To boost our understanding of recent frost damage events in apricot trees, we focused on estimating the cell death point in the receptacle and pistil organs of apricots by simulating the unexpected temperature changes occurring in early spring under laboratory-based freezing experiments. The hypothesis also that organic acids (oxalic, propionic, tartaric, butyric, malonic, malic, lactic, citric, maleic, fumaric and succinic acids) and soluble sugar compositions (glucose, fructose, sucrose and total sugar) may directly stimulate the change of the frost tolerance in apricot receptacle and pistil organs was investigated using two apricot (Prunus armeniaca L.) cultivars, one tolerant to frost (‘Iğdır Şalak’) and the other sensitive to frost (‘Mihralibey’). Our results indicated that the mean the cell death point (CDP) of flower pistil (from −13.26 to −14.18 °C) was at lower temperatures than those of flower receptacle (from −6.28 to −8.65 °C) in both apricot cultivars during the full blooming stage. In both apricot cultivars, receptacle organs showed more sensitive changes to the frost tolerance in response to low temperatures compared with pistil organs. In terms of organic acid and soluble sugar contents, significant differences were determined for both apricot cultivars and between the pistil and the receptacle organs of the flowers. Organic acid content was higher in the freezing-tolerant apricot cultivar (‘Iğdır Şalak’) than the freezing-sensitive apricot cultivar (‘Mihralibey’), but it was lower in the freezing-tolerant organ (pistil) in comparison with the freezing-sensitive organ (receptacle). Moreover, fructose concentrations for both ‘Mihralibey’ and ‘Iğdır Şalak’ were significantly higher in the receptacle compared to the pistil. A significant negative correlation was also observed between the mean CDP values and both all organic acids and sucrose contents in the pistil and the receptacle organs for both apricot cultivars. There was a positive relationship between the CDP values and fructose content in ‘Iğdır Şalak’. Additionally, there was a negative correlation between the CDP values and sucrose in 'Mihralibey'. Overall, the data presented suggest that the high level of sucrose and organic acid content of receptacle and pistil organs contributes to support frost tolerance of organs. The results of this study could help in the understanding of how receptacle and pistil organs of two different apricot cultivars react to frost stress, and how they modulate their soluble sugar and organic acid metabolism.

Graphic abstract

中文翻译：

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有机酸和糖成分能否用于预测细胞死亡点极限？杏 (Prunus armeniaca L.) 的花托和雌蕊器官

为了加深我们对杏树近期霜冻损害事件的了解，我们通过在实验室冷冻实验中模拟早春发生的意外温度变化，专注于估计杏花托和雌蕊器官中的细胞死亡点。还假设有机酸（草酸、丙酸、酒石酸、丁酸、丙二酸、苹果酸、乳酸、柠檬酸、马来酸、富马酸和琥珀酸）和可溶性糖成分（葡萄糖、果糖、蔗糖和总糖）可以直接刺激用两种杏（Prunus armeniaca）研究了杏花托和雌蕊器官的抗冻性L.) 栽培品种，一种耐霜冻 ('Iğdır Şalak')，另一种对霜冻敏感 ('Mihralibey')。我们的结果表明，在两个杏品种中，花蕊的平均细胞死亡点（CDP）（从 -13.26 到 -14.18 °C）低于花托（从 -6.28 到 -8.65 °C）的温度。盛开的阶段。在两个杏品种中，与雌蕊器官相比，贮器器官对低温的抗冻性变化更为敏感。在有机酸和可溶性糖含量方面，两个杏品种以及花的雌蕊和花托器官之间存在显着差异。耐冻杏品种 ('Iğdır Şalak') 的有机酸含量高于对冷冻敏感的杏品种 ('Mihralibey')，但与冷冻敏感器官（容器）相比，耐冷冻器官（雌蕊）中的含量较低。此外，与雌蕊相比，容器中“Mihralibey”和“Iğdır Şalak”的果糖浓度明显更高。在平均 CDP 值与两个杏品种的雌蕊和贮器器官中的所有有机酸和蔗糖含量之间也观察到显着的负相关。'Iğdır Şalak' 中的 CDP 值与果糖含量之间存在正相关关系。此外，“Mihralibey”中的 CDP 值与蔗糖之间存在负相关。总体而言，所提供的数据表明，花托和雌蕊器官的高水平蔗糖和有机酸含量有助于支持器官的耐霜性。

图形摘要