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With the advancement of nanotechnology and the increasing utilization of nanoparticles (NPs), their production and release into the environment are on the rise. Consequently, it is crucial to continuously monitor the toxicity of nanoparticles for humans, animals, and plants, as well as their impact on the environment. This is particularly significant in relation to human health and food production, given the escalating use of nanomaterials in agriculture and horticulture. The aim of the study was to investigate the response of rapeseed seedlings to silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) over different periods of exposure. This research analyzed the impact of these nanoparticles on the biochemical response of rapeseed seedlings after 7, 14, and 21 days of growth in their presence. This study assessed the activity of guaiacol peroxidase (GPOX), pyrogallol peroxidase (PPOX), superoxide dismutase (SOD), and free protein content, as well as the interactions between key elements responsible for oxidative stress and the antioxidant response. The findings demonstrated a significant effect of AgNPs and AuNPs on stimulating the response of rapeseed seedlings, with the activity of PPOX, GPOX, and SOD being dependent on the exposure time and the type and dose of nanoparticles used. Enzyme activity increased with the length of exposure time, while the content of free protein decreased over the weeks. The most intense reaction of seedlings was observed in the case of GPOX, with the lowest activity observed in PPOX and SOD. High effects of the nanoparticle type and rate were also observed in the correlation matrix. This study suggests that a comprehensive analysis of plant reactions to nanoparticles could have a significant impact on the proper and effective use of nanoparticles in agriculture and horticulture. This could lead to the environmentally friendly production of high-quality plant material. [ABSTRACT FROM AUTHOR]

The aim of this study was (i) to produce tissue cultures capable of efficient plant regeneration from European naturally occurring protected and/or pharmacologically important Amaryllidaceae species and (ii) to test them for antioxidant activities in order to select tissue cultures that scavenge efficiently oxygen radicals. Bulb explants were collected from Galanthus woronowii, two Leucojum species, and Sternbergia lutea. Leucojum species were Hungarian isolates. Mostly α-naphthalene acetic acid (NAA) and benzyladenine (BA) were used as growth regulator combinations for the induction and maintenance of tissue cultures and further antioxidant activity studies. Galanthus woronowii and L. vernum cultures produced shoots or whole plants via micropropagation (callus stage was observed only sporadically and callus tissue did not contribute to regeneration), whereas L. aestivum and S. lutea produced efficiently whole plants or multiple shoots via embryogenic calli. Total phenolic content, % inhibition of ABTS radical (ABTS*) cation, and peroxidase activities on native polyacrylamide gels were studied and showed differences between cultures. No relationship could be detected between polyphenol content / radical scavenging capacities and H2O2 reducing enzyme activities. For G. woronowii, S. lutea, and a culture line of L. vernum, polyphenol content and ABTS* cation scavenging activities were high and for G. woronowii, comparable to organs of the native plants used as explant sources. Bulbs of native plants showed low radical scavenging activities in general. For L. vernum and L. aestivum tissue cultures grown in the presence of NAA as the sole growth regulator, ABTS* cation scavenging showed low values. Enzymatic antioxidant (pyrogallol peroxidase) activities were low for all cultures and organs of native plants. This study shows the species conservation value of these cultures and highlights the high antioxidant capacity of G. woronowii and S. lutea, attributed to the presence of non-enzymatic scavengers.

Abstract: Antagonism between entomopathogenic nematodes (EPNs) and plant-parasitic nematodes (PPNs) has been documented over the past two decades but its mechanism and ecological significance remain elusive. We investigated the effects of Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila applied to the potting medium on pyrogallol peroxidase (P-peroxidase), guaiacol peroxidase (G-peroxidase) and catalase activities in Hosta sp. and Arabidopsis thaliana leaves as components of induced systemic resistance. We found that P-peroxidase activity was significantly higher in the leaves from hosta plants treated with S. carpocapsae infective juveniles (IJs) and S. carpocapsae infected insect cadavers than in the leaves from the control plants 2weeks after treatment. The G-peroxidase activity was significantly higher in S. carpocapsae infected cadaver and X. nematophila treatments 10 and 15days after treatment (DAT) and in S. carpocapsae IJs treatment 5 and 15 DAT. The catalase activity in hosta leaves was significantly higher in S. carpocapsae infected cadaver and X. nematophilus treatments compared with the control 5 and 15 DAT and in S. carpocapsae IJs treatment 5 and 10 DAT. Further, the catalase activity in A. thaliana leaves was significantly higher in S. carpocapsae IJs treatment than in the control 7 DAT. We also determined the effects of S. carpocapsae infected cadavers and S. carpocapsae IJs on PR1-gene expression in transgenic A. thaliana leaves through GUS (β-glucuronidase) activity assay and found that the PR1-gene was expressed in leaves from all treatments except the control. Thus, we conclude that the EPNs and their symbiotic bacteria can induce systemic resistance in plants which may explain the elusive antagonistic effect of EPNs on PPNs. [Copyright &y& Elsevier]