Examinando por Autor "Garavaglia, Betiana Soledad"
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Ítem Acceso Abierto 3-methylcrotonyl Coenzyme A (CoA) carboxylase complex is involved in the Xanthomonas citri subsp. citri lifestyle during citrus infection(Public Library of Science (PLOS), 2018-06-07) Tomassetti, Mauro; Garavaglia, Betiana Soledad; Vranych, Cecilia Verónica; Gottig, Natalia; Ottado, Jorgelina; Gramajo, Hugo Cesar; Diacovich, LautaroÍtem Acceso Abierto The dual nature of trehalose in citrus canker disease: a virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses(Oxford University, 2015-03-15) Piazza, Ainelén; Zimaro, Tamara; Garavaglia, Betiana Soledad; Ficarra, Florencia Andrea; Thomas, Ludivine; Marondedze, Claudius; Feil, Regina; Lunn, John E.; Gehring, Chris; Ottado, Jorgelina; Gottig, NataliaXanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant’s metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA–otsB pathway, in Xcc, plays a role in modifying the host plant’s metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant’s resources after infection, but on the other hand, it is a tell-tale sign of the pathogen’s presence that triggers the plant to defend itself against infection.Ítem Acceso Abierto XacFhaB adhesin, an important Xanthomonas citri ssp. citri virulence factor, is recognized as a pathogen-associated molecular pattern(BSPP and Wiley, 2016-11-15) Garavaglia, Betiana Soledad; Zimaro, Tamara; Abriata, Luciano Andrés; Ottado, Jorgelina; Gottig, NataliaAdhesion to host tissue is one of the key steps of the bacterial pathogenic process. Xanthomonas citri ssp. citri possesses a non-fimbrial adhesin protein, XacFhaB, required for bacterial attachment, which we have previously demonstrated to be an important virulence factor for the development of citrus canker. XacFhaB is a 4753-residue-long protein with a predicted β-helical fold structure, involved in bacterial aggregation, biofilm formation and adhesion to the host. In this work, to further characterize this protein and considering its large size, XacFhaB was dissected into three regions based on bioinformatic and structural analyses for functional studies. First, the capacity of these protein regions to aggregate bacterial cells was analysed. Two of these regions were able to form bacterial aggregates, with the most amino-terminal region being dispensable for this activity. Moreover, XacFhaB shows features resembling pathogen-associated molecular patterns (PAMPs), which are recognized by plants. As PAMPs activate plant basal immune responses, the role of the three XacFhaB regions as elicitors of these responses was investigated. All adhesin regions were able to induce basal immune responses in host and non-host plants, with a stronger activation by the carboxyl-terminal region. Furthermore, pre-infiltration of citrus leaves with XacFhaB regions impaired X. citri ssp. citri growth, confirming the induction of defence responses and restraint of citrus canker. This work reveals that adhesins from plant pathogens trigger plant defence responses, opening up new pathways for the development of protective strategies for disease control.