Collaborative Research:RUI: Invasion of land: Using model charophyte Penium margaritaceum to elucidate subcellular responses to stress that were key in the evolution of land plants

4.5亿至5亿年前绿色藻类在陆地上的定居及其演变成陆地植物是地球自然史上的重要事件。这些陆生植物对地球的生物化学和生物圈造成了重大变化。陆地植物是从称为轮藻的绿色藻类进化而来的，轮藻是一种小型但多样的淡水和陆地生物。轮藻在陆地上成功定居的关键是它们细胞周围的细胞外基质（ECM）。这种ECM由覆盖细胞外部的壁和从这些生物体分泌的凝胶状物质组成。该项目将提供一个全面的了解的形成和功能的轮藻被测试，Penium的ECM。这种生物将在各种环境条件下生长，包括水分胁迫和极端干燥。ECM及其相关的生物合成过程将使用以前由美国国家科学基金会资助的尖端技术进行研究。这项研究将深入了解古代轮藻在陆地上开始生存的重要机制，以及当今许多陆地植物仍然使用的机制。这些信息将用于设计植物如何适应陆地生活以及如何忍受干旱等非生物胁迫的模型。该项目还将提供博士后培训和暑期本科生研究的机会，为当地高中生启动外部暑期项目，并作为未来课程开发的基础。该项目的目标是提供对模式轮藻Penium细胞外基质（ECM）及其生物合成动力学的全面了解。它将检查当细胞被置于干燥应力下时ECM处理中发生的变化。ECM及其生物合成机制将使用分子，生物化学和高分辨率显微镜技术进行研究，这些技术以前由美国国家科学基金会资助。这将提供对古代轮藻在陆地上生存的重要机制的深入了解，并继续被许多陆地植物使用，包括那些暴露于干旱的植物。要研究的具体领域包括：（A）Penium中的极性细胞生长，重点是壁扩张期间的果胶和纤维素产生;（B）涉及两种不同途径的ECM组分的分泌，细胞壁多糖沿着递送至特定扩张区的细胞外聚合物（EPS）靶向暂时分泌位点;（C）细胞壁结构的变化;和（D）对于耐受非生物胁迫至关重要的EPS靶向生产和递送。本项目的研究结果对植物进化生物学、细胞生物学、分子生物学和发育生物学等领域具有重要意义。该项目还将为外联和学生培训提供重要机会。

The colonization of land by green algae 450 to 500 million years ago and their evolution into land plants represent important events in the natural history of the planet. These terrestrial (land) plants have caused major changes to the Earth's biochemistry and biosphere. Land plants evolved from green algae called charophytes, a small but diverse group of freshwater and terrestrial organisms. Central to the success of the charophyte colonization of land was the extracellular matrix (ECM) that surrounds their cells. This ECM is made up of a wall that covers the outside of the cell and the gel-like substances that are secreted from these organisms. This project will provide a comprehensive understanding of the formation and function of the ECM of the charophyte being tested, Penium. This organism will be grown under various environmental conditions, including water stress and extreme dryness. The ECM and its related biosynthetic processes will be studied using cutting edge technologies that were previously funded by the National Science Foundation. This research will provide insight into the mechanisms that were important to initiate survival on land by ancient charophytes, as well as mechanisms that are still used by many land plants today. This information will be used to devise models of how plants adapt to life on land and how they tolerate non-biological stresses such as drought. This project will also provide opportunities for post-doctoral training and summer undergraduate research, initiate external summer programs for local high school students, and serve as a basis for future course development.The goal of this project is to provide a comprehensive understanding of the extracellular matrix (ECM) and its biosynthesis dynamics in the model charophyte, Penium. It will examine the changes that occur in ECM processing when cells are placed under desiccation stress. The ECM and its biosynthetic machinery will be studied using molecular, biochemical, and high resolution microscopy technologies previously funded by the National Science Foundation. This will provide insight into mechanisms that were important to survival on land by ancient charophytes and continue to be used by many land plants, including those exposed to drought. Specific areas to be studied include: (A) polar cell growth in Penium, with an emphasis on pectin and cellulose production during wall expansion; (B) the secretion of ECM components involving two distinct pathways, the cell wall polysaccharides delivered to specific expansion zones along with extracellular polymeric substances extracellular (EPS) targeted to transitory secretion sites; (C) changes in cell wall architecture; and (D) EPS targeted production and delivery that are critical for tolerating abiotic stresses. The results of this project will be of significance to the fields of plant evolutionary biology, cell biology, molecular biology, and developmental biology. This project will also provide significant opportunities for outreach and student training.