Moticam pro 252b

). Photomicrographs of leaf sections were made using light microscopy (Leica) tted with a digital camera. The measurements were taken from images obtained from leaf cross sections using a Nikon Eclipse CI microscope equipped with a digital camera (Moticam Pro 252b). To identify the presence of zinc in plant tissues, free-hand cuts were performed on collected leaves, dehydrated at room temperature and exposed to Zincon® reagent, following the method of Seregin et al. (2015) and Seregin and Kozhevnikova (2011) . For scanning electron microscopy observations (SEM), segments of dry leaves were mounted on stubs and coated with a thin layer of gold (Denton vacuum Desk IV, LLC). The abaxial and adaxial surfaces of leaves were analyzed with a JEOL-JSM 6390 LV scanning electron microscopy (JEOL, Tokyo, Japan). To analyze the epidermis in frontal view and count the secretory glands/mm 2 , leaf epidermises were obtained after treatment with a dissociation solution of hydrogen peroxide and glacial acetic acid (1: 1) and heating in an oven at 60ºC for 24h (Franklin 1945). Afterwards, the epidermises were washed in distilled water many times to remove the dissociation solution. Then, they were stained with 0.05% basic fuchsine aqueous and mounted in 50% glycerin on semi-permanent slides (Kraus and Arduin 1997).