Study on the nutritional relationships in mycelia and fruiting bodies of Hypsizygus marmoreus under defined nutrient conditions.

Edible fungal fruiting bodies develop from mycelia that experienced physiological knotting, establishing a tight nutrient connection between mycelia and fruiting bodies. Despite this connection, limited research has explored this field. This study aimed to elucidate the crude polysaccharide and protein contents in mycelia and fruiting bodies of 5 main edible fungi cultivars: Flammulina velutipes, Hypsizygus marmoreus, Lyophyllum decastes etc., under defined nutrient conditions. H. marmoreus was selected as an example, the study investigated nutrient relationships in both mycelia and fruiting bodies across 5 media with varying carbon to nitrogen ratios (C/N). Results indicated higher crude polysaccharide and protein contents in mycelia compared to fruiting bodies. A predictive model for the crude polysaccharide and protein contents of H. marmoreus fruiting bodies was developed using partial least squares (PLS) method. Predicted values closely matched experimental determinations, providing the model's accuracy. The impact of different C/N on crude fiber content in the culture media was minimal. Metabolomics analysis of H. marmoreus revealed significant up-regulation of carbohydrate metabolites (72 %) and amino acid metabolites (84 %) in mycelia relative to fruiting bodies. Specifically, metabolites involved in polysaccharide precursor synthesis pathways (Gal1P, Glc-1P, UDP-Glc) and protein precursor synthesis pathways (9 amino acids) showed heightened levels in mycelia, which suggested a possible reason for the observed higher crude polysaccharide and protein content in mycelia compared to fruiting bodies. Overall, these results provide a crucial theoretical foundation for predicting and enhancing edible fungal quality and diversity through mycelial studies. They also establish a cornerstone for accelerating new variety development and optimizing high-quality mushroom production formulations.