Insights of the Toxic Impact of Microplastic on Flora: Recent Trends and Challenges

Microplastics generated from the fragmentation of plastic polymers constitute one of the emergent pollutants invading both terrestrial and aquatic environments. Microplastics pose serious consequences to life including plants. While the impact of microplastics on soil properties and microbial communities is discussed frequently, research detailing the consequences of microplastics on plants is still at its nascent stage. Recent research has demonstrated that microplastics can impact the plant growth positively and negatively in a variety of ways such as they can impact the water uptake by blocking soil pores; moreover, the impacts could be direct and indirect. Similar to other pollutants, microplastics impact the plant growth and development by exerting oxidative stress. The inhibiting mechanisms include obstructing pores or light, breaking down roots mechanically, preventing gene expression, releasing additives, and altering soil characteristics, microbial communities, and soil animals. It further impacts the bioavailability of other contaminants. Since plants exhibit different growth patterns, the influence of microplastics varies from species to species depending on plastic type, particle size, available concentration, and uptake of polymer. Finally, the pros and cons of current research to understand the molecular effects of microplastics on aquatic and terrestrial plants are also highlighted.