The genus Xanthomonas is a diverse and economically important group of bacterial phytopathogens, belonging to the gamma-subdivision of the Proteobacteria. Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, which affects most commercial citrus cultivars, resulting in significant losses worldwide. Symptoms include canker lesions, leading to abscission of fruit and leaves and general tree decline. Xanthomonas campestris pv. campestris (Xcc) causes black rot, which affects crucifers such as Brassica and Arabidopsis. Symptoms include marginal leaf chlorosis and darkening of vascular tissue, accompanied by extensive wilting and necrosis. Xanthomonas campestris pv. campestris is grown commercially to produce the exopolysaccharide xanthan gum, which is used as a viscosifying and stabilizing agent in many industries. Here we report and compare the complete genome sequences of Xac and Xcc. Their distinct disease phenotypes and host ranges belie a high degree of similarity at the genomic level. More than 80% of genes are shared, and gene order is conserved along most of their respective chromosomes. We identified several groups of strain-specific genes, and on the basis of these groups we propose mechanisms that may explain the differing host specificities and pathogenic processes.

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Crystallization and preliminary X-ray diffraction analysis of XAC1151, a small heat-shock protein from Xanthomonas axonopodis pv. The hspA gene (XAC1151) from Xanthomonas axonopodis pv. citri encodes a protein of 158 amino acids that belongs to the small heat-shock protein (sHSP) family of proteins. These proteins function as molecular chaperones by preventing protein aggregation. The protein was crystallized using the sittingdrop vapour-diffusion method in the presence of ammonium phosphate. X-ray diffraction data were collected to 1.65 Å resolution using a synchrotronradiation source. The crystal belongs to the rhombohedral space group R3, with unit-cell parameters a = b = 128.7, c = 55.3 Å . The crystal structure was solved by molecular-replacement methods. Structure refinement is in progress.

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Aiming to evaluate the potential wood energy of three clones of eucalyptus in different planting spacings, was installed an experiment with a randomized block design in a factorial design, with a combination of six spacings (2,5 x 0,5 m; 2,5 x 1,0 m; 2,5 x 2,0 m; 3,0 x 0,5 m; 3,0 x 1,0 m e 3,0 x 2,0 m) three eucalyptus clones (GG 157, GG 680 e GG 100), with three replicates. At 32 months old, was selected and cut down a medium-diameter tree per plot. These trees were scaled by Smalian method, using sections from 2.0 m to DAP. On these sections were removed wooden disks with 5.0 cm thick, which were used for the analyzes of basic density and calorific value of wood and, based on these values, it was possible to estimate the amount of energy stored per m³. It was observed that the basic density of wood, the gross calorific power and the energy stored in eucalyptus wood were different with the clones and planting spacing. Basic density and the amount of energy stored in a cubic meter of eucalyptus wood tended to increase with in the planting spacing, mainly for GG 680 and GG100 clones. The superior gross calorific of the wood showed no direct relationship with the planting density.