Despite an increase in the use of 1-methylcyclopropene (1-MCP) to delay fruit softening, the role of 1-MCP in the modification of cell wall pectin to maintain apple fruit firmness during storage is poorly understood. Hence, in this study, we investigated whether 1-MCP treatment delayed fruit softening through pectin modification, in “Hwangok” and “Picnic” apple cultivars, stored up to six months at 0 °C. In both cultivars, 1-MCP-treated apples maintained firmness and exhibited lower internal ethylene concentrations compared with untreated fruit. The depolymerization of pectin in all pectin fractions was attenuated in 1-MCP-treated fruit compared with untreated fruit. In addition, a peak location shift was observed in the molecular mass profile of untreated fruit. Neutral sugar contents (arabinose and galactose), which typically change as fruit ripen, were effectively maintained in 1-MCP-treated fruit. The activity of four important enzymes involved in pectin modification (exo-polygalacturonase, pectin methylesterase, β-galactosidase, and α-L-arabinofuranosidase) was reduced in treated fruit compared to the control. Furthermore, 1-MCP treatment reduced the expression of pectin-degrading candidate genes (MdPG1, MdPME1, Mdβ-GAL1, Mdβ-GAL2, and Mdα-ARF2). This study suggests that 1-MCP maintains cell wall pectin and delays the softening of the two apple cultivars by reducing the solubilization of polyuronides and neutral sugars, and limiting the activities of cell wall hydrolysis.

尽管增加了使用1-甲基环丙烯（1-MCP）来延迟水果软化的程度，但人们对1-MCP在修饰细胞壁果胶中保持苹果果实硬度的作用了解甚少。因此，在这项研究中，我们调查了在0℃下最多可保存6个月的“ Hwangok”和“ Picnic”苹果品种中1-MCP处理是否通过果胶修饰延迟了果实的软化。与未经处理的果实相比，在两个品种中，经1-MCP处理的苹果均保持坚挺并显示出较低的内部乙烯浓度。与未经处理的水果相比，在经1-MCP处理的水果中，所有果胶级分中的果胶解聚作用均减弱。另外，在未处理的水果的分子量分布中观察到峰位置偏移。中性糖含量（阿拉伯糖和半乳糖），通常在1-MCP处理过的水果中保持其通常随果实成熟而变化的水平。参与果胶修饰的四种重要酶的活性（外切多聚半乳糖醛酸酶，果胶甲基酯酶，β-半乳糖苷酶和α-与对照相比，处理的果实中的L-阿拉伯呋喃糖苷酶减少。此外，1-MCP处理降低了果胶降解候选基因（MdPG1，MdPME1，Mdβ-GAL1，Mdβ-GAL2和Mdα-ARF2）的表达。这项研究表明1-MCP可以通过减少聚脲醛酸酯和中性糖的增溶作用并限制细胞壁水解的活性来维持细胞壁果胶并延迟两个苹果品种的软化。