Open AccessThe histone‐like protein HupB influences biofilm formation and virulence in Xanthomonas citri ssp. citri through the regulation of flagellar biosynthesis
Author(s) -
Conforte Valeria P.,
Malamud Florencia,
Yaryura Pablo M.,
Toum Terrones Laila,
Torres Pablo S.,
De Pino Verónica,
Chazarreta Cristian N.,
Gudesblat Gustavo E.,
Castagnaro Atilio P.,
R. Marano María,
Vojnov Adrian A.
Publication year - 2019
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/mpp.12777
Subject(s) - biology , xanthomonas citri , citrus canker , mutant , flagellin , virulence , xanthomonas , flagellum , microbiology and biotechnology , wild type , escherichia coli , gene , genetics , bacteria
Summary Citrus canker is an important disease of citrus, whose causal agent is the bacterium Xanthomonas citri ssp. citri ( Xcc ). In previous studies, we found a group of Xcc mutants, generated by the insertion of the Tn 5 transposon, which showed impaired ability to attach to an abiotic substrate. One of these mutants carries the Tn 5 insertion in hupB , a gene encoding a bacterial histone‐like protein, homologue to the β‐subunit of the Heat‐Unstable (HU) nucleoid protein of Escherichia coli . These types of protein are necessary to maintain the bacterial nucleoid organization and the global regulation of gene expression. Here, we characterized the influence of the mutation in hupB regarding Xcc biofilm formation and virulence. The mutant strain hupB was incapable of swimming in soft agar, whereas its complemented strain partially recovered this phenotype. Electron microscope imaging revealed that impaired motility of hupB was a consequence of the absence of the flagellum. Comparison of the expression of flagellar genes between the wild‐type strain and hupB showed that the mutant exhibited decreased expression of fliC (encoding flagellin). The hupB mutant also displayed reduced virulence compared with the wild‐type strain when they were used to infect Citrus lemon plants using different infection methods. Our results therefore show that the histone‐like protein HupB plays an essential role in the pathogenesis of Xcc through the regulation of biofilm formation and biosynthesis of the flagellum.