HrpM is involved in glucan biosynthesis, biofilm formation and pathogenicity in Xanthomonas citri ssp. citri.
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 <KAN-2> 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.
Instituto de Ciencia y Tecnología Dr Cesar Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468 C1440FFX, Ciudad de Buenos Aires, Argentina.
Florencia
F
Malamud
Valeria P
VP
Conforte
Luciano A
LA
Rigano
Atilio P
AP
Castagnaro
María Rosa
MR
Marano
Alexandre
A
Morais do Amaral
Adrian A
AA
Vojnov
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002957:Citrus / Q000187:drug effects / Q000382:microbiology; D005407:Flagella / Q000187:drug effects / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics; D005936:Glucans / Q000096:biosynthesis*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D009068:Movement / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology; D014774:Virulence / Q000187:drug effects; D014974:Xanthomonas / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*
D001426:Bacterial Proteins; D005936:Glucans; D006861:Hydrogen Peroxide