Physiological and Transcriptomic Responses of Armillaria gallica to Selenium: Bioaccumulation, Biotransformation, and Growth Promotion

AIMS: Armillaria gallica is a medicinal fungus and key symbiont for Gastrodia elata cultivation. This study aimed to investigate the dose-dependent effects of exogenous selenium (Se) on mycelial growth, Se accumulation and biotransformation, antioxidant regulation, and transcriptional responses in A. gallica. METHODS AND RESULTS: Dose-response experiments showed that 20 mg L-1 Na2SeO3 optimally promoted mycelial biomass (47% increase) and Se accumulation (837.53 mg kg-1), with 99.71% of Se in organic forms, predominantly associated with polysaccharides and proteins. Physiological assays revealed enhanced SOD, POD, CAT, and GPx activities and reduced MDA content under Se treatment. Transcriptomic profiling identified extensive gene remodeling in ion transport, redox metabolism, carbohydrate metabolism, glutathione metabolism, and MAPK signaling pathways, with qRT-PCR validating key DEG expression patterns. CONCLUSIONS: Appropriate Se concentration promotes A. gallica growth and enhances antioxidant capacity through coordinated transcriptional and metabolic regulation. The strong Se accumulation and biotransformation capacity position A. gallica as a promising candidate for Se biofortification and for developing Se-enriched Gastrodia elata via the Armillaria-Gastrodia symbiotic system.