This study investigated the spatial heterogeneity of rhizosphere microbial communities in alfalfa (Medicago sativa) across desertification gradients in Inner Mongolia, China. Rhizosphere soils were collected from non-, lightly-, and moderately- desertified sites. Using 16S rRNA and ITS high-throughput sequencing alongside soil physicochemical analyses, we found that desertification intensity significantly altered microbial structure and function. Actinobacteriota dominated in moderately-desertified soils, whereas Proteobacteria prevailed in non-desertified areas. Ascomycota was the dominant fungal phylum, with Basidiomycota and Mortierellomycota enriched in non- and lightly- desertified sites, respectively. Soil pH and available phosphorus were the key factors shaping bacterial and fungal communities, respectively. Co-occurrence networks indicated enhanced microbial connectivity and a shift toward cooperative interactions under desertification. Functional prediction revealed conserved bacterial metabolic pathways but increased abundance of fungal stress-response enzymes (e.g., monooxygenases). These findings underscore microbial adaptive strategies to desertification and provide insights for sustainable agriculture in arid regions.

Arid desert regions are among the harshest ecological environments on Earth. Halophytes, with their unique physiological characteristics and adaptability, have become the dominant vegetation in these areas. Currently, research on halophytes in this region is relatively limited, particularly concerning studies related to their root endophytic fungi, which have been rarely reported on. Therefore, investigating the diversity and composition of endophytic fungi in halophytes is crucial for maintaining ecological balance in such an arid environment. This study focuses on eight representative angiosperm halophytes from the West Ordos Desert in China (including Nitraria tangutorum, Salsola passerina, Suaeda glauca, Reaumuria trigyna, Reaumuria kaschgarica, Limonium aureum, Apocynum venetum, and Tripolium vulgare), utilizing Illumina MiSeq high-throughput sequencing technology combined with soil physicochemical factor data to analyze the diversity, composition, and ecological functions of their root-associated fungal communities. Ascomycota dominated the fungal composition in most halophytes, particularly among the recretohalophytes, where it accounted for an average of 88.45%, while Basidiomycota was predominant in Suaeda glauca. A Circos analysis of the top 10 most abundant genera revealed Fusarium, Dipodascus, Curvularia, Penicillium, and other dominant genera. Co-occurrence network analysis showed significant differences in fungal networks across halophyte types, with the most complex network observed in excreting halophytes, characterized by the highest number of nodes and connections, indicating tighter fungal symbiotic relationships. In contrast, fungal networks in pseudohalophytes were relatively simple, reflecting lower community cohesiveness. Redundancy analysis (RDA) and Mantel tests demonstrated that soil factors such as organic matter, available sulfur, and urease significantly influenced fungal diversity, richness, and evenness, suggesting that soil physicochemical properties play a critical role in regulating fungal–plant symbiosis. Functional predictions indicated that endophytic fungi play important roles in metabolic pathways such as nucleotide biosynthesis, carbohydrate degradation, and lipid metabolism, which may enhance plant survival in saline–alkaline and arid environments. Furthermore, the high abundance of plant pathogens and saprotrophs in some fungal communities suggests their potential roles in plant defense and organic matter decomposition. The results of this study provide a reference for advancing the development and utilization of halophyte endophytic fungal resources, with applications in desert ecosystem restoration and halophyte cultivation.

Soil salinization limits the growth of agricultural crops in the world, requiring the use of methods to increase the tolerance of agricultural crops to salinity–alkali stress. Arbuscular mycorrhizal fungi (AMF) enhance plant stress adaptation through symbiosis and offer a promising strategy for remediation. However, in non-model crops such as oat (Avena sativa L.), research has mainly focused on physiological assessments, while the key genes and metabolic pathways involved in AMF-mediated growth and saline–alkali tolerance remain unclear. In this study, we employed integrated multi-omics and physiological analyses to explore the regulatory mechanisms of AMF in oats under normal and saline–alkali stress. The results indicated that AMF symbiosis significantly promoted oat growth and physiological performance under both normal and saline–alkali stress conditions. Compared to the non-inoculated group under normal conditions, AMF increased plant height and biomass by 8.5% and 15.3%, respectively. Under saline–alkali stress, AMF enhanced SPAD value and relative water content by 16.7% and 7.3%, reduced MDA content by 35.8%, increased soluble protein by 21.8%, and decreased proline by 13.3%. In addition, antioxidant enzyme activities (SOD, POD, and CAT) were elevated by 18.4%, 18.2%, and 14.8%, respectively. Transcriptomic analysis revealed that AMF colonization under saline–alkali stress induced about twice as many differentially expressed genes (DEGs) as under non-saline–alkali stressed conditions. These DEGs were primarily associated with Environmental Information Processing, Genetic Information Processing, and Metabolic Processes. According to metabolomic analysis, a total of 573 metabolites were identified across treatments, mainly comprising lipids (29.3%), organic compounds (36.8%), and secondary metabolites (21.5%). Integrated multi-omics analysis indicated that AMF optimized energy utilization and antioxidant defense by enhancing phenylpropanoid biosynthesis and amino acid metabolism pathways. This study provides new insights into how AMF may enhance oat growth and tolerance to saline–alkali stress.

Carminic acid (CA) is a high-value natural anthraquinone pigment used in foods, cosmetics, textiles, and pharmaceuticals, but its current industrial supply depends largely on extraction from the scale insect Dactylopius coccus, creating constraints in yield, cost, sustainability, and allergen control. This review summarizes recent progress from pathway elucidation to microbial production. We first outline the structure, occurrence, applications, and biosynthetic logic of CA, emphasizing the convergence of type III polyketide assembly with insect-associated tailoring reactions, especially C-glycosylation. We then compare heterologous production strategies in Escherichia coli, Saccharomyces cerevisiae, Yarrowia lipolytica, and Aspergillus nidulans, focusing on chassis-specific advantages, bottlenecks, precursor supply, malonyl-CoA engineering, dynamic regulation, enzyme compatibility, compartmentalization, and downstream processing. Structurally related anthraquinone pigments are further discussed to extract broader design principles for pathway diversification and synthetic biology. Finally, we highlight key challenges for industrial translation, including low titers, incomplete enzyme characterization, host–pathway incompatibility, and scalable purification, and propose integrated strategies combining precursor-pathway rewiring, AI-assisted enzyme engineering, biosensor-based regulation, and process optimization to develop competitive microbial cell factories.

Aims Leucocalocybe mongolica is an endemic and culturally significant edible mushroom in the temperate grasslands of Inner Mongolia, China, which typically forms conspicuous fairy rings with distinct vegetation zonation. However, its ecological effects on soil fungal communities, nutrient cycling, and plant growth remain poorly understood. Methods In this study, six typical fairy rings were investigated, and high-throughput sequencing was employed to characterize soil fungal communities across the inner area (IA), fruiting area (FA), and outer area (OA). Soil physicochemical properties, enzyme activities, and plant growth promotion assays were integrated to assess their ecological functions. Results Fungal α-diversity in the fruiting area (FA) was significantly lower than in IA and OA, with Basidiomycota dominated by Leucocalocybe (> 70%). FA soils were more acidic and enriched in ammonium, nitrate, cellulase, and laccase, while IA and OA had higher chitinase, sucrase, and moisture. Network analysis showed FA had the simplest structure dominated by Leucocalocybe, whereas OA exhibited the greatest complexity and stability. Inoculation experiments demonstrated that L. mongolica and its associated fungus Trichoderma harzianum significantly increased plant height, aboveground biomass, photosynthetic rate, and chlorophyll content of Leymus chinensis. Conclusions These findings indicate that the center of L. mongolica fairy rings functions as a core zone for nitrogen cycling and plant growth promotion, achieving a “high-efficiency center–diverse periphery” spatial organization through reshaping the soil microenvironment and fungal networks. The study provides new perspectives for improving grassland soil fertility and restoring degraded land.