Full-length transcriptome analysis of two chemotype and functional characterization of genes related to sesquiterpene biosynthesis in Atractylodes lancea

Functional characterization of sesquiterpene synthase in Mongolian medicine Syringa oblata in heartwood formation

Lilac (Syringa oblata) is a well-known horticultural plant, and its aromatic heartwood is widely utilized in Traditional Mongolian Medicine for treating angina. However, limited research on the dynamic changes and mechanisms of aromatic substance formation during heartwood development hinders the analysis and utilization of its medicinal components. In this study, volatile metabolome analysis revealed that sesquiterpenes are the primary metabolites responsible for the aroma in heartwood, with cadinane and eremophilane types being the most prevalent. Among the identified sesquiterpene synthases, SoSTPS1-5 exhibited significantly increased expression in heartwood formation and was selected for further investigation. Molecular docking simulations predicted multiple amino acid binding sites and confirmed its ability to catalyze the formation of eremophilane, copaene, cadinane, germacrane, and elemane-type sesquiterpenes from FPP (farnesyl pyrophosphate). Co-expression and promoter analysis suggested a transcriptional regulatory network primarily involving WRKY transcription factors. Additionally, aiotic and biotic stress inducers, such as Ag+, Fusarium oxysporum, and especially MeJA, were found to activate the expression of SoSTPS1-5 and promote sesquiterpene accumulation. This study provides insights into the basis of medicinal substance formation and the potential mechanisms of sesquiterpene accumulation in lilac heartwood, laying a foundation for future research on the biosynthesis and utilization of its medicinal components.

Characterization of a group of germacrene A synthases involved in the biosynthesis of β-elemene from Atractylodis macrocephala

β-Elemene, an important component of the volatile oil of Atractylodis macrocephala, has been widely utilized as an antitumor drug for over 20 years. However, the germacrene A synthase (GAS) genes responsible for the biosynthesis of β-elemene in A. macrocephala were previously unidentified. In this study, two new AmGASs were identified from the A. macrocephala transcriptome, demonstrating their capability to convert farnesyl pyrophosphate into germacrene A, which subsequently synthesizes β-elemene through Cope rearrangement. Additionally, two highly catalytic AmGAS1 mutations, I307A and E392A, resulted in a 2.23-fold and 1.57-fold increase in β-elemene synthesis, respectively. Furthermore, precursor supply and fed-batch strategies were employed to enhance the precursor supply, resulting in β-elemene yields of 7.3 mg/L and 33.3 mg/L, respectively. These findings identify a promising candidate GAS for β-elemene biosynthesis and lay the foundation for further functional studies on terpene synthases in A. macrocephala.

Full-length transcriptome sequencing provides new insights into the complexity of flavonoid biosynthesis in Glechoma longituba

Glechoma longituba has been frequently used in treating urolithiasis and cholelithiasis due to the presence of flavonoids, which are its major bioactive constituents. However, research on the molecular background of flavonoid biosynthesis in G. longituba is limited. In this study, we used single-molecule real-time combined with next-generation sequencing technologies to construct the complete transcriptome of G. longituba. We identified 404,648 non-redundant transcripts, including 249,697 coding sequences, 197,811 simple sequence repeats, 174,846 long noncoding RNA, and 176,554 coding RNA. Moreover, we functionally annotated 346,218 isoforms (85.56%) and identified 86,528 differentially expressed genes. We also identified 55 non-redundant full-length isoforms related to the flavonoid biosynthetic pathway. Pearson correlation analysis revealed that the expression levels of some key genes of the flavonoid biosynthesis pathway were significantly positively correlated with the flavonoid metabolites. Furthermore, we performed bioinformatics analysis (sequence and structural) of isoform_47029 (encoding flavanone 3-hydroxylase) and isoform_53692 (encoding flavonol synthase) to evaluate their potential biological functions. Finally, we validated gene expression levels of 12 flavonoid-related key enzyme genes using quantitative real-time PCR. Overall, this study provides full-length transcriptome information on G. longituba for the first time and valuable molecular resources for further research on the medicinal properties of this plant.

Authenticating the geographic origins of Atractylodes lancea rhizome chemotypes in China through metabolite marker identification

Introduction

Atractylodes lancea is widely distributed in East Asia, ranging from Amur to south-central China. The rhizome of A. lancea is commonly used in traditional Chinese medicine, however, the quality of products varies across different regions with different geochemical characteristics.

Method

This study aimed to identify the chemotypes of A. lancea from different areas and screen for chemical markers by quantifying volatile organic compounds (VOCs) using a targeted metabolomics approach based on GC-MS/MS.

Results

The A. lancea distributed in Hubei, Anhui, Shaanxi, and a region west of Henan province was classified as the Hubei Chemotype (HBA). HBA is characterized by high content of β-eudesmol and hinesol with lower levels of atractylodin and atractylon. In contrast, the Maoshan Chemotype (MA) from Jiangsu, Shandong, Shanxi, Hebei, Inner Mongolia, and other northern regions, exhibited high levels of atractylodin and atractylon. A total of 15 categories of VOCs metabolites were detected and identified, revealing significant differences in the profiles of terpenoid, heterocyclic compound, ester, and ketone among different areas. Multivariate statistics indicated that 6 compounds and 455 metabolites could serve as candidate markers for differentiating A. lancea obtained from the southern, northern, and Maoshan areas.

Discussion

This comprehensive analysis provides a chemical fingerprint of selected A. lancea. Our results highlight the potential of metabolite profiling combined with chemometrics for authenticating the geographical origin of A. lancea.