Zinc Oxide Nanoparticles Damage Tobacco BY-2 Cells by Oxidative Stress Followed by Processes of Autophagy and Programmed Cell Death

Abstract

Nanomaterials, including zinc oxide nanoparticles (ZnO NPs), have a great application potential in many fields, such as medicine, the textile industry, electronics, and cosmetics. Their impact on the environment must be carefully investigated and specified due to their wide range of application. However, the amount of data on possible negative effects of ZnO NPs on plants at the cellular level are still insufficient. Thus, we focused on the effect of ZnO NPs on tobacco BY-2 cells, i.e., a widely accepted plant cell model. Adverse effects of ZnO NPs on both growth and biochemical parameters were observed. In addition, reactive oxygen and nitrogen species visualizations confirmed that ZnO NPs may induce oxidative stress. All these changes were associated with the lipid peroxidation and changes in the plasma membrane integrity, which together with endoplasmatic reticulum and mitochondrial dysfunction led to autophagy and programmed cell death. The present study demonstrates that the phytotoxic effect of ZnO NPs on the BY-2 cells is very complex and needs further investigation.

Biostimulation and toxicity: The magnitude of the impact of nanomaterials in microorganisms and plants

“…The most widely considered hypothesis is that they generate ROS [77] , and that depending on the concentration of ROS they can activate cellular defense mechanisms (eustress) or can lead the cell to a state of distress and even cell death [78] . Other reactive species, such as nitrogen reactive species (RNS), also intervene in the signaling processes through NO, causing nitrosative stress [79] , [80] . According to the intensity of stress, it can translate into cell responses from biostimulation to toxicity.…”

Nanoparticle‐mediated gene transformation strategies for plant genetic engineering

“…Recently, many reports have indicated that nanoparticles may have toxic effects on plant germination, growth and development (Wang et al ., 2019; Balážová et al ., 2020; Sun et al ., 2020). The efficiency of gene transformation mediated by magnetic transfection of cotton is low, which may be linked to phytotoxicity (Zhao et al ., 2017).…”

“…Interestingly, a gene expression study has indicated that nanoparticles may inhibit genes involved in pathogen response, hormonal stimulation and stress responses, resulting in a negative role in plant defense and root development (Kaveh et al ., 2013). At the same time, nanoparticles may induce autophagy and programed cell death, thereby negatively regulating the viability and growth of tobacco cells (Balážová et al ., 2020). Therefore, safe nanoparticles should be developed for future applications in plant engineering.…”

“…Previous research has shown that nanoparticles may trigger reactive oxygen species (ROS) in plants and cause plant hormone imbalances, affecting plant growth and development (Balážová et al ., 2020; Dharmalingam et al ., 2020). Graphene oxide, a graphene family nanoparticle, can be catalyzed enzymatically to CO 2 and H 2 O 2 ; however, H 2 O 2 is an ROS and is involved in modulating biotic and abiotic stress responses, thus leading to serious damage in biological systems (Kotchey et al ., 2011; Xing et al ., 2014; Del, 2015).…”

Plant Cell Cultures as a Tool to Study Programmed Cell Death

“…Instead, ethylene (a plant hormone associated with senescence) causes permeability of cells to vital stains without concomitant nuclear DNA fragmentation and cytoplasmic retraction but with very high ROS production, leading to severe oxidative stress [ 45 ]. Similarly, in tobacco BY 2-cultured cells, zinc oxide nanoparticles cause cell death depending on oxidative stress and lipid peroxidation [ 51 ], and in grapevine suspension cell cultures, different concentrations of silver ions cause cell death with different characteristics [ 52 ]. Thus, depending on the genotype/species and level of stress, the same factors may cause different responses.…”