Nanoparticle Trafficking in Trees Visualized by Virus-Like Particles

Pollutants and trace metals are considered to be mainly taken up from contaminated soils and waters by trees through the roots. Recently, it was demonstrated that uptake and transport of nanoparticles (NPs) can occur through the leaves in different tree species. Gold was measured in the wood of trees, and isolated gold NPs were identified inside the leaf blade and a trichome. However, the trafficking routes from leaves to the whole plant are not yet explored. Evidence supporting the phloem transport of NPs after their penetration in the leaves is still lacking. The stomatal pathway seems to be the main route for their uptake, but it is still unclear where the NPs cross the plant cell membrane and if are transported using the apoplastic or symplastic pathways. An insight in these physiological processes and mechanisms can be given by the visualisation of NPs in the plant, but the methods currently employed don't allow the visualisation of NPs in trees. Virus-like particles (VLPs) have b