Plants oxidative response to nanoplastic

Abstract

Pollution of the environment with plastic is an important concern of the modern world. It is estimated that annually over 350 million tonnes of this material are produced, wherein, despite the recycling methods, a significant part is deposited in the environment. The plastic has been detected in the industrial areas, as well as farmlands and gardens in many world regions. Larger plastic pieces degraded in time into smaller pieces including microplastic (MP) and nanoplastic particles (NP). Nanoplastic is suggested to pose the most serious danger as due to the small size, it is effectively taken up from the environment by the biota and transported within the organisms. An increasing number of reports show that NP exert toxic effects also on plants. One of the most common plant response to abiotic stress factors is the accumulation of reactive oxygen species (ROS). On the one hand, these molecules are engaged in cellular signalling and regulation of genes expression. On the other hand, ROS in excess lead to oxidation and damage of various cellular compounds. This article reviews the impact of NP on plants, with special emphasis on the oxidative response.

Keywords: antioxidant enzymes; lipid peroxidation; oxidative stress; polystyrene (PS); reactive oxygen species.

Figure 1

Composition of plastic waste generated globally in 2015 (Geyer et al., 2017).

Figure 2

Plastic pollution sources (Horton et al., 2017; Pinto Da Costa et al., 2020; Kiran et al., 2022; Law and Narayan, 2022).

Figure 3

Sources of plastics in the terrestrial environment and factors that influence their vertical and horizontal distribution in the soil.

Figure 4

Uptake NP (blue dots) from the surrounded environment and transport through the plant organisms. Plastic particles may enter by roots (marked with red arrows) and leaves (marked with yellow arrows). The NP may enter the cell through pores and cracks in the cell wall and further through plasmodesma or transporters/aquaporins in the cell membrane.

Figure 5

Graphical summary of NP impact on plants. NP – nanoplastic particles, ROS – reactive oxygen species, blue arrows – experimentally evidenced effects, black dotted arrow – possible interactions. Exposure to NP leads to increase in reactive oxygen species, hampered uptake of specific nutrients, decrease in photosynthesis efficiency and cyto- and genotoxic effects. ROS might mediate cyto- and genotoxic effect through direct interaction with genetic material and alert nutrient uptake through mediation of membrane damage. Decrease in the level of certain elements e.g. Fe and Mg might results in impaired chlorophyll synthesis and contribute to lower photosynthesis efficiency. Cyto- and genotoxic effects lead to decreased cell division. Alerted cell division, nutrient level and photosynthesis results in hampered plants growth. In addition, NP alert plants physiology through modulation of genes expression on the transcriptomic level.