Alterations in Glutathione, Phytochelatin and Micronutrients of Corn Plants Exposed to Cadmium Stress at Different Time Periods

Phytochelatin (PC) and glutathione (GSH) are important internal strategy of plants to detoxifying heavy metal (HMs) stress. In this study, the effect of cadmium (Cd) concentrations (0, 10, 25 and 40 µM) on GSH, PC, some micronutrients' concentration in corn plants, and the role of PC in detoxifying Cd was assayed in different exposure time periods (2, 4, 8, and 16 day). The results showed that exposing corn plants to different Cd concentrations and various time period, decreased the fresh weight of corn plants (4% to 31% for shoots and 11% to 32% for roots) and nutrient uptake rates (NUR). The increase in Cd concentrations increased GSH and PC biosynthesis in corn plants (GSH increased from 72 to 235 nmol g−1 F.W and PC increased from 79 to 505 nmol g−1 F.W) and positive correlation was observed (in the range of 0.67 to 0.99). The concentrations of GSH and PC decreased by increasing Cd exposure time periods and was more intensified at the highest Cd concentration (40 µM). These results indicate that PC plays an effective but transient role in Cd detoxification and the levels of PC are related to Cd concentration in cytoplasm and its threshold limit.