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Pseudomonas – plant interactions
We study biocontrol bacteria of the Pseudomonas fluorescens group that colonize roots and suppress plant diseases caused by pathogenic fungi and oomycetes. The bacteria release a blend of exoproducts with antibiotic, metal-chelating, lytic, phytohormonal, and signaling activities that contribute to their environmental fitness and to disease-suppressive activity. We develop molecular tools, such as fluorescent protein-based reporters, that help us monitor at the single cell level how the pseudomonads adjust biocontrol trait expression and regulation during interaction with plants, fungal pathogens, other rhizosphere bacteria, and predatory nematodes and protozoa.
We investigate how crop plants influence biocontrol activity, population behavior and diversity of beneficial pseudomonads on roots, and to which extent plant genotype, plant health and nutrition status, and environmental factors are involved. Intriguingly, such experiments reveal that plants not only select for and accumulate specific Pseudomonas genotypes, but also specifically manipulate the expression of plant-beneficial genes, most probably via specific compounds released in the root exudates. The effect on Pseudomonas activity depends on the plant’s physiological status and varies for instance as a consequence of pathogen attack. Vice-versa, pseudomonads influence the plant’s metabolism, e.g. by inducing host defense responses against pathogens.
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