Effects of over-expression of allene oxide cyclase on camptothecin production by cell cultures of Camptotheca acuminata

Abstract

Camptothecin (CPT) is an anticancer and antiviral monoterpene-derived indole alkaloid which can be induced by plant hormone, jasmonates. To improve the production of the pharmaceuticals, the jasmonate biosynthesis related gene allene oxide cyclase from Camptotheca acuminate was transferred back into C. acuminate using the method of Agrobacterium-mediated genetic transformation and over expressed. The results of high performance liquid chromatography (HPLC) analysis indicated that the camptothecin content of transgenic callus was higher than that of non-transgenic callus. The highest camptothecin content in transgenic callus was 3.9310 mg/g DW. However, camptothecin content in both transgenic and non-transgenic calli significantly decreased after further extrinsic methyl-jasmonate’s (MeJA's) induction, whereas the content of CPT in transgenic callus was still higher than in non-transgenic one. All the results indicate that endogenic jasmonate's accumulation may be promoted after allene oxide cyclase gene was transformed into C. acuminate and over expressed. In this way, jasmonates can affect second metabolism pathway genes' expression and then the camptothecin content improved. Inexpectantly, the mechanism of extrinsic jasmonate to secondary metabolism of C. acuminate was different from that of endogenic jasmonates.

Key words: Agrobacterium tumefaciens, Allene oxide cyclase, Camptotheca acuminata, camptothecin, methyl-jasmonates, transformation.