4.3. Fluorescence Microscopy

To determine the localization of peptides in root cells, the FITC-labeled dipeptides and Gly were used at a concentration of 10⁻⁵ M; control FITC and FITC without peptides were used as controls [62]. The incubation time was 20 h. Root tips (4–5 mm) were excised from tobacco seedling roots, and fixed in 4% paraformaldehyde (Sigma-Aldrich, St. Louis, USA) for 1.5 h at room temperature. After three washes with phosphate-buffered saline (PBS), the root tips were mounted on glass slides and embedded in Moviol. Fluorescence was analyzed at a wavelength of 490 nm using Olympus BX51 microscope (Tokyo, Japan) with 10× and 20× objective lens. Photographs were obtained using Color View digital camera (Munster, Germany) [63].