A Plant Model for Assessing Arsenic Phytotoxicity: Effect on Growth and Oxidative Stress Response Molecules

Abstract

Abstract-The word 'Arsenic' elicits a fearful response in most people. It poses a major environmental and health problems. Widespread groundwater pollution by arsenic (As) has raised serious concern around the world. It has recently been recognized that As-contaminated groundwater used for irrigation may pose an equally serious health hazard to people eating food from the crops irrigated and that As accumulating in irrigated soils poses a serious threat to sustainable agriculture in affected areas. Tomato (Solanum lycopersicum L.) was selected as a model plant. To assess the phytotoxic effects of As, the tomato plants were grown hydroponically under controlled conditions and treatment was given to the roots. As caused reduction in plant growth by inducing an oxidative stress. Our observation on some growth parameters of tomato plants have revealed that given As dose was proved toxic, causing significant reduction in the growth of plants. It was clear that greater As accumulation in plant caused greater oxidative stress. Results from experiments are reproducible with respect to the morphological effects and cell death. In our study, a concomitant increase in ROS production (oxidative burst), the down-regulation of the antioxidant defence system and a change of lipid peroxidation were crucial for the onset of cell death. Results demonstrate that production of some phytohormones potentiated the oxidative burst. Significant increase of PAL activity was observed in consonance with increase of ROS level which shows primary defence system of plant against As exposure. Results, thus, clearly indicate that As induced oxidative stress in plants resulting in a range of responses in plants including readjustment of transport and metabolic processes and growth inhibition.