REDECKER, D., I.S.FEDER, P. VINUESA, T. BATINIC, U. SCHULZE, K. KOSCH, D. WERNER (1999): Biocontrol strain Pseudomonas sp. W34: specific detection and quantification in the rhizosphere of Cucumis sativus with a DNA probe and genotypic characterization by DNA fingerprinting. Zeitschrift für Naturforschung 54c, 359-370.
A DNA probe specific for biocontrol strains of Pseudomonas
was produced by screening
randomly amplified polymorphic DNA (RAPD) PCR fragments. Specificity of the probe
was assessed by dot blot and colony hybridization. It was used to specifically determine the
population of these strains on roots of Cucumis sativus cv. Delikatess. Two polymorphic
RAPD fragments of 750 bp and 550 bp showed identical specificity. The biocontrol strain
Pseudomonas sp. W34 was shown to be competitive in the rhizosphere of cucumber and to
maintain a stable population for at least 10 days when inoculated on the seed
The phylogenetic relationships between the biocontrol and reference strains were analyzed
at the strain level by means of RAPD and repetitive sequence-based PCR genomic finger-printing
(rep-PCR), and at higher taxonomic levels by means of amplified 16S ribosomal
DNA restriction analysis (ARDRA). It was shown that the antagonistic strains are closely
related, forming a separate cluster from other non-antagonistic and reference Pseudomonas
strains, their taxonomic placement remaining uncertain.