The ecnA Antitoxin Is Important Not Only for Human Pathogens: Evidence of Its Role in the Plant Pathogen Xanthomonas citri subsp. citri

Author(s)

Granato, Lais Moreira ^[1] ; Picchi, Simone Cristina ^[1] ; Andrade, Maxuel de Oliveira ^{[2, 3]} ; Martins, Paula Maria Moreira ^[1] ; Takita, Marco Aurelio ^[1] ; Machado, Marcos Antonio ^[1] ; de Souza, Alessandra Alves ^[1]

Affiliation

^[1] Inst Agron, Ctr Citricultura Sylvio Moreira, Cordeiropolis, SP - Brazil

^[2] Ctr Nacl Pesquisa Energia & Mat, Lab Nacl Biociencias, Campinas, SP - Brazil

^[3] Univ Florida, Dept Microbiol & Cell Sci, Citrus Res & Educ Ctr, Lake Alfred, FL - USA

• Document type: Journal article
• Source: Journal of Bacteriology; v. 201, n. 20 OCT 2019.
• Web of Science Citations: 0

Abstract

Xanthomonas citri subsp. citri causes citrus canker disease worldwide in most commercial varieties of citrus. Its transmission occurs mainly by wind-driven rain. Once X. citri reaches a leaf, it can epiphytically survive by forming a biofilm, which enhances the persistence of the bacteria under different environmental stresses and plays an important role in the early stages of host infection. Therefore, the study of genes involved in biofilm formation has been an important step toward understanding the bacterial strategy for survival in and infection of host plants. In this work, we show that the ecnAB toxin-antitoxin (TA) system, which was previously identified only in human bacterial pathogens, is conserved in many Xanthomonas spp. We further show that in X. citri, ecnA is involved in important processes, such as biofilm formation, exopolysaccharide (EPS) production, and motility. In addition, we show that ecnA plays a role in X. citri survival and virulence in host plants. Thus, this mechanism represents an important bacterial strategy for survival under stress conditions. IMPORTANCE Very little is known about TA systems in phytopathogenic bacteria. ecnAB, in particular, has only been studied in bacterial human pathogens. Here, we showed that it is present in a wide range of Xanthomonas sp. phytopathogens; moreover, this is the first work to investigate the functional role of this TA system in Xanthomonas citri biology, suggesting an important new role in adaptation and survival with implications for bacterial pathogenicity. (AU)

• FAPESP's process: 13/10957-0 - Xylella fastidiosa-vector-host plant interaction and approaches for citrus variegated chlorosis and citrus canker control
• Grantee: Alessandra Alves de Souza
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50880-0 - INCT 2014: comparative and functional genomics and citrus-assisted breeding
• Grantee: Marcos Antonio Machado
• Support Opportunities: Research Projects - Thematic Grants