Probing mechanisms of pathogen effector recognition by plant Resistance proteins to elevate defence gene activation

植物病害是每年作物损失的主要原因，对全世界粮食安全构成真实的威胁。事实上，许多其他粮食和经济作物，如小麦、水稻、玉米、大豆、大麦、马铃薯、棉花、油菜等易受许多不同类型的疾病的影响。在世纪的爱尔兰大饥荒中，超过一百万人死于马铃薯枯萎病。目前，世界上最受欢迎的水果，卡文迪什香蕉，由于受到高毒性真菌病原体的感染而面临灭绝的威胁[1]。近年来，由于“杀树”细菌的感染，柑橘产量的减少也在很大程度上影响了生产和经济。有超过8000万灰树生长在英国森林和沿着社区道路目前受到灰枯梢病的威胁，由无情的真菌病原体引起[3]。最近的估计预测，到2018年，英格兰南部和东部75%的白蜡树将受到这种疾病的感染[3]。与影响作物和树木的疾病作斗争是一项全球性挑战，需要学术界和工业界的科学家以及政策制定者和政府的努力。病原体能够感染植物并导致疾病，主要是因为它们可以抑制植物的免疫系统。因此，只有当我们清楚地了解植物免疫力时，我们才能为影响我们作物的疾病提供可持续的解决方案。英国科学家一直在寻求如何实现作物持久和可持续抗病性的知识。了解植物对各种病原体建立完全抗性的分子机制对于设计更好的保护作物免受田间病害的策略至关重要。植物免疫系统是多方面的，由许多具有广泛功能的不同蛋白质组成。在植物与病原体的斗争中，植物基因的表达和调控在建立有效的免疫应答中起着核心作用，本研究的目的是明确免疫基因调控因子，尤其是转录因子（调控基因表达的蛋白质）在分子水平上是如何发挥作用的，它们是如何被激活或抑制的，以及它们是如何影响免疫应答的幅度的。不同的病原体使用不同的策略来攻击相同的宿主植物，因此一个主要的挑战是如何在不妥协的情况下提高植物对所有病原体的免疫力;使用正确的组合，以及如何精确地控制它们的表达。了解免疫过程中发生的染色质（含DNA分子的组蛋白）的变化是破解免疫基因调控遗传信息的关键。为了解决这些重要问题，我将研究参与模式植物拟南芥与病原体相互作用的宿主蛋白。与直接研究作物植物相比，使用模式植物提供了许多优势，最重要的是可用的遗传和技术工具（完全测序和注释的基因组，数千个突变体和全球数据库）以及实验的一般容易性（身材矮小，生长迅速，方便的育种技术）。该项目将在诺里奇的塞恩斯伯里实验室进行，这是一家致力于研究植物-微生物相互作用的世界领先研究机构，并将与加拿大的实验室合作。从这个项目中获得的知识将促进我们对植物如何防御病原体的理解，并提供农业实践来提高作物产量。[1]“是的，我们没有香蕉”《经济学人》（2014年3月1日）; [2]“佛罗里达的橙子格罗夫斯林正在被杀死树木的细菌消灭”《哥伦比亚广播公司新闻》（2016年10月26日）; [3]“灰枯梢病”可能影响75%的树木受灾最严重的地区“《卫报》（2014年4月30日）; [4] www.tsl.ac.uk。

Plant diseases contribute greatly to annual crop losses and pose a real threat to food security worldwide. Indeed, many other food- and cash-crops such as wheat, rice, maize, soybean, barley, potato, cotton, canola, and others are susceptible to many different types of diseases. Over a million people died during the Great Irish Famine in the 19th century as the result of a potato blight epidemic. Currently, the world's most popular fruit, the Cavendish banana, is under threat of extinction due to infection by highly virulent fungal pathogens [1]. Recently, the reduction of citrus yields also largely affects the manufacture and economy, due to the infection of 'tree-killing' bacteria [2].Plant diseases also threaten the environment. There are >80 million Ash trees growing in UK forests and along neighborhood roads currently under threat of Ash dieback disease, caused by a relentless fungal pathogen [3]. Recent estimates project that 75% of Ash trees in the south and east England will be infected by this disease by 2018 [3]. Battling diseases that affect our crops and trees is a global challenge requiring the work of scientists in both academia and industry, as well as the work of policy-makers and government.Pathogens are capable of infecting plants and causing disease largely because they can suppress plant immune systems. Thus, only when we clearly understand plant immunity will we be able to offer sustainable solutions to diseases that affect our crops.Scientists in the UK have always been seeking knowledge of how to achieve durable and sustainable disease resistance for crops. Understanding the molecular mechanism by which plants establish full resistance against various pathogens is essential to design better strategies for protecting crops from field diseases. The plant immune system is multifaceted and composed of many different proteins with broad functions. In the battle between the host and pathogens, plant gene expression and regulations play a central role in establishing an effective immune response.The aim of this work is to find out exactly how immune gene regulators, especially transcription factors (proteins that regulate gene expressions), work at the molecular level, how they are activated or repressed, and how they influence the amplitude of immune responses. Different pathogens use different strategies to attack the same host plants, so a major challenge is how to boost the plant immunity against all pathogens without compromise; with the correct combinations, and how to control their expression precisely. Understanding the changes to chromatin (histone protein with DNA molecules) that occur during the immune process is key to decode the genetic information of immune gene regulations.To address these important questions, I will study host proteins involved in the interaction between the model plant Arabidopsis and its pathogens. Working with a model plant offers many advantages over directly studying crop plants, the most important being the wealth of genetic and technological tools available (fully sequenced and annotated genome, thousands of mutants and worldwide data repositories) and the general ease of experimentation (small stature, fast growth, and convenient breeding techniques). The project will be undertaken at the Sainsbury Laboratory in Norwich [4], a world-leading research institute dedicated to working on plant-microbe interactions, and will involve collaborative work with laboratories in Canada. Knowledge gained from this project will advance our understanding of how plants defend themselves against pathogens and provide agricultural practices to improve crop yield.[1] 'Yes, we have no bananas' The Economist (1 March 2014); [2] 'Florida's orange groves are being wiped out by tree-killing bacteria' the Columbia Broadcasting System (CBS) News (26 October 2016); [3] 'Ash dieback 'could affect 75% of trees worst hit areas'' The Guardian (30 April 2014); [4] www.tsl.ac.uk.