<b>Action of Ponceau 4R (E-124) food dye on root meristematic cells of <i>Allium cepa</i> L.

This study aimed to evaluate the toxicity of Ponceau 4R food dye on the cell cycle in root meristematic cells of Allium cepa L. at three concentrations: 0.25, 0.50 and 0.75 g L-1, at exposure times of 24 and 48 hours. For each concentration, we used a set of five onion bulbs that were first rooted in distilled water and then transferred to their respective concentrations. Radicles were collected and fixed in acetic acid (3:1) for 24 hours. The slides were mounted with the crushing technique and stained with 2% acetic orcein. Cells were analyzed throughout the cell cycle, totaling 5,000 cells for each control and exposure time. The calculated mitotic indices were subjected to the Chi-square test (p < 0.05). From the results, we observed that the concentrations of 0.25 and 0.50 g L-1 at the 48-hour exposure, and the concentration of 0.75 g L-1, the two exposure times time significantly reduced (p < 0.05) the cell division rate. Importantly, all the three concentrations at the two exposure times tested caused cellular aberrations in significant numbers in this testing system. Therefore, under the conditions studied, the Ponceau 4R was cytotoxic