Cytogenetic responses of Allium cepa after exposure to contaminated pond waters

Resumen

Biomarkers may refer to certain changes in living cells induced by environmental contaminants. To assess these, plants act as excellent systems for genetic tests as they are sensitive to pollutants. Therefore, the present study aimed to evaluate a coastal pond (Brazil) used for fishing and recreation, but also affected by several environmental impacts. Three sampling stations were established around the pond to collect water during the rainy and a post-rainy period. The A. cepa test was conducted using seeds exposed to water samples and controls. Slides of root meristems were prepared using the Feulgen method and analyzed to calculate the mitotic index, the rate of chromosomal aberrations and the frequency of micronuclei. Statistical analysis was performed using ANOVA followed by the Tukey or Bonferroni test (p <0.05). The results showed significant changes in the mitotic index, chromosomal aberrations and frequency of micronuclei when compared to the negative control. Among the aberrations observed, C-metaphase, chromosomal breaks, nuclear buds and chromosomal losses showed significant values. In addition, it was observed that the rate of chromosomal aberrations during the rainy period was superior to that in the post-rainy period. These results may be associated with the presence of potentially toxic compounds such as aluminum and cadmium, although the pond presents a good water quality index. Therefore, we suggest a combination of more sensitive methods, such as the Allium cepa test, with traditional systems of surveillance and monitoring of aquatic environments.