Evaluation of chemical induced DNA damage in tomato crop

Abstract

Genotoxic effects are considered among the most serious of the possible potential side effects of agrochemicals. Data of genotoxicity and carcinogenicity of insecticides and chemical fertilizers are rather controversial, depending on the genetic system or the assay used. Therefore, in present study, the genotoxicity profile of two agrochemicals viz. fungicide Mancozeb and insecticide Azinophos-methyl was evaluated with two genotoxicity assays using two different genetic systems. First assay was cytological assay which was conducted using root tips of non-target plant Allium cepa at three different conc. of each of the tested agrochemicals. The parameters evaluated in cytological assay were number of cells in dividing stage, mitotic indices (MI), % mitodepressive (MD) effect and chromosomal aberrations (CA) on A. cepa roots exposed to 0.125%, 0.375% and 0.625% concentrations of the fungicide Mancozeb and 0.125%, 0.375% and 0.625% conc. of Azinophos-methyl. The results demonstrated that Mancozeb and Azinophos-methyl showed genotoxicity towards A. cepa meristematic cells, inducing chromosomal changes. Second assay i.e. molecular assay was performed with SSR primers using leaves of tomato plant, extracted after 2 days, 4 days and 6 days of the exposure to different conc. of both the test chemicals. The mutagenic activity of the active compounds was demonstrated by the detection of DNA changes in simple sequence repeat (SSR) markers in the treated cells compared to the control. Both chemicals used in present study are capable of inducing genetic mutation which is reflected through SSR electrophoretic profile due to which in treated population some new bands were generated or there is loss of few bands then compared to control. This is also reflected in reduction of the value of genomic template stability. The SSR profiles showed a great variation in banding patterns, particularly in intensity, number, thickness and mobility of the generated DNA fragments by the used primers. Together, these results contribute to a better understanding of the damage caused by these substances in living organisms and reveal a promising strategy for prospective studies of the toxic effects of selected agrochemicals. Keywords : Mancozeb, Azinophos-methyl, Mitotic Index (MI), mitodepressive (MD) effect, chromosomal aberrations (CA), A. cepa ,Tomato, Mutagenicity, SSR, Genomic Template Stability (GTS), PIC value, RP value