PARTICIPATION OF Xanthomonas axonopodis pv. citri EFFECTOR PROTEINS IN CITRUS CANKER

DUNGER, G.; ORELLANO, E; JORGELINA OTTADO

Villa Carlos Paz

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular; 2008

SAIB

Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, a serious disease that results in important losses. Xac is a Gram (-) bacterium and uses secretion systems for translocation of pathogenicity and avirulence proteins to the plant cells. There are many genes characterized like elicitors of the host plant response and/or of hypersensitive response (HR) in non host plants. In the sequenced genome of Xac several genes have been identified as putative effector proteins that exert their function in the plant cell, among these are XAC3090, avrXacE1 (XAC0286) and avrXacE2 (XAC3224). We isolated XAC3090, avrXacE1 and avrXacE2 of Xac and constructed mutants in these genes, using a suicide vector transferred by biparental mating. For disease symptoms assays, bacterial suspensions were infiltrated into leaves of host plant orange (Citrus sinensis) and in non-host plants tomato, tobacco and cotton, showing differences in virulence phenotype only in the interaction with the host plant. No differences were observed in bacterial growth curves in host plant, but when photosynthetic parameters were analyzed, we detected differences between mutant and wild type Xac. The results suggest that these effector proteins could have different roles in pathogenicity, but may not be indispensables in citrus canker.