Peach fruit is often subjected to postharvest chilling injury (CI) during long-term cold storage and the degree of CI is related to the storage temperature. Analysis of the data on softening, ethylene production and internal browning (IB) showed that CI occurred in fruit stored at or below 12 °C. Impairment of ethylene production and softening was greater in fruit stored at 0 and 5 °C and was consistent with lower expression of related critical genes. Lower malondialdehyde and hydrogen peroxide contents and enhanced hydroxyl radical contents were observed in fruit stored at 0 and 5 °C. These changes were associated with higher transcript levels of polyphenol oxidases and peroxidase, but lower expression levels of lipoxygenase, superoxide dismutase and catalase. To investigate whether DNA methylation is involved in the CI development in peach fruit, single-base resolution DNA methylome and transcriptome analysis was carried out. The DNA methylation level was higher in CI fruit and a close positive correlation was observed between the methylation level and IB index. Furthermore, for most genes involved in softening, ethylene biosynthesis and signal transduction, IB and reactive oxygen species metabolism, the expression level was found to be well correlated with low temperature-induced DNA hyper- or hypo-methylation in promoter, genebody or downstream regions. It was concluded that changes in DNA methylation in different genomic regions regulate CI associated gene expression and contribute to the development of temperature-dependent CI in postharvest peach fruit.

桃果实在长期冷藏过程中易发生采后冷害（CI），冷害程度与贮藏温度有关。对软化、乙烯产生和内部褐变 (IB) 数据的分析表明，在 12 °C 或以下储存的水果中会发生 CI。在 0°C 和 5°C 下储存的水果中乙烯产生和软化的损害更大，这与相关关键基因的较低表达一致。在 0°C 和 5°C 下储存的水果中观察到较低的丙二醛和过氧化氢含量以及增加的羟基自由基含量。这些变化与多酚氧化酶和过氧化物酶的转录水平较高有关，但脂肪氧化酶的表达水平较低，超氧化物歧化酶和过氧化氢酶. 为了研究 DNA 甲基化是否参与桃果实的 CI 发展，进行了单碱基分辨率 DNA 甲基化和转录组分析。CI果实的DNA甲基化水平较高，甲基化水平与IB指数呈密切正相关。此外，对于大多数参与软化、乙烯生物合成和信号转导、IB 和活性氧代谢的基因，发现其表达水平与低温诱导的启动子、基因体或下游区域的 DNA 高甲基化或低甲基化密切相关。 . 得出的结论是，不同基因组区域中 DNA 甲基化的变化调节 CI 相关基因的表达，并有助于采后桃果实中温度依赖性 CI 的发展。