Zinc Treatment Effects on the Expression of Enzyme Genes Related to Lysine Synthesis Pathway in Flammulina filiformis Mycelia

Zinc and lysine have been identified as beneficial components of Flammulina filiformis. This work investigated the effects of different concentrations of Zn2+ on mycelia growth, zinc content, amino acid composition of F. filiformis. To explore the mechanism of action of zinc on lysine synthesis in F. filiformis mycelia, this work studied at the molecular level. The cultivated strain FV8 and the wild strain FV18 were utilized as the research subjects. Various concentrations of Zn2+ (0, 10, 20, 30 mg/L) were added in the PDA medium for the experiments. The results indicated that the maximum lysine content was reached in the 20 mg/L treatment. A positive correlation was identified between Zn2+ and the lysine content in F. filiformis mycelia, suggesting a regulatory role for Zn2+ in the expression of lysine synthesis pathway genes. Zn2+ has been observed to promote the upregulated expression of HDH and HCD, while concomitantly exerting a negative effect on the expression of AAT in key enzyme genes of the lysine synthesis pathway. The F. filiformis mycelia exhibited a notable enrichment capacity for zinc, with the highest zinc content observed in the 30 mg/L treatment. The zinc-enriched growth performance of wild strain FV18 was found to be superior to that of cultivated strain FV8, which is considered a suitable breeding material. This study provides a foundation for further exploration of the lysine synthesis pathway in F. filiformis mycelia, and selection of functional varieties of F. filiformis.