Identification of an Extracellular Endoglucanase That Is Required for Full Virulence in Xanthomonas citri subsp. citri

• Published in: PloS one 2016-03, Vol.11 (3), p.e0151017-e0151017
• Main Authors: Xia, Tian, Li, Yanjiao, Sun, Dongling, Zhuo, Tao, Fan, Xiaojing, Zou, Huasong
• Format: Article
• Language: English
• Subjects: Analysis; Biology and Life Sciences; Canker; Cell density; Cellulase; Cellulase - deficiency; Cellulase - genetics; Cellulase - metabolism; Cellulose; Citrus; Citrus - microbiology; Clonal deletion; Cloning; Deoxyribonucleic acid; Diseases and pests; DNA; E coli; Ectopic expression; Endoglucanase; Enzymes; Extracellular Space - enzymology; Gene Deletion; Genes; Genetic aspects; Health aspects; Hydrolysis; Infiltration; Inoculation; Laboratories; Lesions; Medicine and Health Sciences; Mutagenesis; Mutation; Physical Sciences; Physiological aspects; Phytopathogenic fungi; Plant Diseases - microbiology; Plant tissues; Planting density; Plasmids; Proteins; Research and Analysis Methods; Sucrose; Virology; Virulence; Virulence (Microbiology); Wounds; Xanthomonas - cytology; Xanthomonas - enzymology; Xanthomonas - genetics; Xanthomonas - pathogenicity; Xanthomonas campestris; Xanthomonas citri; Xanthomonas oryzae
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0151017

Xanthomonas citri subsp. citri causes citrus canker disease, which is characterized by the formation of water-soaked lesions, white or yellow spongy pustules and brown corky canker. In this work, we report the contribution of extracellular endoglucanase to canker development during infection. The ectopic expression of nine putative cellulases in Escherichia coli indicated that two endoglucanases, BglC3 and EngXCA, show carboxymethyl cellulase activity. Both bglC3 and engXCA genes were transcribed in X. citri subsp. citri, however, only BglC3 protein was detected outside the cell in western blot analysis. The deletion of bglC3 gene resulted in complete loss of extracellular carboxymethyl cellulase activity and delayed the onset of canker symptoms in both infiltration- and wound-inoculation assays. When growing in plant tissue, the cell density of bglC3 mutant was lower than that of the wild type. Our data demonstrated that BglC3 is an extracellular endoglucanase required for the full virulence of X. citri subsp. citri.