With the intensification of desertification in northwest China, drought has become a serious environmental problem restricting plant growth and ecological restoration. Recently, dark septate endophytes (DSEs) have attracted more attention because of their ability to improve plants’ resistance to drought. Here, we investigated DSE colonization and species diversity in roots of Lycium ruthenicum collected from Anxi and Minqin, in northwest China, during July, September, and December 2019. This study aimed to evaluate the influence of seasonality and sampling sites on DSEs. In different seasons, DSE colonization varied with the phenology of L. ruthenicum. At different sites, DSE colonization significantly differed. Four isolates were reported in desert ecosystems for the first time. The results showed microsclerotial colonization was directly affected by changing seasons, while hyphal colonization and species diversity were directly affected by sampling sites. The soil organic carbon, pH, alkaline phosphatase, and alkali-hydrolyzable nitrogen were the main predictors of DSE colonization and species diversity. We conclude that DSE colonization and diversity showed significant spatial–temporal heterogeneity and were closely related to soil factors. This research provides a basis for the further understanding of the ecological functions of DSEs and their application potential for vegetative restoration and agricultural cultivation in drylands.

Foliar fertilization, an effective method to regulate plant nutrition has attracted much attention. In this study, the effects of different foliar fertilizers (F1: NPK formulation, F2: NPK+Fe-Mn-Zn formulation, F3: Fe-Mn-Zn formulation, and CK: deionized water) on plant growth, chemical composition, rhizosphere soil properties, and fungal community of Dioscorea opposita Thunb. were assessed by a field plot experiment. Rhizosphere fungal community was examined via Illumina MiSeq sequencing of ITS2 rRNA genes. Spraying foliar fertilizer directly affected the growth and chemical content of the plant, which depends on different foliar fertilizers. Ascomycota and Moraxella were the dominant fungal phyla. Nutrient elements were the main factors affecting fungal composition, and soil microelements positively influenced soil fungi, while soil macroelements negatively influenced soil fungi. Macroelement foliar fertilizer affected soil fungi by directly affecting the growth parameters and macroelement content of the plant or by directly affecting soil properties, while microelement foliar fertilizer affected soil fungi by directly affecting the microelement content of the plant or by directly affecting the soil pH and organic matter content. These factors were involved in the formation of a “leaf-root-soil microbe” conduction system similar to the “brain-gut-microbe” axis. Our results provide a basis for the application of foliar fertilizer in the cultivation of medicinal plants.

Arbuscular mycorrhizal fungi (AMF) act as intermediaries between the root systems of host plants and the surrounding soil, offering various benefits to medicinal plants, such as promoting growth and enhancing quality. However, the host range of AMF in medicinal plants and the characteristics of plant–AMF networks in farmland ecosystems remain insufficiently studied. In the present study, we measured AMF colonization, species diversity, and soil properties of 31 medicinal plants at the Anguo Medicine Planting Base in Northwest China. The medicinal plant–AMF network was subsequently analyzed, and the growth-promoting effects of AMF on Astragalus mongholicus were examined. Spore density, species richness, and total colonization exhibited significant variation across different medicinal plant species. Glomus melanosporum, G. claroideum, and Septoglomus constrictum were the dominant species among 61 AMF species. Soil organic matter, phosphatase, available nitrogen, and glomalin-related soil proteins (GRSPs) were the main factors affecting the AMF composition. Structural equation models and a variation partitioning analysis suggested a highly plant species-specific pattern of AMF distribution patterns, where the host identities explained 61.4% of changes in spore density and 48.2% of AMF colonization. The soil nutrient availability and phosphatase activity also influenced AMF colonization. Our results confirmed glomalin as an important contributor to the soil carbon in farmland for cultivating medicinal plants. The medicinal plant–AMF symbiotic network exhibited highly nested patterns, a low specialized structure, high connectance, and low modularity, which suggested saturated AMF colonization and symbiosis stability provided by redundant plant–AMF associations. Despite the wide host range among medicinal plants, AMF inoculation revealed species-specific effects on the growth performance and active ingredient content levels in A. mongholicus, G. claroideum and Sep. constrictum induced the highest biomass and active ingredient content accumulation in A. mongholicus. These findings advance our understanding of AMF community dynamics in the rhizosphere of medicinal plants and offer valuable insights for optimizing medicinal plant cultivation practices.

Dark septate endophyte (DSE), a group of widely distributed root-symbiotic fungi has been reported to enhance plant growth, nutrient acquisition, and secondary metabolism, yet its mechanisms in Dioscorea opposita (yam) remain poorly understood. Here, we utilized yam-DSE sterile co-culture system, combined with physiological index detection and non-targeted metabolomic analysis of root secretions, to investigate two DSE strains, Poaceascoma sp. and Podospora sp., isolated from the yam roots. The results showed that DSE inoculation promoted yam growth and increased the content of nutritional active components such as flavonoid compounds, polysaccharides, and amino acids in the tubers. DSE inoculation changed the metabolite profiles of the secretions of yam roots. Inoculation of Podospora sp. was associated with changes in tricarboxylic acid (TCA) metabolism, while inoculation of Poaceascoma sp. was associated with changes in galactose metabolism, pentose phosphate metabolism, and ketone body pathways. Our study deepens the understanding of the symbiotic mechanism between plants and DSE, and provides a theoretical framework for further revealing the effects of DSE on active components and root secretions of medicinal plants, and also provides a reference basis for further evaluating DSE strains to improve the growth and quality of medicinal plants.