Ascorbate Attenuates Damages Caused by Paraquat-Induced Oxidative Stress in Fenugreek (Trigonella foenum-graecum L.) Seedlings

Ascorbate (vitamin C), a major antioxidant in plants, significantly mitigates cellular reactive oxygen species (ROS) accumulation caused by many abiotic stresses such as herbicides. This study examined the protection by ascorbate of a medicinal plant, fenugreek (Trigonella foenum-graecum L.), from oxidative stress induced by paraquat herbicide. Fenugreek was irrigated with 50 mM of ascorbate solution before herbicide treatment at 100 mu M. The effects of both treatments were assessed at the physiological and biochemical level by evaluating: shoot and root dry weight, total chlorophyll, malondialdehyde (MDA), proline, and hydrogen peroxide (H2O2) contents, and reactive oxygen detoxifying enzymes. Results showed that paraquat treatment provoked a set of damages in plants. The total chlorophyll content was diminished, fenugreek shoot and root dry weights were retarded, and the contents of proline, MDA, and H2O2 were increased. When ascorbate was combined with paraquat, it reduced the proline, MDA, and H2O2 contents, fenugreek shoot, root dry weight and catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) activities which were significantly different compared to that noted after paraquat applications. The results conclude that paraquat induces oxidative stress and that ascorbate treatment before herbicide prevents ROS accumulation in plant cells, elicits antioxidative responses, and repairs damages in fenugreek seedlings.