SeaWall: Understanding environmentally induced cell wall remodelling in the green seaweed Ulva sp.

海藻如世界范围内广泛存在的绿色大型藻类石榴藻。(绿藻)在其沿海栖息地面临恶劣的环境条件，但它们产生了被称为“绿潮”的巨大生物量积累。这些水华的主要物质是多层细胞壁，这是一种包裹在每个细胞周围的富含多糖的基质，占藻类干物质的60%。细胞壁是敏感的藻类原生质体与环境之间唯一的物理屏障。这使得它们成为胁迫生存的关键要素，例如，通过增加细胞的保水能力，或通过在干燥-再水化循环中帮助受控的收缩和扩张。然而，Ulva细胞壁的组成和结构如何响应外部非生物因素，如缺水，在很大程度上是未知的。这是知识上的一个根本差距，因为它限制了我们对海藻如何应对沿海栖息地的压力并保持其高度生态意义的理解。为了更好地了解Ulva的生态成功，我们将结合生态生理监测与最先进的生物成像和化学生物学工具，研究环境因素如何塑造Ulva细胞壁的组成、重塑和结构。首先，我们将从田间采集各种石榴体，并建立稳定的培养体系。下一步，我们将建造一个环境室，使我们能够将石榴暴露在沿海栖息地典型的水、温度和光照压力下。最后，我们将利用成像和化学生物学工具来可视化和量化由于体内和原位环境条件变化而导致的Ulva细胞壁成分的化学和结构变化。我们预计，我们的跨学科方法将使我们能够揭示海藻细胞壁重组的未知特征(例如，细胞壁成分的酶促重塑)，帮助我们更好地了解海藻如何应对压力。这将为未来旨在最大限度提高生物量产量的海藻养殖努力提供关键信息，并为揭开海藻细胞壁重塑的分子基础奠定基础。

Seaweeds such as the worldwide occurring green macroalgae Ulva sp. (Chlorophyta) face harsh environmental conditions in their coastal habitats, yet they produce tremendous biomass accumulations known as “green tides”. The bulk material in these blooms are multi-layered cell walls, which are a polysaccharide-rich matrix that surrounds every cell and constitute up to ~60% of the algal dry matter. Cell walls are the only physical barrier between the sensitive algal protoplast and the environment. This makes them key elements in stress survival, for example, by increasing the water holding capacity of cells or by assisting a controlled shrinkage and expansion during desiccation-rehydration cycles. However, it is largely unknown how the Ulva cell wall composition and architecture respond to external abiotic factors such as water scarcity. This is a fundamental gap in knowledge, because it limits our understanding of how seaweeds cope which stress in coastal habitats and sustain their high ecological significance. To better understand Ulva’s ecological success, we will combine eco-physiological monitoring with state-of-the-art bioimaging and chemical biology tools to investigate how environmental factors shape the composition, remodelling and architecture of the Ulva cell wall. First, we will collect various Ulva thalli from the field and establish stable cultures. Next, we will construct an environmental chamber allowing us to expose Ulva thalli to defined water, temperature, and light stresses typical for coastal habitats. Finally, we will implement imaging and chemical biology tools to visualize and quantify chemical and structural changes of the Ulva cell wall composition due to changing environmental conditions in vivo and in situ. We anticipate that our interdisciplinary approach will allow us to uncover unknown features of seaweed cell wall reorganisation (e.g. enzymatic remodelling of cell wall components), helping us to better understand how seaweeds cope with stress. This will provide crucial information for future seaweed farming efforts that aim to maximize biomass production and provide a foundation for unravelling the molecular basis of cell wall remodelling in seaweeds.