IDENTIFICATION OF RAPD MARKERS LINKED TO A PHYTOPHTHORA-FRAGARIAE RESISTANCE GENE (RPF1) IN THE CULTIVATED STRAWBERRY

Bulked segregant analysis (BSA) was used to identify seven random ampl ified polymorphic DNA (RAPD) markers linked to the Rpf1 gene. Rpf1 con fers resistance to Phytophthora fragariae var. fragariae, the causal a gent of red stele root rot in Fragaria spp. The bulked DNAs represente d subsets of a F-1 population obtained from the cross Md683 x Senga Se ngana which consisted of 60 plants and segregated in a 1:1 ratio for r esistance or susceptibility to race 2.3.4 isolate NS2 of P. fragariae. Seven markers were shown to be linked to Rpf1 and were generated from four primers; five of these markers were in coupling phase and two in repulsion phase with respect to the gene. A linkage map of this resis tance gene region was generated using JoinMap 2.0(TM). Th, manner in w hich Rpf1 and the linked markers co-segregated indicated that they are inherited in a disomic fashion. These markers could enable gene pyram iding and marker-assisted selection of resistance genes in strawberry breeding programmes.