Regulation of the metabolic adaptation of the phytopathogenic bacteria Xanthomonas campestris pv. campestris and Xanthomonas campestris pv. armoraciae during infection of Arabidopsis thaliana

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This proposal focuses on the metabolic regulatory networks of Xanthomonas campestris pv. campestris (Xcc) and Xanthomonas campestris pv. armoraciae (Xca) as pathogens of cruciferous plants. Complete genome sequences for both pathovars are available and the model plant Arabidopsis thaliana will be used as host. The specific focus of this proposal is the dynamics of bacterial metabolic adaptation during infection on the level of metabolic pathways and gene regulatory networks. We assume that the bacterial activity changes the plant metabolism, what in turn influences the bacterial activity. Or in other words, the bacterial plant interaction can be seen as a cascading network of (metabolic) interactions. The hypothesis is that bacteria exist in different metabolic stages during the pathogenic interaction. We aim to establish a metabolic model allowing for simulation of these stages. The model should predict changes in metabolic flux in accordance to different nutrient sources and the adaptation to mutations in genes coding for central enzymes. A signature-tagged mutagenesis approach for the identification of genes relevant to infection and colonization of the host plant will be carried out. 13C-labeling experiments and specific mutagenesis is planned to establish the metabolic flux under conditions relevant for the adaptation to the in planta life style. Finally, in planta monitoring of the colonization process using fluorescent reporter gene constructs will be used to establish a dynamic view of the metabolic adaptation of Xanthomonas during the different stages of infection.