IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Blue Light Regulation of Xanthomonas citri subsp. citri Virulence during the Interaction with Citrus Plants
Autor/es:
KRAISELBURD, I.; TONDO, M.L.; DAURELIO, L. D.; ALET, A.I.; MONZÓN, J.; MERELO, P.; CORTADI, A.A.; TALÓN, M.; TADEO, F.; GÄRTNER, W.; LOSI, A.; ORELLANO, E.G.
Lugar:
Córdoba
Reunión:
Congreso; 16th International Congress on Photobiology; 2014
Institución organizadora:
International Union of Photobiology
Resumen:
Xanthomonas citri subsp. citri (Xcc) is a Gram-negative bacterium responsible for the citrus canker disease. The Xcc genome has been fully sequenced, and includes four genes encoding proteins with domains involved in the perception of light. Among them is a protein belonging to the family of photoreceptors with LOV domains (Light, Oxygen and Voltage), which are sensitive to the blue region of the electromagnetic spectrum. It also has two BLUFs and one phytochrome. Xcc-LOV is composed by a LOV domain, a histidine kinase domain and a response regulator domain, being a hybrid histidine kinase protein. Xcc-LOV was characterized by biophysical and photochemical methods and by enzymatic activity showing that this protein is a canonical photoreceptor. The Xcc-LOV displays a photocycle that involves the generation of an excited triplet state, followed by the generation of a covalent proteincofactor photo-adduct that returns to the ground state in the dark with an unusually prolonged recovery time. Additionally, the photo-adduct has an increased kinase activity under light condition, probably involved in intracellular signaling. Furthermore, an Xcc mutant strain in the gene encoding the LOV photoreceptor was used to evaluate its role in the bacterial physiology and in the development of the disease during plant infection. It was observed that the synthesis of flagella, adhesins and exopolysaccharides are modulated by the lov gene. Moreover, a blue light dependence was observed in the bacterial adhesion to target tissues. Additionally, a global transcriptomic analysis was performed on orange leaves inoculated with the wild type and mutant strains of Xcc, and biochemical and histological methods were used to assess the defense mechanisms triggered by plants against bacterial infection. These results suggest that the LOV protein is probably involved in the regulation of bacterial effectors that counteract plant defense responses thus favoring the development of citrus canker disease.