Volume 19 Part 1 Article 21: Characterization of Pseudomonas species causing brown blotch of Agaricus bisporus

Volume 19 Part 1 Article 21
Year 2016
Title: Characterization of Pseudomonas species causing brown blotch of Agaricus bisporus
Author: Jan van der Wolf1, Pieter Kastelein, Marion Krijger, Marc Hendriks, Johan Baars, Jos Amsing, Theo van der Lee & Sven Warris

Bacterial blotch is occasionally causing damage in the production of common mushroom
(Agaricus bisporus). The disease is found worldwide and can be caused by different
fluorescent Pseudomonas species present in casing material. For identification of the
causative agents of blotch in the Netherlands and Belgium, fluorescent Pseudomonas species
were isolated from mushrooms with mild or severe brown blotch symptoms collected at six
growers. Strains were tested for pathogenicity by streaking the mushroom head with bacterial
slime using a cotton swab and incubation of mushrooms for eight days at 15°C. In total 16
isolates were collected varying in virulence. These, together with 14 other Pseudomonas
strains present in different culture collections (LMG and at WUR), including the type strains
of P. gingeri, P. tolaasii, P. agaricus and P. reactans were characterized and tentatively
identified by multilocus sequence analysis based on four genes (rpoD, rpoB, gyrB, glyA) and
by average nucleotide identity using whole genome sequences . We found three species, P.
tolaasii, P. gingeri
and an unnamed species able to cause severe symptoms whereas other
unnamed species were able to cause mild symptoms. The information can be used for the
development of diagnostic tools and in studies on epidemiology and disease management.

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