5%. In the latter case, cultivation is then prohibited in the area for the next 3 years and there is no payment for lost production to the growers. Considering the importance of the disease Selleckchem Y27632 worldwide, especially for Brazil, a Brazilian group sequenced and annotated the complete genome of X. citri subsp. citri (Xcc) strain 306 [4], which causes citrus canker, and compared it with X. campestris pv. campestris

strain ATCC 33913, the etiological agent of crucifer black rot. The citrus subspecies has 4,313 open reading frames (ORFs), of which 62.83% have been assigned function. In addition, Xcc also has two plasmids that have 115 genes, and for 55 (47.82%) of them, no role has been proposed. Although the genome of Xcc has been characterized

and annotated, the inferences made based on in silico analyses require experimental selleck investigation to accurately detect which genes are related to the pathogen-host adaptation process, and which are associated with pathogenesis itself. Therefore, functional genomics studies are necessary to elucidate the machinery required for pathogen installation and proliferation in plants, and the induction of citrus canker symptoms in the host. From the functional genomic perspective, large scale analysis of mutants by inoculation in host plants allows identification of the genes required for adaptation, pathogenesis and virulence, providing a best understanding of the colonization and infection potential of the bacteria. In this work, using transposon insertion mutagenesis [5], a library containing 10,000 mutants of the citrus canker etiological agent X. citri subsp. citri strain 306

stiripentol was prepared and 3,300 mutants were analyzed after individual inoculation of host plants. Eight mutants with absent pathogeniCity and 36 mutants with reduced symptoms in planta, at varying intensities, were identified. Mutated genes were identified by sequencing the total DNA of the mutants with altered virulence, allowing the identification of the site of insertion of the transposon used for mutagenesis. A random selection of these genes was immobilized on a nylon membrane array and expression profiles were analyzed in vivo through nucleic acid 17DMAG hybridization to labeled cDNA probes, using targets corresponding to wild Xcc strains multiplied in non-infective (Xcc multiplied in rich culture medium) or infective conditions (Xcc multiplied in a host plant). Finally, a comparative genomic analysis of each mutated ORF region from Xcc with other sequenced Xanthomonas genomes allowed the identification of five interesting genomic regions, with two being exclusive to Xcc. The unique characteristics presented by these five regions suggest that they are probably new pathogeniCity islands [6] in Xcc. The implications of the proteins encoded by these mutated ORFs in host adaptation and colonization processes and citrus canker symptoms induction are discussed.