Impacts of Varying Concentrations of 1-MCP on Glyoxylic Acid-Treated D'Anjou Pear Fruit
European pears (Pyrus communis) are climacteric fruits that require prolonged cold exposure to ripen properly. This chilling requirement is genotype-specific and is thought to involve epigenetic and transcriptional changes analogous to endodormancy release. To extend shelf life, postharvest 1-methylcyclopropene (1-MCP) treatment is widely used to inhibit ethylene perception and response. However, some cultivars, such as 'DAnjou', fail to ripen properly after 1-MCP treatment, remaining green, firm, and starchy, lacking critical organoleptic qualities.To preserve the utility of 1-MCP in postponing ripening, glyoxylic acid (GLA) has been proposed as a chemical means of restoring ripening competency. Previous studies used pears that were treated with 1-MCP at harvest and subsequently cold conditioned prior to GLA application; here, we applied 1-MCP (plus/minus GLA) to unconditioned pear fruit. In this study, peak ethylene evolution was higher and terminal flesh firmness was lower in 1-MCP + 3% GLA-treated fruit relative to 1-MCP-only fruit. GLA-treated fruit also exhibited elevated respiration rates but no discernable differences in endogenous organic acid pools. Browning and necrosis in GLA-treated fruit were consistent with lipid peroxidation. Transcriptomic profiling showed that GLA induced genes related to senescence, oxidative stress, and lipid and cell wall degradation, paralleling the physiological observations.