P-565 - Metabolic Shifts in "Hass" Avocado During Stem-End Rot Infection and Cold Storage

Stem-end rot (SER), caused by Botryosphaeriaceae fungi, is a significant postharvest disease responsible for up to 30% fruit loss in avocados. Despite the economic importance of SER, the specific metabolic responses of “Hass” avocados to infection and storage duration are poorly understood, prompting this investigation into their biochemical shifts. Fruits were inoculated immediately after harvest and others after 35 days of cold storage (4°C) with Neofusicoccum parvum. The firmness and dry matter of the fruits were measured to assess ripening. Samples were collected at 0, 24, 48, and 96 hours post-inoculation (hpi) and analyzed using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). Of 260 metabolites identified, 207 exhibited significant changes (p < 0.05). Principal Component Analysis revealed distinct metabolic clustering between storage treatments, separating harvest and stored controls, indicating storage-related metabolic shifts. Additionally, inoculated samples clustered separately, particularly at 48 and 96-hpi. Heatmap analysis confirmed widespread metabolite changes, with stored fruit undergoing significant reprogramming. Volcano plots highlighted key differentially abundant metabolites, including triterpenoids, glycerolipids, flavonoids, and fatty acids, revealing storage- and infection-driven responses. These findings provide new insights into the biochemical complexity of SER progression and the metabolic effects of cold storage in avocado fruits, contributing to a deeper understanding of this devastating disease.