01749nas a2200145   4500008004100000245007600041210006900117260001200186300001400198520126600212100002101478700001901499700001901518856006601537       2013                        eng d00aChange of Mating Type in an EU1 Lineage Isolate of Phytophthora ramorum0 aChange of Mating Type in an EU1 Lineage Isolate of Phytophthora   c07/2013  an/a - n/a3 a<p>All <em>Phytophthora ramorum </em>EU1 lineage isolates tested are of A1 mating type, except for three rare isolates from 2002 to 2003 from Belgium, which were originally assigned the A2 mating type. In one of these isolates (2338), a switch from A2 to A1 mating type was observed in 2006. This observation initiated a larger study in which all cultures and subcultures of the original three EU1 A2 isolates, maintained in three laboratories under different storage conditions, were checked for mating type change. The A2 to A1 mating type switch was observed in four of seven independently maintained isolates that were derived from isolate 2338 in two laboratories, using different transfer regimes and storage conditions. Following the mating type switch to A1 in these four derived isolates, no reversion back to A2 mating was observed, even after up to 5&nbsp;years of additional isolate maintenance and several more subculturing events. The three other isolates that were derived from isolate 2338 as well as the other EU1 A2 isolates collected in 2002 and 2003 and stored in the same conditions did not display such mating type change. The potential causes of the mating type conversions as well as their epidemiological implications are discussed.</p>1 aChandelier, Anne1 aHeungens, Kurt1 aWerres, Sabine  uhttp://onlinelibrary.wiley.com/doi/10.1111/jph.12150/abstract