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

Authors :
Simone Cristina Picchi
Laís Moreira Granato
Maria Júlia Festa Franzini
Maxuel Oliveira Andrade
Marco Aurélio Takita
Marcos Antonio Machado
Alessandra Alves de Souza
Source :
Microorganisms, Vol 9, Iss 6, p 1176 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

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 (ΔxanA) 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.

Details

Language :
English
ISSN :
20762607
Volume :
9
Issue :
6
Database :
Directory of Open Access Journals
Journal :
Microorganisms
Publication Type :
Academic Journal
Accession number :
edsdoj.bdbe970cf61645e3bcbfa4b15d178235
Document Type :
article
Full Text :
https://doi.org/10.3390/microorganisms9061176