Abstract
The tolerance mechanism of chemical pesticide is necessary to combat the pest infestation challenges. This study intended to analyze the responses of enzymatic activity and expression level of an antioxidant gene to organophosphate pesticide stress. The alteration of anti-oxidative correlated with pesticide treatment in eggplant (S. melongena L.cv. Longai) using varying concentrations (0, 50, 100, 150 and 200 ppm) of malathion (PM) and tatafen (PTF) each. The enzyme activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were observed to be elevated with pesticide treatment in eggplant seedling. FeSOD (iron SOD), CAT and APX genes associated in defense mechanisms were significantly expressed under PM and PTF stress which contributed to stress tolerance to the plant. The different concentration of both pesticide stresses altered the expression level of mRNA, FeSOD, CAT and APX genes in comparison to the non-treated plant. While mRNA level of three antioxidant genes were evaluated and found to be APX gene expression was more potent than the CAT and FeSOD gene subjected to different concentrations of PM and PTF in eggplant. The current experiment highlights the presence of minimum level of pesticide concentration impacted positively towards the plant growth and metabolism, while high level of pesticide concentration impacted negatively. In summary, antioxidant enzymes activity responded to both pesticide stresses at an early stage of exposure and their gene expression profiles provided more details about their complex interaction and effectively scavenge reactive oxygen species. This allows the plant to maintain growth under pesticide stress.