Physiological Responses of Orthosiphon stamineus Plantles to Gamma Irradiation (original) (raw)

2008, American Eurasian Journal of Sustainable Agriculture

In vitro mutagenesis by means of gamma irradiation can be used to produce economically improved mutants. Gamma irradiation was used to induce biochemical changes in a prominent medicinal plant, Orthosiphon stamineus. Shoot tip explants of O. stamineus were subjected to gamma irradiation at 0, 10, 20, 30, 40, 50, 60 and 70 Gray (Gy). Biochemical studies on O. stamineus revealed that the total soluble protein and total chlorophyll content decreased notably as the gamma dosage increases. However, plantlets irradiated at 10 and 20Gy exhibited total soluble protein content of 39.61 ± 0.66mg/g FW and 34.00 ± 0.85mg/g FW, respectively which was higher than all other treatments. Severe increased in specific activity of peroxidase was observed especially in plantlets irradiated at high dosages (70Gy). Analysis on protein banding profile of O. stamineus using Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) demonstrated that gamma irradiation at the treatment dosages did not produce a significant change in protein constituent. Nine major bands of relatively similar intensities were observed at 10, 12, 15, 16, 25, 27, 46, 50, 80kDa. Rosmarinic acid content was the lowest (5.27±0.35mg/g FW) in plantlets irradiated at 10Gy, and the highest (8.40±0.57mg/g FW) in plantlets irradiated at 30Gy. However, it was suggested that gamma irradiation at low dosages did not produce an apparent change in rosmarinic acid content as an irregular trend of production profile was observed. Due to the potential future of O. stamineus in pharmaceutical industries, further research on this plant could be done to facilitate the propagation of superior mutants that is able to produce vast quantities of valuable secondary metabolites.