Picrorhiza kurroa

Cloning genes involved in biosynthesis of picrosides

Differential display of mRNA was adopted to identify genes involved in picrosides biosynthesis. Analysis of ESTs yielded partial sequences of thiamine biosynthesis gene (TBS), DXR and GDPS. Using the sequence information, primers for RACE were designed and RACE was performed to obtain full-length sequence data of TBS and GDPS (Fig. 6.11). To understand regulation of these genes, expression was studied in response to a range of external stimuli. Also internal control gene primers were developed and used to validate the expression data (Fig. 6.12). Expression analysis revealed that the treatments showed enhancement of GDPS. However, TBS did not alter (Fig.6.13).

Fig. 6.11 Cloning of picroside biosynthetic pathway genes: (A) 5’ and 3’ RACE for TBS (B) 5’ RACE for GDPS and (C) 3’ RACE for GDPS

Fig. 6.12 Development of internal control gene primers for Picrorhiza

Fig. 6.13 Expression of GDPS and TBS in response to external stimuli in Fig. 6.13 Expression of GDPS and TBS in response to external stimuli in P. kurroa