True morels (Morchella spp.) are renowned for their aroma and taste, and hot air drying is widely used to extend the shelf life of harvested morels. However, the effects of different drying temperatures on volatile flavor compounds and non-volatile metabolites in the morel are poorly understood. Here, fresh morels (Morchella sextelata) were air-dried at low (45 °C, LT), medium (55 °C, MT), and high temperatures (65 °C, HT). The volatile flavor compounds and non-volatile metabolites were analyzed using GC-IMS and LC-MS/MS, respectively. The GC-IMS revealed that aldehydes, hydrocarbons, and pyrazines increased at greater temperatures, while acids, alcohols, and esters decreased. Random forest machine learning indicated that 1-hexanol and ethyl 3-methylbutanoate were indicative flavor compounds at LTs, while those at MTs and HTs were hexanal and valeraldehyde, respectively. Greater temperatures reduced acetic acid, an unpleasant sour flavor. The LC-MS/MS showed that the relative abundance of amino acids and nucleotides increased with the temperature, with the same trend in 5′-nucleotides and flavor amino acids. Sorbitol 6-phosphate was indicative of the non-volatile metabolites at LTs, while several amino acids were indicative at MTs and HTs. This study revealed the flavor and taste characteristics of morels dried at different temperatures, providing a theoretical reference for establishing a standardized postharvest morel drying process and maintaining morel quality.

Nitrate (NO ₃ ⁻ ) and ammonium (NH ₄ ⁺ ) are the two main forms of inorganic nitrogen (N) found in soil. Most macrofungi show a preference for specific forms of N; however, the mechanisms behind these preferences remain poorly understood. In this study, we explored the metabolic responses induced by NO ₃ ⁻ and NH ₄ ⁺ uptake and assimilation in the ascomycete Morchella importuna , a highly valued soil-grown mushroom. Through transcriptomics, proteomics and metabolomics, we demonstrated that growth on NO ₃ ⁻ inhibited the expression and activity of NADP-glutamate dehydrogenase while increasing the expression and activity of glutamate synthase (GOGAT) and glutamate levels, underscoring the significant role of the GOGAT pathway in glutamate synthesis in NO ₃ ⁻ -grown mycelia. Furthermore, growth on NO ₃ ⁻ results in the downregulation of proteins involved in ribosome biogenesis and RNA transport pathways, inducing a status analogous to N starvation and oxidative stress. Simultaneously, nitrate initiated metabolic alterations related to sexual morphogenesis, such as increased glutathione levels to counter oxidative stress, the upregulated expression of tyrosinase and its substrates to accelerate melanin deposition and enhanced glycosylation to supply cell-wall formation. These findings enhance our understanding of the differential response mechanisms to N sources that affect mushroom cell homeostasis.

Protein phosphorylation modification plays a role in cells’ response to oxidative stress, a key factor leading to postharvest browning of Flammulina filiformis. However, the molecular mechanism by which protein phosphorylation contributes to postharvest browning of F. filiformis remains unclear. This study aimed to characterize the basal phosphoproteomic landscapes associated with variations in different browning phenotypes of F. filiformis. Using data-independent acquisition (DIA) mass spectrometry, we comprehensively profiled the phosphorylation dynamics in susceptible-to-browning (SB) and resistant-to-browning (RB) cultivars at harvest and after 24 h storage. We identified 84,244 phosphorylation sites on 4494 phosphoproteins, with the SB cultivar displaying more altered sites (21,195) than the RB (16,087). Functional enrichment analysis revealed that the differential phosphorylation was significantly implicated in kinases and energy metabolism pathways. Notably, the SB cultivar exhibited a more pronounced phosphorylation profile on key proteins involved in ATP synthesis and glycolysis. Protein–protein interaction (PPI) network analysis further indicated a kinase-mediated regulatory network targeting core energy metabolism components, including ATP synthase and 6-phosphofructokinase. This distinct phosphosignature in the SB cultivar correlated with its more severe browning phenotype and a sharper decline in ATP content during storage. Our findings suggest that divergent phosphorylation-mediated regulation of energy metabolism is strongly associated with the differential postharvest browning susceptibility between these two cultivars, providing a valuable molecular resource for future functional studies.