Postharvest discoloration of the cultivated mushroom Agaricus bisporus caused by Pseudomonas tolaasii, P. 'reactans', and P. 'gingeri'

• Published in: Phytopathology 1996-10, Vol.86 (10), p.1098
• Main Authors: Wells, J.M. (USDA, ARS, ERRC, Philadelphia, PA.), Sapers, G.M, Fett, W.F, Butterfield, J.E, Jones, J.B, Bouzar, H, Miller, F.C
• Format: Article
• Language: English
• Subjects: ACIDE GRAS; ACIDOS GRASOS; AGARICUS BISPORUS; AGENT PATHOGENE; BACTERIOSE; BACTERIOSES; BACTERIOSIS; BIOASSAYS; BIOCHEMISTRY; BIOCHIMIE; BIOQUIMICA; BROWN BLOTCH; CLASIFICACION; CLASSIFICATION; DECOLORACION; DECOLORATION; DENDOGRAM; DISCOLORATION; ENFERMEDADES DE LAS PLANTAS; ENSAYO BIOLOGICO; FATTY ACID PROFILE; FATTY ACIDS; FENOTIPOS; FISIOLOGIA POSTCOSECHA; GINGER BLOTCH; MALADIE DES PLANTES; ORGANISMOS PATOGENOS; PATHOGENS; PATHOTYPE; PATHOTYPES; PATOTIPOS; PHENOTYPE; PHENOTYPES; PHYSIOLOGIE APRES RECOLTE; PLANT DISEASES; POSTHARVEST DISEASE; POSTHARVEST PHYSIOLOGY; PSEUDOMONAS; PSEUDOMONAS GINGERI; PSEUDOMONAS REACTANS; SINTOMAS; SYMPTOME; SYMPTOMS; TEST BIOLOGIQUE
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/Phyto-86-1098

A postharvest discoloration of the cultivated mushroom Agaricus bisporus in Pennsylvania was associated with three pathotypes of fluorescent pseudomonads. Pathotype A strains caused pitted, dark-brown blotches on mushroom caps, formed precipitates in agar ('white line' reactions) with Pseudomonos tolaasii strain ATCC 14340 (reclassified as P. 'reactants'), were phenotypically like P. fluorescens biovar V, and fit descriptions of P. tolaasii. Pathotype B strains caused pitted, yellow-brown, sometimes slimy lesions on mushrooms, formed no 'white line' reactions, were phenotypically like P. fluorescens biovars III and V, and fit descriptions of P. 'gingeri'. Pathotype C strains caused mild, light brown discoloration on mushrooms with little tissue collapse, formed 'white line' reactions with P. tolaasii ATTC 33618 (type strain), had P. fluorescens biovar III and V phenotypes, and fit descriptions of P. 'reactans'. Isolations from mushroom casing material yielded all pathotypes including both pathogenic and nonpathogenic strains of P. 'reactans' with distinguishing phenotypic or chemical characteristics Cellular fatty acid analysis suggested pathogenic strains of P. 'reactans' were more similar to P. tolaasii and P. 'gingeri' than to saprophytic strains of P. fluorescens, and nonpathogenic strains were more similar to saprophytic P. fluorescens than to P. tolaasii or P. 'gingeri'