Desiccation tolerance is a developmental program enabling seed survival in a dry state and is common in seeds categorized as orthodox. We focused on NAD and its phosphorylated form (NADP) because their continual switching between reduced (NAD(P)H) and oxidized (NAD(P)⁺) forms is involved in the modulation of redox signaling and the determination of the reducing power and further antioxidant responses. Norway maple and sycamore seeds representing the orthodox and recalcitrant categories, respectively, were used as models in a comparison of responses to water loss. The process of desiccation up to 10% water content (WC) was monitored in Norway maple seeds, while dehydration up to 30% WC was monitored in desiccation-sensitive sycamore seeds. Norway maple and sycamore seeds, particularly their embryonic axes, exhibited a distinct redox status during dehydration and desiccation. High NADPH levels, NAD⁺ accumulation, low and stable NAD(P)H/NAD(P)⁺ ratios expressed as reducing power and high NADPH-dependent enzyme activity were reported in Norway maple seeds and were considered attributes of orthodox-type seeds. The contrasting results of sycamore seeds contributed to their low antioxidant capacity and high sensitivity to desiccation. NADPH deficiency, low NADPH-dependent enzyme activity and lack of NAD⁺ accumulation were primary features of sycamore seeds, with implications for their NAD(P)H/NAD(P)⁺ ratios and reducing power and with effects on many seed traits. Thus, we propose that the distinct levels of pyridine nucleotides and their redox status contribute to orthodox and recalcitrant phenotype differentiation in seeds by affecting cellular redox signaling, metabolism and the antioxidant system.

中文翻译：

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NAD（P）驱动的氧化还原状态有助于提高Acer种子的耐干旱性。

耐干燥性是一项发展计划，能够使种子在干燥状态下存活，并且在归为正统的种子中很常见。我们专注于NAD及其磷酸化形式（NADP），因为它们在还原（NAD（P）H）和氧化（NAD（P）⁺）形式参与氧化还原信号的调节以及还原能力和进一步的抗氧化剂反应的确定。在分别比较失水反应的模型中，分别使用挪威枫树和无花果种子分别代表正统和顽固的类别。在挪威枫树种子中监测了高达10％水分含量（WC）的干燥过程，而在对干燥敏感的无花果种子中监测了高达30％WC的脱水过程。挪威枫树和无花果种子，特别是它们的胚轴，在脱水和干燥过程中表现出独特的氧化还原状态。高NADPH水平，NAD ⁺积累，低而稳定的NAD（P）H / NAD（P）⁺在挪威枫树种子中报道了以降低能力和高NADPH依赖性酶活性表示的比率，被认为是正统型种子的属性。无花果种子的对比结果有助于降低其抗氧化能力和对干燥的高度敏感性。NADPH缺乏，NADPH依赖性酶活性低和缺乏NAD ⁺积累是无花果种子的主要特征，影响了它们的NAD（P）H / NAD（P）⁺比例和还原力，并影响了许多种子性状。因此，我们认为吡啶核苷酸的不同水平及其氧化还原状态通过影响细胞氧化还原信号传导，代谢和抗氧化系统，有助于种​​子中的正统和顽固表型分化。