Rm. Wu et al., PHENOTYPIC VARIATION AND SURVIVAL OF GENETICALLY MARKED PSEUDOMONAS-TOLAASII IN MUSHROOM COMPOST, Canadian journal of microbiology, 44(4), 1998, pp. 373-377
The role of Pseudomonas tolaasii as an important pathogen of the commo
n mushroom Agaricus bisporus is difficult to study in the microbially
complex growth medium used for mushroom production. Two strains of P.
tolaasii that had been marked with kanamycin resistance and xylE genes
were introduced individually into casing soil over mushroom compost.
Survival studies revealed that P. tolaasii numbers in casing soil over
mushroom compost decreased a 1000-fold in the first 9 days and then r
emained relatively stable over the rest of the monitoring period. The
presence of the pathogenic colony form and the nonpathogenic colony va
riant was monitored on mushroom caps and in mushroom compost to detect
any phenotypic variation while incubated in these environments. Rever
sion from the nonpathogenic to pathogenic form was detected following
isolation and culture from diseased mushroom caps. Inoculation of the
marked strains directly onto the cap or into compost beds seeded with
A. bisporus resulted in the appearance of brown blotch symptoms.