Sclerotial formation of Polyporus umbellatus by low temperature treatment under artificial conditions

Cloning and Expression Analysis of Bioluminescence Genes in Omphalotus guepiniiformis Reveal Stress-Dependent Regulation of Bioluminescence

Bioluminescence is a type of chemiluminescence that arises from a luciferase-catalyzed oxidation reaction of luciferin. Molecular biology and comparative genomics have recently elucidated the genes involved in fungal bioluminescence and the evolutionary history of their clusters. However, most studies on fungal bioluminescence have been limited to observing the changes in light intensity under various conditions. To understand the molecular basis of bioluminescent responses in Omphalotus guepiniiformis under different environmental conditions, we cloned and sequenced the genes of hispidin synthase, hispidin-3-hydroxylase, and luciferase enzymes, which are pivotal in the fungal bioluminescence pathway. Each gene showed high sequence similarity to that of other luminous fungal species. Furthermore, we investigated their transcriptional changes in response to abiotic stresses. Wound stress enhanced the bioluminescence intensity by increasing the expression of bioluminescence pathway genes, while temperature stress suppressed the bioluminescence intensity via the non-transcriptional pathway. Our data suggested that O. guepiniiformis regulates bioluminescence to respond differentially to specific environmental stresses. To our knowledge, this is the first study on fungal bioluminescence at the gene expression level. Further studies are required to address the biological and ecological meaning of different bioluminescence responses in changing environments, and O. quepiniiformis could be a potential model species.

De Novo RNA Sequencing and Transcriptome Analysis of Sclerotium rolfsii Gene Expression during Sclerotium Development

Sclerotium rolfsii is a destructive soil-borne fungal pathogen that causes stem rot in cultivated plants. However, little is known about the genetic basis of sclerotium development. In this study, we conducted de novo sequencing of genes from three different stages of S. rolfsii (mycelia, early sclerotium formation, and late sclerotium formation) using Illumina HiSeqTM 4000. We then determined differentially expressed genes (DEGs) across the three stages and annotated gene functions. STEM and weighted gene-co-expression network analysis were used to cluster DEGs with similar expression patterns. Our analysis yielded an average of 25,957,621 clean reads per sample (22,913,500-28,988,848). We identified 8929, 8453, and 3744 DEGs between sclerotium developmental stages 1 versus 2, 1 versus 3, and 2 versus 3, respectively. Additionally, four significantly altered gene expression profiles involved 220 genes related to sclerotium formation, and two modules were positively correlated with early and late sclerotium formation. These results were supported by the outcomes of qPCR and RNA-sequencing conducted on six genes. This is the first study to provide a gene expression map during sclerotial development in S. rolfsii, which can be used to reduce the re-infection ability of this pathogen and provide new insights into the scientific prevention and control of the disease. This study also provides a useful resource for further research on the genomics of S. rolfsii.

PuCRZ1, an C2H2 transcription factor from Polyporus umbellatus, positively regulates mycelium response to osmotic stress

Polyporus umbellatus is an edible and medicinal mushroom with the capacity to produce sclerotia. However, the mechanism of P. umbellatus sclerotia formation is unclear. CRZ1 is a C2H2 family transcription factor involved in the Ca2+-calcineurin signaling pathway, which has the function of regulating sclerotia formation, maintaining ion homeostasis, and responding to stress. In this study, we identified 28 C2H2 transcription factors in P. umbellatus genome, 13 of which are differentially expressed between mycelium and sclerotia, including PuCRZ1. Combining DNA affinity purification and sequencing (DAP-seq) and quantitative real-time PCR (qRT-PCR), three genes (PuG10, PuG11, PuG12) were identified as putative PuCRZ1 target genes containing a putative binding motif (GTGGCG) within their promoter. Yeast single hybridization (Y1H) and EMSA further confirmed that PuCRZ1 can bind to the promoter region of PuG10, PuG11, and PuG12. PuCRZ1 gene could reduce the sensitivity of NaCl in yeast cells. Furthermore, overexpression of the PuCRZ1 target gene, especially the FVLY domain containing gene PuG11, could improve the mycelia growth rate and mannitol tolerance in P. umbellatus. These results demonstrate that PuCRZ1 in the Ca2+-calcineurin signaling pathway plays an important role in mycelia growth, as well as osmotic stress tolerance.

New Inonotus Polysaccharides: Characterization and Anticomplementary Activity of Inonotus rheades Mycelium Polymers

Inonotus is a small genus of xylotrophic basidiomycetes and a source of bioactive fungochemicals among which a special place is occupied by polymeric compounds. In this study, polysaccharides that are widespread in Europe, Asia, and North America and a poorly understood fungal species, I. rheades (Pers.) Karst. (fox polypore), were investigated. Water-soluble polysaccharides of I. rheades mycelium were extracted, purified, and studied using chemical reactions, elemental and monosaccharide analysis, UV-Vis and FTIR spectroscopy, gel permeation chromatography, and linkage analysis. Five homogenic polymers (IRP-1-IRP-5) with molecular weights of 110-1520 kDa were heteropolysaccharides that consist mainly of galactose, glucose, and mannose. The dominant component, IRP-4, was preliminary concluded to be a branched (1→3,6)-linked galactan. Polysaccharides of I. rheades inhibited the hemolysis of sensitized sheep erythrocytes by complement from human serum, signifying anticomplementary activity with the greatest effects for the IRP-4 polymer. These findings suggest that I. rheades mycelium is a new source of fungal polysaccharides with potential immunomodulatory and anti-inflammatory properties.

Relationship between antioxidant enzymes and sclerotial formation of Pleurotus tuber-regium under abiotic stress

In order to explore the relationship between sclerotial formation and antioxidant enzymes under abiotic stresses, the effects of abiotic stresses including temperature, pH value, osmotic pressure, limited nitrogen, and hydrogen peroxide (H₂O₂) on the activities of antioxidant enzymes, ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in Pleurotus tuber-regium were studied. Meanwhile, the sclerotial formation under these abiotic stress conditions was also investigated. It was found that low temperature, weak alkaline, appropriate osmotic stress, and H₂O₂ can promote sclerotial formation, and sclerotial formation always tended to occur when the activities of antioxidant enzymes were at a high value. During the prolonged low temperature stress, SOD acted mainly in the early stage of stress, while POD and CAT had higher activity in the middle and late stage. Moreover, the reverse transcription quantitative polymerase chain reaction (RT-qPCR) results showed that SOD.193 and POD.535 were significantly down-regulated in sclerotia, and CAT.1115 and POD.401 were up-regulated instead. These antioxidant enzyme genes played an important role in the sclerotial formation under low temperature stress. It is strongly suggested that antioxidant enzymes and abiotic stresses are closely related to sclerotial formation in P. tuber-regium. KEY POINTS: • Low temperature and H2O2 can promote sclerotial formation. • Sclerotia are more likely to form under high antioxidant enzyme activity. • POD.401, POD.535, SOD.193, and CAT.1115 are important for sclerotial formation.

Isolation, genomic characterization, and mushroom growth-promoting effect of the first fungus-derived Rhizobium

Polyporus umbellatus is a well-known edible and medicinal mushroom, and some bacteria isolated from mushroom sclerotia may have beneficial effects on their host. These mushroom growth-promoting bacteria (MGPBs) are of great significance in the mushroom production. In this work, we aimed to isolate and identify MGPBs from P. umbellatus sclerotia. Using the agar plate dilution method, strain CACMS001 was isolated from P. umbellatus sclerotia. The genome of CACMS001 was sequenced using PacBio platform, and the phylogenomic analysis indicated that CACMS001 could not be assigned to known Rhizobium species. In co-culture experiments, CACMS001 increased the mycelial growth of P. umbellatus and Armillaria gallica and increased xylanase activity in A. gallica. Comparative genomic analysis showed that CACMS001 lost almost all nitrogen fixation genes but specially acquired one redox cofactor cluster with pqqE, pqqD, pqqC, and pqqB involved in the synthesis of pyrroloquinoline quinone, a peptide-derived redox participating in phosphate solubilization activity. Strain CACMS001 has the capacity to solubilize phosphate using Pikovskaya medium, and phnA and phoU involved in this process in CACMS001 were revealed by quantitative real-time PCR. CACMS001 is a new potential Rhizobium species and is the first identified MGPB belonging to Rhizobium. This novel bacterium would play a vital part in P. umbellatus, A. gallica, and other mushroom cultivation.

A Mycorrhizal Bacteria Strain Isolated From Polyporus umbellatus Exhibits Broad-Spectrum Antifungal Activity

The microbes in the rhizosphere (or mycorrhizosphere) could promote plant growth, however, it is unclear whether mycorrhizosphere microbes could fight multiple fungal pathogens. In this study, twenty-one bacterial strains distributed in 6 genera, including 5 Pseudomonas strains, were isolated from mycorrhizal samples of Polyporus umbellatus that rely on other fungi during their life cycles. Further screening and pot experiments showed that the Pseudomonas strain ZL8 not only inhibited the growth of phytopathogenic fungi, but also promoted the growth of Salvia miltiorrhiza through inhibiting its wilting. In addition, strain ZL8 was found to have the ability to dissolve phosphate, produce IAA and siderophore. Nineteen compounds were identified from the fermentation broth of strain ZL8, of which 2,4-diacetylphloroglucinol (DAPG) had a significant inhibitory effect on phytopathogenic fungi with a minimum inhibitory concentration of 3.12-25 μg/mL. Molecular docking predicted that DAPG could bind to myosin I at two unique sites, which may be responsible to the inhibition of fungal growth. The evaluation results showed that strain ZL8 can be used to develop a dual-purpose biocontrol agents and biofertilizer. These results also provide new insights into the discovery and utilization of new resources for biocontrol agents and biolfertilizers.

Influence of rutin on fruiting of Hericium coralloides, Polyporus umbellatus, and Flammulina velutipes

We studied the effect of rutin on mycelial growth and fruiting of Hericium coralloides, Polyporus umbellatus, and Flammulina velutipes on sunflower husks and on agar nutrient media. On sunflower husks, rutin (300 mg/30 g husk) inhibits the mycelial growth of H. coralloides, but the formation of fruiting bodies of the fungus occurs 3 weeks earlier than on the substrate, where rutin was not used. In half of the cases with rutin, we observed two waves of fungus fruiting. The weight of fruiting bodies formed on sunflower husks with rutin was 2.5 times greater than the weight of fruiting bodies formed on sunflower husks without rutin. For P. umbellatus and F. velutipes, adding rutin (300 mg/30 g husk) confers no net benefit. On wort agar (WA), the addition of rutin at concentrations of 50, 100, 200, and 300 mg per Petri dish inhibits the mycelial growth of H. coralloides but stimulates the rapid emergence of the fungus fruiting bodies rudiments. For F. velutipes on WA, rutin accelerates the complete overgrowth of the fungus on the Petri dish twice as fast, but it is not effective for accelerating fruiting. Rutin does not stimulate the formation sclerotia of P. umbellatus. Due to the fact that rutin is a stimulant of fruiting bodies only for H. coralloides, we believe that the initiating mechanism causing fungal fruiting is not isolated only to rutin. However, it may be more widely effective in influencing growth in mycelium than is shown in this study due to a limited number of strains. Production of metabolites as a result of secondary synthesis need to be tested as do more strains/species from a diverse group of Agaricomycetes.

Use of transcriptomic profiling to identify candidate genes involved in Polyporus umbellatus sclerotial formation affected by oxalic acid

Polyporus umbellatus is a precious medicinal fungus. Oxalic acid was observed to affect sclerotial formation and sclerotia possessed more medicinal compounds than mycelia. In this study, the transcriptome of P. umbellatus was analysed after the fungus was exposed to various concentrations of oxalic acid. The differentially expressed genes (DEGs) encoding a series of oxidases were upregulated, and reductases were downregulated, in the low-oxalic-acid (Low OA) group compared to the control (No OA) group, while the opposite phenomenon was observed in the high-oxalic-acid (High OA) group. The detection of reactive oxygen species (ROS) in P. umbellatus mycelia was performed visually, and Ca²⁺ and H₂O₂ fluxes were measured using non-invasive micro-test technology (NMT). The sclerotial biomass in the Low OA group increased by 66%, however, no sclerotia formed in the High OA group. The ROS fluorescence intensity increased significantly in the Low OA group but decreased considerably in the High OA group. Ca²⁺ and H₂O₂ influx significantly increased in the Low OA group, while H₂O₂ exhibited efflux in the High OA group. A higher level of oxidative stress formed in the Low OA group. Different concentrations of oxalic acid were determined to affect P. umbellatus sclerotial formation in different ways.

Characterization of Two Mitochondrial Genomes and Gene Expression Analysis Reveal Clues for Variations, Evolution, and Large-Sclerotium Formation in Medical Fungus Wolfiporia cocos

Wolfiporia cocos, a precious mushroom with a long history as an edible food and Asian traditional medicine, remains unclear in the genetic mechanism underlying the formation of large sclerotia. Here, two complete circular mitogenomes (BL16, 135,686 bp and MD-104 SS10, 124,842 bp, respectively) were presented in detail first. The salient features in the mitogenomes of W. cocos include an intron in the tRNA (trnQ-UUG²), and an obvious gene rearrangement identified between the two mitogenomes from the widely geographically separated W. cocos strains. Genome comparison and phylogenetic analyses reveal some variations and evolutional characteristics in W. cocos. Whether the mitochondrion is functional in W. cocos sclerotium development was investigated by analyzing the mitogenome synteny of 10 sclerotium-forming fungi and mitochondrial gene expression patterns in different W. cocos sclerotium-developmental stages. Three common homologous genes identified across ten sclerotium-forming fungi were also found to exhibit significant differential expression levels during W. cocos sclerotium development. Most of the mitogenomic genes are not expressed in the mycelial stage but highly expressed in the sclerotium initial or developmental stage. These results indicate that some of mitochondrial genes may play a role in the development of sclerotium in W. cocos, which needs to be further elucidated in future studies. This study will stimulate new ideas on cytoplasmic inheritance of W. cocos and facilitate the research on the role of mitochondria in large sclerotium formation.

Identification and expression of DoCCaMK during Sebacina sp. symbiosis of Dendrobium officinale

Dendrobium officinale Kimura et Migo is a famous precious medicinal plant in China. Seed and seedling were cultivated with the mycorrhizal fungus Sebacina sp. CCaMK was initially cloned from D. officinale based on a SSH cDNA library of symbiotically germinated seeds with Sebacina sp. Phylogenetic analysis was performed among DoCCaMK and other CCaMKs. The particle bombardment technique was used to visualize DoCCaMK-GFP. qRT-PCR and western blot analysis were conducted to determine the tissue expression patterns of DoCCaMK with (SGS) and without (UGS) Sebacina sp. Furthermore, the effect of KN-93 on CCaMK expression was also examined. Using NMT the net Ca²⁺ fluxes and the CCaMK concentration were measured during D. officinale seed germination. DoCCaMK had the highest homology with Lilium longiflorum CCaMK. The DoCCaMK-GFP protein localized in the nucleus and cell membrane. CCaMK expression was significantly upregulated after symbiosis with Sebacina sp. KN-93 could be used as an inhibitor of CCaMK to inhibit D. officinale seed germination. Ca²⁺ influx and the concentration of the CCaMK in the SGS group was significantly more than that of the UGS group. The characterization of CCaMK provides certain genetic evidence for the involvement of this gene during seed germination and mycorrhizal cultivation in D. officinale.

Biogenesis of macrofungal sclerotia: influencing factors and molecular mechanisms

Sclerotia are dense, hard tissue structures formed by asexual reproduction of fungal hyphae in adverse environmental conditions. Macrofungal sclerotia are used in medicinal materials, healthcare foods, and nutritional supplements because of their nutritional value and biologically active ingredients, which are attracting increasing attention. Over the past few decades, the influence of abiotic factors such as nutrition (e.g., carbon and nitrogen sources) and environmental conditions (e.g., temperature, pH), and of the local biotic community (e.g., concomitants) on the formation of macrofungal sclerotia has been studied. The molecular mechanisms controlling macrofungal sclerotia formation, including oxidative stress (reactive oxygen species), signal transduction (Ca²⁺ channels and mitogen-activated protein kinase pathways), and gene expression regulation (differential expression of important enzyme or structural protein genes), have also been revealed. At the end of this review, future research prospects in the field of biogenesis of macrofungal sclerotia are discussed. KEY POINTS: • We describe factors that influence biogenesis of macrofungal sclerotia. • We explain molecular mechanisms of sclerotial biogenesis. • We discuss future directions of study of macrofungal sclerotia biogenesis.

SWATH label-free proteomics analyses revealed the roles of oxidative stress and antioxidant defensing system in sclerotia formation of Polyporus umbellatus

Understanding the initiation and maturing mechanisms is important for rational manipulating sclerotia differentiation and growth from hypha of Polyporus umbellatus. Proteomes in P. umbellatus sclerotia and hyphae at initial, developmental and mature phases were studied. 1391 proteins were identified by nano-liquid chromatograph-mass spectrometry (LC-MS) in Data Dependant Acquisition mode, and 1234 proteins were quantified successfully by Sequential Window Acquisition of all THeoretical fragment ion spectra-MS (SWATH-MS) technology. There were 347 differentially expressed proteins (DEPs) in sclerotia at initial phase compared with those in hypha, and the DEP profiles were dynamically changing with sclerotia growth. Oxidative stress (OS) in sclerotia at initial phase was indicated by the repressed proteins of respiratory chain, tricarboxylic acid cycle and the activation of glycolysis/gluconeogenesis pathways were determined based on DEPs. The impact of glycolysis/gluconeogenesis on sclerotium induction was further verified by glycerol addition assays, in which 5% glycerol significantly increased sclerotial differentiation rate and biomass. It can be speculated that OS played essential roles in triggering sclerotia differentiation from hypha of P. umbellatus, whereas antioxidant activity associated with glycolysis is critical for sclerotia growth. These findings reveal a mechanism for sclerotial differentiation in P. umbellatus, which may also be applicable for other fungi.

Hypovirulence of Sclerotium rolfsii Caused by Associated RNA Mycovirus

Mycoviruses associated with hypovirulence are potential biological control agents and could be useful to study the pathogenesis of fungal host pathogens. Sclerotium rolfsii, a pathogenic fungus, causes southern blight in a wide variety of crops. In this study, we isolated a series of dsRNAs from a debilitated S. rolfsii strain, BLH-1, which had pronounced phenotypic aberrations including reduced pathogenicity, mycelial growth and deficient sclerotia production. Virus-curing and horizontal transmission experiments that eliminated or transmitted, respectively, all dsRNA elements showed that the dsRNAs were involved in the hypovirulent traits of BLH-1. Ultrastructure examination also showed hyphae fracture and cytoplasm or organelle degeneration in BLH-1 hyphal cells compared to the virus-free strain. Three assembled cDNA contigs generated from the cDNA library cloned from the purified dsRNA indicated that strain BLH-1 was infected by at least three novel mycoviruses. One has similarity to the hypovirulence-associated Sclerotinia sclerotiorum hypovirus 2 (SsHV2) in the family Hypoviridae, and the other two are related to two different unclassified dsRNA mycovirus families. To our knowledge, this is the first report of S. rolfsii hypovirulence that was correlated with its associated dsRNA.

De novo assembly and transcriptome analysis of sclerotial development in Wolfiporia cocos

Wolfiporia cocos Ryvarden et Gilbertson, a well-known medicinal fungus in the Basidiomycetes, is widely distributed in East Asia. Its dried sclerotium, which is known as Fuling in China, has been used as a traditional crude drug in Chinese traditional medicine for thousand years. However, little is known about how the sclerotium is developed at the genetic level. In this study, the de novo sequencing of sclerotia of W. cocos (S1_initial stage; S2_developmental stage and S3_mature stage) was carried out by illumina HiSeq 2000 technology. 27,438 unigenes were assembled from ~30Gbp raw data, and 12,093 unigenes were significantly annotated. The analysis of expression profiles during development returned 304 differentially expressed genes (DEGs), which were clustered into four different groups according to their expression trends. Especially for the maturation stage (S3), the sclerotium exhibited a markedly different expression profile from other stages. We further showed that peroxisome, unsaturation of fatty acids and degradation pathway were respectively prevalent in S1, S2 and S3 stages as evidenced by enrichment analysis. To our knowledge, this study represents the first report of sclerotial development transcriptomics in W. cocos. The obtained results provide novel insights into the developmental biology of the sclerotia, which is helpful for future studies about cultivation and breeding of W. cocos.

Transcriptome analysis of genes involved in defence response in Polyporus umbellatus with Armillaria mellea infection

Polyporus umbellatus, a species symbiotic with Armillaria mellea and it also exhibits substantial defence response to Armillaria mellea infection. There are no genomics resources databases for understanding the molecular mechanism underlying the infection stress of P. umbellatus. Therefore, we performed a large-scale transcriptome sequencing of this fungus with A. mellea infection using Illumina sequencing technology. The assembly of the clean reads resulted in 120,576 transcripts, including 38,444 unigenes. Additionally, we performed a gene expression profiling analysis upon infection treatment. The results indicated significant differences in the gene expression profiles between the control and the infection group. In total, 10933 genes were identified between the two groups. Based on the differentially expressed genes, a Gene Ontology annotation analysis showed many defence-relevant categories. Meanwhile, the Kyoto Encyclopedia of Genes and Genomes pathway analysis uncovered some important pathways. Furthermore, the expression patterns of 13 putative genes that are involved in defence response resulting from quantitative real-time PCR were consistent with their transcript abundance changes as identified by RNA-seq. The sequenced genes covered a considerable proportion of the P. umbellatus transcriptome, and the expression results may be useful to strengthen the knowledge on the defence response of this fungus defend against Armillaria mellea invasion.

Oxalic acid and sclerotial differentiation of Polyporus umbellatus

The present investigation aimed to uncover the effects of exogenous oxalic acid during the sclerotial formation of Polyporus umbellatus, with an emphasis on determining the content of the endogenic oxalic acid in the fungus. To this end, the oxalic acid content of the vegetative mycelia, sclerotia, culture mediums and sclerotial exudate were measured using High Performance Liquid Chromatography (HPLC). Furthermore, the lipid peroxidation was estimated by detecting thiobarbituric bituric acid reactive substances (TBARS). The results showed that the exogenous oxalic acid caused a delay in sclerotial differentiation (of up to 9 or more days), suppressed the sclerotial biomass and decreased the lipid peroxidation significantly in a concentration-dependent manner. Oxalic acid was found at very low levels in the mycelia and the maltose medium, whereas it was found at high levels in the mycelia and sucrose medium. After sclerotial differentiation, oxalic acid accumulated at high levels in both the sclerotia and the sclerotial exudate. Oxalic acid was therefore found to inhibit P. umbellatus sclerotial formation.

Effect of revulsive cultivation on the yield and quality of newly formed sclerotia in medicinal Wolfiporia cocos

Wolfiporia cocos is a well-known medicinal mushroom widely used in China, Japan and other Asiatic countries for its various therapeutic effects. 'Revulsive cultivation' is a newly developed method for promoting sclerotia growth in W. cocos field cultivation in China. In this report, we have systematically examined the effects of 'revulsive cultivation' on the yield and quality of newly formed sclerotia. The results showed that the genetic differences between the cultivated strain and the revulsive strain of T1 used in this study did not affect the formation process of new, large sclerotia in which the mycelia of the cultivated strain grew on pine logs directionally assembled on the revulsive strain. Additionally, 'revulsive cultivation', in which the cultivated strain and the revulsive strain used had the same or different genotypes, could remarkably increase the yield, lower the water content, and increase the water-soluble polysaccharide content of the newly formed sclerotia. Moreover, we observed that the changes in the values of the tested economic traits obtained from different genotype combinations through 'revulsive cultivation' were dissimilar. The correlations of these changes with the original sclerotium-forming ability of the cultivated strains and the genetic differences between the cultivated strain and the revulsive strain were not significant. These results will broaden our knowledge regarding the field cultivation of this medical fungus, stimulate new thinking on the study of sclerotium formation in some sclerotium-forming fungi, and promote further studies on the mechanism of sclerotium formation in W. cocos.

Nox gene expression and cytochemical localization of hydrogen peroxide in Polyporus umbellatus sclerotial formation

The effect of temperature shift on Polyporus umbellatus sclerotial development was investigated. Micromorphology of the sclerotia was observed by using scanning electron microscopy (SEM). The cytochemical localization of H2O2 expressed as CeCl3 deposition at the subcellular level was observed by using transmission electron microscopy (TEM). Nox gene expression in sclerotia and mycelia was detected by quantitative real-time PCR (qRT-PCR) analysis. In addition, superoxide dismutase (SOD) and catalase (CAT) specific activities increased during sclerotial development and decreased after the antioxidant diphenyleneiodonium (DPI) was used. Results indicated that the temperature shift treatment induced P. umbellatus sclerotial formation. Compared with the mycelia, the Nox gene was respectively upregulated by 10.577-, 30.984- and 25.469-fold in the sclerotia of SI, SD and SM stages respectively. During the sclerotial formation, H2O2 accumulation was observed in the cell walls or around the organelle membranes of the mycelial cells. The antioxidant DPI decreased the generation of H2O2 in mycelial cells. The specific activity of SOD and CAT levels was decreased significantly by DPI. The activity of the two antioxidant enzymes in the mycelia increased much more during sclerotial formation (p < 0.05). Oxidative stress was closely associated with sclerotial development in P. umbellatus induced by temperature shift treatment.

Traditional uses, phytochemistry, pharmacology, pharmacokinetics and quality control of Polyporus umbellatus (Pers.) Fries: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Polyporus umbellatus (Pers.) Fries (Polyporaceae, Zhuling ) has been commonly used in medicine for a wide range of ailments related to the edema, scanty urine, vaginal discharge, urinary dysfunction, as well as jaundice and diarrhea.

AIM OF THE REVIEW

The present paper reviewed the traditional uses, propagation, phytochemistry, pharmacology, pharmacokinetics and quality control of Polyporus umbellatus.

MATERIALS AND METHODS

All the available information on Polyporus umbellatus was collected via a library and electronic search (using Web of Science, Pubmed, ScienceDirect, Splinker, Google Scholar, etc.).

RESULTS

Phytochemical studies showed the presence of many valuable secondary metabolites such as steroids, polysaccharides, anthraquinones and nucleosides. Crude extracts and isolated compounds showed a wide spectrum of pharmacological activities including diuretic, nephroprotective, anti-cancer, immuno-enhancing, hepatoprotective, anti-inflammatory and antioxidative activities. The pharmacokinetic studies demonstrated that the ergosterol and ergone had a high distribution and absorption in the plasma and the two main components of Polyporus umbellatus were mainly excreted by faeces. The determination of multiple chemical components was successfully applied to the quality control of Polyporus umbellatus.

CONCLUSIONS

Modern phytochemical, pharmacological and metabonomic investigations showed that the crude extracts and isolated compounds from Polyporus umbellatus possess many kinds of biological functions, especially in the diuretic activities and the treatment of kidney diseases as well as anti-cancer, immuno-enhancing and hepatoprotective activities. The pathways of the distribution, absorption, metabolism and excretion of main steroidal compounds were clarified by pharmacokinetic studies. Most of the pharmacological studies were conducted using crude and poorly characterized extracts of Polyporus umbellatus in animals especially in case of diuretic activities and the treatment of kidney diseases. Thus, more bioactive components especially diuretic compounds should be identified using bioactivity-guided isolation strategies and the possible mechanism of action as well as potential synergistic or antagonistic effects of multi-component mixtures derived from Polyporus umbellatus need to be evaluated integrating pharmacological, pharmacokinetic, bioavailability-centered and physiological approaches. In addition, more experiments including in vitro, in vivo and clinical studies should be encouraged to identify any side effects or toxicity. These achievements will further expand the existing therapeutic potential of Polyporus umbellatus and provide a beneficial support to its future further clinical use in modern medicine.