Engineering synthetic disease resistance genes to tackle plant pathogens

植物病原体阻碍了农业生产力，并对我们的食品系统构成了明显和现实的危险。仅植物病害一项就占全球农作物损失的10%-80%，足以养活数十亿人。选育广谱抗病品种被认为是作物病害可持续管理的途径。植物依靠由抗性(R)基因编码的免疫受体来感知和消除病原体。由于它们在植物保护中的高效力，R基因几乎已经被从各种种质中培育到每种作物中。问题是，R基因介导的抗性往往被病原菌种群的快速进化所击败。因此，及时识别对新出现的病原菌小种有效的新的R基因是一个重大的挑战。在这里，我们的目标是产生具有新的抗药性特异性的合成免疫受体(R基因)，以跟上快速进化的病原体。R基因携带亮氨酸重复序列(LRR)结构域，该结构域由与配体感应有关的单个重复模块组成。我们将利用这些蛋白质的模块化性质，并专注于对LRR结构域进行工程，以产生新的配体结合界面。我们将使用一种新的基于重组的方法来生成一个合成的LRR文库，这种方法可以有效地对现有R基因中存在的LRR进行改组。我们将使用成熟的蛋白质组学方法，筛选含有病原体编码的配体的合成LRR文库，以确定新的LRR-配体伙伴。能够与病原体配体结合的LRRs将被整合到各种现有的R基因支架(“合成R基因”)中，以确定最合适的合成R基因-配体对，从而实现适当的免疫应答。在这项工作完成后，我们希望设计合成的抗病基因，赋予对农学上重要的植物病原体新的特异性或广谱抗性。

Plant pathogens hamper agricultural productivity and pose a clear and present danger to our food systems. Plant diseases alone account for 10-80% of global crop losses, enough to feed several billion people. Breeding broad-spectrum disease resistance is regarded as sustainable way of managing crop diseases. Plants rely on immune receptors encoded by the resistance (R) genes that can sense and eliminate pathogens. Due to their high potency in plant protection, R genes have been bred into virtually every crop from various germplasms. The problem is that R gene mediated resistance is often defeated by the rapid evolution of pathogen populations. Therefore, timely identification of new R genes that are effective against emerging pathogen races is a major challenge. Here we aim to generate synthetic immune receptors (R genes) with new resistance specificities to keep up with rapidly evolving pathogens. R genes carry leucine-reach repeat (LRR) domains comprised of individual repeat modules implicated in ligand sensing. We will exploit the modular nature of these proteins and focus on engineering the LRR domains to generate new ligand binding interfaces. We will generate a synthetic LRR library by using a novel recombination-based approach that efficiently allows the shuffling of LRRs that are present in existing R genes. We will screen the synthetic LRR library with ligands encoded by the pathogens to identify new LRR-ligand partners by using a well-established proteomics approach. The LRRs capable of binding pathogen ligands will be incorporated into various available R gene scaffolds ("synthetic R genes") to identify the most suitable synthetic R gene-Ligand pairs that can mount appropriate immune responses. At the completion of this work, we expect to design synthetic disease resistance genes that confer new specificities or broad-spectrum resistance against agronomically important plant pathogens.