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22 June 2024, Volume 43 Issue 6

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    Research papers
  • HU Yujuan, HU Jiangxin, ZHANG Chunguang, CHANG Xiaoyun, CHEN Mingjun
    Mycosystema. 2024, 43(6): 240037.
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    Seventy isolates of Diporthe fungi from healthy Camellia oleifera leaves were obtained by using tissue isolation method. Based on morphological characteristics and phylogenetic analysis of five fragment sequences (ITS, TEF, TUB, CAL, HIS), eight representative isolates were identified as six species, D. biguttulata, D. eres, D. hongkongensis, D. fusicola, D. qimenensis sp. nov. and D. reniformis sp. nov. β-Type conidia were not observed in the two new species. D. reniformis produces distinct reniform conidia.

  • LIANG Lingyu, WANG Huimin, LIU Fu, LÜ Quan
    Mycosystema. 2024, 43(6): 240040.
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    Species of Geosmithia (Ascomycota, Hypocreales) are commonly associated with bark beetles, and several species can infect tree hosts and cause serious diseases. In this study, a culture-dependent and pathogenic trial was conducted to classify a species of Geosmithia associated with Tomicus armandii infesting Pinus armandii in southwest China. In total, 387 Geosmithia isolates were obtained from 45 adults and 64 galleries of T. armandii in Yuxi and Fuyuan Cities, Yunnan Province, China. Ten representative isolates were further identified on the basis of morphological and physiological characteristics and the phylogenetic analyses were conducted based on ITS, TUB2, and TEF1-α sequences. Among these, 90 isolates were used for the establishment of the ITS tree, 66 of the TUB tree, and 77 of the TEF tree. As a result, a novel species, G. armandii was identified. This is the first species of Geosmithia reported to be associated with T. armandii. In vivo pathogenicity analysis of the two isolates selected indicated that in one month after inoculation, there was no significant difference between average lesion length caused by the inoculated isolates and the experimental control, showing that G. armandii is a weak pathogen of Pinus armandii.

  • LI Guoqing, LIANG Yuhua, LU Linqin, LIU Feifei
    Mycosystema. 2024, 43(6): 240033.
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    The genus Diplodia (Botryosphaeriales, Botryosphaeriaceae) comprises many important pathogens or latent pathogens associated with stem canker, shoot blights and die-back of plants across a wide geographic distribution. In this study, a total of 13 Diplodia isolates was obtained from diseased branches of loquat (Eriobotrya japonica) trees in Yunnan Province. Based on phylogenetic analyses of ITS, tef1 and tub2 loci, combined with morphological characteristics, two species were identified, D. mutila new to China and D. pipa sp. nov. The pathogenicity tests conducted on potted loquat trees demonstrated that both species can infect loquat trees, with D. mutila exhibiting a higher level of virulence as compared with D. pipa. To our knowledge, this is the first report of Diplodia from loquat trees in China.

  • LIANG Jiaqi, ZHANG Yizhe, ZHANG Hongshun, ZHOU Jing, SI Jing, LANG Nan, ZHONG Jiaju, WU Anzhong, LI Zhongfeng, LI Haijiao, SUN Chengye
    Mycosystema. 2024, 43(6): 230331.
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    Based on systematic resource investigation, species identification, and literature arrangement, the checklist of poisonous mushrooms in Beijing was complied. The poisonous mushrooms were classified according to the poisoning type. Scientific name, Chinese name, and references of each poisonous mushroom are provided. By 2023, 130 poisonous mushrooms have been found in Beijing, causing five known damage types. However, there are still some poisoning types difficult to confirm. The most toxic mushrooms to be concerned are Amanita subjunquillea and Lepiota brunneoincarnata, which can cause acute liver failure, as well as Amanita oberwinklerana, which can lead to acute renal failure.

  • WU Tao, BAO Dapeng, WANG Weixia, TONG Letao, LI Fuhou, TANG Lihua
    Mycosystema. 2024, 43(6): 230287.
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    Histone deacetylation is one of the most important epigenetic modifications and plays a variety of roles in development, but the detailed function and mechanism of histone deacetylation in Lentinula edodes is unknown. An extensive deacetylation inhibitor (HDACi), trichostatin A (TSA) was used to determine the role of histone deacetylation on the developmental process of Lentinula edodes. It was observed that exogenous application of TSA could inhibit the process of ripening and brown mycelium film formation of pack-cultured Lentinula edodes. Transcriptomic analysis revealed that TSA treatment produced 393 differentially expressed genes, which were mainly enriched in the biosynthesis of secondary metabolites, protein processing in the endoplasmic reticulum, and microbial metabolism in different environments. Analysis of the differences in gene expression between TSA treatment and control groups indicated that TSA might directly or indirectly affect the genes of cytochrome P450, laccase, and glycoprotein family by affecting histone acetylation levels, and thereby exert an influence on the formation of Lentinula edodes brown mycelium membrane. This paper provides a reference helpful to shortening the cycle of industrial production of Lentinula edodes.

  • BAI Xiaoxuan, LI Jing, ZHU Gaojie, LIU Siyu, ZHANG Jifeng, LIU Chao, LIU Shiping
    Mycosystema. 2024, 43(6): 230320.
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    Penicillium oxalicum is an important biocontrol fungus. Previously, a new linear pentapeptide, sanxiapeptin, was obtained from the fermentation product of P. oxalicum isolated from vicinity of citrus orchard, which hada potent inhibitory effect on rot-causal fungus P. digitatum on citrus. To reveal the molecular regulatory mechanism and increase the production of sanxiapeptin, the transcriptome data of different strains of P. oxalicum previously determined under various cultural conditions were systematically analyzed. By establishing sets of differentially expressed genes among different comparison groups and taking the intersection of each set, nine candidate transcription factors were screened from 478 transcription factors that were highly correlated with the production level of sanxiapeptin, of which three were negatively and six were positively correlated with sanxiapeptin production. Bioinformatics analysis of the candidate transcription factors and their coding genes was performed, and the accuracy of transcriptome data was verified through qRT-PCR. This study provides a theoretical foundation for analyzing the molecular regulatory mechanism of sanxiapeptin and promoting the development of fruit and vegetable preservatives using sanxiapeptin as main component. It also serves as a reference for mining target genes through transcriptome data.

  • ZHANG Shu, CHEN Denghui, CHEN Guocan, XU Xinran, YIN Wenbing
    Mycosystema. 2024, 43(6): 230297.
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    Penicillium raistrickii can yield plenty of secondary metabolites. However, there are few reports about its synthetic pathways and unexpressed biosynthetic gene clusters because of the lack of a genetic transformation system, as a result, the study of its biosynthesis mechanism and natural products is seriously hampered. An efficient genetic transformation system for P. raistrickii CGMCC 3.1066 was built in this study. The conditions for spore germination, the antibiotic concentration, the optimum condition for preparing protoplasts, and the concentration of DNA fragments have been determined. Five genes ranging in length from 1-10 kb were knocked out by polyethylene glycol-mediated protoplast transformation, and the average positive rate of gene knockout was 17.5%. In addition, the gene for synthesizing 1,8-dihydroxy naphthalene (DHN)-melanin has been knocked out. The results show that the lack of this gene can cause spore discoloration from green to white, but the growth of the strain is not affected, making this site to act as a fixed insertion site because the transformants can be identified quickly through observation. The genetic transformation system successfully established in P. raistrickii CGMCC 3.1066 will facilitate the identification of gene function, analysis of biosynthetic pathways of compounds, and other studies, and this study can provide a reference for building the transformation system of other non-model fungi.

  • WANG Yajiao, JI Zengfa, LI Qiusheng, WU Yuxing, HAN Sen, KONG Lingxiao
    Mycosystema. 2024, 43(6): 230288.
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    Corn southern leaf blight is one of the important diseases in maize production in China, causing significant yield reduction every year. Bipolaris maydis partitivirus 1 (BmPV1) is a dsRNA virus carried by B. maydis, the pathogens of corn southern leaf blight. It has hypovirulence and can reduce the pathogenicity of B. maydis, but the effect of BmPV1 on host infection is not clear. In this study, the Agrobacterium-mediated transformation method was used to introduce the gfp gene into the BmPV1 carrying strain 3086-BmPV1 and the non-virus strain 3086-non of B. maydis. The stability of the fluorescent-labeled strains was analyzed by PCR and fluorescence observation. The effect of the introduction of gfp gene on biological characteristics of the fluorescent-labeled strains were analyzed. Spore suspensions were sprayed on maize leaves for inoculation, and the infection of B. maydis on maize leaves was observed using fluorescence microscopy. PCR amplification and fluorescence observation results showed that the gfp gene was successfully integrated into strains 3086-BmPV1 and 3086-non. There were no significant differences in growth rate, sporulation, and pathogenicity between the fluorescent-labeled strains and the non-labeled strains. The infection results revealed that the non-virus strain 3086-non-GFP could invade maize leaves through two pathways: directly infecting epidermal cells and spreading to adjacent cells, or invading stomata and spreading through intercellular spaces. The virus-carrying strain 3086-BmPV1-GFP could only grow on the leaf surface and had minimal ability to infect epidermal cells. This study clarifies that the BmPV1 virus can reduce the pathogenicity and inhibit the infection of B. maydis.

  • JIAO Xiaoying, TIAN Jinghua, GAO Yajie, LI Shoumian
    Mycosystema. 2024, 43(6): 230279.
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    One hundred hybrid strains selected by monospore crossbreeding of Stropharia rugosoannulata were used as test materials. By observing the mycelial recovery growth of each strain after high temperature stress, seventeen hybrid strains were screened with stronger heat tolerance than parents in mycelial stage. After eight hours of high temperature stress at 44 ℃, these strains could survive, while both parents were dead. Among them, four hybrid strains (QM2, QM15, QM46, and QM83) had stronger heat tolerance and could survive after eight hours of high temperature stress at 46 ℃. The hybrid strain QM15 with strong heat resistance and hybrid strain QM27 with poor heat resistance were used as test materials to determine the dynamic changes of antioxidant physiological indexes related to heat resistance in the mycelial stage, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and malondialdehyde (MDA). The results showed that under high temperature stress the activities of CAT and SOD of the two strains in the mycelial stage increased first and then decreased. The POD activity of strain QM27 increased first and then decreased, while that of strain QM15 with strong heat resistance recovered the level prior to stress treatment after six hours of high temperature stress at 44 ℃, and the activity increased slightly after eight hour stress. The activities of three enzymes of strain QM15 were always higher than those of QM27. The results indicate that strain QM15 with strong heat resistance has stronger antioxidant capacity and can mitigate membrane damage under high temperature stress. The changes of activities of the three antioxidant enzymes under high temperature stress can be used as physiological indexes for identification of heat resistance in the mycelial stage of Stropharia rugosoannulata strains.

  • LUO Yu, SHEN Xiulin, ZHANG Jingsong, FENG Jie, LIU Liping, GUO Qingbin, LIU Yanfang
    Mycosystema. 2024, 43(6): 230245.
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    Steam explosion was used to assist hot water extraction of Lyophyllum decastes polysaccharides. Considering the yield of the crude polysaccharide, total sugar content and polysaccharide extraction rate, the conditions of steam explosion process was optimized by using response surface method on the basis of one-way test. The optimum conditions obtained were 2.0 MPa of pressure, 90 s of pressure maintenance and 3 mm of material size. Under optimized conditions, the yield of the crude polysaccharide, the total sugar content and the extraction rate were 2.05, 1.70 and 3.49 times higher than that of the untreated control group. The content of β-glucan was 2.28 times higher than that of the control. The infrared spectra showed that the typical absorption peaks of polysaccharides still existed after the steam explosion treatment, but the molecular weight distribution characteristics differed greatly before and after the treatment, and the proportion of glucose in the monosaccharide composition of the polysaccharides obtained by the steam explosion treatment was increased, being consistent with the elevation of the β-glucan content. Cell culture test indicated that the immunomodulatory effect of polysaccharides obtained after steam explosion treatment were significantly improved as compared with that of polysaccharides of untreated control, possible due to the higher percentage of β-glucan in the treating samples.

  • HU Xinyue, DU Yuanyuan, HU Qiuhui, SU Anxiang, PEI Fei, YANG Wenjian
    Mycosystema. 2024, 43(6): 230238.
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    This study aims at prolonging the postharvest shelf life of fresh Agaricus bisporus fruiting bodies and improving their freshness quality and economic value. The changes in physiological indexes such as appearance quality, moisture content, texture characteristics, microstructure, antioxidant enzyme activity of A. bisporus fruiting bodies were investigated after intense pulsed light treatment at different frequencies (1, 2, 3 Hz). The effect of intense pulsed light treatment on the storage quality of A. bisporus was also studied. The results showed that intense pulsed light treatment could delay the appearance of brown spots on the surface of A. bisporus fruiting bodies, keep the L* value above 90 and the BI and ∆E* below 12 in 15th day of storage, reduce the moisture loss rate of post-harvest, maintain the hardness of A. bisporus fruiting bodies above 17 N and elasticity above 0.75, protect the integrity of cell membrane, maintain the denseness of tissues, maintain the malondialdehyde (MDA) content below 44 nmol/g, and maintain the relative conductivity below 15%. At the 15th day of storage, in comparison with the CK, the intense pulsed light treatment resulted in 11%-18% decrease in polyphenol oxidase (PPO) activity, 18%-29% increase in total sugar content, 1%-9% increase in total phenol content, and 21%-67% increase in catalase (CAT), significantly increasing the soluble solids (P<0.05). The results of this study showed that the intense pulsed light technology can effectively improve the storage quality and nutritional value of A. bisporus, prolonging the postharvest shelf life of the edible mushrooms.

  • ZHANG Baosheng, ZHA Lei, ZHAO Yan, ZHANG Mengke, YU Panling, XU Baoting, CHEN Mingjie
    Mycosystema. 2024, 43(6): 230322.
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    Edible fungi can provide a variety of nutrients necessary for human bodies, including lots of proteins, polysaccharides and other active substances. Small molecular peptides produced by protease hydrolysis are important forms of protein activity. Protease-hydrolyzed peptides in edible fungi have received extensive attention due to their natural, safe, and good hypoglycemic effect. In this study, the proteins of 12 species of common edible fungi were selected as the research objects, and were extracted by ammonium sulfate precipitation method. The obtained proteins were then enzymatically hydrolyzed by alkaline protease. The inhibition rate of α-amylase and α-glucosidase were used as the screening indexes. The results showed that the protease hydrolysates of Hericium erinaceus had the best effect on the inhibition of α-amylase and α-glucosidase. The inhibition rate of α-amylase was (65.70±0.33)%, and that of α-glucosidase was (69.25±0.27)%, suggesting that H. erinaceus may have good hypoglycemic activity. The hydrophobic and alkaline amino acids contained in the enzymatic-hydrolyzed peptides of H. erinaceus may be important factors for the hypoglycemic effect.

  • XIAO Zitian, HE Huanqing, PENG Yangyang, LIU Ming, XU Jiang, QIU Yuanhui, SUN Yifei, CUI Baokai
    Mycosystema. 2024, 43(6): 230253.
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    Sanguinoderma is an important group of Ganodermataceae, many physiological functions have been found in the species of the genus, which are better than those of many well-known edible and medicinal fungi. Domestication of five wild Sanguinoderma species was attempted, and the cultivation characteristics and antioxidant activities of the species were studied, including the optimal temperature of mycelial growth, basidioma development process, polysaccharide and triterpene content and biological efficiency. The results showed that the optimum temperature for mycelium growth of the five species ranged from 25 to 30 ℃, and 25-38 days were needed for the fruiting body growth from primordium formation to harvest of basidiomata. S. rugosum growth is fastest and sporulation is early, while Sanguinoderma sp. growth is slowest and no sporulation was observed during cultivation. The morphological characters of cultivated basidiomata were quite different among different strains. The pilea were fan-shaped, reniform to nearly circular, with surface of greyish brown, ash-black, black and beige red, and length ranged from 4.96 cm to 12.56 cm, while width ranged from 3.84 cm to 10.76 cm, and height ranged from 0 cm to 10.1 cm. The first harvest biological efficiencies were 6.59%-18.34% for different strains, and the crude polysaccharide content and the total triterpene content were 1.89%-2.95% and 0.78%-1.68%, respectively. The antioxidant activities of polysaccharides and total triterpenes were compared with those of six Ganoderma species. It was found that Sanguinoderma spp. have better antioxidant activity. Sanguinoderma sp. and S. microporum have radical scavenging rate of over 80% to DPPH, and of 28% to total oxidant, under concentration of 3 mg/mL crude polysaccharide and 1 mg/mL total triterpene, respectively. In conclusion, Sanguinoderma spp. grow fast, contain rich polysaccharide and triterpene in basidiomata, and have good antioxidant activities for potential utilization.