Identification of protein-protein interactions between Xanthomonas axonopodis pv. citri and orange

GERMÁN DUNGER; PEREDA ROSA, M.C.; CHUCK FARAH; ELENA G. ORELLANO; JORGELINA OTTADO

Rosario

Congreso; XLII Reunión Anual de SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular); 2006

Xanthomonas axonopodis pv. citri (Xac) causes citrus canker. Xac is a bacteria Gram (-) and uses different secretion systems for the translocation of pathogenicity and avirulence proteins to the plant cells. There are many genes characterized as elicitors of the host plant response and/or of the hypersensitive response (HR) in non host plants. Several genes in the sequenced genome of Xac may be considered as effector proteins that exert their functions in the plant cell. XAC3090, avrXacE1 and avrXacE2 are among these genes, with similarity to avirulence proteins from other plant pathogens. In this context, a XAC3090 mutant was constructed by marker exchange. However, the mutant strain showed no differences to the wild type Xac in its interaction with host and non host plants, possibly due to redundant functions. In order to further characterize the function of these proteins, two-hybrids assays in yeasts were carried out with XAC3090, AvrXacE1 and AvrXacE2 and a cDNA library of orange leaves. In total, 192 positive clones were sequenced and analyzed, from which 33 were positive preys for AvrXacE1, 28 for XAC3090 and 58 for AvrXacE2. A variety of proteins with different functions were found with a great prevalence of transcription factors, DNA binding proteins and heat shock proteins. The results suggest that these proteins may have a role in the regulation of the disease process.