Submitted to: Crucifer Genetics Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2002
Publication Date: 3/25/2002
Citation: Giovannelli, J.L.; Farnham, Mark W.; Wang, Min; Strand, Allan E. 2002. Development of sequence characterized amplified region (SCAR) markers linked to downy mildew resistance in broccoli. Proceedings of 13th Crucifer Genetics Worksop. March 23-26, 2002, Davis, CA. p. 84
Technical Abstract: Downy mildew, caused by the fungal parasite Peronospora parasitica (Pers.:Fr.) Fr., is one of the most destructive diseases of Brassica oleracea L. crops, including broccoli. As environmental concerns regarding pesticide usage increase, the development and deployment of downy mildew resistant broccoli cultivars is becoming a priority for breeders and producers. Our long-term goal is to identify genetic markers linked to downy mildew resistance genes to facilitate marker-assisted selection for resistance and the pyramiding of resistance genes into cultivars. We employed bulked segregant analysis in conjunction with Random Amplified Polymorphic DNA (RAPD) analysis to assess resistant and susceptible F2 plants from a broccoli population segregating for a single, dominant, downy mildew resistance gene. Eight RAPD markers linked to the resistance locus were identified following a screen with 848 decamer primers. Subsequently, two of these markers (UBC359-620) and OPM6-750) were cloned and sequenced, and RAPD sequences were used to develop Sequence Characterized Amplified Region (SCAR) markers. The respective SCAR markers were shown to be linked to the resistance locus at a distance of 6.7 and 3.3 cM. These SCAR markers are among the first genetic markers found linked to a gene conferring cotyledon-stage downy mildew resistance in B. oleracea. Results of this work provide breeders with useful information and tools for the systematic development of resistant cultivars.