Molecular marker assessment of ma ting type of Phytophthora infestans isolates co llected in potato fields of Costa Rica

Abstract

Mating type of 88 isolates of Phytophthora infestans was assessed using molecular markers. Isolates were collected from March 1999 to February 2001 in the potato-producing zones of Costa Rica. Isolates for DNA extraction were grown in liquid medium. Mating type was determined by PCR, using the S1A and S1B primers in order to amplify the S1 mating type locus. All isolates showed only the A1 mating type; therefore, the lack of mating type A2 can be an indication that the populations tested could be formed only by clonal lineages with the A1 mating type.