Figure 3

DAPI-DNA staining of cytological sections for cauline leaves. (A-C) Second cauline leaf from a 19-day-old plant. (D-F) Second cauline leaf from a 23-day-old plant. (G-I) Second cauline leaf from a 26-day-old plant. Leaves were sectioned by hand and immediately fixed with glutaraldehyde. Chlorophyll autofluorescence (A, D, G), DAPI-DNA staining (B, E, H), and merged images (C, F, I) are shown. These images are representative of 9–10 microscopic fields from mid-leaf sections of the leaves. Images of autofluorescence and DAPI-DNA staining were recorded at the same exposure times for all samples. White bar in (G), 10 μm, applies to all panels. White arrows indicate chloroplasts that have been magnified 2.9-fold and displayed in the insets shown in the bottom right corners of B and C, E and F, and H and I.