Transcriptomics and Physiological Analysis Reveal Response Strategies of Sanghuangporus baumii to Aluminum Exposure

Sanghuangporus baumii, a medicinal macrofungus, remains unexplored in its response to aluminum stress, despite the widespread environmental relevance of this metal. This study investigated the dose-dependent effects of Al³⁺ on mycelial growth and metabolic regulation. Exposure to 1 mM Al³⁺ moderately stimulated growth (1.11-fold of control) and induced mild oxidative stress, which activated an effective antioxidant response-including increased SOD, CAT, and POD activities and elevated reduced glutathione content-thereby maintaining redox balance and increasing soluble sugar content. In contrast, 10 mM Al³⁺ led to pronounced intracellular Al³⁺ accumulation, severe growth inhibition, and marked oxidative damage, accompanied by impairment of the antioxidant system, yet a marked increase in total triterpenoid content (1.72-fold). Transcriptomic analysis identified 642 and 3019 differentially expressed genes (DEGs) in the 1 and 10 mM Al³⁺ treatments, respectively. KEGG enrichment analysis revealed concentration-dependent alterations in pathways related to peroxisome function, glutathione metabolism, starch and sucrose metabolism, and terpenoid backbone biosynthesis. Collectively, these findings suggest that Al³⁺ modulates S. baumii growth and metabolism in a dose-dependent manner, with redox remodeling as a potential mechanism, offering novel insights into fungal metal adaptation and the targeted modulation of medicinal metabolite production.