After cryopreservation, the occurrence of apoptosis-like programmed cell death events induced by the accumulation of ROS reduces pollen viability. Cryopreservation, as a biotechnological means for long-term preservation of pollen, has been applied to many species. However, after cryopreservation, the viability of pollen significantly decreases via a mechanism that is not completely clear. In this study, the pollen of Paeonia lactiflora 'Zi Feng Chao Yang', which exhibits significantly reduced viability after liquid nitrogen (LN2) storage, was used to study the relationship among pollen viability, programmed cell death (PCD) and reactive oxygen species (ROS). The apoptosis rate was increased significantly in pollen with decreased viability after cryopreservation, and the changes in ROS generation and hydrogen peroxide (H2O2) were consistent with the apoptosis rate. Correlation analysis results showed that the apoptosis rate is positively correlated with ROS generation and H2O2 content. In addition, ascorbic acid (AsA), glutathione (GSH) and ascorbic acid reductase (APX) levels were significantly correlated with ROS and H2O2. After LN2 preservation for 8 months, the exogenous antioxidants AsA and GSH at appropriate concentrations significantly decreased H2O2 content, inhibited PCD indicator levels, and increased cryopreserved pollen viability. These observations suggest that PCD occurred in pollen during LN2 preservation for 1-8 months and was induced by the accumulation of ROS in pollen after cryopreservation, thus explaining the main reasons for the reduction in pollen viability after cryopreservation in LN2.

中文翻译：

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与 ROS 相关的程序性细胞死亡导致芍药从冷冻保存中恢复的花粉活力下降。

冷冻保存后，由 ROS 积累诱导的细胞凋亡样程序性细胞死亡事件的发生降低了花粉活力。冷冻保存作为一种长期保存花粉的生物技术手段，已应用于许多物种。然而，冷冻保存后，花粉的活力会通过一种尚不完全清楚的机制显着降低。本研究采用液氮 (LN2) 储存后活力显着降低的芍药‘紫峰朝阳’花粉研究花粉活力、程序性细胞死亡 (PCD) 和活性氧之间的关系。罗斯）。冷冻保存后花粉的细胞凋亡率显着增加，活力降低，并且ROS生成和过氧化氢（H2O2）的变化与细胞凋亡率一致。相关性分析结果表明，细胞凋亡率与ROS产生和H2O2含量呈正相关。此外，抗坏血酸 (AsA)、谷胱甘肽 (GSH) 和抗坏血酸还原酶 (APX) 水平与 ROS 和 H2O2 显着相关。LN2 保存 8 个月后，适当浓度的外源抗氧化剂 AsA 和 GSH 显着降低了 H2O2 含量，抑制了 PCD 指标水平，并增加了冷冻保存的花粉活力。这些观察结果表明，在 LN2 保存 1-8 个月期间，花粉中发生了 PCD，并且是由冷冻保存后花粉中 ROS 的积累引起的，