CHARACTERIZATION OF BIOFILM FORMATIONDEFECTIVE MUTANTS OF Xanthomonas axonopodis pv.citri (XAC)

FLORENCIA MALAMUD; VALERIA CONFORTE; RAFAEL HOMEN; MARCOS MACHADO; MARÍA ROSA MARANO; ATILIO CASTAGNARO; ALEXANDRE DO AMARAL; ADRIÁN VOJNOV

Tucumán

Congreso; 45th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2009

SAIB

Xanthomonas axonopodis pv. citri (Xac) is the causative agent ofcitrus canker, an important threat to the citrus industry worldwide.Previous work from our laboratory demonstrated that Xac is able toform biofilm communities in biotic and abiotic surfaces where theextracellular polysaccharide xanthan (EPS) plays a key role in thebiofilm maturation. To obtain new genes involved in Xac biofilmformation we performed a screening using a library of 6000 Tn5Xac mutants. We used a 96-well microtiter polyestirene plate as theabiotic attachment surface and the crystal violet staining techniqueto evaluate attached cells. We found 25 mutants defective inadhesion that also shows impairment in the infective process. Someof them are also impaired in flagellar independent motility andswimming motility. The genes disrupted were identified by usinginverse PCR. The genes can be grouped in different functionalcategories: 1-transcriptional regulators, 2-membrane proteins, 3-structural proteins, 4-hypotetical proteins. The identification ofthese new genes related with biofilm formation in Xac andinfection is a great step towards the understanding of plantpathogeninteractions and could allow the development ofstrategies to control citrus canker.