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Article|22 Apr 2022|OPEN
Identification of WRKY transcription factors involved in regulating the biosynthesis of the anti-cancer drug camptothecin in Ophiorrhiza pumila
Can Wang1,2 ,† , Xiaolong Hao1 ,† , Yao Wang1 , Itay Maoz3 , Wei Zhou1 , and Zhigang Zhou2 , , Guoyin Kai,1 ,
1Laboratory for Core Technology of TCM Quality Improvement and Transformation, The Third Affiliated Hospital, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, China
2Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources Conferred by Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China
3Department of Postharvest Science, ARO, The Volcani Center, HaMaccabim Rd 68, POB 15159, Rishon LeZion, 7528809, Israel
*Corresponding author. E-mail: zhouwei19810501@163.com,zgzhou@shou.edu.cn,kaiguoyin@163.com
†Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac099 (2022)
doi: https://doi.org/10.1093/hr/uhac099
Views: 439

Received: 21 Jan 2022
Accepted: 15 Apr 2022
Published online: 22 Apr 2022

Abstract

Camptothecin is a chemotherapeutic drug widely used to treat various cancers. Ophiorrhiza pumila is an ideal plant model for the study of camptothecin production, with various advantages for studying camptothecin biosynthesis and regulation. The DNA-binding WRKY transcription factors have a key regulatory role in secondary metabolite biosynthesis in plants. However, little is currently known about their involvement in camptothecin biosynthesis in O. pumila. We identified 46 OpWRKY genes unevenly distributed on the 11 chromosomes of O. pumila. Phylogenetic and multiple sequence alignment analyses divided the OpWRKY proteins into three subfamilies. Based on spatial expression and co-expression, we targeted the candidate gene OpWRKY6. Overexpression of OpWRKY6 significantly reduced the accumulation of camptothecin compared with the control. Conversely, camptothecin accumulation increased in OpWRKY6 knockout lines. Further biochemical assays showed that OpWRKY6 negatively regulates camptothecin biosynthesis from both the iridoid and shikimate pathways by directly downregulating the gene expression of OpGES, Op10HGO, Op7DLH, and OpTDC. Our data provide direct evidence for the involvement of WRKYs in the regulation of camptothecin biosynthesis and offer valuable information for enriching the production of camptothecin in plant systems.