Changes in precipitation and snow melt during warmer winters can increase low‐temperature waterlogging. Such conditions may bring about different effects when compared with a single stress trigger, such as low‐temperature or water excess. The effects of waterlogging are clearly related to water temperature, and the consequences of water excess might be less severe, as more oxygen is dissolved in colder water. The effect of waterlogging during cold acclimation (CA) is poorly understood; most experiments concerning water excess are performed at relatively high‐temperatures. In this study, we examined the effect of 3 weeks of waterlogging (approx. 2 cm above the soil level) on CA in Festuca pratensis Huds. (Fp), a cool‐season grass. Measurements were taken before CA (after prehardening, before flooding) and after 3 weeks of CA in waterlogged (treated) and non‐waterlogged (control) plants. The work included: (i) freezing tolerance test (regrowth after freezing), (ii) analysis of abscisic acid (ABA) content in the leaf, (iii) leaf stomatal conductance, (iv) leaf water content, (v) carbohydrates analysis, including fructans, and (vi) transcript levels of selected genes involved in freezing tolerance, ABA signalling and fructan biosynthesis. The aim of the study was to test a hypothesis that low‐temperature waterlogging in Fp enhances freezing tolerance (plant regrowth after freezing) related to increased ABA accumulation, increased C‐repeat‐binding transcription factor expression and/or increased carbohydrate accumulation, including fructans. Two out of four genotypes exhibited enhanced regrowth following freezing due to waterlogging relative to control. Principal component analysis (PCA) revealed a positive correlation between ABA levels and freezing tolerance in both treatments, with a more pronounced effect observed in the waterlogged plants. However, the phytohormone played different roles in these two treatments. In the context of low‐temperature waterlogging, ABA may be involved in the dehydration tolerance response in genotypes suffering from physiological drought, as well as the induction of C‐repeat‐binding transcription factors (CBFs) and sucrose, which may improve freezing tolerance. The increased fructan amount and polymerisation degree due to waterlogging may provide a carbohydrate sink to maintain a high photosynthetic efficiency, but are not directly responsible for freezing tolerance changes. The study indicates that tolerance mechanisms of Fp exposed to low‐temperature waterlogging involve maintaining a high photosynthetic rate, as well as oxidative and dehydration stress tolerance.

中文翻译：

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涝渍引起的 ABA、碳水化合物和 CBF6 变化改变了预硬羊茅的耐冻性


暖冬期间降水和融雪的变化会加剧低温内涝。与单一的应激触发因素（例如低温或水分过多）相比，这些条件可能会带来不同的影响。内涝的影响显然与水温有关，而且水过多的后果可能不太严重，因为更多的氧气溶解在较冷的水中。冷驯化 (CA) 过程中水涝的影响知之甚少；大多数关于水过量的实验都是在相对较高的温度下进行的。在本研究中，我们研究了 3 周的涝渍（高于土壤水平约 2 厘米）对 CA 的影响。羊茅平视显示器。 (Fp)，一种冷季草。在 CA 之前（预硬化后，淹没前）和 CA 3 周后，对浸水（处理）和非浸水（对照）植物进行测量。工作内容包括：（i）耐冻性测试（冷冻后再生），（ii）叶片中脱落酸（ABA）含量分析，（iii）叶片气孔导度，（iv）叶片含水量，（v）碳水化合物分析，包括果聚糖，以及 (vi) 参与冷冻耐受性、ABA 信号传导和果聚糖生物合成的选定基因的转录水平。该研究的目的是检验一个假设，即 Fp 的低温浸水增强了耐冻性（植物在冷冻后重新生长），这与 ABA 积累增加、C 重复结合转录因子表达增加和/或碳水化合物积累增加（包括果聚糖）相关。 。相对于对照，四分之二的基因型在由于水涝而冻结后表现出增强的再生能力。 主成分分析 (PCA) 显示两种处理中 ABA 水平与耐冻性之间呈正相关，在浸水植物中观察到更明显的影响。然而，植物激素在这两种治疗中发挥着不同的作用。在低温涝害的背景下，ABA可能参与生理干旱基因型的耐脱水反应，以及C-重复结合转录因子（CBF）和蔗糖的诱导，从而可能提高耐冻性。由于水涝而增加的果聚糖量和聚合度可能提供碳水化合物库以维持高光合效率，但并不直接导致耐冻性变化。研究表明，Fp对低温涝害的耐受机制包括维持高光合速率以及氧化和脱水胁迫耐受性。