What is the evidence for sexual reproduction of <i> <scp>P</scp> hytophthora infestans </i> in <scp>E</scp> urope?

Abstract

The biology of late blight of potato and tomato, caused by P hytophthora infestans , changed when sexual reproduction by the pathogen became possible in many parts of the world, including E urope. In northern E urope, especially S candinavia, there is increasing evidence that the pathogen is reproducing sexually on a regular basis, although in other regions further south or to the west it appears to reproduce primarily in a clonal manner. The presence of both mating types, the production of viable oospores, and observations of fields with soilborne sources of inoculum are consistent with sexual reproduction. Studies with different marker systems have revealed a population structure without any dominating clonal lineages in S candinavia, and that is most easily explained by sexual reproduction. P hytophthora infestans recovered from the soil can also be linked to parental genotypes using likelihood‐based methods when codominant markers are used. A synthesis of all the available data points to a second centre of sexual reproduction in northern E urope.