TiO2 nanoparticles may alleviate cadmium toxicity in co-treatment experiments on the model hydrophyte Azolla filiculoides

Abstract

Water ecosystems polluted by heavy metals, such as cadmium, may also be affected by the increasing presence of TiO2 NPs. Several researchers have studied the effects of the two contaminants individually, however only a few studies on their joint action have been published for plants. Focusing on the aquatic environment, the hydrophyte Azolla filiculoides can be a useful model to assess if TiO2 NPs may in some way alleviate the Cd injuries and improve the ability of the plant to cope with this metal. With this mechanistic hypothesis, after a pre-treatment with TiO2 NPs, A. filiculoides plants were transferred to cadmium contaminated water with or without TiO2 nanoparticles. After five days of treatment, cadmium uptake, morpho-anatomical and physiological aspects were studied in plants. The continuous presence of TiO2 nanoparticles, though not increasing the uptake of cadmium in comparison with a priming treatment, induced a higher translocation of this heavy metal to the aerial portion. Despite the translocation factor was always well below 1, cadmium contents in the fronds, generally greater than 100 ppm, ranked A. filiculoides as a good cadmium accumulator.Higher cadmium contents in leaves did not induce damages to the photosynthetic machinery probably thanks to a compartmentalization strategy aimed at confining most of this pollutant to less metabolically active peripheral cells. The permanence of NPs in growth medium ensured a better efficiency of the antioxidant apparatus (proline and glutathione peroxidase and catalase activities), induced a decrease in H2O2 content, however was not able to lower the oxidative damage (in terms of TBARS).

Application of Polypodiopsida Class in Nanotechnology–Potential towards Development of More Effective Bioactive Solutions

“…Similar studies, regarding the toxicity different pesticides were performed by Liu et al [ 149 ] (evaluating the glyphosate effect on Salvinia natans (L.) All) and by De et al [ 150 ] (evaluating the 2,4-Dichloro-phenoxy acetic acid effect on A. pinnata in the presence of TiO 2 nanoparticles). Their conclusions, that TiO 2 nanoparticles may alleviate the toxic effects, were also confirmed by Spanò et al [ 151 ], who used A. filiculoides pre-treated with TiO 2 NPs and evaluated the Cd-induced injuries in the model fern.…”

Early evidence of the impacts of microplastic and nanoplastic pollution on the growth and physiology of the seagrass Cymodocea nodosa

“…For plant organ observations, fresh leaves and rhizomes excised from three samples of treated and control plants were cut into small pieces, fixed in 3% glutaraldehyde in 100 mM sodium phosphate buffer (pH 7.4) for 24 h and then processed as previously described (Spanò et al, 2019). After critical-point drying, both leaves and rhizomes blocks were cross sectioned, coated with gold and examined and captured with SEM (JSM-5410, Jeol, Tokyo, Japan) (Lian et al, 2020).…”

Effect of Zinc Priming on Salt Response of Wheat Seedlings: Relieving or Worsening?

“…Zinc concentration in roots and leaves was determined according to Jorhem [54] with minor modifications as in Spanò et al [55]. In particular, the samples, after drying, were ashed in a muffle furnace at 525 • C for 2 h and ground in a porcelain mortar.…”