Untargeted Metabolomics Reveals the Dynamic and Time-Dependent 'Hass' Avocado Response to Stem-End Rot Infection at...

Stem-end rot (SER), caused by Botryosphaeriaceae fungi, is an important postharvest disease in avocados. However, the metabolic processes shaping fruit-pathogen interactions during postharvest ripening remain poorly understood, particularly following cold storage. This study evaluated the impact of postharvest ripening and pathogen infection on the fruit metabolome, specifically comparing how a 35-day cold storage period alters these metabolic responses relative to freshly harvested, unripe fruit. 'Hass' avocados were inoculated with Neofusicoccum luteum both immediately after harvest and after 35 days of cold storage (5°C). Fruit samples were collected at 0, 24, 48, and 96 h postinoculation and analyzed using untargeted ultra-high-performance liquid chromatography-mass spectrometry, alongside firmness and dry matter measurements. Multivariate analyses indicated that cold storage altered the baseline fruit metabolome, with subsequent SER infection driving additional changes over time. Metabolomic changes were largely driven by lipid-associated metabolites, reflecting possible remodeling of membrane-associated lipids during cold storage and infection. Sphingolipids such as phytosphingosine and sphinganine consistently accumulated in infected fruit, especially after storage, suggesting involvement in stress and fruit-pathogen responses during disease progression. In addition to the lipid changes, a smaller set of non-lipid metabolites, such as eicosanoids, indoles, and various terpenoid forms, were also differentially abundant across treatments. These findings indicate that cold storage preconditions the avocado metabolome and influences the metabolomic landscape accompanying subsequent SER infection. To the best of our knowledge, this is the first study to characterize the avocado metabolome in both intact and SER-infected fruit under postharvest, cold storage conditions.