From health to sickness; the metabolomics transition associated with plant disease and defense

由于植物牢牢地扎根于地面，它们容易受到各种各样的害虫，如昆虫、真菌、细菌和病毒的侵袭。有趣的是，尽管这种隐私不断受到侵犯，但疾病是一个例外，因为它部署了一个非常复杂和高效的协同防御策略网络-统称为基础防御或非宿主抵抗。许多防御性屏障是一种或多种代谢产物--小分子化学物质--作用的组合。代谢物由植物合成，并以多种方式起作用-作为信号，作为镇静剂，作为修饰剂甚至作为毒素-以单独或协同防止病原体侵入。当病原体（如细菌）成功入侵植物时，它们本身会采用各种策略来进一步抑制或逃避宿主的防御，并操纵宿主的新陈代谢，为它们的繁殖提供营养。总之，它们将细胞内环境变成了一个舒适的公寓，食物和营养在线。他们通过主动将蛋白质注入植物细胞中来实现这种“成功”，这种蛋白质基本上是一种被称为III型分泌系统的蛋白质样结构。这些“效应”蛋白操纵宿主转录（作为蛋白质合成模板的基因的表达），并通过定义蛋白质表达来协调信号事件的复杂网络。偶尔，这些效应蛋白中的一个或多个被识别并触发警报信号，局部和全身诱导免疫，导致植物消毒。我们支持这一提议的研究使用了一种称为转录谱分析的技术来研究所有植物基因的表达如何被各种病原体挑战所改变。对非常复杂的表达模式的分析揭示了专门参与基础防御和疾病的基因家族。特别是，我们发现成功的病原体诱导的基因表达模式与不成功感染中的基因表达模式不同。这些数据代表了我们理解植物防御的一个重要里程碑，因为这些基因中的许多编码蛋白质，这些蛋白质本身产生或修饰增强或干扰植物免疫的代谢物。通过现代技术的结合，我们希望发现在植物周围移动以协调防御的信号化合物的性质。我们将尝试查看所有小分子/称为代谢组学或代谢物分析的程序/并确定哪些分子在特定处理后发生数量变化。分析可以是有针对性的（以识别已知化合物）或非有针对性的，测量变化的模式。新技术使我们能够进行大规模的代谢分析，以确定以不同方式处理或经历不同反应的植物组织之间的差异。这样我们就可以识别不同的代谢物，即使我们实际上可能无法识别这种代谢物。通过将这项技术与不能完全激活特定防御途径的突变体结合使用，我们将能够找到重要化合物保护或破坏植物防御的线索，甚至可能是关于启动整个过程的信号的身份的想法。我们的目标是确定代谢物的“签名”具体相关的各个方面的防御。这项工作的长期成果将是更好地了解小分子（i）为植物防御招募和（ii）与成功感染相关的代谢物。这些结果将为未来的策略提供信息，旨在操纵植物对病原体的广谱免疫反应。

Since plants are firmly rooted to the ground, they are open to investigation, insult or attack by a wide variety of nasties such as insects, fungi, bacteria and viruses. Fascinatingly, despite this constant invasion of privacy, disease is an exception due to the deployment of an extraordinary complex and highly effective network of synergistic defensive strategies -collectively known as basal defense or non-host resistance. Many of these defensive barriers are the combination of actions of one or more metabolites - small chemicals. Metabolites are synthesised by the plant and act in a multitude of ways - as a signal, as a sedative, as a modifier or even as a toxin - to individually or cooperatively prevent pathogen ingress. When pathogens, such as bacteria, do successfully invade a plant, they themselves employ a variety of strategies to further suppress or evade host defenses and manipulate host metabolism to provide nutrients for their multiplication. In sum, they turn their intracellular environment into a cosy apartment with food and nutrients online. They achieve this 'success' by actively injecting proteins into the plant cell via what is basically a syringe-like structure known as a Type III secretion system. These 'effector' proteins manipulate host transcription (expression of genes which are the template for protein synthesis) and by definition protein expression to orchestrate a complex network of signalling events. Occasionally, one or more of these effector proteins is recognised and triggers an alarm signal that both locally and systemically induces immunity, leading to disinfection of the plant. Our studies underpinning this proposal have used a technique known as transcriptional profiling to look at how the expression of all plant genes is modified by various pathogen challenges. Analysis of the very complex expression patterns revealed families of genes specifically involved in basal defense and disease. In particular, we found the successful pathogens induced modified gene expression patterns from those seen in unsuccessful infections. These data represent a significant milestone in our understanding of plant defense as many of these genes encode proteins which themselves produce or modify metabolites that enhance or interfere with plant immunity. Through a combination of modern technologies we wish to discover the nature of the signalling chemical compounds that move around the plant to coordinate defence We will attempt to look at all the small molecules/ a procedure known as metabolomics or metabolite profiling / and identify which ones change in quantity following specific treatments. Profiling can be targeted (to identify known compounds) or non-targeted, measuring the pattern of changes. New technologies allow us to undertake large scale metabolic profiling to identify differences between plant tissues treated in different ways or undergoing different reactions. That way we can identify metabolites that differ, even though we may not actually be able to identify that metabolite. By using this technology in combination with mutants which cannot fully activate specific defense pathways, we will be able to clues to what the important compounds protect or destablise plant defenses and maybe even an idea as to the identity of the signal that starts the whole process in the first place. We aim to identify metabolite 'signatures' specifically associated with various aspects of defense. The long-term outcome of this work will be better understanding of the small molecules (i) recruited for plant defense and (ii) those metabolites associated with successful infections. These results will inform future strategies aimed toward manipulating plant responses toward developing broad spectrum immunity to pathogens.