Preliminary development of real time PCR for quantification of Erwinia species infecting potato tubers.

Erwinia carotovora subsp. atroseptica (Van Hall) (Eca), Erwinia carotovora subsp. carotovora (Dye) (Ecc), Erwinia chrysanthemi (Burkholder) (Ech) are pathogenic bacterias of potato crop, causing blackleg of stems in the field and soft rot of tubers in storage. During these last years, an outbreak of soft rot potatoes caused by the 3 Erwinia species has been observed in Belgium. Several methods are currently available for the detection of Erwinia sp. in potato tubers. These methods include plating on selective media, roting by the “Erwinia kit”, immunological methods and classical PCR tests. The probability of black leg or soft rot development depends on the population level of Erwinia on potato tubers (Perombelon, 2002). So, the development of methods able to quantify the Erwinia population on tubers is required. Such quantification may be achieved by the use of real-time PCR. This technique combines the advantages of classical PCR (specificity, sensitivity, rapidity) with unique characteristics (lower limit of detection, no post-PCR step, easier quantification of the target). In this paper, we describe the first steps of the development of a real-time PCR method for the quantification of Erwinia population on potato tubers. To our knowledge, this is the first report of the development of a real-time PCR to detect Erwinia spp. on potato tubers.