Effect of cytokinins on shoot proliferation, metabolite production and antioxidant activity in Venus flytrap (Dionaea muscipula Ellis)

Cytokinins (CKs) are regulatory molecules that affect a number of important structural and functional aspects in plants. In this study, the effect of four CKs including the Thidiazuron (TDZ), Kinetin (Kin), 6-Benzylaminopurine (BA) and 2-isopentenyladenine (2ip) (1, 2, 4, and 8 μM) on the shoot proliferation, photosynthetic pigments (chlorophyll a and b and carotenoids), flavonoids, anthocyanins and phenolics, antioxidant activity and survival rate of Venus flytrap plantlets was investigated. The results showed that the increasing the concentration of the CKs resulted in increase in plantlets root and leaf growth as well as photosynthetic pigments content. The leaf and root growth and also photosynthetic pigments content (chlorophyll a and b and carotenoids) were most effective in TDZ-supplemented medium. The shoots from medium supplemented with 2 µM TDZ demonstrated the highest production of total flavonoids, anthocyanins and phenolics as well as antioxidant activity, which was 1.95, 0.23, 8.51 mg/g FW and 28.62 µg/ml, respectively. The highest shoot proliferation (7.5/explant) was observed at the 8 μM TDZ, which showed a 40% increase in compared to cultures with its least level. Regression analysis justified 81.02% and 70.2% of changes in survival rate in both TDZ and Kin by root length and total chlorophyll content. Correlation analyses revealed that regenerated plantlets with more growth indices in organs, metabolites and antioxidant activity had better survival rates. It seems that more developed organs, photosynthetic pigments and secondary metabolites content as well as antioxidant activity in micropropagated plantlets contributes to better ex vitro survival.