CONICET | Buscador de Institutos y Recursos Humanos

Xanthomonas axonopodis pv. citri (Xac) is the causative agent of citrus canker, an important threat to the citrus industry worldwide. Previous work from our laboratory demonstrated that Xac is able to form biofilm communities in biotic and abiotic surfaces where the extracellular polysaccharide xanthan (EPS) plays a key role in the biofilm maturation. To obtain new genes involved in Xac biofilm formation we performed a screening using a library of 6000 tn5 Xac mutants. We used a 96-well microtiter polyestirene plate as the abiotic attachment surface and the crystal violet staining technique to evaluate attached cells. We found 25 mutants defective in adhesion that also show impairment in the infective process. Some of them are also impaired in flagellar independent motility and swimming motility. The genes disrupted were identified by using inverse PCR. The genes can be grouped in different functional categories: 1-transcriptional regulators, 2-membrane proteins, 3-structural proteins, 4-hypotetical proteins. The identification of these new genes related with biofilm formation in Xac and infection is a great step towards the understanding of plant-pathogen interactions and could allow the development of strategies to control citrus canker.