Fig. 2. Diagram showing the mechanism of uptake and transport of SiNPs in leaf and root tissues. In the leaf tissue, SiNPs penetrate through the cuticle and then enter the leaf mesophyll via passing through the epidermis layer, and from the leaf mesophyll tissue they enter the vascular tissues. In the root, SiNPs are taken up by root hairs, subsequently, they pass through the epidermis and cortex by following the apoplastic and symplastic pathways, and finally reach the xylem and phloem, and then they are further transported to the upper parts of the plant system.
