Dynamic Shifts in Rhizosphere Microbiome and Soil Nutrients Drive Tuber sinense Mycorrhizal Development in Castanea mollissima Seedlings

The Chinese black truffle (Tuber sinense) is an economically vital ectomycorrhizal fungus threatened by unsustainable harvesting. Cultivating truffles using mycorrhizal seedlings is essential for sustainable production, yet the rhizosphere microbiome dynamics remain unclear. This study explored microbial community succession in the rhizosphere of Chinese chestnut (Castanea mollissima) seedlings inoculated with T. sinense over 8 months. High-throughput sequencing and soil physicochemical analysis were conducted at 1, 3, and 8 months post-inoculation. Significant changes in soil properties, such as decreased pH and increased total nitrogen (TN), total potassium (TK), available phosphorus (AP), and calcium (Ca), influenced microbial assembly. Tuber relative abundance rose from 0.02% in non-inoculated samples to 8.81% at 8 months. Inoculation altered microbial structures, enriching fungal genera like Tuber, Staphylotrichum, and Sphaerosporella. Network analysis showed 79.23% positive bacterial-fungal interactions, crucial for rhizosphere stability. Tuber correlated positively with Staphylotrichum and Spizellomyces, indicating potential synergies in mycorrhizal development and nutrient cycling. Tuber also showed significant positive correlations with TN, TK, AP, and Ca, highlighting its preference for nutrient-enriched conditions. This study provides the first comprehensive profile of microbial succession during the mycorrhizal development of T. sinense on chestnut, offering a scientific basis for optimizing truffle seedling production and supporting sustainable cultivation.