PCR - detection of Synchytrium endobioticum (Schilb.) Perc.

The ITS-DNA region of Synchytrium endobioticum (Schilb.) Perc, the causal agent of po-tato wart disease, was used to generate specific primers for a PCR. DNA was extracted from wart galls of all S. endobioticum pathotypes (1, 2, 6, 18) currently occurring and used for official testing purposes in Germany. Using the universal ITS primer # 4 and the S. endobioticum specific primer Kbr1, a PCR fragment of 525 bp was obtained from all four fungal pathotypes. DNA for PCR based diagnosis of the fungus could be extracted easily from summer sori, however, we did not succeed to extract amplifiable DNA from resting sori found in contaminated soils. To circumvent this problem, zoospores emerging from resting sori were used for DNA extraction and indirect detection. PCR was also useful to discriminate between of weakly resistant and moderately susceptible response of potato varieties in addition to the routine visual inspection, since only alive summer sori of the weakly susceptible reacting potato varieties released quantities of zoospores sufficient to be detected. No PCR signal was obtained from weakly resistant or resistant potato varie-ties, since no zoospores were released from the dead sori, due to the resistance response of the potato.