Integrated metabolomic and transcriptomic analysis of Pogostemon cablin shed new light on the complete biosynthesis pathway of pogostone

Sen Wang ¹ Zhaoqi Zeng ^1,2* Qi Zhang ^1* Jinlong Bei ^1* Wenhua Liu ^1* Qianjian Liu ^1* Chong Xie ^1,3* Bingxian Chen ^1* Aixia Zhang ^1*

• ¹ Argo biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou, China
• ² College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, China
• ³ College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou, China

Pogostemon cablin (patchouli) is a well-known perennial herbaceous plant for traditional 28 Chinese medicine, and its primary bioactive compounds are patchoulol and pogostone. The 29 biosynthesis pathway of patchouli has been well resolved early, while the biosynthesis pathway of 30 pogostone is still not fully resolved due to the lack of terminal enzyme directly synthesizing 31 pogostone. Here, the present study aims to predict the terminal enzyme of pogostone biosynthesis 32 and reconstruct its most possible complete biosynthesis, through the integrated transcriptomic and 33 metabolomic analysis. 34The metabolomic and transcriptomic profiles of patchouli leaf were largely different to those 35 of root and stem. Patchoulol analogs like patchoulene and germacrene mainly accumulated in leaf, 36 while pogostone content was much higher in root. Based on the integrated analysis of differentially 37 expressed genes and metabolites, we reconstructed the biosynthesis pathways of patchoulol, and 38 predicted the most likely complete biosynthesis pathway of pogostone. Besides, we identified 29 39 highly-expressed genes involved in pogostone biosynthesis for the neo-octoploid genome of 40 patchouli, and most of their expression levels were strongly correlated with pogostone content. In 41 particular, patchouli BAHD-DCR acyltransferases (BAHD-DCRs) were phylogenetically distant 42 from but structurally similar to the other known plant BAHD acyltransferases. Most of them 43 possessed the conservative catalysis motif HXXXD, and the catalysis center could bind to the 44 widely recognized substrate molecules of 4-hydroxy-6-methyl-2-pyrone and 4-methylvaleryl-CoA 45 and product molecule of pogostone. Thus, the highly-expressed BAHD-DCRs in patchouli root 46 were proposed to be terminal enzymes directly synthesizing pogostone. 47The findings here provide more supporting evidence for the medical use of patchouli whole 48 plants, and make an important step forward fully resolving the pogostone biosynthesis pathway. 49The identified genes involved in pogostone biosynthesis, especially BAHD-DCRs, deserve further 50 investigation and utilization in the synthetic production of pogostone.