Unraveling plasmodesmata formation in C4 plant Gynandropsis gynandra

解开C4植物白花菜胞间连丝的形成

• 批准号: BB/X010015/1
• 负责人: Tina Schreier
• 金额: $ 51.8万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX010015%2F1
• 关键词: Unraveling; plasmodesmata; formation; C4; plant

Feeding the rapidly growing human population requires continuous increases in crop yield. An important strategy towards higher crop productivity is to improve the efficiency of photosynthesis in plants, so that plants capture CO2 more efficiently from the atmosphere and sequester it into biomass. A small number of plant species already perform a more efficient type of photosynthesis than others - called C4 photosynthesis. C4 photosynthesis evolved independently over 60 times in different plant lineages and involves modified biochemistry that occurs between two cell types in the leaf: the mesophyll and bundle sheath cells. In C4 plants, CO2 is initially fixed in mesophyll cells into a four-carbon acid, which is then transferred into bundle sheath cells. There, the acid is decarboxylated and CO2 is regenerated, thus forming a pump action that concentrates CO2 in the bundle sheath cells. The CO2 is then fixed primarily within these bundle sheath cells, where the high CO2 concentration increases photosynthetic efficiency by up to 50% in comparison to non-C4 plants. It is therefore a major goal of plant biotechnology to engineer C4 photosynthesis into non-C4 crop species (e.g: rice, wheat, potatoes) to improve their productivity and yield.The exchange of metabolites between the mesophyll and bundle sheath cells is central to the biochemistry of C4 photosynthesis. Typical C4 plants therefore have specialised leaf anatomy that maximises physical connections between these two cell types, with numerous pores named plasmodesmata that mediate metabolite exchange. Despite the critical importance of cell-to-cell connectivity in facilitating C4 metabolism, almost nothing is known about how the large numbers of plasmodesmata form between the mesophyll and bundle sheath cells. My research is focused on this process in the C4 plant Gynandropsis gynandra, where I discovered that light is the cue that triggers the rapid and numerous formation of plasmodesmata at the mesophyll-bundle sheath interface during leaf development.In my fellowship project, I will aim to understand the cell biological mechanisms underpinning plasmodesmata formation at the mesophyll-bundle sheath interface in G. gynandra and its importance to photosynthetic efficiency. Since G. gynandra is the closest known C4 relative to the non-C4 model plant Arabidopsis thaliana, I will use the latest findings on plasmodesmata formation in Arabidopsis as a starting point. Plasmodesmata are known to contain components of the cytoskeleton, as well as plasma membrane with specialised lipid composition (lipid microdomains), and previous work in Arabidopsis suggests that both cytoskeleton and lipid microdomains are involved in plasmodesmata regulation. I will further explore this in the context of the mesophyll-bundle sheath interface in G. gynandra, testing the impact of specific chemical inhibitors of the cytoskeleton and lipid microdomains on plasmodesmata formation. I will also use gene editing in G. gynandra to generate knockout mutants in three candidate genes that could link plasmodesmata formation to the cytoskeleton and lipid biosynthesis. The effect of the gene knockouts on plasmodesmata formation at the mesophyll-bundle sheath interface, and consequences on photosynthetic efficiency, will be assessed. Finally, I also aim to discover novel candidate genes in plasmodesmata formation in G. gynandra using proximity labelling to find novel proteins associated with known plasmodesmata localised proteins. The role of these proteins will be investigated in future independent work. Overall, my findings will not only create new understanding of how plasmodesmata form in C4 plants, but reveal new cell biological and biochemical mechanisms that underpin plasmodesmata formation in plants. The knowledge can be used in the global effort to engineer C4 photosynthesis in major crops to increase photosynthesis and yield.

养活迅速增长的人口需要不断提高作物产量。提高作物产量的一个重要战略是提高植物的光合作用效率，使植物更有效地从大气中捕获CO2并将其封存到生物质中。少数植物物种已经进行比其他植物更有效的光合作用--称为C4光合作用。C4光合作用在不同的植物谱系中独立进化超过60次，并且涉及发生在叶中的两种细胞类型之间的修饰的生物化学：叶肉细胞和维管束鞘细胞。在C4植物中，CO2最初在叶肉细胞中被固定为四碳酸，然后被转移到维管束鞘细胞中。在那里，酸被脱羧并再生CO2，从而形成将CO2浓缩在维管束鞘细胞中的泵作用。然后，CO2主要固定在这些维管束鞘细胞内，与非C4植物相比，高CO2浓度使光合效率增加高达50%。因此，将C4光合作用工程化到非C4作物物种（例如：水稻、小麦、马铃薯）中以提高其生产力和产量是植物生物技术的主要目标。因此，典型的C4植物具有专门的叶解剖结构，最大限度地提高了这两种细胞类型之间的物理连接，具有许多称为胞间连丝的孔，介导代谢物交换。尽管细胞与细胞之间的连接在促进C4代谢中至关重要，但几乎没有人知道叶肉细胞和维管束鞘细胞之间如何形成大量的胞间连丝。我的研究主要集中在C4植物Gynandrosisgynandra的这一过程中，我发现，光是一个线索，触发快速和大量的形成在叶肉-维管束鞘界面在叶片发育过程中的胞间连丝。gynandra及其对光合效率的重要性。自G. gynandra是已知的与非C4模式植物拟南芥（Arabidopsis thaliana）最接近的C4植物，我将使用拟南芥胞间连丝形成的最新发现作为起点。已知胞间连丝包含细胞骨架的组分，以及具有专门脂质组成（脂质微结构域）的质膜，并且在拟南芥中的先前工作表明细胞骨架和脂质微结构域都参与胞间连丝调节。我将在G. gynandra，测试细胞骨架和脂质微区的特定化学抑制剂对胞间连丝形成的影响。我还将在G中使用基因编辑。gynandra的基因敲除突变体，在三个候选基因，可以连接胞间连丝形成的细胞骨架和脂质生物合成。将评估基因敲除对叶肉-维管束鞘界面胞间连丝形成的影响以及对光合效率的后果。最后，我们也希望发现新的候选基因在G。gynandra使用邻近标记来发现与已知胞间连丝定位蛋白相关的新蛋白。这些蛋白质的作用将在未来的独立工作中进行研究。总的来说，我的研究结果不仅将创造新的理解如何胞间连丝形成C4植物，但揭示新的细胞生物学和生化机制，支持胞间连丝形成的植物。这些知识可以用于全球努力，在主要作物中设计C4光合作用，以增加光合作用和产量。