HrpM is involved in glucan biosynthesis, biofilm formation and pathogenicity in Xanthomonas citri ssp. citri

Summary Xanthomonas citri ssp. citri (Xcc) is the causal agent of citrus canker. This bacterium develops a characteristic biofilm on both biotic and abiotic surfaces. A biofilm‐deficient mutant was identified in a screening of a transposon mutagenesis library of the Xcc 306 strain constructed using...

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Bibliographic Details
Published in:Molecular plant pathology 2012-12, Vol.13 (9), p.1010-1018
Main Authors: Malamud, Florencia, Conforte, Valeria P., Rigano, Luciano A., Castagnaro, Atilio P., Marano, María Rosa, Morais do Amaral, Alexandre, Vojnov, Adrian A.
Format: Article
Language:English
Subjects:
Adaptations
Agar
Biofilms
Biological and medical sciences
Canker
Citrus
Complementation
Enzymes
Fundamental and applied biological sciences. Psychology
glucans
Host plants
Hydrogen peroxide
Inoculation
Mutation
Original
Pathogenicity
Phytopathology. Animal pests. Plant and forest protection
Plant diseases
Plasmids
Promoters
transposon mutagenesis
Transposons
Xanthomonas
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Summary:Summary Xanthomonas citri ssp. citri (Xcc) is the causal agent of citrus canker. This bacterium develops a characteristic biofilm on both biotic and abiotic surfaces. A biofilm‐deficient mutant was identified in a screening of a transposon mutagenesis library of the Xcc 306 strain constructed using the commercial Tn5 transposon EZ‐Tn5 Tnp Transposome (Epicentre). Sequence analysis of a mutant obtained in the screening revealed that a single copy of the EZ‐Tn5 was inserted at position 446 of hrpM, a gene encoding a putative enzyme involved in glucan synthesis. We demonstrate for the first time that the product encoded by the hrpM gene is involved in β‐1,2‐glucan synthesis in Xcc. A mutation in hrpM resulted in no disease symptoms after 4 weeks of inoculation in lemon and grapefruit plants. The mutant also showed reduced ability to swim in soft agar and decreased resistance to H 2 O 2 in comparison with the wild‐type strain. All defective phenotypes were restored to wild‐type levels by complementation with the plasmid pBBR1‐MCS containing an intact copy of the hrpM gene and its promoter. These results indicate that the hrpM gene contributes to Xcc growth and adaptation in its host plant.
ISSN:1464-6722
1364-3703
DOI:10.1111/j.1364-3703.2012.00809.x