We are interested in the molecular aspects of symbiotic plant-microbe interactions and particularly in signalling and cell differentiation processes involved in establishment of symbiosis. Symbiotic nitrogen fixation is profoundly important for the environment and sustainable agriculture. Most crop plants assimilate nitrogen only from soil via added fertilizers. An alternative source is the rhizobia-legume symbiosis that provides a major source of fixed nitrogen. Rhizobia are capable of inducing the formation of nodules on the roots of their leguminous host plants. These specialized plant organs are invaded by the bacteria which fix nitrogen in an endosymbiotic bacteroid state within the plant cell. This process involves specific recognition and coordinated differentiation of both bacterial and host cells. Our studies are mainly based on Sinorhizobium meliloti that forms a symbiotic interaction with certain genera of leguminous plants. Among the host plants are Medicago sativa and Medicago truncatula, both forage legumes. M. truncatula serves as a model for grain legume crops.

Our research also focuses on interactions between bacterial phytopathogens and their host plants. We study Xanthomonas campestris pv. campestris and X. campestris pv. armoraciae as pathogens of cruciferous plants like cabbage or the model plant Arabidopsis thaliana. A further focus of our research is the biosynthesis of the exopolysaccharide xanthan gum by X. campestris strains. Xanthan gum is applied as a viscosifier at large scale in industries related to food and pharmaceuticals production, and in the oil drilling industry.

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