RESUMEN
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.
RESUMEN
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.
RESUMEN
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.
