Qi Mi

Tuber indicum , an ectomycorrhizal fungus endemic to southwestern China, typically forms brûlés, which underlying microbial and edaphic dynamics remain poorly understood. In this study, we investigated bacterial community composition associated with T. indicum ascocarps and soils in‐ and outside the brûlé at two natural sites (LB and BZL). Soil properties were analyzed to evaluate the correlation between the bacterial community and the soil properties. LB soils show higher pH, calcium, organic matter, total nitrogen, and available phosphorus, whereas BZL soils were enriched in iron and manganese. These factors significantly shaped the microbial communities, as shown by canonical correspondence analysis. Proteobacteria dominated all samples and positively correlated with organic matter, manganese, and pH, indicating potential roles in brûlé formation. Verrucomicrobia showed positive correlations with potassium, calcium, and magnesium. Site‐specific enrichment patterns suggested that soil mineral composition exerts selective pressure on microbial assembly. Notably, Bradyrhizobium elkanii and other beneficial taxa such as Bacillus , Ensifer , and Pseudomonas were differentially distributed in ascocarps and adjacent soils, implying their potential involvement in truffle symbiosis and fruiting body development. This study elucidates the interactions between soil physicochemical properties and microbial communities, offering novel ecological insights into the mechanisms underlying T. indicum fruiting body formation.

This study demonstrates that the ericoid mycorrhizal (ERM) fungus RM2 can colonize the non-ericaceous host Malus robusta as a functional endophyte, enhancing drought resilience through an active avoidance strategy. Under drought, inoculation was associated with qualitative changes in root growth patterns, and inoculated seedlings showed a more extensive and branched root appearance compared with non-inoculated controls. This morphological tendency was accompanied by a distinctive physiological state of oxidative priming, characterized by elevated H₂O₂ as a signaling molecule, reduced antioxidant enzyme activity, and a marked shift toward proline-mediated osmotic adjustment. Transcriptomic analysis suggested a molecular basis for these responses: endophytic colonization reprogrammed auxin and brassinosteroid signaling, including the repression of auxin inactivation (GH3) and activation of genes involved in auxin transport (AUX1) and cell wall loosening (TCH4), which is consistent with sustained root growth under drought. Our findings indicate that ERM fungi can transcend traditional host barriers and improve drought performance via integrated oxidative signaling and hormonal regulation, highlighting their potential as cultivable biostimulants for sustainable horticulture.