lifesciences
Innopsys

Transcriptional reprogramming and phenotypical changes associated with growth of Xanthomonas campestris pv. campestris in cabbage xylem sap

Thomas Dugé de Bernoville1,2, Laurent D. Noël1,2, Magali SanCristobal3,4,5, Saida Danoun6,7, Anke Becker8, Paul Soreau9, Matthieu Arlat1,2, Emmanuelle Lauber1,2
1. Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR 441, INRA, Castanet-Tolosan, France
2. Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR 2594, CNRS, Castanet-Tolosan, France
3. UMR 1388 Génétique, Physiologie et Systèmes d'Elevage, INRA, Castanet-Tolosan, France
4. UMR 1388 Génétique, Physiologie et Systèmes d'Elevage, Université de Toulouse INPT ENSAT, Castanet-Tolosan, France
5. UMR 1388 Génétique, Physiologie et Systèmes d'Elevage, Université de Toulouse INPT ENVT, Toulouse, France
6. Laboratoire de Recherches en Sciences Végétales (LRSV), UMR 5546, Université de Toulouse, UPS, CastanetTolosan, France
7. Laboratoire de Recherches en Sciences Végétales (LRSV), UMR 5546, CNRS, Castanet-Tolosan, France
8. Loewe Center for Synthetic Microbiology and Department of Biology, Philipps-Universität Marburg, Marburg, Germany
9. CEA Cadarache, IBEB-SBVME, Research Group in Applied Phytotechnics, UMR 6191 CNRS-CEA, Aix-Marseille University, Saint-Paul-lez-Durance Cedex, France 

Abstract

Xylem sap (XS) is the first environment that xylem phytopathogens meet in planta during the early infection steps. Xanthomonas campestris pv. campestris (Xcc), the causative agent of Brassicaceae black rot, colonizes the plant xylem vessels to ensure its multiplication and dissemination. Besides suppression of plant immunity, Xcc has to adapt its metabolism to exploit plant-derived nutrients present in XS. To study Xcc behaviour in the early infection steps, we used cabbage XS to analyse bacterial growth. Mineral and organic composition of XS were determined. Significant growth of Xcc in XS was allowed by the rapid catabolism of amino acids, sugars and organic acids, and it was accompanied by the formation of biofilm-like structures. Transcriptome analysis of Xcc cultivated in XS using cDNA microarrays revealed a XS-specific transcriptional reprogramming compared to minimal or rich media. More specifically, up-regulation of genes encoding transporters such as TonB-dependent transporters (TBDTs), that could be associated with nutrient acquisition and detoxification, was observed. In agreement with the aggregation phenotype, expression of genes important for twitching motility and adhesion was up-regulated in XS. Taken together, our data show specific responses of Xcc to colonization of cabbage XS that could be important for the pathogenesis process and establish XS as a model medium to study mechanisms important for the early infection events.

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