Umami loss mechanism upon shiitake mushrooms under cold storage: Revisiting the role of energy metabolism via integrated physiological and transcriptomic analysis

Umami loss of shiitake mushrooms (Lentinula edodes) is still an inevitable developmental process and a significant challenge hampering its storage and marketing. The present study explores the physiological and molecular responses to umami quality loss involved in energy metabolism during postharvest storage under room temperature (RT) and low temperature (LT) in shiitake mushrooms. Results showed that LT storage prolonged the mushroom shelf life while inhibiting electrolyte leakage, malondialdehyde (MDA), mitochondrial permeability transition pore (MPTP), Ca2+, and H2O2 contents. Moreover, transcriptome analysis revealed that LT storage maintained high umami quality and sufficient energy supply by suppressing the degradation genes of umami nucleotides and the genes related to the mitochondrial energy metabolism pathway, including metabolic pathways and biosynthesis of secondary metabolites. Additionally, the depression activities and gene transcription levels of key enzymes related to umami nucleotide degradation contributed to maintaining umami taste in cold storage. A conceptual model was proposed to elucidate the molecular mechanism of cold storage alleviated umami loss in shiitake mushrooms. The results provide a theoretical foundation for the umami loss mechanism of mushrooms under cold storage.