An RNA cascade and disease resistance in tomato

所有生物体--生命--的生长、发育和对环境的反应都取决于基因的调节活动。如果这种调节没有发生，后果是死亡或疾病，但在某些例子中，如果它受到干扰，就会有进化的进步。例如，在农作物和农业中，有许多由于调节途径突变而持续存在的重要性状的例子，因为农民从这些突变植物中选择了种子。最近，植物育种家进行了选择。在这个项目中，我们将说明这一过程的现代变化，我们将工程突变植物增强抗病性。在历史上，突变体是随机出现的，它们会被选中，因为它们比非突变的祖先表现得更好或产生更高质量的产品。在这个项目中，与历史上的植物育种不同的是，突变将被称为基因编辑的新兴技术所瞄准。这些突变将被引入基因组中的遗传调控位点，这些位点通常会降低植物中抗病途径的活性。因此，突变的结果将是增强抗病性。实验方法是基于初步的实验中，我们破坏了影响番茄先天免疫系统的调节级联。这个级联反应中的节点是编码防御蛋白的mRNA，连接边缘是称为miRNA的小调控RNA。目前，我们还不知道这种级联的全部范围，也不知道不同的分支是否具有重叠或不重叠的功能，但我们知道，当级联系统被阻断时，植物表现出对晚疫病的增强的抗性，晚疫病是由导致19世纪40年代爱尔兰马铃薯饥荒的丝状病原体引起的。这种病原体经常是番茄种植者的一个问题。这些植物也对细菌有部分抗性，因为这些是如此不同的病原体，我们推断，破坏这种miRNA级联可能会赋予对其他病原体的广谱抗性。在拟议的工作中，我们的目标是更详细地了解miRNA级联调控抗病性。在获得这些信息的过程中，我们将更多地了解miRNAs的作用方式，因此来自该项目的信息将对理解遗传调控具有更广泛的相关性。该项目将测试通过破坏miRNA级联可以实现的害虫和病原体抗性谱，我们将建立后期的转化工作，将使用具有增强抗病性的基因编辑植物作为可持续农业新方法的一部分。这些实验都将在番茄中进行，但许多植物的抗病性特征的miRNA级联调节，因此我们的发现将更广泛地与各种作物相关。

Growth, development and responses to the environment of all organisms - life - depends on regulated activity of genes. If this regulation does not occur the consequence is death or disease but, in some examples, if it is perturbed there is evolutionary advance. In crops and agriculture, for example, there are many examples of important traits due to mutation of regulatory pathways that have persisted because farmers selected the seed from these mutant plants. More recently plant breeders have carried out the selection. In this project we will illustrate a modern variation on this process in which we will engineer mutant plants with enhanced disease resistance. In the historical situations the mutants arose randomly and they would have been selected because they performed better or gave higher quality produce than the non-mutant progenitor. In this project the difference from the historical plant breeding is that the mutations will be targeted by an emerging technology known as gene editing. These mutations will be introduced at genetic regulatory sites in the genome that normally reduce the activity of disease resistance pathways in the plant. The consequence of the mutation will, therefore, be enhanced disease resistance. The experimental approach is based on preliminary experiments in which we disrupted a regulatory cascade affecting the innate immune system of tomato. The nodes in this cascade are the mRNAs encoding defense proteins and the connecting edges are small regulatory RNAs known as miRNAs. At present we do not know the full extent of this cascade or whether the different branches have overlapping or non-overlapping functions but we know that when the cascade system is blocked the plants exhibit enhanced resistance against late blight caused by a filamentous pathogen responsible for the potato famine in Ireland in the 1840s. This pathogen is often a problem for tomato growers. The plants were also partially resistant against a bacterium and, because these are such different pathogens, we infer that disrupting this miRNA cascade may confer resistance against a broad spectrum of other pathogens.In the proposed work we aim to understand the miRNA cascade regulation of disease resistance in more detail. In getting this information, we will learn more about the ways that miRNAs act and so the information from this project will have more general relevance to understanding of genetic regulation. The project will test the spectrum of pest and pathogen resistance that can be achieved through the disruption the miRNA cascade and we will have set up later translational work that will use gene edited plants with enhanced disease resistance as part of a new approach to sustainable agriculture. The experiments will all be carried out in tomato but the miRNA cascade regulation of disease resistance features in many plants and so our findings will be more generally relevant to a wide range of crops.