Enhancing the ripening profile of 1-methylcyclopropene treated 'Rocha' pear through abscisic acid treatment

Recently, several studies have investigated strategies to reduce the antagonistic ripening effect of 1-methylcyclopropene (1-MCP). In this study, we examined how abscisic acid (ABA) influences ethylene production and fruit ripening in 'Rocha' pears treated with 1-MCP. To explore potential mechanisms for reactivating ripening, 'Rocha' pears treated with 1-MCP were exposed to 50 mg mL-1 of ABA and stored at 20 ± 2 °C for 15 days. Typical ripening indicators, such as firmness, skin colour, ethylene and aroma volatile production, sugar content, and the expression of ethylene-related enzymes and receptors, were measured throughout the 15 days of storage. Multivariate and clustering analyses showed that the treatment countered the effects of 1-MCP, with ABA significantly increasing ethylene production, fruit softening, yellowing, simple sugar accumulation, and the emission of specific ripening volatile organic compounds, especially acetates, compared to pears exposed only to 1-MCP. Furthermore, ABA boosted the expression of ethylene biosynthesis genes (PcACS, PcACO) and the receptor gene (PcETR2), confirming its role in enhancing ethylene metabolism. Overall, the findings indicate that ABA influences metabolic pathways closely associated with ripening. This research provides new insights into the ripening mechanisms of pears and highlights the regulatory interaction between ABA and ethylene.