Abstract Seed dormancy determines population dynamics and it is an essential feature of the ecology of high-mountain plants. Although altitudinal changes in the ecological and physiological performance of Pyrenean saxifrage (Saxifraga longifolia Lapeyr.) has been investigated to some extent, nothing it still know about how seed dormancy is influenced by environmental conditions imposed by altitude in these plants. Here, we evaluated altitudinal changes in seed viability and germination, but also on the endogenous contents of phytohormones and antioxidants in Pyrenean saxifrage. We found that, despite seed germination decreased at the highest population (2100 m a.s.l.) relative to the other two populations (at 570 and 1100 m a.s.l.), the highest population showed the highest seed viability, thus indicating increased seed dormancy. Hormonal profiling of the seeds revealed that this dormancy was modulated physiologically, in particular by increased abscisic acid accumulation, while gibberellin contents kept constant, relative to the seeds of the other two populations. Furthermore, seed xanthophyll contents, in particular those of lutein, neoxanthin, violaxanthin and antheraxanthin increased with altitude, while those of α-tocopherol kept unaltered. We conclude that the lower temperature imposed by altitude strongly influences not only seed viability and germination, but also seed dormancy, and that changes associated to temperature differences among populations are modulated at the physiological level by increasing the accumulation of abscisic acid and xantophylls in mature seeds. Results strongly support the contention that physiological seed dormancy has evolved as a means to increase plant survival under harsh environmental conditions in Pyrenean saxifrage plants growing in their natural habitat.

中文翻译：

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比利牛斯虎耳草（Saxifraga longifolia Lapeyr）的生理种子休眠在高海拔地区增加。

摘要 种子休眠决定种群动态，是高山植物生态学的基本特征。尽管已经对比利牛斯虎虎耳 (Saxifraga longifolia Lapeyr.) 的生态和生理性能的海拔变化进行了一定程度的调查，但它仍然不知道种子休眠如何受这些植物中海拔所施加的环境条件的影响。在这里，我们评估了种子活力和发芽的海拔变化，以及比利牛斯虎耳草中植物激素和抗氧化剂的内源含量。我们发现，尽管相对于其他两个种群（在 570 和 1100 m asl），最高种群（2100 m asl）的种子发芽率下降，但最高种群表现出最高的种子活力，从而表明种子休眠增加。种子的激素分析表明，这种休眠在生理上受到调节，特别是通过增加脱落酸积累，而赤霉素含量相对于其他两个种群的种子保持不变。此外，种子叶黄素的含量，特别是叶黄素、新黄质、紫黄质和花黄素的含量随海拔升高而增加，而α-生育酚的含量保持不变。我们得出结论，海拔高度施加的较低温度不仅强烈影响种子活力和发芽，而且强烈影响种子休眠，并且通过增加成熟种子中脱落酸和叶黄素的积累在生理水平上调节与种群间温度差异相关的变化.