Browse Articles

Article|01 Jan 2021|OPEN
The transcription factor OpWRKY2 positively regulates the biosynthesis of the anticancer drug camptothecin in Ophiorrhiza pumila
Xiaolong Hao1, Chenhong Xie1, Qingyan Ruan1, Xichen Zhang2, Chao Wu2, Bing Han1, Jun Qian1, Wei Zhou1, Hans-Wilhelm Nützmann3 & Guoyin Kai1,
1Laboratory of Medicinal Plant Biotechnology, College of Pharmacy, Zhejiang Chinese Medical University, 310053, Hangzhou, China
2Institute of Plant Biotechnology, School of Life Sciences, Shanghai Normal University, 200234, Shanghai, China
3The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK

Horticulture Research 8,
Article number: 7 (2021)
doi: 10.1038/hortres.2021.7
Views: 397

Received: 28 Jul 2020
Revised: 22 Sep 2020
Accepted: 17 Oct 2020
Published online: 01 Jan 2021

Abstract

The limited bioavailability of plant-derived natural products with anticancer activity poses major challenges to the pharmaceutical industry. An example of this is camptothecin, a monoterpene indole alkaloid with potent anticancer activity that is extracted at very low concentrations from woody plants. Recently, camptothecin biosynthesis has been shown to become biotechnologically amenable in hairy-root systems of the natural producer Ophiorrhiza pumila. Here, time-course expression and metabolite analyses were performed to identify novel transcriptional regulators of camptothecin biosynthesis in O. pumila. It is shown here that camptothecin production increased over cultivation time and that the expression pattern of the WRKY transcription factor encoding gene OpWRKY2 is closely correlated with camptothecin accumulation. Overexpression of OpWRKY2 led to a more than three-fold increase in camptothecin levels. Accordingly, silencing of OpWRKY2 correlated with decreased camptothecin levels in the plant. Further detailed molecular characterization by electrophoretic mobility shift, yeast one-hybrid and dual-luciferase assays showed that OpWRKY2 directly binds and activates the central camptothecin pathway gene OpTDC. Taken together, the results of this study demonstrate that OpWRKY2 acts as a direct positive regulator of camptothecin biosynthesis. As such, a feasible strategy for the over-accumulation of camptothecin in a biotechnologically amenable system is presented.