Abstract

The genetic diversity and phylogenetic relationships among cowpea (Vigna unguiculata L. Walp) genotypes used in breeding for resistance to Striga gesnerioides in Burkina Faso have been evaluated using simple sequence repeat(SSR) molecular markers. Sixteen primer combinations were used to polymerase chain reaction (PCR) amplify SSRs from 16 different cowpea genotypes yielding a total of 96 (76.3%) polymorphic bands ranging in size from 220 to 1018 bp. High coefficients of genetic similarity were obtained among Striga resistant varieties. Very few (~22%) primer combinations showed polymorphic bands capable of discriminating Striga-resistant from susceptible cultivars. The 16 Burkinabe cowpea cultivars examined clustered into three main groups, two formed by resistant phenotypes (Group I: Gorom and Wango and Group II: B301, IT82D-849, HTR, KVX 745-11P, KVX 61-1 and IT84S-2049) and one by a combination of resistant and susceptible cultivars (Group III). These data will be helpful in designing streamlined breeding strategies for cowpea improvement for Burkina Faso and specifically for the introgression of the Striga resistance trait into local farmer acceptable types.

Key words: Cowpea, genetic diversity, germplasm, microsatellite, phylogenetic structure, simple sequence repeat.

Abbreviation

Abbreviations: MAS, Marker-assisted selection; RFLP, restriction fragment length polymorphisms; AFLP, amplified fragment length polymorphisms; DAF, DNA amplification fingerprinting; RAPDs, random amplified polymorphic DNA; SSRs,simple sequence repeats; STMS, sequence tagged microsatellites; EDTA,ethylenediaminetetraacetic acid; PCR, polymerase chain reaction; EST, expressed sequence tag.