A quantitative PCR assay for detection of the mycotoxigenic plant pathogen and food spoiling moldPaecilomyces niveusin fruit, food, and soil

Abstract

AbstractThe postharvest fruit pathogenPaecilomyces niveusproduces ascospores that can survive some pasteurization temperatures, spoil fruit products, and contaminate them with patulin, an FDA-regulated mycotoxin. PreventingP. niveusfrom entering food systems requires a robust detection method to effectively determine sources ofP. niveusspoilage and disease inoculum. We designed a new robust and culture-independent detection method using species-specific primers (PnPATf/r) based on the patK gene, encoding a 6-methylsalicylic acid synthase, inP. niveus, for use in a rapid qPCR assay. Primer specificity was validated using 24 differentP. niveusisolates and 16 other important food spoilage and fruit pathogenic fungi. The threshold for detection of qPCR was 18 genome equivalents. To further validate our new detection method, we demonstrate its use in detectingP. niveusin infected fruits, infested soils and ciders, and in fruit arising from apple blossoms sprayed with aP. niveusspore suspension. Results from this study may help fruit producers address spoilage and patulin contamination by this food spoiling fungus.HighlightsNew primers specific toPaecilomyces niveus(PnPATf/r) were developed based on the patK geneA qPCR assay to detectP. niveuswas validated, and shown to be able to detect quantities ofP. niveusDNA as low as 18 genome equivalentsThe new qPCR assay was used to investigate the ability ofP. niveusascospores to infect strawberry fruits and enter apple fruits through apple blossom infestation