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A standardised set of differential potato cultivars to identify pathotypes in Synchytrium endobioticum

Gerard van Leeuwen: National Reference Centre NPPO-NL

<div>Several pathotypes are known for the quarantine potato pathogen Synchytrium endobioticum whose identification is based on their virulence (or avirulence) on specific potato cultivars, known as differentials. In former research, the cultivar Miriam was proved unsuitable for separating pathotypes 6(O1) and 18(T1). In the Euphresco-project “SENDO” (2012-2015), a group of five European laboratories tested a set of differential cultivars using the same bio-assay method, Glynne-Lemmerzahl. Compared with the standard set described in the EPPO Diagnostic Protocol, two new cultivars were tested: cultivars Talent and Logo. Two different pathotypes were tested, pathotype 6(O1) and 18(T1), and each partner tested ten eye fields per cultivar in three independent replications. The reaction of the sprouts was analysed after 25 days of incubation. Results were scored in two classes: ‘wart formation’ vs ‘no wart formation’. Comparing Talent and Logo, it was explicitly shown that Talent was the most suitable candidate to replace Miriam in the differential set. No wart formation occurred when infected with pathotype 6(O1), while in all labs wart formation did occur in Talent infected by pathotype 18(T1). The results of the SENDO-project support the use of one standardized method and one uniform set of differentials to identify pathotypes in S. endobioticum, thus facilitating clear and unambiguous communication between scientists, risk managers and policy makers.</div>