The ties that bind: Understanding actin-organelle interactions in planta.

植物是地球上粮食安全和能源/二氧化碳捕获的基础。我们面临着气候变化和人口增长的重大挑战，这意味着我们需要在2050年之前增加60%的粮食产量，而此时冷暖两种温度冲击都在频繁发生。因此，在基础发现的基础上利用植物生长的新见解是必要的。在细胞水平上，植物表现出生物学中已知的一些最快的运动，例如藻类中的细胞质流动。植物体内的细胞器，包括细胞核、内质网和高尔基体，在植物细胞内表现出快速和协调的运动。这种运动对于正常生长和发育以及对环境条件的反应都是至关重要的。众所周知，细胞器会根据一定的压力改变形状和运动，包括热或冷的温度压力。然而，我们不知道这种运动如何发生的确切机制，尽管我们知道它是由肌动蛋白细胞骨架和肌球蛋白马达蛋白驱动的。肌动蛋白是植物细胞皮质中错综复杂的丝状网络。如果被破坏，细胞器的运动就会停止。然而，我们还不知道肌动蛋白细胞骨架是如何与细胞器相互作用的，从而驱动细胞内的运动。我将揭示内质网和细胞核是如何与肌动蛋白细胞骨架相互作用的。已知内质网在正常发育和植物胁迫期间会迅速重塑，细胞核具有高度的移动性，它与肌动蛋白细胞骨架的相互作用已知调节基因组组织和转录。如果我们能够了解肌动蛋白如何与这些细胞器和相关蛋白质相互作用，我们就可以设计这些系统来促进植物的生长，培育出对温度胁迫具有抵抗力的植物。要回答这些挑战，我们首先需要能够看到肌动蛋白与这些细胞器之间的具体相互作用。肌动蛋白细胞骨架究竟是如何与它们相互作用的？我已经修改并验证了一种荧光报告程序，它只允许细胞器膜上的肌动蛋白相互作用被成像，而不是肌动蛋白网络的其余部分。这将使我能够准确地描述细胞骨架如何与这些细胞器相互作用，以及在正常和应激诱导的细胞器运动过程中这种变化是如何变化的。这将改变我们对植物细胞器动力学的理解。在这一新方法的基础上，我将使用最近开发的一种称为邻近标记的技术，该技术可以识别位于肌动蛋白和细胞器之间的这些接触点的蛋白质。通过识别和描述控制这些相互作用的蛋白质，我将能够准确地确定肌动蛋白如何驱动这些细胞器的流动性。众所周知，细胞器动态变化的速度对植物的生长有直接的影响。更快的移动会产生更大的植物。因此，我将利用并设计肌动蛋白-ER的相互作用，以微调植物生长并培育出耐受温度冲击的气候智能植物，从而可持续地促进农业。

Plants are the basis of food security and energy / CO2 capture on planet earth. We face a major challenge with climate change and population growth meaning we need to grow 60% more food by 2050 in a period where both cold and warm temperature shocks are occurring with increased frequency. Therefore, novel insights into harnessing plant growth based on fundamental discoveries are required. At the cellular level plants display some of the fastest movements known in biology such as cytoplasmic streaming in algae. Organelles within plants including the nucleus, ER and Golgi bodies show rapid and coordinated movements within plant cells. This movement is critical for normal growth and development as well as responses to environmental conditions. Organelles are known to change shape and move according to certain stresses, including hot or cold temperature stress. However, we do not know the exact mechanism of how this movement occurs although we know it is driven by the actin cytoskeleton and myosin motor proteins. Actin is an intricate filamentous network in the cortex of plant cells. Which if disrupted, organelle movement stops. However, we do not yet understand how the actin cytoskeleton interacts with the organelles, driving movement within the cell. I will uncover how the ER and nucleus interact with the actin cytoskeleton. The ER is known to rapidly remodel during normal development and plant stress and the nucleus is highly mobile and its interaction with the actin cytoskeleton is known to regulate genome organisation and transcription. If we can understand how actin interacts with these organelles and the proteins involved, we can engineer these systems to improve plant growth and develop plants which are resistant to temperature stresses.To answer these challenges, we first need to be able to see the specific interactions between actin and these organelles. How exactly does the actin cytoskeleton interact with them? I have adapted and validated a fluorescent reporter which allows only actin interaction at the organelle membrane to be imaged, not the rest of the actin network. This will allow me to characterise precisely how the cytoskeleton interacts with these organelles and how this changes during normal and stress induced organelle movement. This will be transformational for our understanding of organelle dynamics in plants. Expanding on this novel approach, I will use a recently developed technique called proximity labelling that allows identification of proteins located at these contact sites between actin and an organelle. By identifying and characterising the proteins which control these interactions I will be able to determine exactly how actin drives mobility of these organelles. It is known that changing the rate of organelle dynamics has a direct effect on plant growth. Faster movement results in larger plants. As such, I will harness and engineer actin-ER interactions to fine-tune plant growth and generate climate smart plants which are resistant to temperature shocks, therefore sustainably enhancing agriculture.