Biological Barriers, Processes, and Transformations at the Soil–Plant– Atmosphere Interfaces Driving the Uptake, Translocation, and Bioavailability of Inorganic Nanoparticles to Plants

Abstract

The development of nanotechnologies for more sustainable agriculture is an innovative strategy proposed to increase food production while decreasing material inputs and reducing environmental impacts. Nanoparticles (NPs) applied to seeds, soil, or leaves interact with plants at two major interfaces: the rhizoplane (root–rhizosphere interface) or the phylloplane (atmosphere–leaf interface). NP transformations occurring at these interfaces control their bioavailability, while plant structures are barriers to NP absorption and bottlenecks for their translocation. This chapter focuses on the complex interplays driving NP uptake, translocation, and accumulation into plant tissues. Foliar treatments appear to present advantages over soil application for the delivery of NPs to certain compartments. The adjustment for nanoparticle’s shape and surface properties could allow specific targeting (e.g., apoplast, symplast, organelles) and designed mobility to freely reach the phloem or accumulate in the mesophyll. This chapter highlights the knowledge gaps that need to be overcome for the safe and efficient development of nano-enabled agriculture. The parameters influencing for NP movement across cuticle barriers, cell walls, and cell membranes are still to be identified. Consequently, NP mobility in the root cortex and through the endodermis before entering the xylem or in the mesophyll before loading the phloem is not predictable yet. The processes that drive NP movement from the mesophyll cells to the sinks and their capacity to load the phloem are also poorly characterized. In addition, plant physiological responses and in vivo transformations, such as dissolution rates, or protein corona formation around NPs, remain important knowledge gaps that need to be addressed to understand, predict, and regulate NP translocation in plants and their bioavailability, thus enabling safe and efficient, targeted delivery of NPs for agricultural purposes.