Microbial Community Response and Assembly Process of Yellow Sand Matrix in a Desert Marginal Zone Under Morchella Cultivation

In this study, we investigated the adaptation of yellow-sand-substrate <i>Morchella</i> cultivation in the desert fringe and its effect on soil physicochemical properties and microbial communities. The qPCR and high-throughput sequencing with null modeling analyzed microbial diversity, networks, and assembly of <i>Morchella</i> cultivation under nutrient supplementation, linking physicochemical changes to microbial dynamics. The results showed that the yellow sand substrate can be planted with Morchella in the desert fringe area, as the <i>Morchella</i> cultivation with nutrient bags resulted in a yield of 691 g/m² of <i>Morchella</i> fruit units. Cultivation of <i>Morchella</i> could significantly increase the physicochemical properties of the yellow sand substrate, such as soil organic matter (SOM), total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), and the microbial amount of carbon and nitrogen (MBC/MBN). The fungal community was dominated by <i>Ascomycota</i>, and <i>Basidiomycota</i>, <i>Firmicutes</i>, <i>Bacteroidota</i>, and <i>Actinobacteriota</i>. RDA analysis showed that <i>Ascomycota</i> and <i>Proteobacteria</i> were positively correlated with NH₄⁺-N, MBN, SOM, MBC, acting potassium (AK), TN, and C/N. <i>Morchella</i> cultivation promoted a positive correlation-dominant microbial network pattern in the yellow sand substrate. The nutrient bag treatment reduced bacterial network complexity while enhancing fungal network complexity, connectivity and stability, accompanied by significant increases in <i>Proteobacteria</i>, <i>Bacteroidota</i>, <i>Cladosporium</i>, and <i>Thermomyces</i> relative abundances during cultivation until original substrate degradation. Deterministic processes dominated bacterial and fungal communities, and morel cultivation drove bacterial and fungal community assembly toward heterogeneous selection processes. The results of the study revealed the economic value of <i>Morchella</i> cultivation in the desert fringe and the application potential of improving the physicochemical properties of yellow sandy soil, which is of great importance for practical cultivation and application of morel mushrooms in the desert.