Inhibitory Effect and Mechanism of Hexanal on the Maturation of Peach-Shaped Phallus impudicus

Phallus impudicus is a fungus used as a medicine and nutrient-rich food. However, the shelf life of mature Phallus impudicus is only a few hours. Therefore, research on its preservation technology is essential for improving its economic value. This study investigated the effects of hexanal concentrations (25-100 μL/L) and treatment time (4-8 h) on the inhibition of peach-shaped Phallus impudicus (CK) maturation and found that the maturation rate was 25% under optimal conditions of 25 μL/L hexanal treatment for 6 h. Quantitative transcriptomic and lipidomic analyses were conducted among CK, mature Phallus impudicus (M-P), and hexanal-treated peach-shaped Phallus impudicus (H-P-P). In total, 2933 and 2746 differentially expressed genes (DEGs) and 156 and 111 differentially abundant lipids (DALs) were identified in CK vs. H-P-P and M-P vs. H-P-P, respectively. Functional analysis demonstrated that hexanal treatment inhibited phospholipase D gene expression and reduced phosphatidic acid abundance, thereby inhibiting the activation of the phosphatidylinositol signaling system and the signal amplification of the cell wall integrity mitogen-activated protein kinase pathway. These blocked signal transductions inhibited the gene expression of most β-glucanases, chitinases and chitin synthases, further affecting cell wall reconstruction. Moreover, hexanal treatment enhanced membrane stability by reducing the monogalactosyl diglyceride/digalactosyl diacylglycerol ratio and increasing the phosphatidylcholine/phosphatidylethanolamine ratio. This study contributed to the development of hexanal treatment as a postharvest preservation technology for Phallus impudicus.