Enhanced Ganoderic Acids Accumulation and Transcriptional Responses of Biosynthetic Genes in Ganoderma lucidum Fruiting Bodies by Elicitation Supplementation

4-Coumarate-CoA ligase (4-CL) enhances flavonoid accumulation, lignin synthesis, and fruiting body formation in Ganoderma lucidum

It is now understood that 4-Coumarate-CoA ligases (4-CL) are pivotal in bridging the phenylpropanoid metabolic pathway and the lignin biosynthesis pathway in plants. However, limited information on 4-CL genes and their functions in fungi is available. In this study, we cloned the 4-CL gene (Gl21040) from Ganoderma lucidum, which spans 2178 bp and consists of 10 exons and 9 introns. We also developed RNA interference and overexpression vectors for Gl21040 to investigate its roles in G. lucidum. Our findings indicated that in the Gl21040 interference transformants, 4-CL enzyme activities decreased by 31 %-57 %, flavonoids contents decreased by 10 %-22 %, lignin contents decreased by 20 %-36 % compared to the wild-type (WT) strain. Conversely, in the Gl21040 overexpression transformants, 4-CL enzyme activity increased by 108 %-143 %, flavonoids contents increased by 8 %-37 %, lignin contents improved by 15 %-17 % compared to the WT strain. Furthermore, primordia formation was delayed by approximately 10 days in the Gl21040-interferenced transformants but occurred 3 days earlier in the Gl21040-overexpressed transformants compared to the WT strain. These results underscored the involvement of the Gl21040 gene in flavonoid synthesis, lignin synthesis, and fruiting body formation in G. lucidum.

Combined NMR and MS-based metabonomics and real-time PCR analyses reveal dynamic metabolic changes of Ganoderma lucidum during fruiting body growing

Ganoderma lucidum (G. lucidum) is a rare medicinal fungus with various beneficial properties. One of its main components, ganoderic acids (GAs), are important triterpenoids known for their sedative and analgesic, hepatoprotective, and anti-tumor activities. Understanding the growth and development of the G. lucidum fruiting body is crucial for determining the optimal time to harvest them. In this study, we used nuclear magnetic resonance (NMR) spectroscopy to systematically characterize the metabolites of G. lucidum at seven distinct developmental stages. We also measured the contents of seven kinds of GAs using LC-MS/MS. A total of 49 metabolites were detected in G. lucidum, including amino acids, sugars, organic acids and GAs. During the transition from the bud development period (I) to the budding period (II), we observed a rapid accumulation of glucose, tyrosine, nicotinamide ribotide, inosine and GAs. After the budding period, the contents of most metabolites decreased until the mature period (VII). In addition, the contents of GAs showed an initial raising, followed by a decline during the elongation period, except for GAF, which exhibited a rapid raise during the mature stage. We also detected the expression of several genes involved in GA synthesis, finding that most genes including 16 cytochrome P450 monooxygenase were all down-regulated during periods IV and VII compared to period I. These findings provide valuable insights into the dynamic metabolic profiles of G. lucidum throughout its growth stage, and it is recommended to harvest G. lucidum at period IV.

Expression Analysis of CoHMGS in Cornus officinalis and Subcellular Localization of the Enzyme It Encodes

Cornus officinalis is a perennial deciduous tree or shrub. Its mature fruits are extracted and used in Traditional Chinese Medicine, called Shanzhuyu. The characteristic active components of C. officinalis include loganin and morroniside, which belong to iridoid glycosides. 3-Hydroxy-3-methylglutaryl-CoA synthase (HMGS) is a key enzyme in the cytoplasmic mevalonate pathway providing the precursor molecules isopentenyl pyrophosphate and dimethylallyl pyrophosphate for isoprenoid biosynthesis such as sterols, triterpenes, and their derivatives such as iridoid glycosides. Different concentrations of methyl jasmonate (MeJA) and ethephon (ETH) solutions were sprayed on C. officinalis seedlings, and the effect of hormones on CoHMGS gene expression was detected by real-time fluorescence quantitative PCR. The quantitative real-time PCR results showed that 750 mg/L ETH treatment had the most significant induction effect on CoHMGS gene expression. The HPLC analysis of extracts revealed that the treatment could also significantly increase the content of morroniside and loganin in the leaves of C. officinalis. By use of a CoHMGS-green fluorescent protein (GFP) fusion construct for heterologous expression in tobacco, laser scanning confocal microscopy revealed a cytoplasmic localization. This preliminary study of the CoHMGS gene could prepare the ground for more precisely elucidating the synthesis of secondary metabolite in C. officinalis.

A Review of Ganoderma Triterpenoids and Their Bioactivities

For centuries, Ganoderma has been used as a traditional medicine in Asian countries to prevent and treat various diseases. Numerous publications are stating that Ganoderma species have a variety of beneficial medicinal properties, and investigations on different metabolic regulations of Ganoderma species, extracts or isolated compounds have been performed both in vitro and in vivo. However, it has frequently been questioned whether Ganoderma is simply a dietary supplement for health or just a useful "medication" for restorative purposes. More than 600 chemical compounds including alkaloids, meroterpenoids, nucleobases, nucleosides, polysaccharides, proteins, steroids and triterpenes were extracted and identified from Ganoderma, with triterpenes serving as the primary components. In recent years, Ganoderma triterpenes and other small molecular constituents have aroused the interest of chemists and pharmacologists. Meanwhile, considering the significance of the triterpene constituents in the development of new drugs, this review describes 495 compounds from 25 Ganoderma species published between 1984 and 2022, commenting on their source, biosynthetic pathway, identification, biological activities and biosynthesis, together with applications of advanced analytical techniques to the characterization of Ganoderma triterpenoids.

Transcriptome and metabolome analyses reveal transcription factors regulating ganoderic acid biosynthesis in Ganoderma lucidum development

Ganoderma lucidum is an important medicinal fungus in Asian countries. Ganoderic acid (GA) is the major variety of bioactive and medicative components in G. lucidum. Biosynthesis of secondary metabolites is usually associated with cell differentiation and development. However, the mechanism underlying these phenomena remain unclear. Transcription factors play an essential regulatory role in the signal transduction pathway, owing to the fact that they represent the major link between signal transduction and expression of target genes. In the present study, we performed transcriptome and metabolome analyses to identify transcription factors involved in GA biosynthesis during development of G. lucidum. Transcriptome data revealed differentially expressed genes between mycelia and primordia, as well as between mycelia and the fruiting body. Results from gene ontology enrichment analysis and metabolome analyses suggested that GAs and flavonoids biosynthetic process significantly changed during fungal development. The analysis of predicted occurrences of DNA-binding domains revealed a set of 53 potential transcription factor families in G. lucidum. Notably, we found homeobox transcription factor and velvet family protein played important role in GA biosynthesis. Combined with previous studies, we provided a model diagram of transcription factors involved in GA biosynthesis during fruiting body formation. Collectively, these results are expected to enhance our understanding into the mechanisms underlying secondary metabolite biosynthesis and development in fungi.

Integrated Transcriptomics and Nontargeted Metabolomics Analysis Reveal Key Metabolic Pathways in Ganoderma lucidum in Response to Ethylene

Ganoderic acid (GA) is an important secondary metabolite of Ganoderma lucidum with a diverse array of pharmacological properties. In this study, we found that exogenous ethylene increased the production of endogenous ethylene and ganoderic acid in G. lucidum. However, the mechanism by which ethylene is regulated remains unclear. As a result, we performed a combined transcriptomics and nontargeted metabolomics analysis to evaluate the regulatory mechanism of ethylene. A total of 4070 differentially expressed genes (1835 up-regulated and 2235 down-regulated) and 378 differentially accumulated metabolites (289 up-regulated and 89 down-regulated) were identified in all groups. The transcriptomics and nontargeted metabolomics data revealed that genes involved in the tricarboxylic acid (TCA) cycle, polyamine metabolic pathway, acetyl-CoA carboxylase (ACC) pathway, and triterpenoid metabolism were up-regulated, whereas the metabolic intermediates involved in these metabolic pathways were down-regulated. These findings imply that ethylene potentially accelerates normal glucose metabolism, hence increasing the number of intermediates available for downstream biological processes, including polyamine metabolism, ethylene synthesis pathway, and ganoderic acid biosynthesis. The findings will contribute significantly to our understanding of secondary metabolites biosynthesis in fungi.

Transcriptomic and Non-Targeted Metabolomic Analyses Reveal the Flavonoid Biosynthesis Pathway in Auricularia cornea

Flavonoids, which are abundant in plants, are recognized for their antioxidant and anticancer roles in clinical applications. However, little is known about the molecular basis of flavonoid biosynthesis in fungi. In this study, we found that inclusion of leachate of Korshinsk peashrub (Caragana korshinskii) in the fermentation medium increased the total flavonoid content of the edible fungus Auricularia cornea by 23.6% relative to that grown in a control medium. Combined transcriptomic and non-targeted metabolomic analysis of the flavonoid biosynthesis pathway in A. cornea illustrated that there are important metabolites in the phenylpropanoid, coumarin and isoflavonoid biosynthesis pathways. In addition, we found that certain homologous genes encode phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and chalcone isomerase (CHI) in these biosynthesis pathways. These results, in this study, provide a new line for studying the regulation of flavonoid production in edible fungi.

Biosynthesis and regulation of terpenoids from basidiomycetes: exploration of new research

Basidiomycetes, also known as club fungi, consist of a specific group of fungi. Basidiomycetes produce a large number of secondary metabolites, of which sesquiterpenoids, diterpenoids and triterpenoids are the primary components. However, these terpenoids tend to be present in low amounts, which makes it difficult to meet application requirements. Terpenoid biosynthesis improves the quantity of these secondary metabolites. However, current understanding of the biosynthetic mechanism of terpenoids in basidiomycetes is insufficient. Therefore, this article reviews the latest research on the biosynthesis of terpenoids in basidiomycetes and summarizes the CYP450 involved in the biosynthesis of terpenoids in basidiomycetes. We also propose opportunities and challenges for chassis microbial heterologous production of terpenoids in basidiomycetes and provide a reference basis for the better development of basidiomycete engineering.

Growth Characteristics of Polyporales Mushrooms for the Mycelial Mat Formation

Mushroom strains of Polyporales from the genera Coriolus, Trametes, Pycnoporus, Ganoderma, and Formitella were explored in terms of mycelial growth characteristics for the application of mushroom mycelia as alternative sources of materials replacing fossil fuel-based materials. Among the 64 strains of Polyporales, G. lucidum LBS5496GL was selected as the best candidate because it showed fast mycelial growth with high mycelial strength in both the sawdust-based solid medium and the potato dextrose liquid plate medium. Some of the Polyporales in this study have shown good mycelial growth, however, they mostly formed mycelial mat of weak physical strength. The higher physical strength of mycelial mat by G. lucidum LBS5496GL was attributed to its thick hyphae with the diameter of 13 µm as revealed by scanning electron microscopic analysis whereas the hyphae of others exhibited less than 2 µm. Glycerol and skim milk supported the best mycelial growth of LBS5496GL as a carbon and a nitrogen source, respectively.

The MADS-box transcription factor GlMADS1 regulates secondary metabolism in Ganoderma lucidum

MADS-box transcription factors play crucial roles in regulating development processes and biosynthesis of secondary metabolites in eukaryotes. However, the role of MADS-box transcription factors vary among fungal species, and their function remains unclear in the medicinally and economically important fungus Ganoderma lucidum. In this study, we characterized a MADS-box gene, GlMADS1, in G. lucidum. Analyses using quantitative real-time polymerase chain reaction (qRT-PCR) showed that GlMADS1 expression levels were up-regulated from the mycelia to the primordia stage. In order to further evaluate the effect of MADS-box transcription factors on secondary metabolism, we utilized RNA interference (RNAi) to silence GlMADS1 in G. lucidum. Ganoderic acid (GA) and flavonoid contents were enhanced in GlMADS1-silenced strains, suggesting that GlMADS1 negatively regulates GA and flavonoid accumulation.