Effect of different plant growth regulators on callus and adventitious shoots induction,polysaccharides accumulation and antioxidant activity of Rhodiola dumulosa

Objective:As a medicinal plant,the resource of Rhodiola dumulosa is deficient along with the large collection.For the protection and utilization of R.dumulosa,the influence of plant growth regulators(PGRs)on callus induction and adventitious shoots differentiation,polysaccharide production and the antioxidant activity were tested.Methods:Internodes of R.dumulosa were used as explants and cultured on MS medium plus different plant growth regulators(PGRs).The anti-oxidative activities of polysaccharides were evaluated using radical scavenging assays.Results:By response surface plot,0.85 mg/L N6-benzyladenine(BA),0.34 mg/L naphthaleneacetic acid(NAA)and 0.33 mg/L 2,4-dicholorophenoxyacetic acid(2,4-D)were the optimal factors for callus induction(90.03%)from internodes explants on MS medium.The fresh weight of green callus increased 47.26 fold,when callus was inoculated on MS+thidiazuron(TDZ)0.5 mg/L+NAA 2.0 mg/L.Adventitious buds regenerated from callus on the media of MS were fortified with BA 1.0 mg/L plus NAA 0.5 mg/L,and the induction rate was 40.00%.MS plus indole-3-butyric acid(IBA)1.0 mg/L produced the highest rooting rate with 10 to 15 roots in a length of 2–3 cm per shoot.The content of total polysaccharides in callus developed on MS+TDZ 0.5 mg/L+NAA 2.0 mg/L and MS+BA 1.0 mg/L+NAA 0.5 mg/L was as high as 1.72%
2.15%.At the dose of 0.5 mg/mL polysaccharides extracted from different callus induced on MS+NAA 2.0 mg/L+TDZ 0.5 mg/L or MS+BA 1.0 mg/L+NAA 0.5 mg/L or MS+BA 0.5 mg/L+2,4-D 0.5 mg/L,the ABTS radical eliminating percentages were 82.78%,80.18%and 68.59%,respectively,much higher than that of wild plant.Conclusion:A rapid micropropagation system for R.dumulosa has been developed.The combination of TDZ and NAA or BA and NAA can increase the yield of the total polysaccharides.The polysaccharides isolated from callus and whole wild plants had stronger free radicals scavenging activities,indicating that polysaccharides from R.dumulosa are the potential pharmaceutical supplements.