Metabolism and regulation of ancient protective biopolymers in the moss, Physcomitrella

大约5亿年前植物从水生环境向陆地环境的转变是地球生命进化中最重要的事件之一。在陆地上，早期的陆地植物遇到了新的挑战，包括在紫外线照射、干燥和重力下存活。为了应对这些挑战，早期的陆地植物发展出了保护性的胞外基质，其中包括孢粉、角质层和木质素。孢粉蛋白是孢子和花粉粒外壁的主要聚合物成分，角质层是气生植物组织的脂类外层。木质素是后来发展起来的一类酚类聚合物，它能使维管植物组织具有刚性。苔藓植物由苔藓、苔藓和角藻组成，是陆地植物中最简单和最早分化的谱系，为了解陆地植物的早期进化提供了独特的窗口。由于拥有完整的基因组序列和其他研究资源，小立苔藓已成为研究植物进化的模式苔藓植物。在Physcomitrella中，可以有效地敲除目标基因，使研究人员能够研究目标基因的功能。本研究试图了解保护物质在早期陆地植物进化过程中的代谢途径是如何进化的，这是植物科学中的一个基本的突出问题。利用多方面、跨学科和基于假设的方法，我们将确定孢粉蛋白在孢子成熟过程中如何聚合，在孢子萌发过程中如何解聚。我们还将研究角质层和木质素类酚类化合物的生物合成、代谢和调节，以提供植物的脱水耐受性和机械强度。这项研究将导致适用于其他植物物种的新发现，并为最早的植物如何成功适应陆地提供新的见解。孢粉素生物合成基因是产生植物雄性不育的良好靶标，可用于杂交制种和森林/作物控制。作为最强大的生物聚合物，孢粉蛋白在生物技术(可生物降解聚合物)、医药(口服疫苗和药物载体)和废水处理(金属吸附剂)方面也有独特的应用。我们的研究也可能为提高其他重要农业植物的脱水耐性提供新的策略。该计划利用各种研究工具，从而提供从分子生物学到植物化学等不同植物科学领域的培训机会。在植物科学的多个核心领域接受培训的HQP将有助于加拿大科学和技术的进步。

The transition of plants from aquatic to terrestrial environments about 500 million years ago is one of the most important events in the evolution of life on earth. On land, early land plants encountered new challenges, which included surviving exposure to UV irradiation, desiccation and gravity. In order to cope with these challenges, early land plants developed, among other attributes, protective extracellular matrices of sporopollenin, cuticle and lignin. Sporopollenin is the main polymeric constituent of the outer walls of spore and pollen grain and the cuticle is a lipidic outer layer of aerial plant tissues. Lignin, which evolved later, is a class of phenolic polymers that lend rigidity to vascular plant tissue. Bryophytes comprising liverworts, mosses, and hornworts are the simplest and earliest-diverging lineages of land plants, and offer unique windows into the early evolution of land plants. With a complete genome sequence and other research resources, the moss Physcomitrella patens has emerged as a model bryophyte for research on plant evolution. In Physcomitrella, a target gene can efficiently be knocked out, allowing researchers to study the function of the target gene. This research program seeks to understand how the metabolic pathways for the protective materials evolved during early land plant evolution, which is one of the fundamental outstanding questions in plant science. Using multi-faceted, interdisciplinary and hypothesis-based approaches, we will determine how sporopollenin is polymerized during spore maturation and depolymerized during spore germination. We will also study the biosynthesis, metabolism and regulation of the cuticle and lignin-like phenolic compounds that provide the plant with desiccation tolerance and mechanical strength. This research will lead to novel discoveries that are applicable to other plant species, and provide new insights into how the earliest plants successfully adapted on land. Sporopollenin biosynthetic genes are good targets to generate plant male sterility for hybrid seed production and forest/crop control. Being the most robust biopolymer, sporopollenin also has unique applications in biotechnology (biodegradable polymer), medicine (oral vaccination and drug carrier) and wastewater treatment (metal sorbents). Our research may also lead to a new strategy for improving desiccation tolerance in other plants of agricultural importance. This program utilizes diverse research tools and thereby offers training opportunities in different areas of plant science ranging from molecular biology to phytochemistry. HQPs trained in multiple core areas in plant science will contribute to the advancement of science and technology in Canada.