Department of Botany, University of Innsbruck, Innsbruck, Austria.
Department of Botany, Charles University of Prague, Prague, Czech Republic.
Plant Biol (Stuttg). 2022 Oct;24(6):939-949. doi: 10.1111/plb.13454. Epub 2022 Aug 11.
Success or failure of plants to cope with freezing temperatures can critically influence plant distribution and adaptation to new habitats. Especially in alpine environments, frost is a likely major selective force driving adaptation. In Arabidopsis arenosa (L.) Lawalrée, alpine populations have evolved independently in different mountain ranges, enabling studying mechanisms of acclimation and adaptation to alpine environments. We tested for heritable, parallel differentiation in freezing resistance, cold acclimation potential and ice management strategies using eight alpine and eight foothill populations. Plants from three European mountain ranges (Niedere Tauern, Făgăraș and Tatra Mountains) were grown from seeds of tetraploid populations in four common gardens, together with diploid populations from the Tatra Mountains. Freezing resistance was assessed using controlled freezing treatments and measuring effective quantum yield of photosystem II, and ice management strategies by infrared video thermography and cryomicroscopy. The alpine ecotype had a higher cold acclimation potential than the foothill ecotype, whereby this differentiation was more pronounced in tetraploid than diploid populations. However, no ecotypic differentiation was found in one region (Făgăraș), where the ancient lineage had a different evolutionary history. Upon freezing, an ice lens within a lacuna between the palisade and spongy parenchyma tissues was formed by separation of leaf tissues, a mechanism not previously reported for herbaceous species. The dynamic adjustment of freezing resistance to temperature conditions may be particularly important in alpine environments characterized by large temperature fluctuations. Furthermore, the formation of an extracellular ice lens may be a useful strategy to avoid tissue damage during freezing.
植物应对冰冻温度的成败可能会极大地影响植物的分布和对新栖息地的适应。特别是在高山环境中，霜是一种可能的主要选择压力，推动着适应的发生。在高山环境中，Arabidopsis arenosa (L.) Lawalrée 的高山种群已经在不同的山脉中独立进化，这使得我们能够研究适应高山环境的驯化和适应机制。我们使用 8 个高山种群和 8 个山麓种群，测试了冰冻抗性、冷驯化潜力和冰管理策略的可遗传、平行分化。来自三个欧洲山脉（Niedere Tauern、Făgăraș 和 Tatra Mountains）的植物是从四倍体种群的种子在四个普通花园中生长的，同时还有来自 Tatra Mountains 的二倍体种群。使用受控冷冻处理和测量光系统 II 的有效量子产量来评估冰冻抗性，通过红外视频热成像和冷冻显微镜来评估冰管理策略。高山生态型比山麓生态型具有更高的冷驯化潜力，而这种分化在四倍体种群中比二倍体种群更为明显。然而，在一个地区（Făgăraș）没有发现生态型分化，在这个地区，古老的谱系具有不同的进化历史。在冷冻过程中，通过叶组织的分离，在栅栏组织和海绵状薄壁组织之间的空隙内形成一个冰透镜，这是以前在草本物种中没有报道过的机制。对冰冻抗性的动态调整以适应温度条件可能在温度波动较大的高山环境中尤为重要。此外，形成细胞外冰透镜可能是避免组织在冷冻过程中受损的一种有用策略。
