Changes in Fruit Characteristics and Expression of Ripening-Related Genes in 'Madoka' Peaches Treated with 1-Methylcyclopropene and Aminoethoxyvinylglycine

Changes of the characteristics were investigated during storage of peach fruits following foliar application of 1-methylcyclopropene (1-MCP, 120 mg.L-1 and 240 mg.L-1), aminoetoxyvinylglcine (AVG, 75 mg.L-1), and a combination of 1-MCP (240 mg.L-1) and AVG (75 mg.L-1) onto peach trees 3 weeks before harvesting. There were no significant differences in fruit characteristics including total soluble solids, acid content, and Hunter's value a between control and 1-MCP- or AVG-treated fruits of 'Madoka' peaches during ambient (25 degrees C) and cold storage (12 degrees C). However, we observed a delayed decrease in firmness, as well as inhibition of ethylene production and respiration during storage of peach fruits after foliar application of 1-MCP, AVG, and AVG combined with 1-MCP in 2017 and in 2018 compared to untreated peach fruits. Quantitative real-time PCR using RNA isolated from peach fruits revealed significantly inhibited expression of sugar accumulation-related genes (polygalacturonase, PpPG and PpPGL; and lipoxygenase, PpLOX), cell wall softening-related gene (pectin methylesterase, PpPME), ethylene biosynthesis-promoting genes (ACC synthase, PpACS1; and ACC oxidase, PpACO), and genes responsive to ethylene receptors (ethylene insensitive protein, PpEIN; and ethylene response sensor 1, PpERS1) in fruits treated with 1-MCP or AVG after harvest. This suggests that foliar application with 1-MCP or AVG can extend the shelf-life of peaches through inhibition of ethylene production and respiration. These results are informative for the development of technology necessary to extend shelf-life, which may ultimately lead to increased consumption and export to foreign countries of peaches produced in Korea.