Combined effects of Piriformospora indica and Azotobacter chroococcum enhance plant growth, antioxidant potential and steviol glycoside content in Stevia rebaudiana

摘要

The herb Stevia rebaudiana Bertoni is an important sugar substitute due to the presence of steviol glycosides-mainly stevioside and rebaudioside-A. These compounds possess antioxidant activity with industrial importance. The fungus Piriformospora indica has been used to improve medicinally important biomolecules, growth and secondary metabolite content in plants. The soil bacterium Azotobacter chroococcum has also been reported to possess plant growth promoting ability. The present study was undertaken to test the ability of P. indica (Pi) and A. chroococcum (Az), alone and in combination to improve the growth, antioxidant activity and steviol glycoside (SG) content of in vitro S. rebaudiana plantlets. Inoculation with Pi or Az alone showed enhancement in all these characters compared with non-inoculated plantlets. Combined inoculation with Pi and Az further enhanced these traits.