First Report of White Mucus Disease Caused by Fuligo gyrosa on Agrocybe chaxingu in China.

Agrocybe chaxingu is an edible and medicinal mushroom widely cultivated in China (Liu et al. 2021). Agrocybe chaxingu is extremely well-liked for the unique flavor and nutritional value. In May 2021, a serious white mucus disease was observed in the farms of A. chaxingu in the Ganxian district of Ganzhou City, Jiangxi Province, China, with an approximate disease incidence of 20%. In the years of 2022 and 2023, the same white mucus disease on A. chaxingu was observed in the farms in Nanchang City, Jiujiang City and Guangchang County, Jiangxi Province, China. The disease generally occurs on the media, stipe or pileus of A. chaxingu under condition of high humidity. The plasmodial slime molds migrated from the surface of culture media (78% hardwood sawdust, 15% wheat bran, 5% tea seed shell, 1% lime, and 1% gypsum) to the base of fruiting bodies, stipes and finally to pilei, showing as moist, sticky, and white reticulated structures. The infected fruiting bodies of A. chaxingu were completely covered by reticulated plasmodia, displaying a white or pale-yellow color. This resulted in the growth cessation, wilting and eventual death of fruiting body. Microscopic observation found that the plasmodia of slime mold enveloped the hyphae of A. chaxingu, resulting in the fragmentation of the hyphae. The disease can spread quickly, resulting in a 30% reduction in production. Slime mold cultures were isolated by transferring diseased fruiting bodies of A. chaxingu onto oat-agar medium (2% agar and 1% oatmeal) at 25 ℃. The isolates can be obtained after being subcultured for two to three generations. Purified plasmodia were placed on the semi-defined medium (1% tryptone, 1% glucose, 0.15% yeast extract, chick embryo extract and a balanced salt solution) to confirm the absence of bacteria (Daniel et al. 1964) and thus obtained the pure culture. Specimen of the voucher has been deposited in the Institute of Agricultural Applied Microbiology, Jiangxi Academy of Agricultural Sciences as number IAAM-W0002. The vegetative plasmodia have a large and well-developed scalloped structure that were white or milky white in colour. The white plasmodium became opaque pale yellow when exposed to light before fruiting. The veins merged and thickened. Fruiting bodies can be formed on the lid or side of the Petri dish under light condition. The fruiting bodies formed papillae with irregular shape, and then the color changed from translucent yellow to greyish black. Spores were usually spherical or subglobose, free, greyish brown in mass, purplish brown, 7-12 µm in diameter under light microscopy. These morphological characteristics were found to be consistent with those of Fuligo gyrosa (Synonym: Physarum gyrosum) (Kim et al. 2009; Shi et al. 2005; Jahn 1902). The identity of the isolates was further confirmed by sequence analysis of the 18S ribosomal RNA gene with primer SMNUR101/NS4 (Rusk et al. 1995; White et al. 1990). Using BLASTn searches, the sequence of 18S rRNA gene (GenBank accession number OR186216) matched the sequence of F. gyrosa (GenBank accession number LC744593) with the identity of 99.91% and coverage of 97%. A phylogenetic tree based on the 18S rRNA gene also demonstrated that the slime mold clustered with F. gyrosa. Over ten isolates have been obtained from the diseased A. chaxingu samples in different factories and identified as F. gyrosa. To test the pathogenicity of F. gyrosa, five healthy young fruiting bodies (three to five days of primordium) of A. chaxingu cultivated in mushroom-growing room were gently inoculated by a 12 mm diameter oat-agar medium with plasmodia at 24 ± 2 ℃ and then were kept with relative humidity of 90%-95%. Five fruiting bodies inoculated with a 12 mm oat-agar medium served as controls. After 5 days, white mucus characteristics and three fifths of death symptoms were observed on the fruiting bodies inoculated with the plasmodia, while the controls remained asymptomatic. The slime mold on the inoculated fruiting bodies was morphologically identical to F. gyrosa that was observed on the initial diseased fruiting bodies. It was also observed the envelopment A. chaxingu hyphae by the plasmodia of slime mold and fragmentation of the hyphae, and the fragmentation was not observed in the controls. Reisolations were prepared from the inoculated fruiting bodies and confirmed to be F. gyrosa based on morphological characteristics and 18S rRNA sequence, thus fulfilling Koch's postulates. Fuligo gyrosa has been reported to cause severe disease in oriental melon in Korea (Kim et al. 2009). This is the first report of F. gyrosa causing white mucus disease in cultivated A. chaxingu. The findings will provide important information on prevention and control of the disease, and be helpful for the development of A. chaxingu industry.

First Report of Yellow Rot Caused by Physarum galbeum in Grifola frondosa in China.

Grifola frondosa (Dicks.) Gray, named "Maitake" in Japan, is mainly cultivated in China, Japan and Korea as a rare delicacy (Park et al. 2015). G. frondosa is a medicinal and edible mushroom that can enhance the human immunology system. In recent years, the production of G. frondosa has increased in China due to its high economic value and as a source of livelihood for small scale farmers. From August to September 2017, a serious slime mold disease was observed on G. frondosa under greenhouse conditions in Qingyuan County, Lishui city, Zhejiang Province, China. Incidence was 10 to 30% in most surveyed mushroom greenhouses, sometimes more than 80% in mushroom greenhouses without proper management. The disease reduced G. frondosa production by 10% on average, and over 80% in severe cases. Slime mold disease usually appeared after irrigation, the kelly plasmodia migrate firstly from the root of fruiting body to stem and finally to pileus, then the infected parts became soft and putrid with slime on the surface. Additionally, many other organisms grow on decayed fruiting bodies, such as bacteria, fungi, and insects. The disease can spread rapidly through soil to adjacent fruiting bodies resulting in yield reduction. Samples were collected and cultures were isolated by transferring diseased fruiting bodies with yellow green plasmodia onto 2% water agar medium. Plasmodia were purified through aseptically transferring their edge segment to a new sterile 2% water agar medium, and this procedure was repeated three or four times to free the isolate from contaminating organisms. Purified plasmodia were then placed on the solid bacteriological test medium (SGM), containing glucose, peptone, yeast extract, mineral salts and hematin used in the axenic culture of Physarum polycephalum (Daniel et al. 1964), to verify bacteria presence. Plasmodia were also induced to form sporocarps. Voucher specimens were deposited in the Fungarium of Jiangxi Academy of Agricultural Sciences (FJAAS-M0001) and the Herbarium of the Mycology, Engineering Research Center of Edible and Medicinal Fungi, Chinese Ministry of Education, Jilin Agricultural University (HMJAU-M1561). Sporocarps were stalked, globose to discoid, golden-yellow, 0.9-1.8 mm in height, 0.28-0.55 mm in diameter. Hypothallus was small, thin, orange. Stalks were subulated, about twice to thrice the diameter of the sporotheca, bright orange below, yellow above, furrowed. Peridium was weak, thin, and plated with yellow calcareous flakes. Capillitium was a small meshed, persistent net of tubules with small and yellow angular lime nodes. Spores were globose, free, dark brown to black in mass, purplish brown in transmitted light, 8-10 µm in diameter, smooth under light microscopy. Irregular spinulose spores showed clusters of small warts that are conspicuous under scanning electron microscopy. Plasmodia were yellow green. The 18S ribosomal RNA gene was amplified with primer SMNUR101/NS4 (Rusk et al. 1995; White et al. 1990). The 18S rRNA gene sequence was submitted to GenBank (OP373728) and an 18S rRNA gene phylogenetic tree of Physarum obtained by maximum likelihood analysis (ML) and Bayesian inferences (BI) of 23 taxa and 1,608 aligned positions was produced. Based on sporocarps morphological characteristics, plasmodial cultural traits, and the sequence of 18S rRNA, the slime mold was identified as Physarum galbeum. A pathogenicity test was performed by gently inoculating a 12 mm diameter circinal patch of SGM with plasmodia on three healthy fruiting bodies of G. frondosa. All treatments were cultured in a mushroom-growing room with temperature 24 to 29 ℃ and relative humidity of 87 to 96%. Three fruiting bodies inoculated with a 12 mm diameter SGM served as controls. All fruiting bodies inoculated with plasmodia showed the same symptom. No symptoms developed on the controls. The pathogen was consistently reisolated from the symptomatic fruiting bodies of G. frondosa and confirmed to be P. galbeum based on cultural, morphological and molecular characteristics, thus fulfilling Kock's postulates. This is the first report of P. galbeum causing yellow rot disease on cultivated G. frondosa. References: Daniel, J. W., et al. 1964. Page 9 in: Methods in Cell Biology. Academic Press, New York. Denchev, C. M. 2008. Mycologia Balc. 5:93. Park, H. S., et al. 2015. Biosci., biotechnol., and biochem. 79:147. Rusk, S. A., et al. 1995. Mycologia. 87:140. White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA.

Life cycle and plasmodial axenic culture of Physarum galbeum.

Myxogastrea is a group of eukaryotic microorganisms included in Amoebozoa. Its life cycle includes two trophic stages: plasmodia and myxamoeflagellates. However, only about 102 species have their complete life cycle known in literature and only about 18 species have their plasmodial axenic culture accomplished in laboratory conditions. The research presented herein involved culturing of Physarum galbeum on the water agar medium. The events that transpired during its life cycle including spore germination, plasmodia formation, and sporocarp development were documented especially the subglobose or discoid sporotheca and the stalk formation. The spores germinated by the V-shape split method to release a single protoplasm. Yellow-green pigmented phaneroplasmodia developed into sporocarps by subhypothallic type. The present article gives details of the sporocarp development of P. galbeum and its plasmodial axenic culture on solid and liquid mediums.

Multiple evidence reveals two new species and new distributions of Calocybe species (Lyophyllaceae) from northeastern China.

The Calocybe species possess notable economic and medicinal value, demonstrating substantial potential for resource utilization. The taxonomic studies of Calocybe are lacking in quality and depth. Based on the specimens collected from northeast China, this study provides a detailed description of two newly discovered species, namely Calocybebetulicola and Calocybecystidiosa, as well as two commonly found species, Calocybedecolorata and Calocybeionides. Additionally, a previously unrecorded species, C.decolorata, has recently been discovered in Jilin Province, China. The two newly discovered species can be accurately distinguished from other species within the genus Calocybe based on their distinct morphological characteristics. The primary distinguishing features of C.betulicola include its grayish-purple pileus, grayish-brown to dark purple stipe, smaller basidiomata, absence of cellular pileipellis, and its habitat on leaf litter within birch forests. Calocybecystidiosa is distinguished by its growth on the leaf litter of coniferous forests, a flesh-pink pileus, a fibrous stipe with a white tomentose covering at the base, non-cellular pileipellis, larger basidiospores, and the presence of cheilocystidia. The reconstruction of phylogenetic trees using combined ITS, nLSU, and tef1-α sequences, employing maximum likelihood and Bayesian inference analyses, showed that C.betulicola formed a cluster with C.decurrens, while C.cystidiosa clustered with C.vinacea. However, these two clusters formed separate branches themselves, which also supported the results obtained from our morphological studies. A key to the Calocybe species reported from northeast China is provided to facilitate future studies of the genus.

Characterization, antioxidant activity, and mineral profiling of Auricularia cornea mushroom strains.

Background: Mushrooms are considered as next-generation healthy food components. Owing to their low-fat content, high-quality proteins, dietary fiber, and rich source of nutraceuticals. They are ideally preferred in formulation of low-caloric functional foods. In this view, the breeding strategies of mushroom Auricularia cornea (A. cornea) focusing on high yield and higher quality with rich nutritional values and health benefits are still needed. Materials and methods: A total of 50 strains of A. cornea were used to analyze the bio efficiency and the time required for fruiting body formation following the cultivation experiment. The calorimetric method was used to evaluate the antioxidant activity and quantify the crude polysaccharides and minerals content thereafter. Results: The results showed that the time required for fruiting body formation and biological efficiency varied significantly among the selected strains. Noticeably, the wild domesticated strain Ac13 of A. cornea mushroom showed the shortest fruit development time (80 days). Similarly, the hybrid strains including Ac3 and Ac15 possessed the highest biological efficiency (82.40 and 94.84%). Hybrid strains Ac18 (15.2%) and cultivated strains Ac33 (15.6%) showed the highest content of crude polysaccharides, while cultivated strains Ac1 and Ac33, demonstrated the highest content of total polysaccharides in the fruiting body (216 mg. g-1 and 200 mg. g-1). In the case of mineral content, the highest zinc contents were observed from the cultivated strain Ac46 (486.33 mg·kg-1). The maximum iron content was detected from the hybrid strain Ac3 (788 mg·kg-1), and the wild domesticated strain Ac28 (350 mg·kg-1). The crude polysaccharides of the A. cornea strain showed significant antioxidant potential, and the ability of Ac33 and Ac24 to scavenge DPPH radicals and ABTS, which was significantly improved compared to other strains, respectively. Principal component analysis was applied to examine the agronomic traits and chemical compounds of various strains of A. cornea mushrooms. The results revealed that cultivated, wild domesticated, and hybrid strains of A. cornea exhibited distinct characteristics in terms of growth, yield, and nutritional properties. Conclusion: The crude polysaccharides from A. cornea mushroom strains act as natural antioxidants, the wild, hybrid, and commercial A. cornea mushroom strains can achieve rapid growth, early maturation, and high yields. The evaluation of biochemical indexes and nutritional characteristics of strains with excellent traits provided a scientific basis for initiating high-quality breeding, provided germplasm resources for the production of "functional food" with real nutritional and health value.

Analysis of the Genome Sequence of Strain GiC-126 of Gloeostereum incarnatum with Genetic Linkage Map.

Gloeostereum incarnatum has edible and medicinal value and was first cultivated and domesticated in China. We sequenced the G. incarnatum monokaryotic strain GiC-126 on an Illumina HiSeq X Ten system and obtained a 34.52-Mb genome assembly sequence that encoded 16,895 predicted genes. We combined the GiC-126 genome with the published genome of G. incarnatum strain CCMJ2665 to construct a genetic linkage map (GiC-126 genome) that had 10 linkage groups (LGs), and the 15 assembly sequences of CCMJ2665 were integrated into 8 LGs. We identified 1912 simple sequence repeat (SSR) loci and detected 700 genes containing 768 SSRs in the genome; 65 and 100 of them were annotated with gene ontology (GO) terms and KEGG pathways, respectively. Carbohydrate-active enzymes (CAZymes) were identified in 20 fungal genomes and annotated; among them, 144 CAZymes were annotated in the GiC-126 genome. The A mating-type locus (MAT-A) of G. incarnatum was located on scaffold885 at 38.9 cM of LG1 and was flanked by two homeodomain (HD1) genes, mip and beta-fg. Fourteen segregation distortion markers were detected in the genetic linkage map, all of which were skewed toward the parent GiC-126. They formed three segregation distortion regions (SDR1-SDR3), and 22 predictive genes were found in scaffold1920 where three segregation distortion markers were located in SDR1. In this study, we corrected and updated the genomic information of G. incarnatum. Our results will provide a theoretical basis for fine gene mapping, functional gene cloning, and genetic breeding the follow-up of G. incarnatum.