Evolution and diversity of secretory pathways in land plants.

大多数人口依靠植物获取食物、燃料、衣物、建筑材料和药品(木材、石油、棉花、谷物、豆类、亚麻等)。随着对植物生物学认识的加深，植物很可能在不久的将来能够生产新型燃料和药物，并以较低的投入或在更边际的土地上提供传统产品。我们想更多地了解植物是如何生长和生产这些有价值的产品的。特别是，植物细胞壁提供了从膳食纤维到潜在的新生物燃料的各种重要商品，但这些结构的复杂性和多样性仍在揭示中。我们对细胞内部的成分如何组装和组织细胞外部不同的壁成分知之甚少。大约在15亿年前，植物、动物和真菌拥有共同的祖先。这位祖先是一个单一的细胞，具有现代后代所有细胞所共有的基本元素。虽然植物细胞中发生的许多过程与动物和真菌中的过程相似，但也很明显，在进化过程中，每一组生物都详细阐述了原始机制，以满足它们在海洋和陆地上日益复杂的特定需求。这一证据的一部分来自基因组测序项目，该项目揭示了有机体可以制造的蛋白质的复杂性。我们特别关注一个蛋白质家族(‘Rab蛋白质’)，它在确定植物细胞的内部隔间和引导它们之间的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，新制造的分子必须被引导到适当的位置。我们可以看到，Rab蛋白家族的一些分支在过去4.5亿年的土地殖民期间，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以前没有认识到的新的内部隔室。此外，在根和茎的生长顶端的细胞中，这个隔间沿着细胞的边缘独特地定位，蛋白质的功能受到干扰会导致细胞在生长过程中失去对其形状的控制。我们现在想用遗传学和生物化学的方法来更多地了解这个隔室的组成和功能，以及新型Rab蛋白的进化如何促进陆地植物特有的特征的获得，这些特征有助于陆地环境中的生长和生存。虽然声称我们提出的研究将直接改进任何商业产品或工艺是不真诚的，但我们获得的知识可能有助于未来植物材料的合理设计。我们也有好奇心驱动的理由想要进行这项研究。植物是由细胞组成的，每个细胞的生长都采用了特定的大小和形状，这对有机体的整体形式和功能做出了贡献。我们正在试图了解一些允许细胞做到这一点的机制。具体地说，我们想要了解细胞的不同内部隔间如何有助于细胞的生长和形状，以及如何促进动态过程，如防御致病微生物。我们还想了解这些系统是如何进化的，以及它们与在其他复杂生物体(如人类)中执行类似功能的系统相比如何。

The majority of the human population relies on plants for their food, fuel, clothing, building material, and medicines (timber, oil, cotton, grain, pulses, flax, etc). With increased understanding of plant biology, plants are likely 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 revealed. 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. Plants, animals, and fungi shared a common ancestor approximately a one and half billion years ago. That ancestor was probaby a single cell that had the basic elements shared by all cells of modern day descendants. While many of the processes that occur in plant cells share 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 increasing 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 can make. We focus specifically on one family of proteins (the 'Rab proteins') which have a key role in defining the internal compartments of plant cells and directing material between them. It is essential 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 colonisation 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 and shoot this compartment is uniquely localised along the edges of the cells and pertubing the 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 learn more about the composition and function of this compartment and how the evolution of new types of Rab protein has facilitated the acquisition of land plant-specific traits that contribute to growth and survival in terrestrial environments. While it would be disingenuous to claim that the research we propose will directly improve any commercial product or process, the knowledge we gain may help rational design of plant-based materials in the future. We also have curiosity-driven reasons for wanting to perform this 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, and to dynamic processes such as defence against disease-causing organisms. We also want to understand how these systems evolved, and how they compare to the systems that perform analogous functions in other complex organisms such as humans.