Toxic effects of environmental pollutants: comparative investigation using Allium cepa L. and Lactuca sativa L.

Abstract

Studies that help understand the mechanisms of action of environmental pollutants are extremely important in environmental toxicology. In this context, assays using plants as models stand out for their simplicity and low performance cost. Among the plants used for this purpose, Allium cepa L. is the model most commonly applied for cytogenotoxic tests, while Lactuca sativa L., already widely used in phytotoxic investigations, has been gaining prominence in cytotoxic analyses. The present study aimed to compare the responses of A. cepa and L. sativa via macroscopic (root growth) and microscopic analyses (cell cycle and DNA fragmentation via TdT-mediated deoxy-uracil nick and labeling (TUNEL) and comet assays) after exposure of their roots to environmental pollutants with known cytogenotoxic mechanisms. Both species presented sensitive and efficient response to the applied tests after exposure to the DNA-alkylating agent Methyl Methanesulfonate (MMS), the heavy metal Cadmium, the aluminum industry waste Spent Potliner (SPL) and the herbicide Atrazine. However, they differed regarding the responses to the evaluated endpoints. Overall, A. cepa was more efficient in detecting clastogenic changes, arising from DNA breakage, while L. sativa rather detected aneugenic alterations, related to chromosome segregation in mitosis. In the tests applied to verify DNA fragmentation (comet and TUNEL assays), A. cepa presented higher sensitivity. In conclusion, both models are efficient to evaluate toxicological risks of environmental pollutants.