Variation in root morphology, enhancement in anti-oxidative enzyme responses and improved arbutin and bergenin levels in Bergenia ciliata (Haw.) Sternb. raised in vitro via EMS and gamma irradiations

Plant cells develop defence mechanisms in response to mutagen stress which leads to modulation of certain metabolic and defensive pathways. Owing to alteration in gene expression under mutagens, qualitative and quantitative changes in plant metabolites do occur. Keeping in view the numerous medicinal properties of Bergenia ciliata and its demand in herbal and allopathic medicine, the present work has been carried out with the aim of improving the plant architect by enhancing its antioxidant system and phytoconstituents like bergenin and arbutin. In this regard, the basic biomolecules required by plant cells vis-a-vis pigments, carbohydrates, proteins were estimated, in addition to the anti-oxidative enzymes which have a key role to function in response to stress conditions. The mutagen doses applied in the present study showed enhanced shoot regeneration potential and much variation in the root morphology was observed. With regard to metabolite content of in vitro regenerated non-treated and treated plantlets, enhancement in pigment content and soluble protein content in treated plantlets was observed. However, no significant changes in carbohydrate levels were recorded. While studying the effect of mutagens on anti-oxidative enzyme activities, lower doses of both mutagens have showed enhanced glutathione reductase, superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. A negative correlation between mutagen doses and activities of APX and SOD was found. With the increase in doses of both mutagens, decrease in the activity of APX and SOD was recorded. The lower doses/concentrations of mutagens showed enhancement in shoot regeneration potential and varied root morphology of B. ciliata. HPLC results of arbutin revealed that 0.09% EMS showed significant increase in arbutin content as compared to wild plant samples, in vitro propagated non-treated samples and irradiated samples.