An amplified fragement length polymorphism (AFLP) fragment, E-ACT/M-CAA 524 , tightly linked to the Striga gesnerioides race 1 (SG1) resistance gene Rsg-2-1 in cowpea (Vigna unguiculata L.) was isolated by polyacrylamide gel electrophoresis, cloned, and its nucleotide sequence determined. Based on the resulting sequence information, a pair of sequence specific primers were designed and used to isolate identical and similar fragments from cowpea genomic DNA of different cowpea lines by

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... chain reaction (PCR) amplification. The primers amplified a ~500 bp fragment (SCAR marker designated as 61R) that was present in the resistant parent TVU14676, absent in susceptible parent IT84S-2246, and segregated with the resistance phenotype in an F 2 population, derived from a cross of these two genotypes. The same primers were used to isolate a fragment similar to 61R from another S. gesnerioides resistant line Kvx 61-1. The sequence of this fragment was used to design a new combination of primers that developed a second SCAR marker, designated as 61R-M2. Subsequent analysis of the three markers, E-ACT/M-CAA 524 , 61R and 61M2 showed that they are linked to each other by 0.6 centimorgans (cM). The utility of these SCARs in marker assisted selection programs for cowpea was discussed.