Antioxidative Potential of Garlic on Lead-Induced Oxidative Stress and Effect on Enzyme Activity in Rice Plants

Seedling of Ofada rice (Oryza sativum L) were raised in sand (swampy) and clay (upland) cultures under 500mg/kg lead acetate and 500mg/kg garlic aqueous extract for 40-days. The uptake and distribution pattern of lead with possible induction of oxidative stress and likely alteration in the inherent antioxidant defense systems of the rice plants were determined. The inhibitory potential of garlic against lead-induced oxidative stress in rice seedling was also assessed. From the results, rice seedlings grown for 10-40 days under 500mg/kg lead acetate showed significant (P<0.05) increase in level of lipid peroxides in roots, indicating enhanced lipid peroxidation compared to control. However, incubation of garlic extract with supernatants of rice root and shoot caused a significant (P<0.05) reduction in the accumulation of lipid peroxides in a concentration dependent manner. In addition, there was a marked increase in antioxidant enzymes activities in lead acetate treated seedlings, where the shoot maintained higher defensive enzyme activity than roots. The results suggest that lead-induced oxidative stress could be salvaged by garlic extract and antioxidant enzymes are biomarkers for lead-induced oxidative injury in rice plants.