Species identity and combinations differ in their overall benefits to Astragalus adsurgens plants inoculated with single or multiple endophytic fungi under drought conditions.

Although desert plants often establish multiple simultaneous symbiotic associations with various endophytic fungi in their roots, most studies focus on single fungus inoculation. Therefore, combined inoculation of multiple fungi should be applied to simulate natural habitats with the presence of a local microbiome. Here, a pot experiment was conducted to test the synergistic effects between three extremely arid habitat-adapted root endophytes (Alternaria chlamydospora, Sarocladium kiliense, and Monosporascus sp.). For that, we compared the effects of single fungus vs. combined fungi inoculation, on plant morphology and rhizospheric soil microhabitat of desert plant Astragalus adsurgens grown under drought and non-sterile soil conditions. The results indicated that fungal inoculation mainly influenced root biomass of A. adsurgens, but did not affect the shoot biomass. Both single fungus and combined inoculation decreased plant height (7-17%), but increased stem branching numbers (13-34%). However, fungal inoculation influenced the root length and surface area depending on their species and combinations, with the greatest benefits occurring on S. kiliense inoculation alone and its co-inoculation with Monosporascus sp. (109% and 61%; 54% and 42%). Although A. chlamydospora and co-inoculations with S. kiliense and Monosporascus sp. also appeared to promote root growth, these inoculations resulted in obvious soil acidification. Despite no observed root growth promotion, Monosporascus sp. associated with its combined inoculations maximally facilitated soil organic carbon accumulation. However, noticeably, combined inoculation of the three species had no significant effects on root length, surface area, and biomass, but promoted rhizospheric fungal diversity and abundance most, with Sordariomycetes being the dominant fungal group. This indicates the response of plant growth to fungal inoculation may be different from that of the rhizospheric fungal community. Structural equation modeling also demonstrated that fungal inoculation significantly influenced the interactions among the growth of A. adsurgens, soil factors, and rhizospheric fungal groups. Our findings suggest that, based on species-specific and combinatorial effects, endophytic fungi enhanced the plant root growth, altered soil nutrients, and facilitated rhizospheric fungal community, possibly contributing to desert plant performance and ecological adaptability. These results will provide the basis for evaluating the potential application of fungal inoculants for developing sustainable management for desert ecosystems.

Effects of Dark Septate Endophytes on the Performance of Hedysarum scoparium Under Water Deficit Stress.

Hedysarum scoparium, a species characterized by rapid growth and high drought resistance, has been used widely for vegetative restoration of arid regions in Northwest China that are prone to desertification. Desert soil is typically deficient in available water and the alleviation of drought stress to host plants by endophytes could be an efficient strategy to increase the success of desert restoration. With the objective to seek more beneficial symbionts that can be used in the revegetation strategies, we addressed the question whether H. scoparium can benefit from inoculation by dark septate endophytes (DSEs) isolated from other desert plants. We investigated the influences of four non-host DSE strains (Phialophora sp., Knufia sp., Leptosphaeria sp., and Embellisia chlamydospora) isolated from other desert plants on the performance of H. scoparium under different soil water conditions. Differences in plant performance, such as plant growth, antioxidant enzyme activities, carbon, nitrogen, and phosphorous concentration under all the treatments, were examined. Four DSE strains could colonize the roots of H. scoparium successfully, and they established a positive symbiosis with the host plants depending on DSE species and water availability. The greatest benefits of DSE inoculation occurred in water stress treatment. Specifically, Phialophora sp. and Leptosphaeria sp. improved the root biomass, total biomass, nutrient concentration, and antioxidant enzyme activities of host plants under water deficit conditions. These data contribute to the understanding of the ecological function of DSE fungi in drylands.

[Characteristics of Soil Microbial Community Structure in the Rhizospheric Soil of Ammopiptanthus mongolicus by Phospholipid Fatty Acid (PLFA)].

To measure and manage plant growth in arid and semi-arid sandlands, improved understanding of the spatial patterns of desert soil resources and the role of soil microbes is required. The rhizosphere soils of Ammopiptanthus mongolicus in Wuhai, Dengkou, and Alxa, Inner Mongolia, China were collected in July 2015. Soil microbial community structure in the rhizosphere of A.mongolicus was analyzed by phospholipid fatty acid (PLFA) combined with Sherlock microbial identification system. The results showed that the soil microbial PLFA had a higher diversity and 41, 31 and 48 kinds of phospholipid fatty acids were respectively detected in the rhizosphere of A.mongolicus in three different sites. 16:0, 16:0 10-methy1, 18:1ω9c and 16:1ω7c were the dominant PLFA, and the PLFA of 16:0 (indicating bacteria) had a maximum value. However, the differences in contents of 16:0 10-methy, 18:1ω9c and 16:1ω7c were found in the three sites. Soil microbial community in the rhizosphere of A.mongolicus had obvious spatial heterogeneity:the gram positive bacteria were the dominant microorganisms in all soil samples. AM fungi, gram positive bacteria, gram negative bacteria and fungi were all characterized by Alxa > Wuhai > Dengkou, and total PLFA content of actinomycetes followed the order of Wuhai > Alxa > Dengkou. AM fungi occupied the biggest proportion in the soil fungal biomass, especially in Dengkou and Alxa, which accounted for 91% and 92%, respectively. We concluded that AM fungi were an important component of soil microorganisms in the desert ecosystem. AM fungi, gram positive bacteria, gram negative bacteria, fungi and actinomycetes were positively correlated with soil acid and alkaline phosphatase, total glomalin, ammonia nitrogen and pH. G+/G- were extremely negatively correlated with soil urease, organic carbon and easily extractable glomalin. However, the fungi/bacteria were extremely positively correlated to soil urease, organic carbon and easily extractable glomalin. The results of this study support the conclusion that soil acid and alkaline phosphatase, total glomalin, ammonia nitrogen and pH were the main factors influencing soil microbial biomass and activities in desert zone.Moreover, the changing pattern of soil microbial community might be useful to monitor desertification and soil degradation.

Effects of Enhanced UV-B Radiation on Biochemical Traits in Postharvest Flowers of Medicinal Chrysanthemum.

This article reported UV-B radiation effects on biochemical traits in postharvest flowers of chrysanthemum. The experiment included six levels of UV-B radiation (UV0, 0 µW cm(-2); UV50, 50 µW cm(-2); UV200, 200 µW cm(-2); UV400, 400 µW cm(-2); UV600, 600 µW cm(-2) and UV800, 800 µW cm(-2). Enhanced UV-B radiation significantly increased hydrogen peroxide content (except for UV50), but did not evidently affect malondialdehyde content in flowers. Chlorophyll b and total chlorophyll content were significantly increased by UV600 and UV800. UV400 and UV600 significantly increased anthocyanins, carotenoids and UV-B absorbing compounds content, and the activities of phenylalanine ammonia lyase (PAL) and cinnamic acid-4-hydroxylase (C4H) over the control. 4-coumarate CoA ligase (4CL) activity was significantly decreased by enhanced UV-B radiation (except for UV50). The relationships between UV-B radiation intensities and the activities of secondary metabolism enzymes were best described by a second-order polynomial. The R(2) values for UV-B radiation intensities and the activities of PAL, C4H and 4CL were 0.8361, 0.5437 and 0.8025, respectively. The results indicated that enhanced UV-B radiation could promote secondary metabolism processes in postharvest flowers, which might be beneficial for the accumulation of medically active ingredients in medicinal plants. The optimal UV-B radiation intensities in the study were between UV400-UV600.

Copper-organic cationic ring with an inserted arsenic-vanadium polyanionic cluster for efficient catalytic Cr(VI) reduction using formic acid.

Polyanionic cluster [ß-As8V14O42(H2O)](4-) is well embedded in a large porous eight-membered cationic ring of the copper ligand, giving a stable host-guest supramolecular system. The assembly exhibits an efficient heterogeneous catalytic performance for the reduction of Cr(VI) using formic acid at ambient temperature.

The effects of UV-B radiation intensity on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum.

The article studied UV-B effects on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum during the bud stage. The experiment included four UV-B radiation levels (CK, ambient UV-B; T1, T2 and T3 indicated a 5%, 10% and 15% increase in ambient UV-BBE, respectively) to determine the optimal UV-B radiation intensity in regulating active ingredients level in flowers of two chrysanthemum varieties. Flower dry weight of two cultivars was not affected by UV-B radiation under experimental conditions reported here. UV-B treatments significantly increased the rate of superoxide radical production, hydrogen peroxide (H2O2) (except for T1) and malondialdehyde concentration in flowers of Huai chrysanthemum and H2O2 concentration in flowers of Qi chrysanthemum. T2 and T3 treatments induced a significant increase in phenylalanine ammonia lyase enzyme (PAL) activity, anthocyanins, proline, ascorbic acid, chlorogenic acid and flavone content in flowers of two chrysanthemum varieties, and there were no significant differences in PAL activity, ascorbic acid, flavone and chlorogenic acid content between the two treatments. These results indicated that appropriate UV-B radiation intensity did not result in the decrease in flower yield, and could regulate PAL activity and increase active ingredients content in flowers of two chrysanthemum varieties.

[Effects of three fungicides on arbuscular mycorrhizal fungal infection and growth of Scutellaria baicalensis Georgi].

To make full use of arbuscular mycorrhizal (AM) fungal resources to increase the quantity and quality of Chinese medicinal materials and reduce the use of fungicide and environmental pollution, this research was carried out under pot culture condition to study the effects of benomyl, difenconazole and flusilazol on AM fungal (Glomus mosseae) colonization and the growth of Scutellaria baicalensis. The results showed that Glomus mosseae generally promoted the growth of host plant under the same fungicide application, and the effect of Glomus mosseae was different with different fungicides. The growth of non-mycorrhizal Scutellaria baicalensis was inhibited by applying with different fungicides. On mycorrhizal plants, contents of K in shoot and Fe in root significantly decreased under benomyl treatment; the contents of total N, K in shoot, Baicalin and Ca in root significantly decreased under difenconazole treatment; mycorrhizal colonization, the contents of total P, Baicalin, K and Cu in shoot, total N, Ca, Zn and Fe in root significantly decreased under flusilazol. The inhibitory effects of flusilazol on the Glomus mosseae colonization and growth of Scustellaria baicalensis were greater than those of difenconazole and benomyl. It is reasonable to choose less toxic fungicides in Scutellaria baicalensis cultivation to reduce the harmful effects on arbuscular mycorrhizal fungi.

[Effects of inoculating AM fungi on physiological characters and nutritional components of Astragalus membranaceus under different N application levels].

A pot culture with unsterilized soil as growth substrate showed that AM fungi had significant effects on the growth of Astragalus membranaceus (Fabaceae) under different N application levels. Inoculation with AM fungi promoted the AM infection of A. membranaceus roots, but high N application level suppressed the infection. Inoculating AM fungi increased the growth rate, soluble protein and sugar contents, and SOD, POD and CAT activities of A. membranaceus. Under 50 and 100 mg x kg(-1) of N application, new bands of POD isozyme occurred in inoculated plants, and the contents of flavonoid, N, and P in A. membranaceus also had definite increase. The best inoculation effect was observed under the N application level of 50-100 mg N x kg(-1) soil.

[Spatial distribution of arbuscular mycorrhizal fungi in Astragalus Adsurgens root-zone soil in Mu Us sand land].

This paper studied the spatial distribution of arbuscular mycorrhizal (AM) fungi in Astragalus adsurgens root-zone soil in Mu Us sand land under five different ecological conditions. The results showed that the colonization and spore density of AM fungi differed significantly with sampling sites and soil depths. The highest colonization rate and spore density of AM fungi were found in 10-30 cm soil layer, and the highest spore density was at Dingbian site. Ningtiaoliang and Tawan sites had the highest vesicular colonization, and Tawan site had the highest total and hyphal colonization. The contents of total glomalin (TG) and easily extractable glomain (EEG) were the highest at Tawan site, being 1.18 mg x g(-1) and 0.65 mg x g(-1), respectively. Soil pH had significant positive effects on the vesicular and arbuscular colonization, spore density, TG, and EEG, and the TG and EEG had significant positive correlations with spore density, soil organic carbon (SOC), and soil available N and P. The proportion of glomalin to SOC was higher in desert soils than in agricultural soils, which implied that glomalin could be one of the main origins of SOC in desert ecosystem. Therefore, glomalin could be a useful index for the evaluation of soil AM fungal activity and soil ecology.