Characterization of the antioxidant system during the vegetative development of pea plants

Abstract

The antioxidative system was studied during the development of pea plants. The reduced glutathione (GSH) content was higher in shoots than in roots, but a greater redox state of glutathione existed in roots compared with shoots, at least after 7 d of growth. The 3-d-old seedlings showed the highest content of oxidised ascorbate (DHA), which correlated with the ascorbate oxidase (AAO) activity. Also, the roots exhibited higher DHA content than shoots, correlated with their higher AAO activity. The activities of antioxidant enzymes were much higher in shoots than in roots. Ascorbate peroxidase (APX) activity decreased during the progression of growth in both shoots and roots, whereas peroxidase (POX) activity strongly increased in roots, reflecting a correlation between POX activity and the enhancement of growth. Catalase activity from shoots reached values nearly 3 or 4-fold higher than in roots. The monodehydroascorbate reductase (MDHAR) activity was higher in young seedlings than in more mature tissues, and in roots a decrease in MDHAR was noticed at the 11th day. No dehydroascorbate reductase (DHAR) was detected in roots from the pea plants and DHAR values detected in seedlings and in shoots were much lower than those of MDHAR. In shoots, GR decreased with the progression of growth, whereas in roots an increase was seen on the 9th and 11th days. Finally, superoxide dismutase (SOD) activity increased in shoots during the progression of growth, but specific SOD activity was higher in roots than in shoots.