Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/1998
Publication Date: N/A
Technical Abstract: The Ur-3 gene of common bean, Phaseolus vulgaris, is an important source of dominant genetic resistance to 44 of 89 races of the bean rust fungus, Uromyces appendiculatus, identified and maintained at Beltsville. A 10-mer primer OK-14(620) (Haley et al., 1994, TAG 88:337-342) was used to amplify a RAPD marker that is linked to the Ur-3 rust resistance gene. The nucleotide sequence was determined for a 630 bp DNA fragment amplified fro plants carrying the Ur-3 gene. Based on this sequence, three pairs of SCAR primers were designed and used in PCR. Polymorphism between resistant and susceptible material and high amplification efficiency of SCAR primers were determined by screening various bean germplasm. Among various genotypes, higher correlation was observed between SCARs and actual rust reactions in the greenhouse, which eliminates false results obtained with the RAPD primer. The identification of SCAR primers for the Ur-3 gene will improve accuracy of detection to enhance utility of marker-assisted selection.