Activity of tyrosol glucosyltransferase in Rhodiola kirilowii transgenic root cultures

Rhodiola kirilowii (Crassulaceae) is plant of Asia growing in mountain regions. R. kirilowii is used in traditional medicine for the enhancement of the ability of anti-anoxia. Moreover it shows anticoagulative properties and decreases the level of blood sugar. R. kirilowii also protect people against cardiopulmonary function problems when moving to high altitude [1]. Biologically active compounds of R. kirilowii are salidroside and rosavins. The aim of this work was to study the activity of tyrosol glucosyltransferase (TGase) in R. kirilowii transgenic root culture. These roots was successfully established by transformation with Agrobacterium rhizogenes LBA 9402 [2]. The activity of TGase was measured every 72 hours throughout the 30 day cycle of culture using tyrosol as a precursor and without precursor addition (control) [3]. Simultaneously, the content of tyrosol and salidroside were determined. All assays were performed by RP HPLC DAD method. Neither TGase activity nor salidroside were detected in roots cultured without precursor. Addition of tyrosol to transgenic root culture in the first day of culture resulted in significant increase of both TGase activity and salidroside concentration. Since the highest enzyme activity (0.17 U/µg) as well as salidroside concentration (1mg/g DW) was observed on 18^th day of culture, that day was chosen as optimal day for performance of biotransformation reaction. The addition of tyrosol on 18^th day of culture in further studies resulted in increase of salidroside concentration up to 2.3mg/g DW in root culture. In conclusion, it seems that the activity of TGase in transgenic root culture of R. kirilowii was induced by precursor addition.