Thermal Adaptation of Polar Macroalgae

戴维森9418033使某些植物物种能够在全年气温接近或低于0摄氏度的极地环境中生存和生长的遗传适应机制知之甚少。陆生植物的低温适应由于冰冻、干燥和气孔导度的影响而变得复杂，而海洋浮游植物的低温适应则受到可变和不可预测的物理环境的影响。极地大型藻类提供了一种不受这些并发症影响的实验系统，非常适合于植物冷适应的研究。南极大型藻类对冷的适应性特别强，其光合作用和生长速率与温带物种在10-15oC时达到的速率相当。这项拟议的研究使用了北极和南极特有的海藻来回答这样一个问题：“极地藻类具有哪些适应能力，使它们能够吸收碳，并在极低的温度下快速生长？”本研究重点研究了极温带褐藻三对紧密相关的碳代谢特征：北极海带和温带海带，南极海带和温带海带，以及与海带相似但形态相似的南极大叶大叶海带。在冷适应中重要的碳代谢过程(光合作用、呼吸作用和与光无关的碳固定)将在驯化相同温度的每一种对的孢子体中确定。具体的适应机制将通过比较光合作用装置的组成以及光合作用、呼吸作用和与光无关的固碳作用所涉及的关键酶的含量、活性和热性质来确定。多个物种对和一套广泛的碳同化参数的比较将提供对北冰洋和南极特有藻类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了解。

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.