Thermal Adaptation of Polar Macroalgae

使某些植物物种能够在全年温度接近或低于0摄氏度的极地环境中生存和生长的基因适应性尚不清楚。陆生植物的低温适应因其冻结、干燥和气孔导度而变得复杂，海洋浮游植物的低温适应则因其多变和不可预测的物理环境而变得复杂。极地巨藻提供了一个不受这些复杂因素影响的实验系统，非常适合研究植物的冷适应性。南极大型藻类的冷适应能力特别发达，其在OoC下的光合作用和生长速度与温带物种在10-15℃下的速度相当。这项拟议中的研究利用北极和南极特有的海藻来回答这个问题：“极地藻类具有什么样的适应性，使它们能够吸收碳，并在极低的温度下快速生长？”研究了3对亲缘关系较近的极温带褐藻：Arctic Laminaria solidungula和温带Laminaria saccharina；南极的马蹄莲（Desmarestia）和温带的马蹄莲（Desmarestia aculeata），以及与马蹄莲（Desmarestia）和马蹄莲（D. anceps）有亲缘关系，但在形态上与糖化海带（Laminaria saccharina）相似的南极大菱鲆（Himantothallus trifolius）。碳代谢过程（光合作用、呼吸作用和不依赖于光的碳固定）在冷适应中很重要，将在适应相同温度的每个物种对的孢子体中确定。具体的适应机制将通过比较光合机构的组成以及参与光合作用、呼吸作用和不依赖光的碳固定的关键酶的含量、活性和热性质来确定。多物种对的比较和广泛的碳同化参数将提供对北极和南极海洋特有藻类物种低温适应机制的全面分析，并增加对所有植物低温适应的总体理解。

Davison 9418033 The genetic adaptations that enable certain plant species to survive and grow in polar environments where temperatures are near or below 0oC year-round are poorly understood. Low- temperature adaptation is complicated in terrestrial plants by freezing, desiccation and stomatal conductance, and in marine phytoplankton by a variable and unpredictable physical environment. Polar macroalgae provide an experimental system that is not subject to these complications and that is well- suited to the study of cold-adaptation in plants. Cold- adaptation is particularly well developed in Antarctic macroalgae, in which rates of photosynthesis and growth at OoC are comparable to rates achieved at 10-15oC by temperate species. The proposed research uses endemic Arctic and Antarctic seaweeds to answer the question, "What adaptations do polar algae possess that enable them to assimilate carbon and grow rapidly at very low temperatures?" The research focusses on carbon-metabolism characteristics of three closely related polar-temperate pairs of brown algae: Arctic Laminaria solidungula and temperate Laminaria saccharina; Antarctic Desmarestia anceps and temperate Desmarestia aculeata, and Antarctic Himantothallus grandifolius that is related to Desmarestia aculeata and D. anceps, but is morphologically similar to Laminaria saccharina. Carbon-metabolism processes (photosynthesis, respiration and light-independent carbon fixation) that are important in cold-adaptation will be identified in sporophytes of each species pair acclimated to the same temperature. Specific mechanisms of adaptation will be determined by comparing components of the photosynthetic apparatus as well as contents, activities and thermal properties of key enzymes involved in photosynthesis, respiration and light- independent carbon fixation. Comparisons of multiple species pairs and a broad suite of carbon-assimilation parameters will provide a comprehensive analysis of the mechanisms o f low- temperature adaptation in algal species endemic to both the Arctic and Antarctic Oceans and increase an overall understanding of low temperature adaptation in all plants.