Abstract
Postharvest decay results in substantial losses during yam storage. This study isolated microorganisms from decayed Lichuan yams and investigated deterioration mechanisms using physiological assays and UPLC-MS/MS. Among six isolates, Penicillium sclerotigenum was identified as the primary pathogen. Infection disrupted water-retaining structures, leading to increased weight loss and reduced water activity. It also disrupted carbon-nitrogen metabolism, leading to fluctuations in starch, sugar, and protein content. Although host defense responses were activated via phenolic accumulation and the upregulation of peroxidase (POD) and polyphenol oxidase (PPO) activities, sustained infection resulted in severe membrane lipid peroxidation. Metabolomics revealed alterations in sugars, organic acids, and secondary metabolites, with the specific enrichment of sugar and amino acid pathways. Thus, P. sclerotigenum remodels yam energy metabolism and defense responses. This study clarifies the physiological and metabolic mechanisms underlying this fungal rot, providing a theoretical foundation for the development of preventive control strategies.