Perspectives and challenges of micro/nanoplastics‐induced toxicity with special reference to phytotoxicity

Abstract

Plastic pollution has become a global concern for ecosystem health and biodiversity conservation. Concentrations of plastics are manifold higher in the terrestrial system than the aquatic one. Micro/nanoplastics (M/NP) have the ability to alter soil enzymatic system, soil properties and also affect soil borne microorganisms and earthworms. Despite, the knowhow regarding modulatory effects of plastics are acquired from the study on aquatic system and reports on their phytotoxic potentials are limited. The presence of cell wall that could restrict M/NP invasion into plant roots might be the putative cause of this limitation. M/NP inhibit plant growth, seed germination and gene expression; and they also induce cytogenotoxicity by aggravating reactive oxygen species generation. Dynamic behavior of cell wall; the pores formed either by cell wall degrading enzymes or by plant–pathogen interactions or by mechanical injury might facilitate the entry of into roots M/NP. This review also provides a possible mechanism of large sized microplastics‐induced phytotoxicity especially for those that cannot pass through cell wall pores. As M/NP affect soil microbial community and soil parameters, it is hypothesized that they could have the potential to affect N2 fixation and research should be conducted in this direction. Reports on M/NP‐induced toxicity mainly focused only on one polymer type (polystyrene) in spite of the toxicological relevancies of other polymer types like polyethylene, polypropylene etc. So, the assessment of phytotoxic potential of M/NP should be done using other plastic polymers in real environment as they are known to intract with other environmental stressors as well as can alter the the soil–microbe–plant interaction.

Microplastics negatively affect soil fauna but stimulate microbial activity: insights from a field-based microplastic addition experiment

“…Owing to the long-term persistence of plastics in the environment, their accumulation is one of the most widespread and long-lasting anthropogenic changes to the Earth's surface. Once in the environment, large plastic debris gradually degrades into smaller pieces through weathering and other disintegration processes [2][3][4][5], which can further increase their dispersion and incorporation into the soil [6][7][8]. Microplastics are generally defined as plastic particles with diameters less than 5 mm [9].…”

Uptake and Accumulation of Nano/Microplastics in Plants: A Critical Review

“…MPs and NPs change soil properties and bacterial communities. Rhizobia can potentially change with changes in the soil matrix [166]. The ingestion of MPs by soil organisms could influence bacterial diversity; e.g., Zhu et al reported that in the collembolan gut, MPs potentially enhanced bacterial diversity, possibly due to a move in feeding after MP exposure [102].…”

Searching Nanoplastics: From Sampling to Sample Processing

“…Following the NPs diffusion in the environment, all animal species can be involved in a direct way by ingestion and through the bio-magnification [19]. The plant kingdom is also included within the study because it is closely related to soil pollution [111,112] therefore sampling biological matrices to understand dose-effects of NPs is fundamental for wildlife safeguard.…”

“…They can also interact with membrane proteins and transport of ions. The main ways through which NPs and plant can interact are: cell wall and cuticle by passive transport; proteins on the membrane by diffusion facilitated; endocytosis; plasmodesmata by intercellular translocation; stomata [111]. Laboratory test exposure of plants to NPs has basically the same procedure as animals.…”