Xylaria species are distributed widely from temperate to tropical and subtropical regions. Many novel secondary metabolites such as terpenes, alkaloids, sterols and polyketides, which possess multiple bioactivities including antioxidant, antimicrobial, antitumor activities and etc., have been isolated and identified from the fungi of the genus Xylaria in recent years. In this review, we summarize the research developments on the important secondary metabolites and their bioactivities from the genus Xylaria over the past ten years.
Recently, association analysis based on linkage disequilibrium has been gradually used in dissecting the genetic architecture of complex quantitative traits in fungi. In this paper the methodology of association analysis is introduced, and its research advances and application prospects in fungal genetics are outlined and discussed.
Studies of the genus Dicephalospora from China are briefly reviewed. The generic concept of Dicephalospora is emended. Three new combinations are established based on morphology and ITS sequence data for three taxa previously assigned to the genus Lanzia. A new species is described. Among the ten currently known species in the world, nine of them are distributed in China. A key to the known species of the genus is provided.
The genus Allophylaria is recorded for the first time in China with a new species and a new Chinese record. Allophylaria minispora is described as new to science and characterized by whitish and stipitate apothecia, J+ asci 32-45×3.8-5µm, fusoid and eguttulate ascospores 4.3-5.8×1.5-2.5µm, and growing on herbaceous stems. Allophylaria atherospermatis is new to China. Descriptions and illustrations of the two fungi are given.
Hirsutella tortricicola sp. nov. is isolated from a sample GZUIFR-kks-2 parasitized on Tortricidae. This species is characterized by its obvious polyphialidic conidiogenous cell with neck twisted in 1-2 helical turns. Conidia are orange-segmented and enveloped in a mucous sheath, 2.7-3.6×1.4-1.8μm. Morphological characters and phylogenetic analyses support H. tortricicola as a new species of Hirsutella.
The aim of this research is to illustrate the relationship between distribution of Dendrobium chrysotoxum (Orchidaceae) and mycorrhizal fungal community composition. Clone library technique was used to analyze mycorrhizal fungal community in 8 root samples of D. chrysotoxum collected from Xishuangbanna and Lincang of Yunnan Province. In total, 14 operational taxonomic units (OTUs) were obtained from the two sampling regions. These OTUs mainly belonged to Tulasnellaceae and Atractiellales. The mycorrhizal specificity and preference of D. chrysotoxum were further analyzed. The result suggested that D. chrysotoxum has low mycorrhizal specificity. Each plant can bring about symbiosis with more than one species of mycorrhizal fungi at the same time. Evident differences of mycorrhizal fungal community composition were detected in D. chrysotoxum samples collected from the two sampling regions. Only one OTU was shared in the two regions and the others were all quite different. Mycorrhizal fungi may correlate with ecological adaptation of D. chrysotoxum.
Twenty-four species of arbuscular mycorrhizal fungi (AMF) were isolated and identified from 15 rhizosphere soil samples of three common wild plant species, Myrsine semiserrata, Phytolacca americana and Thalictrum delavayi, from the drawdown zone of Three Gorges Reservoir, including 15 species of Glomus, three species of Acaulospora, two species of Claroideoglomus, one species of Diversispora, one species of Entrophospora, one species of Gigaspora and one species of Paraglomus. D. epigaea and P. pernambucanum were new records in China. Glomus was dominant genera, while G. geosporum, G. monosporum, G. versiforme, G. coronatum and G. flavisporum were dominant species. AMF average spore density was 839±170 per 100g soil and the species richness in each plant sample varied from 14 to 22. Species diversity index and evenness index ranged from 1.97 to 2.21 and 0.409 to 0.479, respectively. It was suggested that the drawdown zone of Three Gorges Reservoir Region was a treasury of AMF diversity.
A preliminary study on diversity of ectomycorrhizal fungi associated with Quercus aliena in Xinjiashan forest region of Qinling Mountains was investigated and observed using the combination of field investigation, morphological and molecular identification methods. The results showed that there were 52 different taxa of ectomycorrhizal fungi under 14 genera of 10 families, of these 48 taxa belonged to basidiomycetes, and 3 to ascomycetes. Tomentella was dominant; Inocybe 1, Russula persicina, Tomentella 1, Tomentella 2, Tuber and Xerocomus were common. The differences of Simpson index, Shannon index and Pielou evenness index of ectomycorrhizal fungi associated with Quercus aliena were not significant between site one and site two, except for differences of species richness. Jaccard index and Sorenson index were 0.1154 and 0.2069, respectively.
One laccase coding gene, ptaE, is located in the pestheic acid biosynthetic gene cluster and predicted to be involved in the phenol oxidative coupling reaction of pestheic acid biosynthesis through gene disruption. To confirm its function both in vivo and in vitro, the ptaE complemented strain was constructed and PtaE was isolated as the His-tagged protein from it. Enzymatic reaction analysis showed that PtaE could catalyze the conversion of chloroisosulochrin to pestheic acid and isosulochrin to RES-1214-1. Moreover, the substrate specificity of PtaE was determined. The results demonstrated that PtaE could catalyze catechol, hydroquinone and bisphenol A, indicating that it has a wide range of substrate catalytic activity.
The hypoglycemic effects and mechanism of the compounds from Sanghuangporus baumii mycelia are investigated. Three of the compounds, baicalein, naringenine-7-rhamnosidoglucoside and benzaldehyde,3,4-dihydroxy-, effectively promoted the glucose consumption of insulin-resistant HepG2 cells. Benzaldehyde,3,4-dihydroxy had distinct inhibition effects on SOCS-3, and baicalein on TNF-α. Baicalein and benzaldehyde,3,4-dihydroxy- contributed to the reduction of blood sugar.
The amylase family genes in the genome of Flammulina velutipes were identified and analyzed. The correlation between the expression levels of amylase family genes and the activity of amylase were analyzed in the F. velutipes dikaryotic strain H1123. It was turned out that there were six α-amylases and one γ-amylase in F. velutipes. All the amylase genes showed the highest expression levels on the 10th day after mycelium incubation, being consistently correlated with the activity of extracellular amylase. The results indicated that the degradation and utilization of starch in medium was the result of mutual coordination among amylase family members. Amylase genes α-Amy-1, α-Amy-4, α-Amy-5 were the main genes functioning in starch degradation and metabolism due to their highest up-regulated expression levels. It was worthy of note that the up-regulated expression level of the intracellular enzyme gene α-Amy-1 multiplied about 90 times in 10 days after inoculation, suggesting that the intracellular amylases were also involved in the absorption and transportation of monosaccharides during the process that extracellular amylases decomposed starch into monosaccharide in F. velutipes.
The diseased pelargonium hortorum samples infected with Pythium blight were collected from Tongliao City, Inner Mongolia, and totally 16 Pythium isolates were obtained. Based on morphological characteristics and rDNA-ITS sequence analysis, the pathogens were identified as Pythium ultimum var. ultimum, P. aphanidermatum, Pythium sp.1 and Pythium sp.2. P. ultimum var. ultimum was the most dominant (75% of the total isolates), followed by P. aphanidermatum (12.5%) and two other Pythium species (both 6.25%). Pathogenicity tests have proved that the four Pythium species are pathogenic, producing blight symptoms. P. ultimum var. ultimum and P. aphanidermatum are more pathogenic, with infection rate of 71.4% and 85.7% respectively.
This study aims at investigation of interacting effects of Funneliformis mosseae on the arbuscular mycorrhizal fungus (AM) community structure of soybean root systems at the branching stage under continuous cropping conditions. F. mosseae was inoculated into the potting soil of three soybean cultivars, Hei Nong 44 (HN 44), Hei Nong 48 (HN 44) and Ken Feng 16 (KF 16). Nested-PCR-DGGE method was used to analyze soybean roots from 0-year, 1-year and 2-year cropping soil samples after inoculation. The results showed that after F. mosseae inoculation, the diversity index and the abundance of AM of different soybean roots were highest in the 2-year cropping soil samples and next came the 1-year and 0-year cropping soil samples. Glomus and F. mosseae were dominant in root systems in all three cultivars. The effects of F. mosseae inoculation on AM community structures in the root systems were significant in one year, and these effects were maintainable in two years.
Different concentrations of Dictyophora rubrovolvata polysaccharides were used to treat ascitic tumor S180 cells for 24h to investigate the effect of the polysaccharides on tumor cell apoptosis. Western blotting analysis was performed to detect the expressions of Bcl-xl, Bax, caspase-9 and caspase-3 proteins, and the flow cytometry assay was conducted to detect cell apoptosis. Western blot test results showed that the Bcl-xl expression decreased with the increase of concentration of Dictyophora rubrovolvata polysaccharides. On the contrary, Bax expression quantity, the ratio of Bax/Bcl-xl, Caspase-9 and Caspase-3 expression quantity of each treated group increased. Flow cytometry test results showed that four dose, 0, 25, 50 and 100mg/L of polysaccharides resulted in the apoptosis rate of 5.12%±0.11%, 9.61%±0.61%, 6.39%±0.19% and 17.05%±0.13%, respectively. Compared with control group, apoptosis rate was increased in a dose-dependent manner. The differences were statistically significant (P<0.05). Thus, Dictyophora rubrovolvata polysaccharides could induce S180 cell apoptosis.