Terminal deoxynucleotidyl-dUTP nick end labeling (TUNEL) assay in Click-iT technology in the untreated control (negative), DNase-treated control (positive), HU-treated and HU/CF-co-treated (i.e. PCC-induced) <i>Vicia faba</i> root meristem cells.

<p><i>Left panel</i>—DNA fragmentation in <i>V</i>. <i>faba</i> cells detected by TUNEL reaction and visualized by AlexaFluor 594. <i>Central panel</i>—DAPI stained nuclei. <i>Right panel</i>—Merged images (AlexaFluor 594 + DAPI). Positively stained nuclei appear in the DNase-treated cells (e.g. A-A'') and in the HU/CF co-treated cells (e.g. B-B''). Positively stained nuclei in the HU-treated series are indicated by arrowheads. Non-reacting nuclei can be seen in the negative control sections (as indicated in the <i>highest panel</i> described as 'CTRL'). <i>Scale bar</i> = 20 μm.