Mao Jipeng, Gao Zhu, Lin Mengfei, Zhang Xiaoli, Ning Xinyi, Gong Xuchen, Lu Yupeng, Chen Lu, Wang Xiaoling
Institute of Biological Resources, Jiangxi Academy of Sciences, Nanchang, Jiangxi, China.
Jinggangshan Institute of Biotechnology, Jiangxi Academy of Sciences, Ji'an, Jiangxi, China.
Front Plant Sci. 2023 Mar 7;14:1120166. doi: 10.3389/fpls.2023.1120166. eCollection 2023.
Kiwifruit is a climacteric fruit, in which the accumulation of flavor substances mainly occurs at the postharvest ripening stage. However, the dynamic changes in metabolite composition remain poorly understood. Here, targeted multi-platform metabolome analysis based on GC-MS and UPLC-MS/MS and enzyme activity analysis were performed at different postharvest ripening stages of kiwifruit. A total of 12 soluble sugars and 31 organic acids were identified. The main soluble sugars are sucrose, glucose and fructose, which exhibited similar variation tendencies along with the extension of ripening. The main organic acids are citric acid, quinic acid and malic acid, which showed different variation patterns. A total of 48 energy metabolites were identified, which were classified into two groups based on the content variation. The content of substances related to the respiratory metabolic pathway decreased gradually along with postharvest ripening, and there was obvious accumulation of downstream products such as amino acids at the late ripening stage. A total of 35 endogenous hormones were identified, among which seven cytokinins were highly accumulated at the later stage of softening. We further investigated the dynamic changes in the activities of 28 ripening-related enzymes. As a result, the activities of 13 enzymes were highly correlated with changes in starch, total pectin, and soluble sugars, and those of seven enzymes were closely associated with the change in firmness. In conclusion, this study comprehensively describes the dynamic changes in soluble sugars, organic acids, hormones, energy substances, and ripening-related enzyme activities during kiwifruit postharvest ripening, and provides a theoretical basis for the postharvest quality improvement of kiwifruit.
猕猴桃是一种跃变型果实，其风味物质的积累主要发生在采后成熟阶段。然而，代谢物组成的动态变化仍知之甚少。在此，对猕猴桃采后不同成熟阶段进行了基于气相色谱-质谱联用（GC-MS）和超高效液相色谱-串联质谱联用（UPLC-MS/MS）的靶向多平台代谢组分析以及酶活性分析。共鉴定出12种可溶性糖和31种有机酸。主要的可溶性糖是蔗糖、葡萄糖和果糖，它们随着成熟时间的延长呈现出相似的变化趋势。主要的有机酸是柠檬酸、奎尼酸和苹果酸，它们表现出不同的变化模式。共鉴定出48种能量代谢物，根据含量变化将其分为两组。与呼吸代谢途径相关的物质含量随着采后成熟逐渐降低，在成熟后期氨基酸等下游产物有明显积累。共鉴定出35种内源激素，其中7种细胞分裂素在软化后期高度积累。我们进一步研究了28种与成熟相关酶的活性动态变化。结果表明，13种酶的活性与淀粉、总果胶和可溶性糖的变化高度相关，7种酶的活性与硬度变化密切相关。综上所述，本研究全面描述了猕猴桃采后成熟过程中可溶性糖、有机酸、激素、能量物质以及与成熟相关酶活性的动态变化，为猕猴桃采后品质改良提供了理论依据。
