Abstract

Effects of UV and butylated hydroxanisol (BHA) on the activities of antioxidant enzymes were studied on the leaves of winter wheat cultivars (Triticum aestivum L. Yildirim). Fifteen days old wheat seedlings were treated with UV radiation (240 nm, 3 day) before they are treated with BHA (20°C). Supplementary UV-B radiation and UV-B+BHA significantly decreased chlorophyll and total phenol contents. The activities of enzyme extracts; polyphenol oxidase, catalase, paraoxonase and peroxidase were determined in the leaves under normal, UV-B (<315 nm) and UV-B + BHA conditions for 4 days. The antioxidant enzymes affected and showed enhanced activities in peroxidase, paraoxonase and polyphenoloxidase (except catalase) in UV-B and then BHA irradiated seedling. UV-B and then BHA-treated winter wheat seedling tries to counteract high level of reactive oxygen species that are produced under UV-B stress through the increased activities of antioxidant enzyme. It brings to mind that BHA tries to counteract high concentrations of oxygen species produced under UV-B radiation stress through increase in UV absorbing compound and antioxidant enzymes. In this study, the changes in quantities of polypeptide in wheat was investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). While the accumulation and pattern of the polypeptides unchanged in UV-treated leaves, they increased in UV+BHA-treated leaves compared to the control. It is concluded that BHA can be involved in UV radition tolerance by regulating antioxidant enzyme activities.

Key words: Oxidative damage, butylated hydroxanisol (BHA), peroxidase, catalase, polyphenol oxidase, paraoxonase, UV, winter wheat.