Discovering novel components and mechanisms of plant oxygen-sensing

本应用程序描述的工作将改变我们对植物氧感应生物化学的理解。氧是有氧生物的关键分子，氧传感是多细胞真核生物的核心组成部分。由于洪水或内涝导致的氧气水平降低（缺氧）大大降低了作物产量，并且由于气候变化，这些重要的非生物胁迫的频率和强度正在增加。最近，在我们的实验室和其他实验室中，许多新的氧传感在植物中被定义。确定植物氧感知的完整生化机制是提供稳定产量的育种或生物技术方法以应对洪水和内涝的必要前提。十年前，我们与其他人一起发现了植物的氧感应机制，表明关键调控转录因子的氧需要降解控制着植物对缺氧的反应（Gibbs et al Nature 2011）。然后，我们证明了通过基因增强大麦的氧感知能力可以增加对内涝的耐受性（Mendiondo等植物生物技术杂志2016），这表明我们的基本生化遗传方法可以转化为解决这一农业问题。氧感应途径，即PCO N-degron途径，与动物缺氧诱导因子（HIF）系统（获得2019年诺贝尔医学和生理学奖）有相似之处，包括通过双加氧酶共价附着氧后转录因子的蛋白酶体破坏，尽管机制不相关。与动物HIF系统不同，植物氧感应途径的几个核心机制和组成部分尚未解决。由于动物也有类似于PCO（动物中的ADO） N-degron通路，这些方面在动物生物学中也未得到解决。本提案旨在通过解决目前公认的植物氧传感模型与实验证据之间的主要不一致来填补这些重要的知识空白。在我们提出的工作中，我们将发现核心植物氧传感系统的新成分和机制（这也将为动物ADO N-degron途径的等效成分和机制提供信息）。通过提供将完全重新定义PCO N-degron途径的新信息（我们也显示了作为植物一氧化氮感知机制的作用；Gibbs et al Molecular Cell 2014），这项工作将有助于创造新的资源和方法来解决与多种非生物胁迫耐受性相关的农学问题，包括洪水/内涝和盐度/干旱。该项目将涉及跨学科的实验方法，包括合成肽合成、质谱、酶学、遗传学和植物生理学，只有通过生物学家和化学家的合作才能实现。因此，该项目为新的跨学科培训提供了巨大的潜力。基于我们的初步数据和项目团队和其他相关领域的最新出版物，提出的工作是及时的，并提供了解决该途径的所有组成部分并定义其在该机制中对植物生长，发育和对环境胁迫的响应至关重要的功能的机会。

This application describes work that will transform our understanding of the biochemistry of plant oxygen-sensing. Oxygen is a key molecule for aerobic organisms, and oxygen-sensing is a central component of multicellular eukaryote biology. Reduced oxygen levels (hypoxia) due to flooding or waterlogging greatly reduce crop yields, and these important abiotic stresses are increasing in frequency and intensity due to climate change. Recently, in our lab and others, many novel roles for oxygen sensing have been defined in plants. Defining the complete biochemical mechanism of plant oxygen-sensing is an essential prerequisite to providing breeding or biotechnological approaches to stabilise yield in response to flooding and waterlogging. Along with others, we discovered a mechanism of plant oxygen sensing a decade ago, showing that oxygen-required degradation of key regulatory transcription factors controlled plant responses to hypoxia (Gibbs et al Nature 2011). We then showed that genetically enhancing oxygen-sensing in barley increased tolerance to waterlogging (Mendiondo et al Plant Biotechnology Journal 2016), demonstrating that our fundamental biochemical genetic approaches could be translated to address this agricultural problem. The pathway of oxygen-sensing, the PCO N-degron pathway, shares similarity to that of the animal Hypoxia Inducible Factor (HIF) system (that won the 2019 Nobel prize for Medicine and Physiology), including proteasomal destruction of transcription factors following covalent attachment of oxygen via dioxygenase enzymes, though the mechanisms are not related. Unlike the animal HIF system several core mechanisms and components of the plant oxygen-sensing pathway are not resolved. As animals also have an equivalent of the PCO (in animals ADO) N-degron pathway, these aspects are also unresolved in animal biology. This proposal seeks to fill these important knowledge gaps by addressing major inconsistencies between the currently accepted model for plant oxygen sensing and experimental evidence. In the proposed work we will discover new components and mechanisms of the core plant oxygen-sensing system (this will also provide information for the equivalent components and mechanisms of the animal ADO N-degron pathway). By providing new information that will completely redefine the PCO N-degron pathway (that we also showed acts as a mechanism of plant nitric oxide sensing; Gibbs et al Molecular Cell 2014), the work will facilitate the creation of novel resources and approaches to address agronomic problems associated with multiple abiotic stress tolerance, including flooding/waterlogging and salinity/drought. The project will involve a combination of inter-disciplinary experimental approaches spanning synthetic peptide synthesis, Mass Spectrometry, enzymology, genetics and plant physiology, only possible through the proposed collaboration of biologists and chemists. The project therefore provides great potential for novel interdisciplinary training. The proposed work is timely, building on our preliminary data and very recent publications by the project team and others in related fields, and offers the opportunity to resolve all the components of the pathway and defining their functions in this mechanism so essential for plant growth, development and response to environmental stresses.