Metabolic profiling of ethephon-treated sweet cherry (Prunus avium L.)

Increasing costs and decreasing labor availability for sweet cherry harvest in Washington State, USA, has reinvigorated commercial and research interest of mechanized harvest. Ethephon (2-chloroethyl phosphonic acid) can be used to improve fruit abscission for mechanical harvest. Our previous work shows that 3.5 l ha⁻¹ ethephon enhances red color and reduces firmness of the cultivar ‘Bing’. In the current study, we used metabolic profiling of cultivars ‘Bing’, Chelan’, and ‘Skeena’ fruit meso and exocarp tissue to better understand underlying quality-related metabolism associated with ethephon application. Trees were treated using air-blast sprayer 13–14 days prior to harvest and fruit samples were harvested every 7–10 days starting at least 17 days prior to commercial harvest. Nearly 200 identified and partially characterized metabolites from mesocarp and exocarp tissue were characterized and evaluated. Principal component analysis models revealed changes in the metabolome associated with both natural ripening and ethephon-induced changes, including associations to key color, acid, and sugar components, such as cyanidin 3-glucoside, malic acid and sugar metabolism.