Allium cepa Root Chromosomal Aberration Assay: An Efficient Test System for Evaluating Genotoxicity of Agricultural Soil

Agricultural soils are increasingly becoming sinks for wide number of hazardous contaminants which ultimately result in pollution. Plant bioassays, because of their sensitivity and affordability, have been recommended as first-tier assays which enable the detection of contaminants. The present study involves genotoxicity of four soil samples collected from different regions of Amritsar employing chromosomal aberration assay in root tip cells of Allium cepa using in situ and root dip modes of treatments. The squash preparations from root tip cells of treated A. cepa bulbs revealed different types of chromosomal aberrations which were apportioned into physiological aberrations (c-mitosis, delayed anaphases, stickiness, laggards, vagrants) and clastogenic aberrations (chromosomal breaks, chromatin bridge and ring chromosomes). Frequencies of chromosomal aberrations induced by soil samples were higher than negative control. A few cells with c-mitosis, delayed anaphase, stickiness, bridges were observed whereas no instance of laggards, vagrants, abnormal anaphase, abnormal metaphase, breaks and ring chromosomes were found in negative control. Among physiological aberrations, percentage of delayed anaphases was maximum where as chromatin bridges dominated clastogenic aberrations.