Differences in Nutritional Composition of Poria cocos Cultivated with Different Raw Materials Based on Non-Targeted Metabolomics Method

The spread of Bursaphelenchus xylophilus has caused a critical shortage of traditional Poria cocos cultivation materials, making bag-based substrates an urgent alternative. Yet, how substrate stoichiometry shapes nutritional quality remains unclear. Using non-targeted metabolomics combined with redundancy analysis (RDA) and weighted gene co-expression network analysis (WGCNA), we profiled P. cocos cultivated on four substrates: healthy pine logs, pine wilt wood bags, oak bags, and pine needle/branch bags. Bag-cultivated P. cocos showed significantly elevated total amino acids, poria cocos acid, and total triterpenoids, with pine wilt wood bags (P1) performing best overall. Nitrogen, phosphorus, and the N/P ratio independently drove metabolomic variation (pairwise overlap < 5%). Nitrogen-line hub metabolites were negatively correlated with amino acid content, suggesting that suppressed lipid metabolism may free carbon skeletons for the accumulation of nitrogenous nutrients. Phosphorus-line hub metabolites were positively associated with polysaccharide indices, whereas the N/P ratio in line lipid amides showed strong negative correlations with polysaccharides under phosphorus limitation. These correlational patterns are consistent with a stoichiometric resource allocation model, although direct validation through controlled-element experiments is required. These findings provide quantitative guidance for optimizing bag-substrate formulations in P. cocos cultivation.