TUNEL assay of condensed nuclei in Zinnia suspension cultured cells exposed to treatment with Z-Asp-CH2-DCB. A. Negative control from a non-induced cultures; B. cells treated with 1 mg/L NAA and 1 mg/L BA; C. 1 mg/L NAA + 1 mg/L BA + 100 nM Z-Asp-CH2-DCB. Images were collected with a Nikon fluorescence microscope at 510 nm wavelength. Green fluorescent dots (arrowheads) indicate nuclei containing cleaved DNA. Scale bars (A, B, C) = 30 μm. D. Effect of Z-Asp-CH2-DCB on the amount of TUNEL positive nuclei (TUNEL scored as percent of cells with secondary wall) in which: C, negative control from non-inductive cultures; 0, cells treated with 1 mg/L NAA and 1 mg/L BA; the remaining variants are combinations of the hormones with 1, 10 or 100 nM Z-Asp-CH2-DCB. Error bars indicate SEM(n-1).