Contribution of Folate Biosynthesis to Ralstonia solanacearum Proliferation in Intercellular Spaces

• Published in: Applied and Environmental Microbiology 2005, Vol.71 (1), p.417-422
• Main Authors: Shinohara, Rena, Kanda, Ayami, Ohnishi, Kouhei, Kiba, Akinori, Hikichi, Yasufumi
• Format: Article
• Language: English
• Subjects: Bacteria; bacterial wilt; Bacteriology; Biological and medical sciences; biosynthesis; cell proliferation; Cells; Chemical synthesis; DNA Transposable Elements; Extracellular Space - microbiology; Flowers & plants; folic acid; Folic Acid - biosynthesis; Folic Acid - pharmacology; Fundamental and applied biological sciences. Psychology; genes; intercellular spaces; Microbiology; Molecular Sequence Data; Mutagenesis, Insertional; mutants; Nicotiana - drug effects; Nicotiana - microbiology; Nicotiana tabacum; nucleotide sequences; p-aminobenzoate synthase; pabB gene; pathogenesis; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Plant Diseases - microbiology; Plant Leaves - drug effects; Plant Leaves - microbiology; Plant Microbiology; plant pathogenic bacteria; Plant Roots - drug effects; Plant Roots - microbiology; Ralstonia solanacearum; Ralstonia solanacearum - genetics; Ralstonia solanacearum - growth & development; Ralstonia solanacearum - pathogenicity; Sequence Analysis, DNA; tobacco; Virulence; Viruses
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.71.1.417-422.2005

The vigorous proliferation of Ralstonia solanacearum OE1-1 in host intercellular spaces after the invasion of host plants is necessary for the virulence of this bacterium. A folate auxotroph, RM, in which a mini-Tn5 transposon was inserted into pabB encoding para-aminobenzoate synthase component I, lost its ability to vigorously proliferate in intercellular spaces along with its systemic infectivity and virulence after inoculation into roots and infiltration into leaves of tobacco plants. Complementation of RM with the pabB gene allowed the mutant to multiply in intercellular spaces and to cause disease. In tobacco plants that were pretreated with folate, RM was able to vigorously proliferate in the intercellular spaces and cause disease. Interestingly, when it was inoculated through cut stems, the mutant multiplied in the plants and was virulent. Moreover, the mutant multiplied well in stem fluids but not in intercellular fluids, suggesting that the folate concentration within intercellular spaces may be a limiting factor for bacterial proliferation. Therefore, folate biosynthesis contributes to the vigorous proliferation of bacteria in intercellular spaces and leads to systemic infectivity resulting in virulence.