Identification of potential sources of striga resistance in cowpea [Vigna Unguiculata (L.) walp.] accessions from Ghana

Striga gesnerioides, commonly called witchweed, is a major constraint to growth and productivity of cowpea (Vigna unguiculata L. Walp) throughout West Africa. We have screened the cowpea accessions available in the germplasm collections from Ghana for their reaction to Striga gesnerioides, with the aim of identifying new sources of resistance to the parasite for use in breeding and improvement activities. Resistance to S. gesnerioides was scored phenotypically using pot trials and the differential response of the various accessions correlated to the presence of molecular markers (61RM2 and SSR1) linked to the major gene cluster for resistance to S. gesnerioides races SG1, SG2 , SG3 and SG5. Of the 141 accessions screened only one, GH3684, exhibited resistance to S. gesnerioides in pot trials. GH3684 carried the S. gesnerioides race SG3 resistance marker SSR1, but not SCAR 61RM2. Our data showed that only limited sources of resistance exist against S. gesnerioides in the Ghana germplasm underscoring the need for more extensive analysis of local landraces and exploitation of exotic materials from outside of the country for cowpea improvement. Key words: Exotic, Germplasm, Molecular markers, Resistance, Striga gesnerioides