Metabolomics to elucidate the mechanisms of resistance in plants against biotic stress

植物对病原体攻击的抗性可以是完全的（垂直的或主要是单基因的）或部分的（水平的或主要是多基因的）。后者，由于数量遗传和缺乏合适的工具来筛选基因型，没有很好地利用育种生物胁迫管理。然而，代谢组学的最新发展带来了光明的未来。真抗性的形成机制可分为结构抗性和生化抗性两大类。在分子/代谢水平上理解植物防御机制可能会导致新的策略来管理破坏性的作物病害。代谢物组学是系统生物学的一个新兴领域，它可以揭示基因的功能，而且代谢物通常是植物抵抗胁迫的最终产物，因此它也可以独立地用于筛选抗性。使用气相色谱和质谱（GC/MS），我们已经确定了200多个耐药相关（RR）代谢物（耐药比敏感丰度高）。然而，GC/MS仅检测挥发物，对于非挥发性代谢物，需要使用高精度质量液相色谱和质谱（LC/MS）。本研究的目的是利用LC/MS技术更好地了解小麦对赤霉病（FHB，禾谷镰刀菌）的抗性机制。本研究旨在建立小麦代谢组数据库。通过对抗性基因型的小穗接种的代谢谱分析和对它们的丰度的多变量分析来鉴定RR代谢物，将研究抗性入侵的机制。通过代谢谱分析接种产生和不产生毒素（DON）的病原体菌株的抗性基因型，并通过基于不同生长阶段的轴节代谢谱的轴节内的病原体遏制，研究通过毒素（DON）降解来抵抗穗内病原体传播的机制。在这里产生的知识库小麦抗赤霉病的机制，生物标志物RR代谢物鉴定，将被利用来开发一个高通量的代谢组学技术，筛选小麦育种系抗赤霉病。

Resistance in plants against pathogen attack can be complete (vertical or mainly monogenic) or partial (horizontal or mainly polygenic). The latter, because of quantitative inheritance and for lack of suitable tools to screen genotypes, is not well exploited by breeders for biotic stress management. However, the latest developments in metabolomics present a bright future. The mechanisms of true resistance are groped into structural or biochemical. Understanding of plant defense mechanisms at the molecular/metabolic level could lead to novel strategies to manage destructive crop diseases. Metabolomics is an evolving field of systems biology that can shed some light on the functions of genes, and furthermore, metabolites are often the end products of plant defense against stresses, thus it can also be used independently to screen for resistance. Using gas chromatography and mass spectrometry (GC/MS) we have identified more than 200 resistance related (RR) metabolites (higher abundance in resistant than in susceptible). However, GC/MS detects only volatiles and for non-volatile metabolites the use of high accurate mass liquid chromatography and mass spectrometry (LC/MS) is needed. The objective of the present study is to use LC/MS to better understand the mechanisms of resistance in wheat to fusarium head blight (FHB, Fusarium graminearum). In this study a wheat metabolome database will be established. The mechanisms of resistance to invasion will be investigated by metabolic profiling inoculated spikelets of resistant genotypes and multivariate analyses of their abundances to identify RR metabolites. The mechanisms of resistance to spread of pathogen within spike, through degradation of toxin (DON), will be investigated by metabolic profiling of resistant genotypes inoculated with pathogen strains producing and non-producing DON, and through containment of pathogen within rachis nodes based on metabolic profiles of rachis nodes at different growth stages. The knowledgebase generated here on the mechanisms of resistance in wheat to FHB, the biomarker RR metabolites identified, will be exploited to develop a high throughput metabolomics technology for screening wheat breeding lines for resistance to FHB.