Effekte von Mikrobiom, Wirts- und Pathogenotyp sowie Umwelt auf die Interaktion zwischen Pseudomonas-Isolaten und Pflanzen

01/02/2019 to 31/01/2023

There has been tremendous progress in understanding the molecules that enable a pathogen to overcome host defenses, especially of so-called effector molecules. Much less is known about how these interactions are modified by both the biotic and abiotic environment. In this project, we will focus on the genus Pseudomonas, which includes pathogens, commensals as well as beneficial bacteria, and its interaction with Arabidopsis thaliana and close relatives. We will ask how natural microbiota shapes the interaction between the plant and different Pseudomonas strains that naturally occur on A. thaliana and for which detailed information on temporal and spatial distribution is available. Our focus will be on Pseudomonas strains similar to widespread, often highly virulent agricultural pathogens, and a second group that has a much more limited effector repertoire, but occurs more commonly on wild A. thaliana plants. We will compare effects of natural microbiota with effects of a synthetic community composed of A. thaliana phyllosphere microbes, and we will determine how changes in the abiotic environment and host genetics affect these multitrophic interactions. We will be testing the following hypotheses: (i) The background microbiota differentially interferes with or competes with different Pseudomonas strains for resources and limits their proliferation; (ii) the plant immune system needs to be educated by prior exposure to microbiota in order to discriminate between different Pseudomonas strains; (iii) these interactions are environment- and host-genotype dependent. Our experiments will start to reveal which aspects of the microbiota are responsible for protection against Pseudomonas infections, when they act to protect A. thaliana, and how pathogen-, environment- and host-genotype-specific the observed interactions are.