RUI: The cell biology of pectin dynamics in the Charophycean Green Algae: Homogalacturonan secretion in the model organism, Penium margaritaceum

细胞壁聚合物是绿色植物生长、发育和生存的重要生化物质，是地球上最丰富的生化物质。果胶是一类主要的细胞壁聚合物，具有调节细胞壁膨胀和细胞生长以及细胞壁孔隙度和关键离子吸收的功能。果胶的合成、分泌和分泌后重塑代表了植物细胞生命中关键的亚细胞事件，阐明这些过程的具体研究才刚刚开始。果胶存在于所有陆生植物群中，最近在Charophycean Green Algae （CGA）中被发现。CGA代表了现存的绿藻群，它们是现代陆地植物的祖先。本项目利用来自CGA的模式生物——margaritaceum，从定量方面研究果胶分泌、亚细胞成分在果胶和细胞壁加工中的具体作用，以及一种关键果胶修饰酶的作用。本项目应用各种实验、显微镜和免疫标记技术来研究内膜系统、细胞骨架/细胞细胞网络以及与果胶向细胞壁分泌复杂相关的细胞表面现象。该项目的研究结果将用于植物果胶动力学模型的构建，并将为绿色植物细胞对细胞壁聚合物的加工、多个亚细胞系统在确定的分泌活动中的协调相互作用以及原始绿色植物的进化提供新的见解。该RUI项目将为斯基德莫尔学院的4名本科生提供暑期研究机会，为6-10名本科生提供学期研究机会。本计画也将促进研究与教育的整合，作为计画的组成部分，将用于加强植物生物学、植物生理学和生物电子显微镜等课程的教学和支持实验室经验。该项目还包括为大学预科学生提供外展体验。具体地说，拓展计划包括一系列由PI和Skidmore生物学专业的学生向小学生和他们的老师介绍微观世界的积极报告。此外，PI和他的学生将带领高中和初中的学生和他们的老师周六去湿地实地考察。实地考察将包括收集显微镜标本的活动，随后进行显微镜鉴定练习。这项研究的结果将通过学生/个人报告和出版物、外展计划以及最近在斯基德莫尔学院建立的CGA网站广泛传播。

Intellectual Merit Cell wall polymers are important biochemicals in the growth, development and survival of green plants and constitute the most abundant biochemicals on the planet. Pectins represent one of the major classes of cell wall polymers and function in regulating cell wall expansion and cell growth as well as cell wall porosity and uptake of key ions. The synthesis, secretion and post-secretory remodeling of pectins represent key subcellular events in the life of a plant cell and specific studies to elucidate these processes have only just begun. Pectins are found in all land plant groups and have been recently characterized in the Charophycean Green Algae (CGA). The CGA represent the extant group of green algae that is ancestral to modern-day land plants. In this project, a model organism from the CGA, Penium margaritaceum, is employed to study quantitative aspects of pectin secretion, the specific role of subcellular components in pectin and cell wall processing, and the role of a key pectin-modifying enzyme. This project applies various experimental, microscopy-based and immunolabeling technologies to studies of the endomembrane system, cytoskeletal/cytomotile networks, and cell surface phenomena that are intricately involved in the secretion of pectins to the cell wall. The results of this project will be synthesized and used in the construction of models of pectin dynamics in plants and will provide insight into cell wall polymer processing by green plant cells, the coordinated interaction of multiple subcellular systems in defined secretory activities, and the evolution of primitive green plants. Broader Impacts This RUI project will provide summer research opportunities for 4 undergraduates and semester-based research opportunities for 6-10 undergraduates at Skidmore College. The project also will promote the integration of research in education as components of the project will be used to enhance instruction and support laboratory experiences in courses as Plant Biology, Plant Physiology, and Biological Electron Microscopy. The project also includes outreach experiences for pre-college students. Specifically the outreach plan includes a series of active presentations by the PI and Skidmore biology majors to elementary students and their teachers on the microscopic world. In addition the PI and his students will lead Saturday field trips to wetlands for high school and middle school students and their teachers. The field trips will include activities in collecting microscopic specimen followed by identification exercises with the microscope. The results of the study will be broadly disseminated through student/PI presentations and publications, outreach programs, and the recently established CGA website at Skidmore College.