Evidence for genotypic differences between the two siderovars of Pseudomonas tolaasii, cause of brown blotch disease of the cultivated mushroom Agaricus bisporus.
Sixteen representative isolates of Pseudomonas tolaasii, the causal agent of brown blotch of the cultivated mushroom Agaricus bisporus, were previously assigned to two siderovars (sv1 and sv2) on the basis of pyoverdines synthesized. Each isolate was pathogenic and produced a typical white line precipitate when cultured adjacent to Pseudomonas "reactans" strain LMG 5329. These 16 isolates of P. tolaasii, representing sv1 and sv2, were further characterized using genotypic methods to examine the relationships between the isolates. Rep-PCR studies revealed two distinct patterns from these isolates, which were consistent with the siderovar grouping. Ribotyping differentiated P. tolaasii LMG 2342T (sv1) and PS 3a (sv2) into two distinct ribotypes. A pair of primers, targeted to a 2.1-kb fragment of tl1 (encoding a tolaasin peptide synthetase), yielded the same PCR product from P. tolaasii LMG 2342T (sv1) and PS 22.2 (sv1), but not from PS 3a (sv2). Southern blot analysis indicated that homologues of tl1 are present in PS 3a, but the pattern of hybridization differed from PS 22.2 and LMG 2342T. Sequence determination and analysis of the internally transcribed spacer region ITSI for P. tolaasii LMG 2342T, LMG 6641, and PS 3a strains further supported the presence of the two siderovars. It is concluded that considerable genotypic differences exist among Finnish isolates of P. tolaasii causing brown blotch disease on the cultivated mushroom, which is in agreement with the phenotypic diversity highlighted through previous siderotyping studies.
Munsch
Patricia
P
University of Oulu, Department of Physical Sciences/Biophysics, Finland. patricia.munsch@oulu.fi
Johnstone
Keith
K
Alatossava
Tapani
T
D000364:Agaricus / Q000254:growth & development*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D047630:Depsipeptides; D005838:Genotype; D008969:Molecular Sequence Data; D009842:Oligopeptides; D010860:Pigments, Biological / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011549:Pseudomonas / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D021521:Ribotyping; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D047630:Depsipeptides; D009842:Oligopeptides; D010860:Pigments, Biological; C067241:tolaasin protein, Pseudomonas tolaasii; C042453:pyoverdin