Nanostructure and plant uptake: Assessing the ecological footprint and root-to-leaf dynamics

Nanostructure design is presented as one of the economically viable technical alternatives for increasing the efficiency of agrochemical use (fertilizers and pesticides) by reducing runoff, increasing foliar uptake and bioavailability, and reducing environmental impact. Nanomaterials (NMs) possess unique properties due to their nanoscale dimensions, typically ranging from 1 to 100 nanometers. At low concentrations, NMs can promote plant growth and development, but at higher doses, they may become toxic, causing oxidative stress, membrane damage, and disrupting key physiological processes. This review aims to comprehensively explore how this toxicity is influenced by NMs properties like chemical composition, dosage, surface structure, and solubility. Gaps in knowledge regarding NMs transport across the root surface and within plants hinder the rational design of NMs for targeted applications. Therefore, this review delves into the physical criteria that affect NMs uptake, translocation, and absorption in plants, as well as the interaction of NMs with plant cells, soil, and their environmental impact. Existing literature on NMs deposited on roots and foliar uptake mechanisms (via stomata, cuticle, trichomes, and necrotic patches) are also examined. The review also discusses how NMs penetrate plant cell walls and utilize plasmodesmata (PD) for translocation between cells, shedding light on the mechanisms and factors influencing these processes. The current knowledge highlights the participation of the symplast, including the PD, in the movement of NMs within the plant. These findings enhance understanding of how plant structure and NM characteristics influence their transport and distribution, aiding the rational design of NMs for controlled uptake and safe application in plants.