Understanding and ameliorating the impact of climate change on plant meiosis

与气候变化相关的气温上升预计将导致许多主要作物的全球产量下降，从而影响粮食安全。植物发育的生殖阶段对温度胁迫非常敏感，在这一阶段暴露于极端高温是许多作物肥力（和产量）下降的主要原因。减数分裂是一种特殊的细胞分裂，产生有性生殖所需的细胞（植物的花粉和卵子，人类的精子和卵子），是植物生殖周期中一个重要的“薄弱环节”，已知在各种植物物种的高温下会失败，导致生育能力丧失。然而，在极端温度下导致减数分裂失败的真正原因，以及如何防止这种情况的发生，几乎仍然是一个谜。我有初步的证据表明，在极高温（33度）下，减数分裂失败是多蛋白复合物（减数分裂轴和突触复合物）的错误组装和聚集的结果，这些复合物在减数分裂的早期阶段协调了动态的染色体相互作用。我在这个项目中的第一个目标是推进这些初步观察，进一步描述在极端温度下进行减数分裂的细胞所面临的问题，并评估这些问题对植物肥力总体下降的贡献。为了实现这一点，我将使用最先进的显微镜系统地分析一系列高温对模式植物拟南芥减数分裂的影响。拟南芥是一种小型的杂草状植物，被植物科学家广泛使用，因为它具有许多特征，使其非常适合研究，可以比其他非模式作物物种更快地从该物种的实验中得出有意义的生物学结论。对于我的第二个目标，我将评估极端温度对正在进行减数分裂的拟南芥细胞中基因表达的影响。这将有助于揭示拟南芥减数分裂细胞中特定基因表达的变化如何增加或减少减数分裂的耐热性。拟南芥的野生种群也可以被发现占据一系列不同的栖息地，经历高度变化的最高和最低温度。我的项目的第三个目标将是确定拟南芥群体是否已经适应在温暖或凉爽的环境中进行受精，在减数分裂热稳定性方面表现出强烈的差异，从而确定这些植物是否通过增强其减数分裂耐热性来适应更热的温度。我的项目主要目的是揭示支持减数分裂热敏性的分子机制，并找到克服这些机制的方法来增加植物减数分裂的耐热性。由于减数分裂是一个高度保守的过程，酵母、人类和植物的减数分裂都是通过类似的机制发生的，因此在拟南芥中取得的任何发现很可能将转化为更具经济意义的作物物种。除了揭示控制减数分裂热稳定性的方面外，我的项目还可能提供关于染色体如何在减数分裂期间交换DNA片段的新见解（植物育种者非常感兴趣的过程），它将有助于回答关于蛋白质和细胞过程如何在极端非生物胁迫下进化的基本问题。总的来说，我的项目的成果将非常有利于确保未来的全球粮食安全，并在气候变化和人口不断增长的情况下保持高作物产量。我的工作与BBSRC“展望英国生物科学”的所有主题相吻合：“推进生物科学发现的前沿”、“应对战略挑战”和“建立坚实的基础”。

Increasing temperatures associated with climate change are expected to impact food security by causing reductions in the global yield of many major crops. The reproductive phase of plant development is acutely sensitive to temperature stress and exposure to high temperature extremes during this phase is the primary cause of reduced fertility (and yield) in many crops. Meiosis, a special cell division that produces the cells required for sexual reproduction (pollen and eggs in plants, sperm and eggs in humans), represents an important 'weak-link' in the plant reproductive cycle and is known to fail at high temperatures in a variety of plant species, leading to losses of fertility. However, what actually causes meiosis to fail under temperature extremes, and how this might be prevented, remains almost completely mysterious. I have preliminary evidence that meiotic failure at extreme high temperature (33 degrees) occurs as a consequence of the misassembly and aggregation of multi-protein complexes (the meiotic axis and synaptonemal complex) that orchestrate dynamic chromosomal interactions during the early stages of meiosis. My first objective in this project will progress these initial observations to further characterise the problems that are faced by cells undergoing meiosis at extreme temperatures and to assess the contribution of these problems to overall reductions in plant fertility. To achieve this, I will systematically analyse the effects of a range of high temperatures on meiosis in the model plant species Arabidopsis thaliana using state-of-the-art microscopy. Arabidopsis is a small weed-like plant and is widely used by plant scientists as it possesses numerous features that make it highly amenable for research, allowing meaningful biological conclusions to be drawn from experiments in this species much more rapidly than they could from other non-model crop species. For my second objective, I will assess the impact of extreme temperatures on the expression of genes in Arabidopsis cells undergoing meiosis. This will shed light on how changes in the expression of particular genes in meiotic cells can either increase or decrease the thermal tolerance of meiosis in Arabidopsis. Wild populations of Arabidopsis thaliana can also be found occupying a range of different habitats, experiencing highly variable maximum and minimum temperatures. The third objective of my project will be to determine if populations of Arabidopsis thaliana that have adapted to undergoing fertilisation in warmer or cooler environments exhibit strong differences in their meiotic thermal stability and, thus, whether these plants have adapted to hotter temperatures by enhancing their meiotic thermal tolerance. My project's main aims are to uncover the molecular mechanisms that underpin the thermal sensitivity of meiosis and to find ways to overcome these mechanisms to increase meiotic thermal tolerance in plants. As meiosis is a highly conserved process, with meiosis in yeast, humans and plants all occurring via similar mechanisms, it is likely that any discoveries made in Arabidopsis will be translatable to more economically important crop species. As well as shedding light on aspects that control meiotic thermal stability, my project is also likely to offer novel insights into how chromosomes exchange segments of DNA during meiosis (a process that is of great interest to plant breeders) and it will help to answer fundamental questions about how proteins and cellular processes can evolve in the face of extreme abiotic stress. Taken together, the outcomes of my project will be highly beneficial for ensuring future global food security and sustaining high crop yields in the combined face of climate change and an ever-expanding population. My work maps to all of BBSRC's 'Forward Look for UK Bioscience' themes: 'Advancing the frontiers of bioscience discovery,' 'Tackling strategic challenges,' and 'Building strong foundations'.