400 Million Years of Food Transport in Plants: unearthing the origin, diversity and genetic toolkit of vasculature

水、矿物质营养物质和食物在整个植物中的分布是通过由两个高度特化的组织——木质部和韧皮部组成的内部管道系统进行的。在植物进化过程中，这些特殊组织的获得是植物从微小的苔藓样物种进化成参天大树和今天主导景观的作物物种多样性的关键创新之一。木质部和韧皮部紧密相连，但功能不同，在整个植物中，木质部运输水分，韧皮部运输食物。所有经济上重要的植物，无论是农作物还是森林物种，都依赖韧皮部以糖的形式运输食物。然而，尽管韧皮部在植物生命的所有部分都发挥着关键作用，但我们不知道韧皮部的结构和功能将如何改变，或者如何设计以应对未来的气候变化。预测未来韧皮部可能如何变化的重要证据，保存在以前未被探索的植物化石记录中，这些植物经历了史前全球气候变化时期和极端的大气二氧化碳。拟议研究的目的是调查关于韧皮部进化的关键悬而未决的问题，韧皮部是最重要但最不为人所知的植物组织之一。我将通过解决三个主要问题来改变我们对韧皮部进化的认识：(I)韧皮部是什么时候形成的；（ii）在过去的4亿年里，韧皮部的结构、功能和遗传工具是如何进化的；（iii）气候变化是如何推动韧皮部进化的？为了回答这些问题，我将结合化石的尖端3D成像技术、从未与化石进行过的韧皮部功能的计算建模，以及对活植物的比较基因组分析。为了回答这些关键问题，我确定了奖学金的三个目标：定义陆地植物韧皮部的起源。揭示地质时期韧皮部结构和功能与气候变化的主要进化创新。结合对现存物种、化石和基因的研究，我将得出关于韧皮部的进化结论，而这些证据都无法单独实现，这标志着我们对韧皮部进化的理解发生了一步变化。这项研究的影响将是揭示这一重要植物组织的进化，并帮助理解韧皮部的结构和功能如何与大气中的二氧化碳水平联系在一起。因此，研究结果对于预测包括经济上重要的作物和树种在内的活植物的韧皮部结构在未来50到100年可能对人为气候变化引起的大气二氧化碳上升作出的反应至关重要。在爱丁堡大学，我将有得天独厚的条件来开展这个研究项目。生物科学学院（SBS）在研究不同谱系中复杂植物性状的结构、功能和遗传变化方面处于世界领先地位。此外，我的奖学金将大大受益于与杰出的地球科学学院古生物学小组的合作以及两个项目合作伙伴组织的藏品；苏格兰国家博物馆（NMS）的化石植物和爱丁堡皇家植物园（RBGE）的活藏品。特别是，NMS包含了一个独特的、未开发的集合，这对我提出的研究至关重要。综上所述，SBS优秀的研究环境，地球科学学院在古生物学方面的实力，以及项目合作伙伴的藏品，使这一奖学金在世界上任何其他地方都无法成功完成。

Distribution of water, mineral nutrients and food throughout the plant is carried out using an internal plumbing system made up of two highly specialised tissues - xylem and phloem. The acquisition of these specialised tissues during plant evolution was one of the key innovations that allowed plants to evolve from tiny moss-like species into the towering trees and the diversity of crop species that dominate the landscape today. The xylem and phloem are intimately linked, but functionally different, with the xylem transporting water and the phloem transporting food throughout the plant. All economically important plants, whether crop or forest species, rely on the transport of food, in the form of sugars, through the phloem. However, despite the key role that the phloem plays in all parts of plant life, we do not know how the structure and function of the phloem will change, or can be engineered to respond, to future climate change. A vital line of evidence for predicting how the phloem will likely change in the future is preserved in the previously unexplored fossil record of plants that lived through prehistoric episodes of global climate change, and extremes of atmospheric CO2. The aim of the proposed research is to investigate key unanswered questions about the evolution of the phloem, one of the most important but least well understood plant tissues. I will transform our knowledge of phloem evolution by tackling three overarching questions: (i) when did the phloem originate, (ii) how has its structure, function and genetic toolkit evolved over the past 400 million years, (iii) how has phloem evolution been driven by climate change? To answer these questions I will combine cutting-edge 3D imaging of fossils, computational modelling of phloem function never before undertaken with fossils, and comparative genomic analyses of living plants. To answer these key questions I have identified three objectives for the Fellowship:1. Define the origin of the phloem in land plants2. Reveal major evolutionary innovations in phloem structure and function in relation to climatic change through geological time.3. Characterise the genetic innovations that underpinned the diversification of the phloemCombining studies of living species, fossils and genes, I will draw evolutionary conclusions about the phloem that none of these lines of evidence alone could achieve, marking a step change in our understanding of phloem evolution. The impact of this study will be to shed light on the evolution of this crucial plant tissue and to help understand how the structure and function of the phloem is tied to the level of atmospheric CO2. The findings of the Fellowship will therefore be essential for predicting how the phloem structure of living plants, including economically important crop and tree species, will likely respond in the next 50 to 100 years to rising atmospheric CO2 caused by anthropogenic climate change.I will be uniquely placed at the University of Edinburgh to carry out this programme of research. The School of Biological Sciences (SBS) is a world leader in studying the structural, functional and genetic changes that underpin complex plant traits in diverse lineages. In addition, my Fellowship will benefit greatly from collaboration with the palaeobiology group in the outstanding School of Geoscience and the collections of the two project partner organisations; the fossil plants in the National Museum Scotland (NMS) and living collections in the Royal Botanic Garden Edinburgh (RBGE). In particular, the NMS contains a unique and unexploited collection that will be essential for my proposed research. Taken together, the excellent research environment in SBS, strength in palaeobiology in the School of Geoscience and access to the collections of the project partners makes this a Fellowship that could not be successfully accomplished anywhere else in the world.