Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2009
Publication Date: 8/28/2009
Citation: Rudell Jr, D.R., Mattheis, J.P., Hertog, M. 2009. Metabolomic Change Precedes Apple Superficial Scald Symptoms. J. Agric. Food Chem. 57:8459-8466. Interpretive Summary: Superficial scald can result in substantial storage-related losses of susceptible apple cultivars when left uncontrolled. Current control means are not registered for organic production and/or lack guarantee of scald control to the end users. Using sophisticated chemical analyses, we uncovered previously unknown changes in apple peel chemistry associated with storage, oxidative stress, ripening, and scald. Our results emphasize the wide-reaching apple peel chemical changes, encompassing more chemical pathways than previously considered, induced oxidative stress provoked by cold-storage. This information will be used to create new cultural and chemical control means as well as to exploit key scald-associated apple peel chemicals as storage/supply chain management tools.
Technical Abstract: Metabolic profiling of 621 metabolites was employed to characterize metabolomic changes associated with ‘Granny Smith’ apple superficial scald development following 1-MCP or DPA treatment. Partial least squares-discriminant analyses were used to link metabolites with scald, postharvest treatments, and storage duration. Models revealed metabolomic differentiation between untreated controls and fruit treated with DPA or 1-MCP within 1 week following storage initiation. Metabolic divergence between controls and DPA-treated fruit after 4 weeks storage preceded scald symptom development by 2 months. a-Farnesene oxidation products with known associations to scald, including conjugated trienols, 6-methyl-5-hepten-2-one, and 6-methyl-5-hepten-2-ol, were associated with pre-symptomatic as well as scalded control fruit. Likewise, a large group of putative triterpenoids with similar mass spectral features to ursolic acid and ß-sitosterol were associated with control fruit and scald. Results demonstrate that extensive metabolomic changes associated with scald precede actual symptom development.