Evolution of Rab GTPase functions and endomembrane compartments in land plants

大多数人类依靠植物获得食物、燃料、衣服、建筑材料和药物（木材、石油、棉花、谷物、豆类、亚麻等）。随着对植物生物学了解的增加，它们很可能在不久的将来能够生产新型燃料和药品，并以更低的投入或更贫瘠的土地生产传统产品。我们想更多地了解植物是如何生长并产生这些有价值的产品的。特别是植物细胞壁提供了多种重要的商品，从膳食纤维到潜在的新型生物燃料，但这些结构的复杂性和多样性仍在揭示中。我们很少了解细胞内部的成分是如何组装和组织细胞外部细胞壁的各种成分的。虽然声称我们提出的研究将直接改善任何商业产品或工艺是不诚实的，但我们获得的知识可能有助于未来植物基材料的合理设计。我们也有好奇心驱使我们进行这项研究的原因。植物是由细胞组成的，每个细胞都生长成特定的大小和形状，这有助于有机体的整体形式和功能。我们正试图了解一些允许细胞这样做的机制。具体来说，我们想要了解细胞的不同内部区室是如何促进细胞生长和形状的，这些系统是如何进化的，以及它们如何与其他复杂生物（如人类）中执行类似功能的系统进行比较。大约15亿年前，植物、动物和真菌有着共同的祖先。那个祖先可能是一个单细胞，拥有现代后代所有细胞共有的基本元素。虽然植物细胞中发生的许多过程与动物和真菌的过程有相似之处，但同样清楚的是，在进化过程中，每一组生物都对原始机制进行了详细阐述，以满足它们在海洋和陆地上日益复杂的环境所施加的特殊要求。部分证据来自基因组测序项目，该项目揭示了生物体所制造的蛋白质的复杂性。我们特别关注一个蛋白家族（“Rab蛋白”），它在定义植物细胞的内部区室和在它们之间指导物质方面起着关键作用。如果植物细胞要进行有组织的生长，新生成的分子被引导到适当的地方是至关重要的。我们可以看到，在过去的4.5亿年里，Rab蛋白家族的一些分支在植物中变得更加多样化。我们最近的工作表明，一个这样的分支定义了一个新的内部隔间，以前没有认识到。此外，在根和芽的生长尖端的细胞中，这种隔室沿着细胞边缘独特地定位，并且通过管道蛋白质的功能导致细胞在生长过程中失去对其形状的控制。我们现在想用遗传和生化的方法来更多地了解这个隔室的组成和功能，以及新的Rab蛋白的进化如何促进了这一点。

The majority of the humal population relies on plants for their food, fuel, clothing, building material, and medicines (timber, oil, cotton, grain, pulses, flax, etc etc). With increased understanding of plant biology, they are likley in the near future to be capable of producing novel types of fuel and medicine and also to deliver traditional products with lower inputs or on more marginal land. We would like to understand more about how plants grow and produce these valuable products. In particular plant cell walls provide a variety of important commodities from dietary fibre to potential new biofuels but the complexity and diversity of these structures is still being revealled. We have very little understanding of how the components on the inside of the cells assemble and organise the diverse components of the wall on the outside of the cell. While it would be disingenuous to claim that the research we propse will directly improve any commercial product or process, the knowldge we gain may help ratuional design of plant-based materials in the future. We also have curiosity-driven reasons for wanting to perform thsi research. Plants are composed of cells that each grow to adopt a specific size and shape that contribute to the overall form and function of the organism. We are trying to understanding some of the mechanisms that allow cells to do this. Specifically we want to understand how the diverse internal compartments of the cells contribute to cell growth and shape, how these systems evolved, and how they compare to the systems that perform analogous functions in other compex organisms such as humans. Plants, animals, and fungi shared a common ancestor approximately a one and half billion years ago. That ancester was probaby a single cell that had the basic elements shared by all cells of modern day descendants. While much of the what occurs in plant cells shares similarity with processes in animals and fungi it is also clear that during evolution, each group of organisms has elaborated on the original mechanisms to meet the specific demands imposed by their inceasing complexity in the sea and on land. Part of this evidence comes from genome sequencing projects which reveals the complexity of the proteins that an organism an make. We focus specifially on one family of proteins (the 'Rab proteins') which have a key role in defining the internal compartents of plant cells and directing material between them. It is essntial that newly made molecules are directed to the appropriate place if plant cells are to undergo organised growth. We can see that some branches of the Rab protein family have become much more diverse in plants during their collonisation of land over the last 450 million years. Our recent work has shown that one such branch defines a new internal compartment not previously recognised. Furthermore in the cells at the growing tips of the root an shoot thsi compartment is uniquely localised along the edges of the cells and pertubing teh function of the protein causes the cells to lose control of their shape as they grow. We would now like to use genetic and biochemical methods to leran more about the compostion and function of this compartment and how the evolution of new types of Rab protein jas facilitated this.