Abstract: In this study, a pair of specific primers was designed according to the polygalacturonase gene of Penicillium expansum to detect Penicillium expansum in rotten apples by polymerase chain reaction (PCR). The results showed that the specificity and sensitivity of the design primer pair were high and only Penicillium expansum DNAs were amplified. The detection limits of Penicillium expansum and DNA were 1.34 × 103 spores/mL and 2.40 × 10-2μg/mL, respectively. The optimal reaction condition was obtained as follows: anneal temperature of 54－59 ℃ and template concentration of 2.40－5.28μg/mL. Owing to its simplicity, rapidity and high specificity and sensitivity, this assay can be used for practical applications.

Key words: PCR(polymerase chain reaction)detection, penicillium expansum, template, primers, specificity