Effects of selenium nanoparticles and ancymidol on physiological responses of Stevia rebaudiana Bertoni colonized by Piriformospora indica

The South American plant, Stevia rebaudiana Bertoni, is a good source of steviol glycosides, antioxidants, all of the essential amino acids, and other important nutritional compounds. The present study was conducted to investigate the effects of 5 and 10 mg L-1 concentrations of selenium nanoparticles (SeNPs) and 50 mg L-1ancymidol (ANC) on physiological and biochemical characteristics of S. rebaudiana colonized by the root endophytic fungus Piriformospora indica at vegetative and initial flowering stages. Results indicated that ANC decreased root colonization rate and antioxidant enzyme activities, but increased the content of H2O2 (vegetative stage), malondialdehyde (initial flowering stage), and phosphorus uptake (initial flowering stage( significantly and had no effect on total carbohydrate content. The adverse effects of ANC reduced after P. indica colonization and somewhat with SeNPs application. Our results suggest that the P. indica colonization and SeNPs application can alter the equilibrium between the production of free radicals and enzymatic defence reactions in S. rebaudiana by enhancing the scavenging capacity of free radicals and by decreasing membrane lipid peroxidation during both vegetative and initial flowering stages. Moreover, the effects of ANC, SeNPs, and P. indica on the measured characteristics at the vegetative stage were higher than those observed at the initial flowering stage.