Engineering synthetic disease resistance genes to tackle plant pathogens

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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.