Antioxidant enzymes activities during secondary somatic embryogenesis in Persian walnut (Juglans regia L.)

Abstract

Somatic embryogenesis was achieved from immature cotyledon explants of Persian walnut (Juglans regia L.) cave. "Chandler" on DKW medium. Secondary somatic embryogenesis, the process by which adventitious embryos are formed from primary somatic embryos, is frequent during somatic embryogenesis in Persian walnut. It has certain advantages compared with primary somatic embryogenesis such as high multiplication rate, independence to the explant source and repeatability. Proteins and activities of antioxidant enzymes including catalase (CAT), peroxidase (POX), superoxide dismutase (SOD) and polyphenol oxidase (PPO) were evaluated in two types of secondary embryogenic calli and secondary somatic embryos in Persian walnut. In dark brown calli from which their secondary somatic embryos were separated, CAT, POX and POX had the highest activities while the activity of SOD and also protein content showed the lowest level. High SOD activity, protein content and low activities of CAT, POX and PPO were determined in secondary somatic embryos and light brown calli containing secondary somatic embryos. According to the obtained results, some proteins and antioxidant enzymes have been regarded as markers for secondary somatic embryogenesis.

Key words: Persian walnut, secondary somatic embryogenesis, antioxidant enzymes.