Astragaloside IV and Cycloastragenol Production Capacity of Astragalus trojanus Calli

Astragalus species are medicinal plants which produce valuable secondary metabolites, especially cycloartane-type glycosides. In this study, stem and leaf explants of Astragalus trojanus were subjected to different plant growth regulators, environmental conditions and media compositions to identify their callus responses. Stem and leaf explants were cultured in Murashige and Skoog (MS) and woody plant (WPM) media supplemented with different concentrations of kinetin, naphthalene acetic acid, 2,4-dichlorophenoxyacetic acid, thidiazurone and indol acetic acid under two light intensities (1000 and 4000 lux) and also in dark conditions. Both MS and WPM media triggered callus regeneration. Although, callus regeneration was observed on both stem and leaf explants, callus biomass accumulation on stem explants were higher. Addition of 100 μg/L selenium and doubled concentration of WPM vitamins enhanced callus biomass on stem explants under dark conditions. Stem explants also regenerated shoots at high frequencies (up to 93%), especially in kinetin added media. Astragaloside IV and cycloastragenol accumulation efficiencies were determined in calli tissues. The highest astragaloside IV production (3.5 μg/mg) was found in callus tissue regenerated from stem explants in D1 medium, whereas the highest cycloastragenol accumulation (4.8 μg/mg) was detected in callus tissue regenerated from stem explants in N2 medium.