Detection, Prevention and Immune Mechanisms for Pathogens with Diverse Lifestyles (Patho-Lifestyle)

我们这个时代最大的挑战之一是养活不断增长的全球人口。由于气候变化和城市发展的影响，世界可耕地实际上已经达到了最大容量，未来几年还会减少。因此，必须提高粮食系统的生产力，以解决世界饥饿问题并加强粮食安全。实现这一目标的一个特殊战略是减少病虫害造成的损失。大麦（Hordeum vulgare）是全球第四大重要作物，在英国排名第二。包括褐锈病（Puccinia hordei）和褐锈病（Ramulaira colo -cygni）引起的疾病是大麦面临的最大威胁，导致产量损失高达40%。根据它们的生活方式和与宿主的相互作用，病原真菌可分为生物营养型和坏死性两类。生物营养真菌和坏死性真菌之间的关键区别在于，生物营养真菌从活的植物细胞中获取营养，维持它们的生命，而坏死性真菌杀死植物组织，然后从中获取营养。然而，许多致病真菌使用顺序的生物营养和坏死性感染阶段。在生物营养阶段，它们以最小的损害侵入并广泛地定植植物，然后进入通常是致命的坏死性营养阶段。重要的是，在感染的早期生物营养阶段施用杀菌剂对减少疾病最有效，但由于这一阶段无法直观识别，因此在病原体已经建立时施用杀菌剂往往太晚。为了应对病原体的攻击，植物启动了足以抵御大多数病原体的免疫反应。然而，适应性病原体隐藏的效应蛋白能够抑制宿主免疫反应并促进成功感染，导致严重的作物损害。这些效应物不断进化，从而避免了现有的寄主抗性或当前的植物保护策略。因此，需要其他方法来提高作物的抗性。使用免疫激发子或保护性生物刺激剂是一种非常有前途的可持续诱导长期抗病的方法，但这些化学物质的作用模式和植物细胞靶点尚不清楚。植物使用保守的泛素蛋白来调节免疫反应。泛素化是一种快速和可逆的蛋白质修饰，调节免疫反应的幅度和强度。利用我们实验室开发的蛋白质组学管道，我们发现蛋白质泛素化是一种比目前可用的基因组和转录组标记更好的早期生物营养病原体感染的生物标志物。在大麦品种的田间试验中，我们的研究结果显示，所有受感染的大麦品种都有普遍的泛素介导的免疫激活，这意味着泛素对免疫系统的调节是一种保守的机制。因此，在本项目中，我们将研究随着生活方式的改变，大麦对激发子/生物刺激剂和经济相关病原体的泛素依赖性反应。这些将与响应生物营养和坏死阶段的植物免疫激素的泛素蛋白质组进行比较，揭示激发子/生物刺激剂的作用模式，精确识别病原体何时改变其生活方式，识别新的生物标志物，用于“看不见的”生物营养疾病阶段的早期检测。综上所述，该项目将填补一个重要的知识空白，揭示生物营养和坏死性真菌感染期间植物免疫的激活和调节的新基本见解，并揭示激发子和生物刺激剂的作用模式，这将用于提高作物的抗性。这些新颖、可持续的方法将对全球粮食安全产生重大影响，并推动农业食品部门的创新。

One of the biggest challenges of our time is to feed the growing global population. World arable land is practically at its maximum capacity, and will decrease in coming years due to climate change and urban development. Therefore, the productivity of our food system must be increased to tackle world hunger and increase food security. One exceptional strategy to achieve this goal is to reduce losses by pests. Barley (Hordeum vulgare) is the fourth most important crop worldwide and second in the UK. Diseases, including those caused by the brown rust Puccinia hordei and Ramulaira collo-cygni, represent the largest threat to barley, causing yield losses of up to 40%. Based on their lifestyle and interaction with the host, pathogenic fungi can be classified as either biotrophic or necrotrophic. The key difference between biotrophic and necrotrophic fungi is that biotrophic fungi derive nutrients from living plant cells, maintaining them alive, while necrotrophic fungi kill the plant tissues and then obtain nutrients from them. However, many pathogenic fungi use sequential biotrophic and necrotrophic infection phases. During the biotrophic phase they invade and extensively colonise the plant with minimum damage, before switching to the often fatalnecrotrophic phase. Importantly, fungicides are most effective at reducing disease when applied during the early biotrophic stages of infection, but since this phase cannot be visually identified, they are often applied too late when the pathogen is already well established. In response to pathogen attack, plants initiate immune responses that are sufficient to fend off most pathogens. However, adapted pathogens secret effector proteins that are capable of suppressing the host immune response and promote successful infection, causing severe crop damage. These effectors are constantly evolving, thereby avoiding existing host resistance or current plant protection strategies. Consequently, alternative methods to enhance crop resistance are required. The use of immune elicitors or protective biostimulants is a highly promising sustainable method for inducing long-lasting disease resistance, but the modes of action and plant cell targets of these chemicals remain unknown. Plants use the conserved protein ubiquitin to regulate immune responses. Ubiquitination is a fast and reversible protein modification that regulates the amplitude and intensity of the immune response. Using a proteomic pipeline developed in our laboratories, we discovered that protein ubiquitination is a far better biomarker for early biotrophic pathogen infection than currently available genomic and transcriptomic markers. Our results in barley cultivars on a field trial with P. hordei showed a general ubiquitin-mediated immune activation of all infected barley cultivars, implying that ubiquitin regulation of the immune system is a conserved mechanism across cultivars. Therefore, in this project we will investigate the ubiquitin-dependent response of barley to elicitors/biostimulants and economically relevant pathogens with changing lifestyles. These will be compared to the ubiquitin proteomes of plant immune hormones responsive to biotrophic and necrotrophic stages, revealing the modes of action of elicitors/biostimulants and precisely identifying when pathogens change their lifestyle, identifying new biomarkers for early detection of the 'invisible' biotrophic disease phase.In summary, this project will address a crucial gap in knowledge and uncover new fundamental insights into the activation and modulation of plant immunity during biotrophic and necrotophic fungal infections, and real the mode of action of elicitors and biostimulants, which will be used to enhance crop resistance. These novel, sustainable approaches will have a significant impact on global food security and drive innovation in the agrifood sector.