Distinguishing the metabolic fingerprints of carbon dioxide apple storage disorders from other disorders [abstract]

Authors: McTavish, Christine; Milne, Shae; TUDOR, ERIN - Former ARS Employee; CELEBREZZE, JOE - Former ARS Employee; HANRAHAN, INES - Washington Tree Fruit Research Commission; Mattheis, James; Rudell, David

Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/29/2021
Publication Date: 8/8/2021
Citation: McTavish, C.K., Milne, S.M., Tudor, E., Celebrezze, J., Hanrahan, I., Mattheis, J.P., Rudell Jr, D.R. 2021. Distinguishing the metabolic fingerprints of carbon dioxide apple storage disorders from other disorders [abstract]. American Society of Horticulture Science Meeting. Paper No. 39019.

Interpretive Summary:

Technical Abstract: Many apple cultivars are sensitive to carbon dioxide (CO2) in storage, leading to disorders that contribute to annual losses for fruit producers. Symptoms can appear both internally and externally, including external dimpling or “orange peel” texture of the peel and internal browning in a radial pattern, both of which can be mistaken for other disorders. Although the antioxidant diphenylamine (DPA) is effective at controlling these injuries, new market restrictions necessitate alternative control methods. In order to prevent or detect these injuries before onset, a better understanding of the peel chemistry is needed. To test the hypothesis that symptomatic tissue will differ in metabolism from asymptomatic tissue, the following experiment was carried out: 64 randomized apples per cultivar were harvested at early (2-3 weeks before first commercial pick) and late (1 week after first commercial pick) timepoints, half were treated with DPA, then all were stored in controlled atmosphere (CA) for 4 months at 0.6 kPa O2 and 5 kPa CO2, keeping DPA-treated fruit in separate chambers from non-treated fruit. DPA was used as a contrast as it is expected to control disorders associated with CO2 sensitivity. After storage, apples were rated for storage injuries and samples of injured tissue and asymptomatic tissue around the periphery of the injury were sampled separately. Samples were flash frozen, ground to a powder, and analyzed using an untargeted polar extraction on an LC-MS QTOF (Agilent Technologies, Santa Clara, CA). Results indicate clear differences in tissue metabolism between asymptomatic and symptomatic tissue for both CO2 injuries and injuries associated with other factors (such as soft scald, a chilling disorder). Cultivars, such as ‘Pazazz’, that developed both disorders related to CO2 sensitivity as well as those not typically associated with CO2 (soft scald) also could be distinguished. Further analysis revealed elevated or lowered levels of specific compounds, such as threonic acid, depending if the tissue had injuries related to CO2 or to soft scald, which may be mistakenly attributed to CO2 sensitivity. Future steps include tailoring CA storage to control for these disorders and delving deeper into the metabolism of cultivars with multiple storage disorders throughout the course of storage to confirm storage disorder differences.