Transcriptomic Insights into the Effects of Iron, Potassium, and Manganese on Mycelial Growth of Lentinula edodes

Lentinula edodes (L. edodes) is a significant edible and medicinal mushroom with essential nutrient elements for its growth, including Fe2+, K+, and Mn2+. However, the molecular mechanisms by which these metal ions regulate the mycelial growth of L. edodes have been poorly elucidated at the transcriptomic level. In this study, plate culture was performed using concentration gradients to screen for optimal concentrations. Based on the plate culture assay results, L. edodes strain 1303 was treated with 40 μg/mL Fe2+, 1200 μg/mL K+, and 50 μg/mL Mn2+, with a control group (CK) without additional metal ion supplementation. Three biological replicates were set for each treatment, and the mycelia were collected for transcriptome sequencing (RNA-seq). The results showed that Fe2+ at concentrations above 20 µg/mL significantly inhibited mycelial growth; K+ at 1200 µg/mL and Mn2+ at 50 µg/mL significantly promoted mycelial growth, with increases in mycelial growth radius on day 7 of 21.22% and 10.77%, respectively, compared with the control group (p < 0.05). Transcriptomic analysis revealed that Fe2+ was associated with impaired protein folding-related functions and suppressed material and energy metabolism, which may contribute to the inhibition of mycelial growth. Mycelial growth promotion by K+ was associated with enhanced detoxification and secondary metabolism, as well as suggested enrichment of mitochondrial function and the oxidative phosphorylation pathway. Mn2+ may contribute to mycelial growth via mechanisms related to DNA repair and recombination, cell cycle progression, and detoxification. This study elucidates the differential gene expression patterns and regulatory effects of the three exogenous metal ions on the mycelial growth of L. edodes at the transcriptomic level, offering a rationale basis for mineral nutrition optimization during the mycelial stage. However, these interpretations are based on transcriptomic data only and lack direct evidence from ion uptake, proteomic, or metabolomic validation. Future studies will focus on validating these results through multilevel omics and functional experiments.