Enhancement of camptothecin production in Camptotheca acuminata hairy roots by overexpressing ORCA3 gene.

ABSTRACT

Being a good anti-tumor drug, camptothecin (CPT) is a kind of modified monoterpene indole alkaloid firstly isolated from the deciduous Chinese happy tree with rapidly increasing clinical demand. Due to the great importance and low content of this compound, it is very important to improve CPT production by modern biotechnology. ORCA3 is a jasmonateresponsive APETALA2-domain transcript factor isolated from Catharanthus roseus, with strong ability to up-regulate expression of serveral key genes involved in TIA biosynthetic pathway. To investigate physiological function of ORCA3 gene in Camptotheca acuminata, the ORCA3 gene was transformed using Agrobacterium-mediated gene transfer technology. PCR analysis confirmed that the ORCA3 gene was integrated into the plant genome. HPLC showed that overexpression of ORCA3 in transgenic hairy root lines can effectively enhance the production of camptothecin with 1.5-fold compared with the control (1.12 mg/g dw). The results revealed that ORCA3 is an effective regulatory gene for improving metabolic flux in camptothecin biosynthetic pathway at the first time.