title: Accumulation of the mycotoxin patulin in the presence of gluconic acid contributes to pathogenicity of Penicillium expansum.
abstract: Penicillium expansum, the causal agent of blue mold rot, causes severe postharvest fruit maceration through secretion of D-gluconic acid (GLA) and secondary metabolites such as the mycotoxin patulin in colonized tissue. GLA involvement in pathogenicity has been suggested but the mechanism of patulin accumulation and its contribution to P. expansum pathogenicity remain unclear. The roles of GLA and patulin accumulation in P. expansum pathogenicity were studied using i) glucose oxidase GOX2-RNAi mutants exhibiting decreased GOX2 expression, GLA accumulation, and reduced pathogenicity; ii) IDH-RNAi mutants exhibiting downregulation of IDH (the last gene in patulin biosynthesis), reduced patulin accumulation, and no effect on GLA level; and iii) PACC-RNAi mutants exhibiting downregulation of both GOX2 and IDH that reduced GLA and patulin production. Present results indicate that conditions enhancing the decrease in GLA accumulation by GOX2-RNAi and PACC-RNAi mutants, and not low pH, affected patulin accumulation, suggesting GLA production as the driving force for further patulin accumulation. Thus, it is suggested that GLA accumulation may modulate patulin synthesis as a direct precursor under dynamic pH conditions modulating the activation of the transcription factor PACC and the consequent pathogenicity factors, which contribute to host-tissue colonization by P. expansum.
authors.forename: Shiri
authors.initials: S
authors.lastname: Barad
authors.forename: Sigal Brown
authors.initials: SB
authors.lastname: Horowitz
authors.forename: Ilana
authors.initials: I
authors.lastname: Kobiler
authors.forename: Amir
authors.initials: A
authors.lastname: Sherman
authors.forename: Dov
authors.initials: D
authors.lastname: Prusky
mesh_terms: D015536:Down-Regulation; D005638:Fruit / Q000382:microbiology*; D015966:Gene Expression Regulation, Fungal; D005942:Gluconates / Q000494:pharmacology*; D005949:Glucose Oxidase / Q000235:genetics / Q000378:metabolism; D054884:Host-Pathogen Interactions; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D009183:Mycotoxins / Q000378:metabolism; D010365:Patulin / Q000378:metabolism*; D010407:Penicillium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014774:Virulence
chemical_list: D005942:Gluconates; D009183:Mycotoxins; D010940:Plant Proteins; D014157:Transcription Factors; D010365:Patulin; D005949:Glucose Oxidase; C030691:gluconic acid