Co-Expression Analysis Reveals Differential Expression of Homologous Genes Associated with Specific Terpenoid Biosynthesis in Rehmannia glutinosa

Abstract

Terpenoids are naturally occurring compounds involved in respiration, photosynthesis, membrane fluidity, and pathogen interactions and are classified according to the structure of their carbon skeleton. Although most terpenoids possess pharmacological activity, knowledge about terpenoid metabolism in medicinal plants is insufficient. Rehmannia glutinosa (R. glutinosa) is a traditional herb that is widely used in East Asia and has been reported to contain various terpenoids. In this study, we performed a comprehensive transcriptome analysis of terpenoid metabolism in R. glutinosa using two RNA sequencing platforms: Illumina and PacBio. The results show that the sterol, saponin, iridoid, and carotenoid pathways are active in R. glutinosa. Sterol and saponin biosynthesis were mevalonate pathway dependent, whereas iridoid and carotenoid biosynthesis were methylerythritol 4-phosphate pathway dependent. In addition, we found that the homologous genes of key enzymes involved in terpenoid metabolism were expressed differentially and that the differential expression of these genes was associated with specific terpenoid biosynthesis. The different expression of homologous genes encoding acetyl-CoA acetyltransferase, 3-hydroxy-3-methylglutaryl-CoA reductase, mevalonate kinase, mevalonate diphosphate decarboxylase, farnesyl pyrophosphate synthase, squalene synthase, and squalene epoxidase was associated with sterol and saponin biosynthesis. Homologous genes encoding 1-deoxy-D-xylulose 5-phosphate synthase were also differentially expressed and were associated with carotenoid and iridoid biosynthesis. These results suggest that the biosynthesis of specific terpenoids can be regulated by the homologous of key enzymes involved in plant terpenoid metabolism.

Enhancing transcriptome analysis in medicinal plants: multiple unigene sets in Astragalus membranaceus

“…In addition, metabolic pathways such as starch, fructose, carbohydrate transport, sucrose, and galactose were activated in the roots ( Figures 6A, B and Supplementary Tables 15, 16 ). Similar results were also confirmed in other comparative combinations ( Supplementary Tables 17-20 ), suggesting that the roots of A. membranaceus play a vital role in the synthesis of carbohydrates and pharmacological substances, potentially offering significant benefits for human health ( Kang et al., 2021 ; Kang et al., 2022 ). The raw information of GO and KEGG based on DEGs was presented in Supplementary Tables 21-23 .…”

Effect of Developmental Stages on the Biosynthesis of Triterpene Saponins and Related Gene Expression in Seedlings of Platycodon grandiflorus

“…Furthermore, farnesyl diphosphate synthase (FPS), SS, and SE have been implicated in regulating triterpenoid saponin synthesis. 30,31 In the present study, FPS and SS were expressed higher in 1-year-old seedlings. Previous research on birch saponins has shown that heterologous expression of FPS in yeast increased squalene expression, resulting in higher production of triterpene saponins, such as bircholic acid, oleanolic acid, and betulinic acid.…”

Genome-Wide Identification and Expression Analysis of TPS Gene Family in Liriodendron chinense

“…The terpenoids of primary metabolism have been shown to play important roles in sustaining life activities [ 7 ]. For example, carotenoids participate in photosynthetic reactions as photosynthetic pigments [ 8 , 9 ]; gibberellins, abscisic acid, and cytokinins participate as regulators of plant growth and development [ 10 ]; phytosterols participate as influencing factors of membrane structure and function [ 11 , 12 ]; ubiquinone and plastoquinone side chains function as electron carriers; and polyphenols participate in protein glycosylation [ 13 ]. However, terpenoids in most plants exist in the form of secondary metabolites, which do not directly participate in plant growth and development, but have certain physiological functions, such as plant defense responses [ 14 ], pharmacological compounds [ 15 ], and fragrance volatilization [ 4 , 16 , 17 ].…”