Real-time PCR assay targeting the veA gene for quantification of Aspergillus carbonarius in grapes

Abstract

In this work, a SYBR Green I real-time PCR method has been developed for the detection and quantification of Aspergillus carbonarius in grapes by targeting the veA gene with a primer pair (veAF4/veAR4) that specifically amplifies a 91-bp PCR product. The quantification of the fungal DNA was performed by generation of standard curves for two A. carbonarius strains, using spectrophotometrically measured DNA quantities (Log) with a linearity range from 50 to 5 × 10-4 ng of DNA. A high positive correlation (R2 > 0.99) between exponential increases of DNA and real-time PCR threshold cycles showed a high amplification efficiency for the assay (E values 100.06 and 101.51%, respectively). Quantification of the fungal genomic DNA in grape samples artificially inoculated with A. carbonarius conidia was successfully performed with a minimum threshold of 10 conidia per g of grape berry. The assay developed would allow reliable, specific, and efficient detection and quantification of A. carbonarius in grapes.