Unveiling the mechanism of blue light treatment in regulating umami quality of Lentinula edodes during spore discharge

Blue light (BL) treatment was found to maintain high levels of umami and energy in Lentinula edodes during spore discharge. The study aimed to elucidate the underlying regulatory mechanism by monitoring the activities of key enzymes and the expression of genes associated with energy and umami metabolism, as well as photoreceptor expression. The results showed that BL treatment preserved high levels of mannitol metabolism-related substances. During the terminal spore discharge period, mannitol, fructose, and soluble sugars increased by 11.1%, 12.0%, and 71.2%, respectively, compared with the control group, which helped maintain low spore discharge intensity. Additionally, enzyme activation and differential transcription of genes in umami and energy metabolism pathways sustained cellular energy homeostasis and umami levels. Under blue light, the expression levels of LePHY1 , LePHRB and LePHY2 showed fold changes ranging from 1.22 to 2.48, 1.13–2.93, and 1.14–1.49, respectively, compared with the control group. Furthermore, correlation and partial least squares discriminant analysis indicated that BL treatment may activate energy metabolism pathway signals via photoreceptor-mediated signaling, inducing umami-related gene expression and ultimately preserving high umami substance contents. This study provides theoretical support for the precise regulation of postharvest flavor quality in mushrooms.