Elucidation of Mechanism of Soil Degradation Caused by Continuous Cropping of Dictyophora rubrovalvata Using Metagenomic and Metabolomic Technologies

Dictyophora rubrovalvata is a soil-cultivated edible fungus with high economic and medicinal value, yet its continuous cultivation is frequently hindered by cropping obstacles. To elucidate the underlying ecological mechanisms, this study employed metagenomic sequencing and untargeted metabolomics (UHPLC–OE–MS) to analyze the changes in soil microbial communities and metabolite profiles under different continuous cropping treatments (CC0: Uncultivated; CC1: one cropping cycle; CC2: two cropping cycle; CC3: three cropping cycle.). Continuous cropping significantly decreased soil pH from 7.94 to 7.52 and available phosphorus (AP) from 213.69 mg/kg to 15.7 mg/kg, while increasing available nitrogen (AN) from 284.5 mg/kg to 886.33 mg/kg. The Shannon index of fungal communities rose from 3.15 to 4.55. Notably, the relative abundance of the beneficial bacterium Sphingomonas declined from 15.63% to 1.12%, whereas the pathogenic fungus Aspergillus increased from 0.06% to 3.06%. A total of 1408 secondary metabolites were detected, with 39 significantly upregulated and 416 downregulated in CC3 compared to CC0. Several autotoxic compounds, including ferulic acid, hydroxycinnamic acid derivatives, and jasmonic acid, were enriched and positively correlated with pathogenic fungi. These results suggest that continuous cropping may reshape the soil microecosystem by promoting autotoxic metabolite accumulation and pathogenic Microbial enrichment, thereby contributing to soil degradation and cropping obstacles.