1 st Annual International Interdisciplinary Conference, AIIC 2013, 24-26 April, Azores, Portugal - Proceedings- 503 RESPONSES OF RECOMBINANT INBRED LINES OF COWPEA [(VIGNA UNGUICULATA (L.) WALP] TO STRIGA GESNERIOIDES INFESTATION IN GHANA Aaron T. Asare Isaac K. A. Galyuon Department of Molecular Biology and Biotechnology, University of Cape Coast, Cape Coast, Ghana Francis K. Padi Cocoa Research Institute of Ghana (CRIG), New Tafo-Akim, Ghana Emmanuel P. Otwe Department of Molecular Biology and Biotechnology, University of Cape Coast, Cape, Coast, Ghana J.F. Takrama Cocoa Research Institute of Ghana (CRIG), New Tafo-Akim, Ghana Abstract: Cowpea [Vigna unguiculata (L.) Walp.] production in West Africa is constraint by Striga gesnerioides parasitism associated with 83-100% yield loses which warrants development of resistance varieties against the parasite. An exotic resistant genotype, IT97K-499-35 developed by International Institute of Tropical Agriculture (IITA) was crossed with SARC-LO2, a local susceptible genotype. SSR-1 and C42-2B markers previously mapped in the region of S. gesnerioides resistance loci were used to amplify genomic DNA of advance recombinant inbred lines (RILs) of this cross. The responses of the RILS to Striga infection in pot culture and a field trial conformed to segregation ratio of resistance to susceptible genotypes of 1:1 among F 7 progenies suggesting monogenic dominant inheritance of the resistance. The markers SSR-1 and C42-2B mapped in the region of the resistance locus, but presented as dominant markers, with amplification only in resistant genotypes. The selective efficiency of SSR-1 (92.6%) was better than that of C42-2B (85.7%). In field trials, growth and morphology of susceptible genotypes were adversely affected by S. gesnerioides which resulted in significant (P ≤ 0.05) reduction in seed yield compared to resistant genotypes. The resistant RILs identified in the current work would be further evaluated in multi-location trials prior to their release to farmers for cultivation. Key Words: Cowpea, Marker-assisted selection, Striga, Recombinant inbred lines Introduction Cowpea [Vigna unguiculata (L.)Walp] is one of the most economically important indigenous African grain legumes with enriched protein as source of food for both human and animal nourishment and a major crop in regional trade within West and Central Africa (Langyintuo et al., 2003). The relatively high protein content of cowpea makes it an essential supplement to the diet of many Africans (Bressani, 1985) who consume high carbohydrate but low in protein cereals, root and tuber crops (Omoigui, 2007). Besides, cowpea is also a valuable commodity that provides income for farmers and fixes atmospheric nitrogen to restore soil fertility for succeeding cereal crops growing in rotation with it. West and Central Africa produce 69% of the world production (Langyintuo et al., 2003). However, a major biological constraint to increase production in smallholder farms is the infection by the parasitic weed, Striga gesnerioides (Willd) Vatke (Ehlers and Hall, 1997). Cowpea yield losses associated with S. gesnerioides range from 83 to 100% (Cardwell and Lane, 1995; Emechebe et al., 1991)