IN VITRO SOMATIC EMBRYOGENESIS AND ANTIOXIDANT ENZYME ACTIVITIES IN RHAPONTICOIDES MYKALEA (HUB.-MOR.) M. V. AGAB. & GREUTER CRITICALLY ENDANGERED ENDEMIC PLANT

摘要

The aim of this study was to induce somatic embryo-genesis from immature zygotic embryos of Rhaponticoides mykalea (Hub.-Mor.) M. V. Agab. & Greuter and determine antioxidant enzyme activity during the somatic em-bryogenesis process. Firstly, the effect of various plant growth regulators on somatic embryogenesis was determined. Immature zygotic embryos isolated from achenes in different developmental period were used as starting materials. Explants were cultured on Murashige and Skoog (MS) basal medium supplemented without or with different concentration of ~1N~6- Benzyladenine (BA) and α-Naphthalene-acetic acid (NAA). The highest rate of embryogenic callus formation was obtained on MS medium with 0.25 mg/L NAA and 1 mg/L BA (75 %). Calli produced numerous somatic embryos on MS medium with 0.1 mg/L BA and sucrose % 6 (On average 19.25 somatic embryo/callus). Well-developed somatic embryos on MS medium with 0.1 mg/L BA and high sucrose (12%) were converted into plantlets on MS basal medium with sucrose 3% (15.75 %). Secondly, the activities of three antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were determined. The result showed that the activity of SOD gradually increased in the stage of embryogenic callus and globular structure formation. In the later stage, SOD activity began to decline. CAT and POX activities were high in the first week of culturing. During the formation of embryogenic callus a significant decrease in the activity of enzymes was observed. CAT and POX activities began to increase in globular structure formation and differentiation process.