Participation of Xanthomonas axonopodis pv. citri Hrp Cluster in Citrus Canker and in Non-Host Plants Response

DUNGER, G.; DAURELIO, L.D.; ORELLANO, E.G.; OTTADO, J.

Iguazú, Argentina

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2004

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, a serious disease of the citrus genus that results in important losses in citriculture regions. Type III secretion system, indispensable for the trafficking of proteins to the plant cell in pathogenicity and avirulence models, is encoded by hrp (hypersensitive response and pathogenicity) cluster. We have characterized the participation of Xac hrp cluster in the interaction with host and non-host plants. We isolated a region of the hrp cluster of Xac and we constructed mutants in the operons hrpB and hrpD and the hrpF gene, using used a suicide vector transferred by biparental mating. For disease symptoms assays bacterial suspensions were infiltrated into leaves of host plant orange (Citrus sinensis) and into leaves of non-host plant cotton. Bacteria mutant strains failed to produce canker in citrus plants or hypersensitive response in cotton plants. We also characterized the interaction of the phytopathogen with different non-host plants. The results show that hypersensitive response is produced in leaves of cotton, bean, tobacco, tomato, pepper and Nicotiana benthamiana and that genes present in operons hrpB and hrpD and the hrpF gene are required for pathogenicity in hosts and hypersensitive response induction in non-host plants.