RAPD molecular differentiation of the cultivated strains of the jelly mushrooms, Auricularia auricula and A. polytricha

Medicinal Value, Genetic Diversity, and Genetic Relationship Analysis of Auricularia cornea (Agaricomycetes) Based on ITS, ISSR, and SRAP Markers

Wild resources of Auricularia cornea (A. polytricha) are abundant in China, and genetic diversity and genetic relationships analysis of A. cornea can provide basis for germplasm resource utilization and innovation and molecular marker-assisted breeding. In this study, 22 Auricularia strains collected were identified as A. cornea based on ITS sequence analysis, and its genetic diversity was examined by ISSR and SRAP markers. The results showed that a total of 415 bands were amplified by 11 selected ISSR primers, with an average amplification of 37.73 bands per primer, and the mean values of Ne, I, and H were 1.302, 0.368, and 0.219, respectively. A total of 450 bands were amplified by 10 SRAP primers, with an average of 45 bands per primer, and the average of Ne, I, and H were 1.263, 0.302, and 0.183, respectively. The unweighted pair-group method with arithmetic means analysis based on ISSR-SRAP marker data revealed that the genetic similarity coefficient between the tested strains was 0.73-0.97, and the strains could be divided into five groups at 0.742, which had a certain correlation with regional distribution. The results of PCOA and population structure analysis based on ISSR-SRAP data also produced similar results. These results demonstrate the genetic diversity and distinctness among wild A. cornea and provide a theoretical reference for the classification, breeding, germplasm innovation, utilization, and variety protection of A. cornea resources.

Solid-state bioprocessing of sugarcane bagasse with Auricularia fuscosuccinea for phenolic compounds extraction

Sugarcane bagasse is a natural source of phenolic compounds. However, these compounds are bound to lignocellulose components, reducing their ability to function as good antioxidants. These linkages are hydrolyzed by enzymes like β-glucosidases, increasing free phenolics. Auricularia is a food-grade genus capable of producing β-glucosidases. The aim of this work was (I) to determine naturally occurring species of Auricularia and (II) to obtain phenolic compounds through the solid-state bioprocessing of sugarcane bagasse. We have successfully isolated five strains that were assigned to the taxon A. fuscosuccinea. We determined β-glucosidase activity by fluorescence plate assay of the five isolated strains and adjusted an optimal temperature for mycelial growth at 30 °C. A. fuscosuccinea LBM 243 was chosen for solid-state bioprocessing of sugarcane bagasse. β-glucosidase activity (12.2 ± 0.62 U l^-1) and protein content (51.58 ± 6.26 mg l^-1) were highest on day 20 of culture. The maximum value of total phenolic content (507.5 ± 9.05 mg l^-1) was obtained at day 20 and antioxidant capacity (34.44% ± 11.20) was highest at day 10, both in ethanolic extracts. The best performance of ethanol against methanol extraction in this work is highlighted considering ethanol to be a safe, efficient, and low-cost solvent.

Isolation, purification, characterization, and immunomodulatory effects of polysaccharide from Auricularia auricula on RAW264.7 macrophages

Auricularia auricula polysaccharide (AAP) was isolated by hot-water extraction and purified to evaluate its structural and immunomodulatory effects on RAW264.7 macrophages. The results show that three kinds of Auricularia auricula polysaccharides (c-AAP) were obtained and named as AAP-I, AAP-II, and AAP-III Their further purification found that AAP-I and AAP-II were glycoproteins, and only AAP-III was a pure polysaccharide, which we named AAP for further experiments. Structural characteristics revealed that AAP was a homogeneous galactan comprising mannose, rhamnose, gluconic acid, glucose, galactose, arabinose, and fucose in a molar ratio of 5.02:0.9:0.12:4.48:0.37:1.0:0.36, and the average molecular weight is approximately 23.51 kDa. Methylation analysis revealed that AAP mainly consisted of 1,4-linked-Glcp, 1,4,6-linked-Glcp, terminal Glcp, 1,4-linked-Manp, 1,2,6-linked-Manp, and terminal Arap. Furthermore, the in vitro immunomodulatory activities of AAP were evaluated by cell proliferation, NO production, and phagocytic ability using RAW264.7 macrophage cells. The results show that AAP not only promoted the activation of macrophages but also provided a scientific basis for the further use of AAP. PRACTICAL APPLICATIONS: Three water-soluble polysaccharides were extracted from Auricularia auricula of Changbai Mountain, two of which contained binding proteins. Determination of molecular weight, structure, and immunoreactivity of pure polysaccharide components. The result clearly demonstrated the benefits of this plant as a healthy functional food.

Genomic Analyses Provide Insights Into the Evolutionary History and Genetic Diversity of Auricularia Species

Species in the genus Auricularia play important roles for people’s food and nutrition especially Auricularia cornea and A. heimuer. To understand their evolutionary history, genome structure, and population-level genetic variation, we performed a high-quality genome sequencing of Auricularia cornea and the corresponding comparative genomic analysis. The genome size of A. cornea was similar to Auricularia subglabra, but 1.5 times larger than that of A. heimuer. Several factors were responsible for genome size variation including gene numbers, repetitive elements, and gene lengths. Phylogenomic analysis revealed that the estimated divergence time between A. heimuer and other Auricularia is ∼79.1 million years ago (Mya), while the divergence between A. cornea and A. subglabra occurred in ∼54.8 Mya. Population genomic analysis also provided insight into the demographic history of A. cornea and A. heimuer, indicating that their populations fluctuated over time with global climate change during Marine Isotope Stage 5-2. Moreover, despite the highly similar external morphologies of A. cornea and A. heimuer, their genomic properties were remarkably different. The A. cornea genome only shared 14% homologous syntenic blocks with A. heimuer and possessed more genes encoding carbohydrate-active enzymes and secondary metabolite biosynthesis proteins. The cross-taxa transferability rates of simple sequence repeat (SSR) and insertion or deletion (InDel) markers within the genus Auricularia were also lower than that previously observed for species within the same genus. Taken together, these results indicate a high level of genetic differentiation between these two Auricularia species. Consequently, our study provides new insights into the genomic evolution and genetic differentiation of Auricularia species that will facilitate future genetic breeding.

RETRACTED ARTICLE: Characterization of the complete mitochondrial genome of an important edible fungus Auricularia Polytricha

We, the Editor, authors and Publisher of Mitochondrial DNA Part B: Resources, have retracted the following article:

Qiang Li, Xin Jin, Zuqin Chen, Chuan Xiong, Ping Li & Wenli Huang (2019) ‘Characterization of the complete mitochondrial genome of an important edible fungus Auricularia Polytricha’ 4:1, 1107–1108, DOI https://doi.org/10.1080/23802359.2019.1586494.

This article has been retracted at the request of the authors as, subsequent to publication, it has been identified that the species reported in the article is incorrect. The species should be Suillus sp. and not Auricularia polytricha as reported. The article has therefore been retracted as the data reported in the article are inaccurate.

We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions.

The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.

Comparative transcriptome analysis reveals relationship of three major domesticated varieties of Auricularia auricula-judae

Auricularia auricula-judae is an edible mushroom and a traditional medicine in China as well as the fourth largest cultivated mushroom species in the world. Here for the first time, we present comparative transcriptome analyses of the fruiting bodies of three morphologically distinguishable A. auricula-judae cultivated varieties (Wujin, smooth; Banjin, partially wrinkled; and Quanjin, fully wrinkled) collected from Jilin Province, China. Biological triplicates were performed to determine the expression levels of 13,937 unigenes. Among them, only 13 unigenes were annotated to A. auricula-judae, highlighting the lack of publicly available reference sequences for this economically important species. Principal component analysis (PCA) determined that the gene expression profile of Quanjin was unique when compared to those of Banjin and Wujin. Such relationships were further supported by analyses of annotated and unannotated unigenes, differentially expressed unigenes, gene ontology functions, and the family of peroxidase genes. Using the KEGG database, significant alternations in biological pathways were detected among the three cultivars. This work contributes a large set of A. auricula-judae sequences to public database, establishes the relationships among major cultivars, and provides molecular guidance for breeding and cultivation.

Synergistic interaction of Auricularia auricula-judae polysaccharide with yam starch: effects on physicochemical properties and in vitro starch digestibility

Thermal stable polysaccharides from Auricularia auricula-judae (AP) have unique molecularstructures and multiple bioactivities. The effects of AP on the physicochemical properties and in vitro starch digestibility of yam starch (YS) were studied. The addition of AP induced a significant increase in the swelling power, solubility, mean volume diameter and adhesiveness as well as a dramatic decrease in the hardness and gumminess (p < 0.05). AP showed a strong suppressive effect on in vitro starch digestibility. Higher modulus (G', G″) and stiffness parameters (Aα), and lower order of relaxation function (α), were observed in oscillatory rheological measurements, indicating that the gels were more elastic-like and had higher pseudoplasticity in the presence of AP. Furthermore, AP remarkably decreased the syneresis and storage modulus (G'), and also retarded the retrogradation process of YS gel at 4°C, revealing a synergistic interaction between AP and YS, which could also be demonstrated by scanning electron microscopy.

Antimicrobial Potential, Identification and Phylogenetic Affiliation of Wild Mushrooms from Two Sub-Tropical Semi-Evergreen Indian Forest Ecosystems

The diversity of wild mushrooms was investigated from two protected forest areas in India and 231 mushroom specimens were morphologically identified. Among them, 76 isolates were screened for their antimicrobial potential against seven bacterial and fungal pathogens. Out of 76 isolates, 45 isolates which displayed significant antimicrobial activities were identified using ITS rRNA gene amplification and subsequently phylogenetically characterized using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. Sequencing of the ITS rRNA region classified the isolates into 16 genera belonging to 11 families. In total, 11 RAPD and 10 ISSR primers were selected to evaluate genetic diversity based on their banding profile produced. In total 337 RAPD and 312 ISSR bands were detected, among which percentage of polymorphism ranges from 34.2% to 78.8% and 38.6% to 92.4% by using RAPD and ISSR primers respectively. Unweighted Pair-Group Method with Arithmetic Mean (UPGMA) trees of selected two methods were structured similarly, grouping the 46 isolates into two clusters which clearly showed a significant genetic distance among the different strains of wild mushroom, with an similarity coefficient ranges from 0.58 to 1.00 and 0.59 to 1.00 with RAPD and ISSR analysis respectively. This reporthas highlighted both DTR and MNP forests provide a habitat for diverse macrofungal species, therefore having the potential to be used for the discovery of antimicrobials. The report has also demonstrated that both RAPD and ISSR could efficiently differentiate wild mushrooms and could thus be considered as efficient markers for surveying genetic diversity. Additionally, selected six wild edible mushroom strains (Schizophyllum commune BPSM01, Panusgiganteus BPSM27, Pleurotussp. BPSM34, Lentinussp. BPSM37, Pleurotusdjamor BPSM41 and Lentinula sp. BPSM45) were analysed for their nutritional (proteins, carbohydrates, fat and ash content), antioxidant potential. The present findings also suggested that the wild edible mushroom strains do not have only nutritional values but also can be used as an accessible source of natural antioxidants.

Branching structure and chain conformation of water-soluble glucan extracted from Auricularia auricula-judae

A water-soluble neutral polysaccharide (AF1) was extracted from Auricularia (A.) auricula-judae with 0.15 M aqueous NaCl at 80-100 °C. Its chemical components and structure were analyzed by GC, GC-MS, and NMR. AF1 was identified as a β-(1→3)-D-glucan with two β-(1→6)-D-glucosyl residues for every three main chain glucose residues, showing a comb-branched structure. The M(w) values of AF1 in both aqueous solution and DMSO determined by LLS and SEC-LLS were in the narrow range of 2.07-2.15 × 10(6), indicating AF1 existed as single chains in the two solvents. The high intrinsic viscosity [η] of 1753 mL/g and the structure-sensitive parameter ρ (≡R(g)/R(h)) value of 2.3 in water revealed that AF1 existed as stiff chain conformation. Moreover, we directly observed the extended stiff chain conformation by AFM. The branching structure led to the water solubility of AF1, and the intramolecular hydrogen bonds sustained the stiff chain conformation. The rheological results showed that this polysaccharide aqueous solution had higher viscosity than even xanthan, a pronounced thickening agent. This work provided important information for developing new thickeners in food fields, and how neutral polysaccharides can be used as good candidates.

Evaluation of the use of SCAR markers for screening genetic diversity of Lentinula edodes strains

In this study, three molecular marker systems including sequence related amplified polymorphism (SRAP), random amplified polymorphic DNA (RAPD), and inter-simple sequence repeats (ISSR) were screened to select polymorphisms of 24 main commercial strains of Lentinula edodes cultivated widely in China. Twenty-nine sequence characterized amplified region (SCAR) markers were developed to set up a dendrogram using UPMGA based on nucleotide sequences of some SRAP, RAPD, and ISSR polymorphic fragments. The grouping showed that the 24 strains were apparently clustered into five groups at a level of 0.68 similarity coefficient, and those that have similar breeding background clustered preferentially into the same subgroup. Results also revealed that the 24 strains had a low level of genetic diversity, and the breeding source of L. edodes should be broadened by exploiting wild types and introducing exotic strains. In addition, the tested strains of L. edodes could be clearly distinguished and identified from others by using different combinations of SCAR primers. Thus, results of this work demonstrated that SCAR was an excellent genetic marker system to characterize and investigate genetic diversity of L. edodes. Furthermore, this provided an alternative method to identify the genetic relationship of different strains of other fungi.

Difference in cultivation characteristics and genetic polymorphism between Chinese and Japanese strains of Wolfiporia cocos Ryvarden et Gilbertson (Poria cocos Wolf)

Poria, a dried sclerotium of Wolfiporia cocos Ryvarden et Gilbertson (Polyporaceae) has been used as a crude drug in both Chinese and Japanese (Kampo) traditional medicines. Recently, cultivated products of Chinese Poria strains have accounted for most of the market, while the cultivation of Japanese Poria strains has not been successful. Aiming to determine the relationship between the differences in cultivation characteristics and genetic polymorphism, we conducted a field cultivation experiment, a rot test, and rapid amplification of polymorphic DNA (RAPD) analysis of Poria strains collected from China and Japan: 3 Chinese and 7 Japanese strains. In field cultivation, although there was no marked inferiority of Japanese strains to Chinese ones in either mycelium propagation or the rate of sclerotium formation, Chinese strains formed whiter sclerotia with a mean size more than twice that of Japanese ones. Representatives of Chinese and Japanese strains, Yunnan and Kaimondake, respectively, were tested for wood-rotting ability. More wood was utilized and the wood color was darker in trials of the Yunnan strain. Amplifications of total DNA of these 10 fungal strains with 2 primers, PC-6 and PC-11, in RAPD analysis showed a difference in the amplicon profile between Japanese and Chinese strains, suggesting differences in their genetic background.

In vitro antioxidant activities of sulfated derivatives of polysaccharides extracted from Auricularia auricular

In this research, two types of sulfated polysaccharide derivatives were successfully synthesized. Their antioxidant activities were investigated by employing various established in vitro systems. In addition, the degree of sulfation was evaluated using ion-chromatography and IR spectra. The results verify that, when employing scavenging superoxide radical tests, both the sulfation of acid Auricularia auricular polysaccharides (SAAAP) and the sulfation of neutral Auricularia auricular polysaccharides (SNAAP) derivatives possessed considerable antioxidant activity and had a more powerful antioxidant competence than that of the native non-sulfated polysaccharides (AAAP and NAAP). On the other hand, AAAP and NAAP exhibited stronger activity on scavenging both the hydroxyl radical and lipid peroxidation. Available data obtained with in vitro measurements indicates that the sulfated groups of AAAP and NAAP played an important role on antioxidant activity. In sum, the research demonstrates that the antioxidant activity of sulfated polysaccharide derivatives in vitro has a potential significance for seeking new natural antioxidant protective agents.