Oxidative stress and antioxidant defense mechanism in mung bean seedlings afer lead and cadmium treatments

Abstract

Tis research was an attempt to study the efect of heavy metals lead and cadmium (0.05 mM and 0.3 mM) on growth andantioxidant enzymes of seedlings of 2 mung bean genotypes (NM 19-19 and Azri mung-2006). Results revealed that germinationpercentage and seedling length decreased when compared with the control for both genotypes. However, seedling length andgermination percentage was better in NM 19-19 as compared to Azri mung-2006. Elevated levels of protein were observed under metalstress in both genotypes. Heavy metals induced oxidative stress in plants, causing membrane injury as observed by enhanced level ofmalondialdehyde (MDA) contents. Increase in antioxidant enzymes activity was detected for guaiacol peroxidase (GPX) and catalase(CAT). However, ascorbate (APX) activity decreased under stress for both genotypes. We observed more MDA content and GPX andAPX activity in Azri mung-2006 as compared to NM 19-19 when high concentrations of Pb and Cd were added. Tis revealed that NM19-19 was tolerant whereas Azri mung-2006 was sensitive to Pb and Cd. It was further noticed that Cd imposed a more deleterious efectthan Pb on both genotypes.