Metabolic Model of the -Tomato Interaction Reveals Metabolic Switches during Host Colonization.

The oomycete pathogen causes potato and tomato late blight, a disease that is a serious threat to agriculture. is a hemibiotrophic pathogen, and during infection, it scavenges nutrients from living host cells for its own proliferation. To date, the nutrient flux from host to pathogen during infection has hardly been studied, and the interlinked metabolisms of the pathogen and host remain poorly understood. Here, we reconstructed an integrated metabolic model of and tomato () by integrating two previously published models for both species. We used this integrated model to simulate metabolic fluxes from host to pathogen and explored the topology of the model to study the dependencies of the metabolism of on that of tomato. This showed, for example, that a thiamine auxotroph, depends on certain metabolic reactions of the tomato thiamine biosynthesis. We also exploited dual-transcriptome data of a time course of a full late blight infection cycle on tomato leaves and integrated the expression of metabolic enzymes in the model. This revealed profound changes in pathogen-host metabolism during infection. As infection progresses, performs less synthesis of metabolites and scavenges more metabolites from tomato. This integrated metabolic model for the -tomato interaction provides a framework to integrate data and generate hypotheses about nutrition of throughout its infection cycle. Late blight disease caused by the oomycete pathogen leads to extensive yield losses in tomato and potato cultivation worldwide. To effectively control this pathogen, a thorough understanding of the mechanisms shaping the interaction with its hosts is paramount. While considerable work has focused on exploring host defense mechanisms and identifying proteins contributing to virulence and pathogenicity, the nutritional strategies of the pathogen are mostly unresolved. Genome-scale metabolic models (GEMs) can be used to simulate metabolic fluxes and help in unravelling the complex nature of metabolism. We integrated a GEM of tomato with a GEM of to simulate the metabolic fluxes that occur during infection. This yields insights into the nutrients that obtains during different phases of the infection cycle and helps in generating hypotheses about nutrition .