The bacterium Xanthomonas citri subsp. citri (Xac) is a phytopathogen that causes citrus canker, which affects citrus production in several countries, causing major economical losses. Several recent studies have shown that bacteria that colonize humans and plants possess mechanisms for sensing chemical signals eliminated by the host. In order to identify this type of sensing mechanism in Xac, this project will analyze the effects of host plant leaf extracts (orange) in the secretion of proteins involved in virulence and/or survival of the bacterium. Preliminary results have led to the development of an efficient protocol for extraction of proteins from Xac culture supernatants, which allowed the detection of differentially secreted proteins in samples grown in the presence of orange extract. We also observed that the addition of non-host plant extract to Xac cultures does not induce changes in the global profile of secreted proteins. Therefore, this project intends to continue this study, expanding and improving the analysis in order to obtain a complete profile of differentially secreted proteins in response to the presence of host plant extracts. Furthermore, the proteins with differential pattern of secretion in the presence of extracts will be further characterized, in order to confirm the data obtained by secretome analysis.This project also aims to analyze the influence of chemical signals present in plant extracts in physiological aspects of the bacterium, such as biofilm formation, motility and activity of degradative enzymes. These characteristics are affected by chemical signals from host plants in other bacterial species. This study will contribute to the understanding of the role of plant-pathogen signalling in Xac physiology.
News published in Agência FAPESP Newsletter about the scholarship: