Modified Monosaccharides Content of Xanthan Gum Impairs Citrus Canker Disease by Affecting the Epiphytic Lifestyle of Xanthomonas citri subsp. citri

Author(s)

Picchi, Simone Cristina ^[1] ; Granato, Lais Moreira ^[1] ; Franzini, Maria Julia Festa ^[1] ; Andrade, Maxuel Oliveira ^[2] ; Takita, Marco Aurelio ^[1] ; Machado, Marcos Antonio ^[1] ; de Souza, Alessandra Alves ^[1]

Affiliation

^[1] Inst Agron Campinas, Ctr Citricultura Sylvio Moreira, Biotechnol Lab, BR-1349070 Sao Paulo - Brazil

^[2] Ctr Nacl Pesquisa Energia & Mat, Biosci Natl Lab, BR-13083100 Campinas, SP - Brazil

• Document type: Journal article
• Source: MICROORGANISMS; v. 9, n. 6 JUN 2021.
• Web of Science Citations: 0

Abstract

Xanthomonas citri subsp. citri (X. citri) is a plant pathogenic bacterium causing citrus canker disease. The xanA gene encodes a phosphoglucomutase/phosphomannomutase protein that is a key enzyme required for the synthesis of lipopolysaccharides and exopolysaccharides in Xanthomonads. In this work, firstly we isolated a xanA transposon mutant (xanA::Tn5) and analyzed its phenotypes as biofilm formation, xanthan gum production, and pathogenesis on the sweet orange host. Moreover, to confirm the xanA role in the impaired phenotypes we further produced a non-polar deletion mutant (Delta xanA) and performed the complementation of both xanA mutants. In addition, we analyzed the percentages of the xanthan gum monosaccharides produced by X. citri wild-type and xanA mutant. The mutant strain had higher ratios of mannose, galactose, and xylose and lower ratios of rhamnose, glucuronic acid, and glucose than the wild-type strain. Such changes in the saccharide composition led to the reduction of xanthan yield in the xanA deficient strain, affecting also other important features in X. citri, such as biofilm formation and sliding motility. Moreover, we showed that xanA::Tn5 caused no symptoms on host leaves after spraying, a method that mimetics the natural infection condition. These results suggest that xanA plays an important role in the epiphytical stage on the leaves that is essential for the successful interaction with the host, including adaptive advantage for bacterial X. citri survival and host invasion, which culminates in 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 type: Research Projects - Thematic Grants
• FAPESP's process: 17/18570-9 - Functional analysis of CsMAF1, an RNA polymerase III repressor involved in cell growth control and pathogen response in plants
• Grantee: Maxuel de Oliveira Andrade
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 14/50880-0 - INCT 2014: comparative and functional genomics and citrus-assisted breeding
• Grantee: Marcos Antonio Machado
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 13/01395-9 - N-acetyl-cysteine (NAC): a molecule with antimicrobial potential for management of citrus canker.
• Grantee: Simone Cristina Picchi
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 19/01901-8 - Gene silecing of citrus floema: modulation of infection hypersensitivity by Candidatus liberibacter spp
• Grantee: Laís Moreira Granato
• Support type: Scholarships in Brazil - Post-Doctorate