Cycloastragenol (CAG) is a triterpenoid saponin compound that is synthesized by Astragalus species. CAG has many bioactivity, including telomerase activation, telomere elongation, anti-inflammatory, and anti-oxidative properties. While CAG activates human telomerase, no study has been conducted to investigate its effect on the plant telomere/telomerase system. In this study, in order to test whether CAG has an impact on plants, 1 mu M and 10 mu M CAG were tested on all in vitro grown plant and callus tissues of a model plant Arabidopsis thaliana. Results revealed that CAG caused an increase in the transcript levels of TER1, CTC1, TRB1, POT1a, TAC1, BT2 which act as positive regulators on the telomere/telomerase system together with the TERT gene encoding the catalytic subunit of telomerase especially calli tissues in A.thaliana. While CAG administration resulted in increase in height, and no remarkable effect on callus growth index was observed. Furthermore, no significant change in cell proliferation was observed in plant root cells due to the CAG treatment. The gene expression results suggest that CAG induced transcription of positive regulators of telomere/telomerase system and it might have a role in plants as well as in humans.