Interactions of nanomaterials and plants at the cellular level: current knowledge and relevant gaps

Nanoparticles (NPs) interact with living organisms through different pathways. These interactions depend on chemical nature of NPs, capping, and size, among others. In the last years, the use of different NPs for agricultural purposes has increased. Their applications mainly involve dosing though soil or foliar spraying. Different studies have indicated that NPs can be absorbed by plant roots or through foliar exposure, and may reach all plant organs including fruits, affecting their quality. In addition, they provide a route of exposure for humans and animals. Due to their physicochemical properties and high reactivity, NPs may influence basic cellular processes such as proliferation, metabolism, and death. In recent years, several studies have evaluated the effects of NPs applications, highlighting their capability to induce oxidative stress, interrupt the transport activity of the cell membrane of electrons/ions, cause oxidative damage, or modulating gene regulation. Given that risk assessment for conventional materials may not be applicable to nanomaterials (NMs), it is of great practical and scientific importance to study the safety of NMs for sustainable food production and consumer health protection. The present review intends to consolidate current knowledge on cellular and related interactions of NPs with plants. With this information we propose what we consider are relevant gaps to be filled in order to provide a more systemic picture of the above-mentioned interactions.