Citrus production in Brazil is the largest in the world, generating 19 million tons of orange annually. The state of São Paulo is the largest producer in the country, being responsible for about 75% of citrus bulk production. However, citric canker is still one of the most devastating diseases and a threat to the production and exportation of high quality orange. Asian citric canker, which is the most agressive, is caused by the bacteria Xanthomonas citri subsp. citri (XAC). The other forms of citric canker are canker B and C, caused by two Xanthomonas fuscans ssp. aurantifolii types (XauB and XauC), and their host range is much smaller than XAC's own host range. Canker C occurs only in Brasil, in the state of São Paulo and affects only C. aurantifolia. The absence of studies on XauB or XauC may be related to its limited geographic distribution or with the fact that Asian citric canker is so agressive that it becomes strikingly important to study it at the expense of forgetting the other citric canker types. The present proposal aims to complement the in vivo analysis of XAC and XauC, initiated previously by the host research group. It is proposed a diversification of the proteomic techniques applied in Xanthomonas studies for maximizing the identification of proteins involved in the interaction between XAC or XauC with their compatible hosts. As proteins synthetized by Xanthomonas, while interfering on the host plant cell metabolism, are determinant for its virulence and compose a unique set for each specific interaction, it is proposed the study of the interaction of XAC with two compatible hosts, C. limon, less sensitive, and C. aurantifolia, more sensitive. In the same way, the set of proteins synthetized during the infection of the same host might correspond to distinct virulence strategies among Xanthomonas subspecies, therefore, it is proposed the study of the interaction between XAC and XauC with the same compatible host, C. aurantifolia. In both approaches the total proteomes will be analysed by 2D-PAGE in separate acidic and basic pH intervals, increasing proteome resolution. The periplasm subproteomes will be equally studied through on-line techniques of nano-liquid chromatography and mass spectrometry, in order to get a better insight of the role of this bacterial structure on the interaction of XAC and XauC with compatible hosts. The present work will allow to greatly enlarge the knowledge on the proteomes of XAC and XauC. Innovation will come not only from the proteomic resolution on pH basic intervals and on 2D-PAGE gel areas of low molecular weight applied to Xanthomonas studies, but also from the detailed analysis of the periplasmic subproteome upon compatible interaction with the intact host. The present work will contribute to increase the experience in proteomics of the host research group and will allow to firmly consolidate other proteomic projects in the context of UFSCar.
News published in Agência FAPESP Newsletter about the scholarship: