Regulation of adaptive responses to flood-induced hypoxia in Marchantia polymorpha

与动物类似，植物需要氧气来呼吸并在其栖息地茁壮成长。当暴露在光下时，植物通过进行光合作用的绿色组织从水分子中释放氧气。然而，限制气体扩散的条件，如洪水，会导致氧气可用性急剧减少。这导致了一种紧张的情况，降低了作物的生产力，而不是直接导致植物死亡。在英国，2007年夏季袭击英格兰东北部和西米德兰兹郡的洪水以及2013/14年冬季影响约克郡和萨默塞特的洪水估计对农业造成的经济损失超过8400万英镑。在某些情况下，每个农场的成本超过20万英镑。发展中国家的经济对此类事件更为敏感（Shresta et al. 2018）。考虑到这一点，洪水压力发挥了主要的更多，沿着环境因素，以限制农业产量在世界范围内，并限制了养活人类人口的可能性，特别是考虑到其快速增长，估计将达到90亿在未来30年内。与诺丁汉大学一起，我的团队描述了植物测量环境中可用氧气浓度并及时激活适应性反应以科普这种情况的机制。应力使用拟南芥作为模式植物物种，我们发现了一种在动物和真菌中保守的酶，该酶控制着介导低氧分子反应的调节蛋白的丰度。此外，我们和来自澳大利亚的同事提供的证据表明，细胞能量发电厂，线粒体，也参与通过称为ANAC的调节蛋白激活适应性反应的需要。它们通常与细胞膜结合，在受到压力时迅速释放，进入细胞核并诱导蛋白质的合成以应对压力。陆地植物起源于水生祖先，大约5亿年前殖民出现的土地。这种环境特征的巨大变化推动植物进化，使其能够利用机会并克服非水生环境的限制。这些创新使陆地植物发展出特殊的功能，确保它们在水和氧气供应强烈波动的环境中取得成功和适应。地钱（Marchantia polymorpha）等地钱在潮湿的栖息地中茁壮成长，但我们发现它们对长时间的淹没非常敏感，而拟南芥则在一系列环境中定居。这些物种在生理学的几个方面存在很大差异，因此我们希望它们使用替代策略来科普低氧。我们相信，在具有这种不同形态和生态的植物物种中识别该过程中的差异和相似性，对于发现有用的但未知的响应氧波动和激活响应的途径具有未开发的潜力，所述响应保护免受氧化应激并允许代谢调节以科普缺氧。我们将通过最先进的技术和应用最新的分子分析技术来研究这两个物种（地钱和拟南芥）对缺氧的反应。通过这样做，我们设想确定和表征参与植物中的氧感知和氧化应激信号传导的分子机制。我们将比较地钱和拟南芥中的机制，并利用这两种模式物种中诱导或抑制每种机制的策略，以确定那些必要的或更有效的保护植物免受洪水胁迫。我们的最终目标是确定关键要素或途径，可以有效地转移到作物品种，以提高其耐淹性。

Similar to animals, plants need oxygen to respire and thrive in their habitat. When exposed to light, plants release oxygen from water molecules through the green tissues that perform photosynthesis. However, conditions that limit gas diffusion, such as flooding, cause a dramatic reduction in oxygen availability. This leads to a stressful situation that diminishes crop productivity, when not directly causing death of the plants. In the UK, flood events such as those of Summer 2007 that hit the North Eastern England and the West Midlands, and of winter 2013/14 that affected Yorkshire and Somerset have been estimated to cause an economic damage to agriculture of over £84 million. In some cases, costs have exceeded £200,000 per farm. Economies of developing countries are even more sensitive to such events (Shresta et al. 2018). Considering this, flooding stress play a major more, along environmental factors, to limit agriculture yield worldwide and restricts the possibility to feed the human population, especially when considering its rapid growth, estimated to reach 9 bn within the next 30 years.Together with the University of Nottingham, my team characterized the mechanism by which plants measure the oxygen concentration available in the environment and activate adaptive response in time to cope with this stress. Using Arabidopsis thaliana as a model plant species, we discovered an enzyme conserved with animals and fungi that controls the abundance of regulatory protein that mediate the molecular response to low oxygen. Moreover, we and colleagues from Australia have provided evidence that the cellular energy powerplants, the mitochondria, also participate to signal the need to activate an adaptive response via regulatory protein called ANACs. These are normally bound to cellular membranes from which they are rapidly released in case of stress, to enter cell nuclei and induce the synthesis of proteins required to face the stress.Land plants derive from aquatic ancestors that colonized emerged lands about 500 M years ago. This big change of ambient feature drove plant evolution towards that enabled to exploit the opportunities and overcome the limitations of nonaquatic environments. These innovations have led land plant to development specialized features that ensure their success and fitness in environments characterized by strong fluctuations in water and oxygen availability. Liverworts, such as Marchantia polymorpha, thrive in humid habitats and yet we found them extremely sensitive to prolonged submergence, while Arabidopsis colonized a range of environments. These species largely differ under several aspects of their physiology, and thus we expect them to use alternative strategies to cope with low oxygen. We believe that the identification of differences and similarities in this process across plant species with such divergent morphology and ecology holds untapped potential to the discovery of useful and yet unknown pathways to response to oxygen fluctuations and activate response that protect from oxidative stress and allow metabolic adjustments to cope with hypoxia.In summary, we will study the response to hypoxia in the two species (Marchantia and Arabidopsis) by means of state-of-the-art technologies and applying the most recent molecular analytic techniques. By doing so, we envisage to identify and characterize the molecular mechanisms involved in oxygen perception and oxidative stress signalling in plants. We will compare the mechanisms set into place in Marchantia and Arabidopsis, and exploit the strategy to induce or repress each mechanism in both model species, to identify those essential or more effective to protect plants from flooding stress. Our final aim is the identification of key elements or pathways that can be effectively transferred to crop species to improve their submergence tolerance.