BIOTECHNOLOGICAL STUDIES ON MEDICINAL PLANT PLECTRANTHUS BARBATUS ANDREWS

Abstract

This study aimed at introducing the new species Plectranthus barbatuse Andrews(Coleus forsckoli) belonging to family: Lamiaceae to the Egyptian flora for its medicinal importance due to the presence of active ingredient forskolin. The conservation of P.barbatuse through in vitro micro-propagation of stem nodsshowed thatthe two cytokinin TDZ and Kin gave the best number of roots and shoot length, respectively. Production of forskolin using callus culturewas inducted in both leaf and stem node explants with 2,4-D auxin, while negative results appeared in the control. For the extractionand quantitative estimation of forskolin by HPLC,the forskolin content in leaf callus on MS medium containing 2mg/L 2,4-Drecorded the highest value (467.76 mg/g)in the fifth subculture. Moreover, the highest forskolin content in stem callus on MS medium containing 0.5mg/L 2,4-D was 751.96 mg/g in the fifth subculture. Using elicitor feeding in leaf callus gave the best forskolin content with sucrose or casine, while in stem callus, casine only gave the best forskolin content. The relative gene expression analysis using quantitative real time-PCR (qRT-PCR) in the previous stage was detected by usingprimer pairs for three Cytochrome 450 genes. P450c4 and P450c6 showed up-regulated expression in stem callus than leaf callus, while P450c7 gave up-regulated expression in leaf callus than stem callus compared with the control (mother plant). These results confirmed the importance of Cytochrome P450 genes expression in stem and leaf.