Development of PCR-Based Markers Linked to Quantitative Resistance to Late Blight in a Diploid Hybrid Potato Population of Solanum phureja x S-stenotomum

A diploid hybrid Solanum phureja x S. stenotomum population that has shown relatively high levels of quantitative resistance to late blight was used to develop polymerase chain reaction (PCR)-based markers for marker-assisted selection (MAS) of disease resistance in potato breeding. Two random amplified polymorphic DNA (RAPD) markers, OPA03(576) and OPA17(559), were identified as being linked to partial resistance. OPA03(576) was found to be associated in coupling phase while OPA17(559) showed association in repulsion phase to resistance. These two markers, together with previously developed amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers, were incorporated into an existing restriction fragment length polymorphism (RFLP)-based chromosomal linkage map of this S. phureja x S. stenotomum population. Linkage analysis located the OPA17(559) marker on chromosome III, 12 cM away from a major quantitative trait locus (QTL) that explained 23.4% of the total phenotypic variation for late blight resistance. Marker OPA03(576) was located in the distal region of chromosome XII where several resistance genes are found clustered. A third PCR-based marker, GP198F-1, derived from the original RFLP marker GP198, was linked to the late blight resistance QTL on chromosome III that explained 23.4% of the total phenotypic variation in this population. The three PCR-based markers were used to screen for their presence in the mapping population and high correlations between the presence of these markers and late blight resistance were found. Our results suggest that these markers may be useful for MAS of late blight resistance in potato breeding programs.