Transcriptome Analysis Reveals the Mechanism Underlying the Production of a High Quantity of Chlorogenic Acid in Young Leaves of Lonicera macranthoides Hand.-Mazz.

Ning Tang,Zhengguo Li,Jianbin Lan,Zexiong Chen,Maoteng Li,Yiqing Liu,Yuming You

doi:10.1371/journal.pone.0137212

Abstract

Lonicera macranthoides Hand.-Mazz (L. macranthoides) is a medicinal herb that is widely distributed in southern China. The biosynthetic and metabolic pathways for a core secondary metabolite in L. macranthoides, chlorogenic acid (CGA), have been elucidated in many species. However, the mechanisms of CGA biosynthesis and the related gene regulatory network in L. macranthoides are still not well understood. In this study, CGA content was quantified by high performance liquid chromatography (HPLC), and CGA levels differed significantly among three tissues; specifically, the CGA content in young leaves (YL) was greater than that in young stems (YS), which was greater than that in mature flowers (MF). Transcriptome analysis of L. macranthoides yielded a total of 53,533,014 clean reads (average length 90 bp) and 76,453 unigenes (average length 703 bp). A total of 3,767 unigenes were involved in biosynthesis pathways of secondary metabolites. Of these unigenes, 80 were possibly related to CGA biosynthesis. Furthermore, differentially expressed genes (DEGs) were screened in different tissues including YL, MF and YS. In these tissues, 24 DEGs were found to be associated with CGA biosynthesis, including six phenylalanine ammonia lyase (PAL) genes, six 4-coumarate coenzyme A ligase (4CL) genes, four cinnamate 4-Hydroxylase (C4H) genes, seven hydroxycinnamoyl transferase/hydroxycinnamoyl-CoA quinate transferase HCT/HQT genes and one coumarate 3-hydroxylase (C3H) gene.These results further the understanding of CGA biosynthesis and the related regulatory network in L. macranthoides.

Highlights

Lonicera. macranthoides (L. macranthoides), a plant distributed widely in south China, belongs to Caprifoliaceae and is often used in traditional Chinese medicine
After processing by Trinity and TGICL software, 145,214 contigs were further assembled into 76,453 unigenes with an average length of 703 bp and an N50 length of 1088 bp
We found that the transcripts of three cinnamate 4-Hydroxylase (C4H) genes (CL11374.contig1, CL11374.contig2 and Unigene36506) were positively correlated with the Chlorogenic acid (CGA) content, indicating their important role in CGA biosynthesis

Summary

Introduction

Lonicera. macranthoides (L. macranthoides), a plant distributed widely in south China, belongs to Caprifoliaceae and is often used in traditional Chinese medicine. Macranthoides (L. macranthoides), a plant distributed widely in south China, belongs to Caprifoliaceae and is often used in traditional Chinese medicine. Flavonoids, volatile oils and saponins are major chemical components of L. macranthoides [2]. These components predominately account for the multiple medicinal effects of L. macranthoides, which include antioxidant [3,4,5], detoxification [6], anti-inflammatory [7], anti-cancer [8,9,10,11], anti-cardiovascular disease and pain relief properties [12]. L. macranthoides can be effectively applied in the treatment of H1N1 respiratory syndrome and hand-foot-and-mouth disease [13]. Chlorogenic acid (CGA) is the most interesting of the biologically active ingredients of L. macranthoides

Methods

Results

Discussion

Conclusion