Arbuscular mycorrhizal and dark septate endophytic fungal colonization in a grassland in Kunming, southwest China, was investigated monthly over one year. All plant roots surveyed were co-colonized by arbuscular mycorrhizal and dark septate endophytic fungi in this grassland. Both arbuscular mycorrhizal and dark septate endophytic fungal colonization fluctuated significantly throughout the year, and their seasonal patterns were different in each plant species. The relationships between environmental (climatic and edaphic) factors and fungal colonization were also studied. Correlation analysis demonstrated that arbuscular mycorrhizal colonization was significantly correlative with environmental factors (rainfall, sunlight hours, soil P, etc.), but dark septate endophytic fungal colonization was only correlative with relative humidity and sunlight hours.

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Monitoring the effects of no-tillage (NT) in comparison with conventional tillage (CT) on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to compare the species composition and ecological function of soil arbuscular mycorrhizal (AM) fungi during the growth and rotation of crops under NT and CT. From late June 2009 to early June 2010, 32 topsoil (0-15 cm) samples from four individual plots per treatment (CT and NT) were collected at both the jointing and maturation stages of maize (Zea mays L.) and wheat (Triticum aestivum L.) from a long-term experimental field that was established in an Aquic Inceptisol in North China in June 2006. The AM fungal spores were isolated and identified and then used to calculate species diversity indices, including the Shannon- Wiener index (H'), Evenness (E), and Simpson's index (D). The root mycorrhizal colonization and soil alkaline phosphatase activity were also determined. A total of 34 species of AM fungi within nine genera were recorded. Compared with NT, CT negatively affected the soil AM fungal community at the maize sowing stage, leading to decreases in the average diversity indices (from 2.12, 0.79, and 0.82 to 1.79, 0.72, and 0.74 for H', E, and D, respectively), root mycorrhizal colonization (from 28% to 20%), soil alkaline phosphatase activity (from 0.24 to 0.19 mg/g/24 h) and available phosphorus concentration (from 17.4 to 10.5 mg/kg) at the maize jointing stage. However, reductions in diversity indices of H', E, and D were restored to 2.20, 0.81, and 0.84, respectively, at the maize maturation stage. CT should affect the community again at the wheat sowing stage; however, a similar restoration in the species diversity of AM fungi was completed before the wheat jointing stage, and the highest Jaccard index (0.800) for similarity in the species composition of soil AM fungi between CT and NT was recorded at the wheat maturation stage. Our results also demonstrated that NT resulted in the positive protection of the community structure of AM fungi and played an important role in maintaining their functionality especially for maize seedlings.

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Two extremely halophilic archaea, strains D90T and D93, were isolated from underground salt deposits of Yunnan salt mine, China. Both strains were pleomorphic or short rods, non-motile, Gram-negative and required 1.7 M NaCl for growth, with optimum at 3.4 M. Mg2+ was not required for growth. Multiple copies of the 16S rRNA gene were obtained for both strains. Sequence similarity analysis of 16S rRNA genes revealed that strains D90T and D93 were closely related to Halobaculum magnesiiphilum MGY-184T and Halobaculum gomorrense DSM 9297T with the sequence similarity between 96.2-98.1 %. The sequence similarity of the rpoB' gene between strain D90T and Halobaculum gomorrenseJCM 9908T was 94.1 %. The DNA G+C contents of strains D90T and D93 were 65.9 and 67.6 mol%, respectively. The major polar lipids of both strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and glycolipid. The DNA-DNA relatedness value between strains D90T and D93 was 90.1±0.5 %, while that between strain D90T and Halobaculum gomorrenseJCM 9908T was 30.0±0.7 %. The comparison of physiological and biochemical characteristics, including the requirements of NaCl, Mg2+, pH, etc., differentiated strains D90T and D93 from Halobaculum magnesiiphilum MGY-184T and Halobaculum gomorrenseJCM 9908T. Therefore, strains D90T and D93 represent a novel species of the genus Halobaculum, for which the name Halobaculum roseum sp. nov. is proposed. The type strain is D90T (=CGMCC 1.15501T=JCM 31273T).

No abstract

Coastal Plain soils are often characterized by low soil organic carbon (SOC) as a result of natural and anthropogenic factors. A rotation of cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) under conventional tillage is typical in this region, but an opportunity to increase SOC and improve soil health by incorporating winter grazing of cover crops exists for producers with row crop and livestock operations. A study to assess winter grazing impacts on soil health was established in the U.S. Coastal Plain. Three cattle removal dates and an ungrazed control were evaluated for impacts on selected soil health indicators: SOC, permanganate oxidizable carbon (POXC), water stable aggregates (WSA), penetration resistance (PR), microbial biomass C (MBC), and arbuscular mycorrhizal fungi (AMF) colonization rates.After two years, MBC was highest in the control treatments, likely due to greater cover crop biomass on the soil surface at termination. No differences were observed between treatments for SOC, POXC, WSA, PR, or AMF. Increased cotton lint yield was observed in control and mid-February treatments in 2019, likely due to greater cover crop residues on the soil surface following grazing, which may have conserved soil moisture during the growing season. Peanut yields were unaffected by treatments in 2020. Lack of differences in soil health indicators suggests that integrating wintergrazing livestock does not negatively nor positively impact selected dynamic soil properties in the short-term, but more time under grazing treatments is needed to thoroughly evaluate how winter-grazing livestock impacts soil health and crop yield.

Arbuscular mycorrhizal (AM) fungi are vital soil microbes that connect many individual plants into a large functional organism via a vast mycelial network under the ground. In this study, the changes of soil AM fungal community in response to road-building disturbance caused by tourism development in Huangshan (Yellow Mountain) Scenic Area are assessed. Road building have brought negative effects on AM fungal community, inducing lower diversity parameters, including species number, spore density and diversity indices. However, the dominant genus and species of AM fungi which play key roles in the AM fungal community composition are quite similar before and after road building. Moreover, there are no significant differences in species richness of AM fungi associated with plants, suggesting the tolerance of AM fungal community to the disturbance of road building.