Vuosku Jaana, Martz Françoise, Hallikainen Ville, Rautio Pasi
Natural Resources Unit, Natural Resources Institute Finland, Rovaniemi, Finland.
Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland.
Front Plant Sci. 2022 Dec 9;13:1050903. doi: 10.3389/fpls.2022.1050903. eCollection 2022.
In northern boreal forests the warming winter climate leads to more frequent snowmelt, rain-on-snow events and freeze-thaw cycles. This may be harmful or even lethal for tree seedlings that spend even a half of the year under snow. We conducted a snow cover manipulation experiment in a natural forest to find out how changing snow conditions affect young Scots pine ( L.) seedlings. The ice encasement (IE), absence of snow (NoSNOW) and snow compaction (COMP) treatments affected ground level temperature, ground frost and subnivean gas concentrations compared to the ambient snow cover (AMB) and led to the increased physical damage and mortality of seedlings. The expression responses of 28 genes related to circadian clock, aerobic and anaerobic energy metabolism, carbohydrate metabolism and stress protection revealed that seedlings were exposed to different stresses in a complex way depending on the thickness and quality of the snow cover. The IE treatment caused hypoxic stress and probably affected roots which resulted in reduced water uptake in the beginning of the growing season. Without protective snowpack in NoSNOW seedlings suffered from cold and drought stresses. The combination of hypoxic and cold stresses in COMP evoked unique transcriptional responses including oxidative stress. Snow cover manipulation induced changes in the expression of several circadian clock related genes suggested that photoreceptors and the circadian clock system play an essential role in the adaptation of Scots pine seedlings to stresses under different snow conditions. Our findings show that warming winter climate alters snow conditions and consequently causes Scots pine seedlings various abiotic stresses, whose effects extend from overwintering to the following growing season.
在北方针叶林中，冬季气候变暖导致融雪、雨雪天气和冻融循环更加频繁。这对于那些一年中有半年时间处于积雪之下的树苗来说可能是有害的，甚至是致命的。我们在一片天然森林中进行了一项积雪控制实验，以了解积雪条件的变化如何影响苏格兰松（Pinus sylvestris L.）幼苗。与自然积雪（AMB）相比，冰层包裹（IE）、无雪（NoSNOW）和积雪压实（COMP）处理影响了地面温度、地面霜冻和雪下气体浓度，并导致幼苗的物理损伤和死亡率增加。对28个与生物钟、有氧和无氧能量代谢、碳水化合物代谢及应激保护相关基因的表达响应表明，根据积雪的厚度和质量，幼苗以复杂的方式受到不同的胁迫。IE处理导致缺氧胁迫，可能影响根系，从而在生长季节开始时导致水分吸收减少。在NoSNOW处理中，没有保护性积雪的幼苗遭受寒冷和干旱胁迫。COMP处理中缺氧和寒冷胁迫的组合引发了包括氧化应激在内的独特转录反应。积雪控制诱导了几个与生物钟相关基因表达的变化，这表明光感受器和生物钟系统在苏格兰松幼苗适应不同积雪条件下的胁迫中起着至关重要的作用。我们的研究结果表明，冬季气候变暖改变了积雪条件，从而给苏格兰松幼苗带来了各种非生物胁迫，其影响从越冬期一直延伸到次年生长季节。
