Fig. 4.

EM images of soybean leaf cross-sections. (A and B) High nano-ZnO treatment. The epidermis (marked with “E”), mesophyll (“M”), and vascular bundles (VB) are visible. A vascular bundle cross-section in A is highlighted (white rectangle) and magnified to higher resolution in B. The nano-ZnO–exposed vascular bundles were highly electron-dense, as indicated by the intense brightness, and showed an elevated Zn signal in EDS compared with controls. (C) Control leaf section show a vascular bundle and mesophyll. The control vascular bundles exhibited less electron density (i.e., less brightness), and were not enriched with Zn according to EDS.