Cyto–Genotoxic Effect Causing Potential of Polystyrene Micro-Plastics in Terrestrial Plants

Abstract

The polystyrene micro-plastics (Ps-MPs) is one of the leading pollutants found in both aquatic and terrestrial ecosystems. While most of the studies on the morphology and cyto-toxicity of MPs have been based on aquatic organisms, their effects on terrestrial plants are still scarcely known. The present study was an attempt to measure the effect of different sizes (80, 100, 200, 500, 1000, 2000, 4000, and 8000 nm) and concentrations (100 and 400 mg/L) of Ps-MPs on the root length and chromosomes of root tip cells of Allium cepa using A. cepa root chromosomal aberration assay. Large size Ps-MPs (4000 and 8000 nm) showed the highest reduction in A. cepa root length; however, the differences were not significant (at p ≤ 0.05), with respect to negative control (Milli-Q water). The mitotic index showed both significant size- and concentration-dependent decreases, being the lowest (12.06%) in 100 nm at 100 mg/L concentration, with respect to the control (25.05%). The chromosomal abnormality index (CAI) and nuclear abnormality index (NAI) showed significant decreases, with respect to negative control. In addition, the induction of micro-nucleated cells was also observed in Allium root tip cells, when treated with MPs of all sizes, which can predict direct DNA damage to the plant cells. Hence, we conclude that most of the MP sizes caused cyto-toxic and nuclear damage by adversely impacting the spindle formation and induction of micro-nucleated cells in Allium cepa root tip cells. To the best of our knowledge, this is the first study that showed the effect of considerable size range of Ps-MP sizes on the root length and cell division in plants.

Phytotoxic Effects of Polystyrene and Polymethyl Methacrylate Microplastics on Allium cepa Roots

“…In this study, no inhibitory effect on onion root growth was observed after exposure to 147 nm sized PS-MPs. This is in agreement with results obtained on A. cepa roots exposed to PS-MPs of sizes ranging from 80 to 8000 nm [ 32 ], as well as on V. faba [ 22 ] and C. sativus roots [ 33 ] treated with 100 nm sized PS-MPs. On the other hand, a positive effect on root elongation of wheat seedlings was reported upon exposure to 100 nm PS-MPs [ 35 ].…”

“…Boots et al [ 31 ] observed no changes in germination rate and chlorophyll content in Lolium perenne treated with high-density PE-MPs, while the 48 or 72 h exposure of L. sativum to NPs and MPs failed to reveal significant differences in root growth [ 21 ]. The lack of effect on root growth was also reported for A. cepa [ 32 ], V. faba [ 22 ], and Cucumis sativus [ 33 ] upon exposure to PS-MPs. Moreover, in some studies, even positive, acclimative responses were recorded.…”

“…In the present study, we conducted a parallel plant exposure to MPs composed of two different polymers, polystyrene (PS) and polymethyl methacrylate (PMMA). Polystyrene is one of the leading pollutants found in both aquatic and terrestrial ecosystems [ 32 ], which is why the effects of PS-MPs and PS-NPs are often investigated in toxicological studies on plants. On the contrary, although PMMA is commonly used, for example for microbeads in cosmetics in Europe [ 37 , 38 ], only a few publications studying the effects of PMMA-MPs on plants can be found in the literature [ 38 , 39 ].…”

An insight into laboratory column experiments for microplastic transport in soil

“…Polystyrene (PS) plastic is widely used as packaging materials such as containers, lids, and trays. It has been reported as a major component of MP found in soil [22]. This study used PSMP (polystyrene microplastic) microspheres with a distribution around 1ߤm mean diameter, within a 0.9ߤm െ 1.1ߤm range, purchased from Bioscientific Pty Ltd (NSW, Australia).…”

Management strategies for single-use plastics: lessons to learn from Indian approach of minimizing microplastic waste

“…7,69 It has also been shown that these particles are able to induce cytotoxic and genotoxic effects on humans as well as plant species. 70,71 Thus, SUP management initiatives will help to deal with the increasing microplastic pollution (Fig. 1).…”