Functional analysis of the rstA (XAC0730) gene from Xanthomonas citri subsp. citri and its relationship with pathogenicity

• Grant number: 20/02238-8
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2021
• Effective date (End): December 31, 2021
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Henrique Ferreira
• Grantee: Mario Nicolas Caccalano
• Home Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated research grant: 15/50162-2 - Protecting plants with antimicrobial peptides and gallates - Pro-Planta, AP.TEM

Abstract

According to IBGE data, the state of São Paulo is the world's largest producer of sweet oranges, with most of the production destined for the manufacture of juice. Citrus cancer is one of the most worrying bacterial diseases for citrus in Brazil. The most widespread and severe form of cancer, citrus cancer type A, is caused by the bacterium Xanthomonas citri subsp. citri (X. citri). The characterization of genes not yet or little studied in X. citri is important for the evaluation of the potential of new compounds to control citrus canker. The two-component system (TCS) RstA-RstB, represents a typical signal transduction system. RstB is a histidine kinase (HK) bound to the inner membrane. After detecting environmental signals, RstB activates the transfer of a phosphate group to RstA, a cytosolic response regulator (RR), which has the function of activating or inhibiting gene transcription. The RSTA-RstB TCS regulates the virulence of numerous pathogenic bacteria, especially those belonging to the Proteobacteria taxon. Several studies, in other pathogens, showed that RstA is a master regulator, which may be related to motility, biofilm formation, protease production, resistance to antibiotics, cell growth and morphology, pathogenicity or the regulation of secreted proteins by the type II system. However, there is no study to our knowledge that reveals the function and importance of the TCS RstA-RstB in any species of the genus Xanthomonas. Therefore, considering the key role of this system for several bacteria and the restriction of studies on Xanthomonas citri subsp. citri, we propose to delete the rstA gene from the TCS RstA-RstB in this bacteria and evaluate its growth profile in culture, morphology, mobility, biofilm formation, secreted proteases and, finally, evaluate its pathogenicity. (AU)