ANALYSIS OF TRANSCRIPTIONAL PROFILES OF Xanthomonas citri pv. citri IN CONDITIONS RELEVANT TO PLANT INFECTION

• Grant number: 24/22312-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2025
• End date: February 29, 2028
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Cristina Elisa Alvarez Martinez
• Grantee: Brenno Wendler Miranda
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center, AP.CEPID

Abstract

Xanthomonas citri pv citri (Xcc) is the bacterium that causes citrus canker, a disease that affects several plant species of the Citrus genus and causes losses for producers. In the process of plant infection, various conditions are encountered by pathogens and mechanisms have been selected to deal with adversity. Of relevance in this process are the different types of secretion systems, which provide advantages in the competition against other organisms in the local microbiota, as well as aiding in the host infection process. In this sense, the type 3 secretion system (T3SS) plays a fundamental role in the virulence of this organism, as it modulates the metabolism of the plant cell to bypass the immune response and even activate the expression of plant genes to ensure the survival of the pathogen. T3SS is encoded by the hrp genes, which are regulated by the HrpG and HrpX regulators. Some mechanisms of HrpG regulation have already been described, such as post-translational modifications and translational and post-translational control. Genes that are essential for virulence have also been described, but their relationship with the regulation of hrp gene expression has not yet been established. However, little is known about the environmental signals encountered by bacteria that trigger the expression of virulence-related genes. Except for the components found in specific minimal media simulating the apoplast, our understanding of the environmental signals triggering T3SS activation and Xcc's transcriptional response to them remains limited. Therefore, this project aims to build genetic sensors based on T3SS regulatory elements to carry out a high-throughput screening using 576 cultivation conditions to evaluate signals capable of activating the expression of this system. Once the T3SS induction conditions have been identified, RNA-seq will be conducted to describe the Xcc transcriptional profile under conditions relevant to infection. With this, we hope to elucidate mechanisms of adaptation to the host and the environments encountered by the bacterium.