaterials-mediated contamination (including the highly reactive metal oxides ZnO nanoparticles) is becoming one of the most concerning issues worldwide. In this study, the toxic effects of two chemical species of Zn (ZnO nanoparticles and bulk ZnSO4) were investigated in bean plants, following either foliar or soil application, at concentrations from 250 to 2000 mg L 121 using biochemical assays, proteomics and metabolomics. The accumulation of Zn in plant tissues depended on the application type, zinc chemical form and concentration, in turn triggering distinctive morphological, physiological, and redox responses. Bean plants were more sensitive to the foliar than to the soil application, and high concentrations of ZnO NP and bulk ZnSO4 determined the highest plant growth inhibition and stress symptoms. However, low dosages of ZnSO4 induced a slight plant growth promotion and better physiological and antioxidative response. Low concentration of Zn leaded to increased activity of stress-related proteins and secondary metabolites with antioxidant capacity, while increasing concentration reached the exhausted phase of the plant stress response, reducing the antioxidant defense system. Such high concentrations increased lipids peroxidation, protein degradation and membranes integrity. Oxidative damage occurred at high concentrations of both chemical species of Zn. Foliar spraying impaired photosynthetic efficiency, while soil applications (especially ZnSO4) elicited antioxidant metabolites and proteins, and impaired chloroplast-related proteins involved in the electron transport chain and ATP production. Taken together, the results highlighted distinctive and nanoparticles-related toxic effects of ZnO in bean, compared to ionic forms of Zn

Relatively Low Dosages of CeO2 Nanoparticles in the Solid Medium Induce Adjustments in the Secondary Metabolism and Ionomic Balance of Bean (Phaseolus vulgaris L.) Roots and Leaves

Nanoparticles (NPs) are known to significantly alter plant metabolism in a dose-dependent manner, with effects ranging from stimulation to toxicity. The metabolic adjustment and ionomic balance of bean (Phaseolus vulgaris L.) roots and leaves gained from plants grown in a solid medium added with relatively low dosages (0, 25, 50, and 100 mg/L) of CeO2 NPs were investigated. Ce accumulated in the roots (up to 287.91 mg/kg dry weight) and translocated to the aerial parts (up to 2.78% at the highest CeO2 dosage), and ionomic analysis showed that CeO2 NPs interfered with potassium, molybdenum, and zinc. Unsupervised hierarchical clustering analysis from metabolomic profiles suggested a dose-dependent and tissue-specific metabolic reprogramming induced by NPs. The majority of differential metabolites belonged to flavonoids and other phenolics, nitrogen-containing low molecules (such as alkaloids and glucosinolates), lipids, and amino acids