Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2008
Publication Date: June 1, 2009
Citation: Wickramasinge, W., Qu, S., Costanzo, S., Haynes, K.G., Christ, B. 2009. Development of PCR-Based Markers Linked to Quantitative Resistance to Late Blight in a Diploid Hybrid Potato Population of Solanum phureja × S. stenotomum. American Journal of Potato Research. 86:188-195.
Interpretive Summary: Late blight is a serious disease of potatoes worldwide. Previously, we found resistance to late blight in a potato species closely related to commercial potatoes. In this study, we report on the development of two molecular markers to help us identify late blight resistant seedlings. One of these markers was found in 73% of the resistant seedlings and the second marker was found in 82% of the resistant seedlings. Neither marker was found in the susceptible seedlings. These markers may help us to identify late blight resistant potatoes earlier in the potato breeding program. This information will be used by potato breeders to speed the development of late blight resistant potato varieties.
A diploid hybrid Solanum phureja × S. stenotomum population which has shown relatively high levels of quantitative resistance to late blight was used to develop PCR–based markers for marker assisted selection (MAS) of disease resistance in potato breeding. Two random amplified polymorphic DNA (RAPD) markers, OPA03576 and OPA17559, were identified as being linked to partial resistance. OPA03576 was found to be associated in coupling phase while OPA17559 showed association in repulsion phase to resistance. These two markers, together with previously developed AFLP and SSR markers, were incorporated into an existing RFLP-based chromosomal linkage map of this Solanum phureja × S. stenotomum population. Linkage analysis located the OPA17559 marker on chromosome III, 12cM away from the QTL region that explained 21.4 % of the total phenotypic variability for late blight resistance. The marker OPA03576 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 a late blight resistance QTL on chromosome III that explained 23.4% of the total phenotypic variation in this population. Plants characterized by the presence of these three markers were correlated with resistance to late blight in the population. Our results suggest that these markers may be useful for MAS of late blight resistance in potato breeding programs.