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，这意味着到2050年，我们需要在寒冷和温暖的温度冲击发生频率增加的时期增加60%的粮食。因此，需要基于基本发现的新见解来利用植物生长。在细胞水平上，植物显示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。植物细胞内的细胞器，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至关重要。已知细胞器根据某些应力（包括热或冷温度应力）改变形状和移动。然而，我们不知道这种运动是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层中的一种复杂的丝状网络。如果被破坏，细胞器的运动就会停止。然而，我们还不了解肌动蛋白细胞骨架如何与细胞器相互作用，驱动细胞内的运动。我将揭示ER和细胞核如何与肌动蛋白细胞骨架相互作用。已知ER在正常发育和植物胁迫期间快速重塑，并且细胞核是高度移动的，并且已知其与肌动蛋白细胞骨架的相互作用调节基因组组织和转录。如果我们能够理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改善植物生长，并培育出能够抵抗温度胁迫的植物。为了回答这些挑战，我们首先需要能够看到肌动蛋白和这些细胞器之间的特定相互作用。肌动蛋白细胞骨架究竟是如何与它们相互作用的？我已经调整和验证了荧光报告，它只允许肌动蛋白相互作用的细胞器膜被成像，而不是其余的肌动蛋白网络。这将使我能够精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期间这种相互作用如何变化。这将是我们对植物细胞器动力学的理解的变革。扩展这种新的方法，我将使用最近开发的技术称为接近标记，允许识别位于这些肌动蛋白和细胞器之间的接触部位的蛋白质。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移动性。已知改变细胞器动力学的速率对植物生长具有直接影响。更快的移动导致更大的植物。因此，我将利用和设计肌动蛋白-ER相互作用来微调植物生长，并产生耐温度冲击的气候智能植物，从而可持续地增强农业。

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.