Browsing by Author "Kusi, F."
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Item Deployment of the cowpea aphid resistance gene for cowpea improvement in Ghana(University of Ghana, 2014-07) Kusi, F.; Asante, S.K; Padi, F.K; Obeng-Ofori, D.; University of Ghana, College of Basic and Applied Sciences, School of Agriculture, Department of Crop ScienceResistance to the cowpea aphid is important component of integrated pest management of cowpea cropping systems most especially at the vegetative stage. The objective of this study was to demonstrate the effectiveness of the aphid resistance locus identified in advanced breeding line SARC 1-57-2 in reducing damage from the cowpea aphid in Ghana. Using an F2 population developed from Apagbaala x SARC 1-57-2, the resistance locus was tagged with the SSR marker CP 171F/172R with a recombination fraction of 5.91%. Based on the CP 171F/172R, recurrent marker assisted backcrossing was carried out to introduce the resistance locus into the susceptible cultivar, Zaayura. This led to the development of several BC4F3 lines that are isogenic except for the region of the resistance locus. In field tests under no insecticide protection, the BC4F3 lines carrying the dominant marker allele suffered 3% loss of biomass and 4% loss of grain yield compared with plots protected with recommended insecticides. The BC4F3 lines carrying the recessive marker allele recorded 12% loss of biomass and 33% reduction in grain yield compared with the sprayed plots. The resistance locus did not influence the number of days to flowering or maturity and no pleiotropic effects were observed in terms of plant morphology or seed characteristics. In all segregating populations analysed, the locus segregated as a single Mendelian gene. Stability of the resistance locus was conducted at 18 locations covering six important cowpea growing Regions in Ghana. The range of damage by the pest on resistant and susceptible progenies were consistent across locations, and did not support the hypothesis of existence biotypes of the insect (based on differences in feeding damage on different varieties) in Ghana. This stability in performance places a premium on the resistance locus in improving cowpea cultivars developed for different agro-climatic regions of the country for resistance to the pest. The study has demonstrated the effectiveness of an insect resistance locus in significantly reducing insect damage under typical cowpea production conditions in GhanaItem Identification of sources of resistance in cowpea lines to Macrophomina root rot disease in Northern Ghana(Heliyon, 2023) Lamini, S.; Kusi, F.; Cornelius, E.W.; Danquah, A.; Attamah, P.; Mukhtaru, Z.; Awuku, F.J.; Owusu, E.Y.; Acheampong, M.; Mensah, G.Macrophomina root rot disease (MRRD) caused by Macrophomina phaseolina is an emerging threat to the profitable cowpea production in northern Ghana. Recommended control methods including the use of fungicides are ineffective and expensive for resource poor farmers whilst biocontrol options are not commercially available. An integrated method based on host plant resistance is considered the cheapest and most effective method of managing the disease. This study sought to confirm and characterize previously identified MRRD isolates from Northern Ghana using molecular technology, and to identify cowpea with potential sources of resistance to the MRRD. A PCR assay of ten isolates of the cowpea root rot pathogen revealed all isolates belonged to the species M. phaseolina, whilst a nucleotide BLAST of eight isolates showed 98% similarity with the sequences of Macrophomina isolates from other host available in GenBank. A sick pot method evaluation of 49 cowpea lines found 10 lines resistant to MRRD on a 1–9 disease severity scale (disease score, less than 5). A selection of eight resistant lines (Suvita 2, Abagbaala, IT97K573-1-1, IT93K 503-1-1, Hewale, AV2 3224, Nhyira and T2T4), and a susceptible check (Songotra) were evaluated against 10 isolates of M. phaseolina using a sick pot method. All the genotypes except for the susceptible check were resistant to MRRD. Thus, these genotypes could be used in cowpea MRRD resistance breeding programs.Item A novel aphid resistance locus in cowpea identified by combining SSR and SNP markers(Plant Breeding, 2018-04) Kusi, F.; Padi, F.K.; Obeng-Ofori, D.; Asante, S.K.; Agyare, R.Y.; Sugri, I.; Timko, M.P.; Koebner, R.; Huynh, B.L.; Santos, J.R.P.; Close, T.J.; Roberts, P.A.The utility of combining simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) marker genotyping was determined for genetically mapping a novel aphid (Aphis craccivora) resistance locus in cowpea breeding line SARC 1‐57‐2 and for introgressing the resistance into elite cultivars by marker‐assisted backcrossing (MABC). The locus was tagged with codominant SSR marker CP 171F/172R with a recombination fraction of 5.91% in an F2 population from ‘Apagbaala’ x SARC 1‐57‐2. A SNP‐genotyped biparental recombinant inbred line population was genotyped for CP 171F/172R, which was mapped to position 11.5 cM on linkage group (LG) 10 (physical position 30.514 Mb on chromosome Vu10). Using CP 171F/172R for foreground selection and a KASP‐SNP‐based marker panel for background selection in MABC, the resistance from SARC 1‐57‐2 was introduced into elite susceptible cultivar ‘Zaayura’. Five BC4F3 lines of improved ‘Zaayura’ that were isogenic except for the resistance locus region had phenotypes similar to SARC 1‐57‐2. This study identified a novel aphid resistance locus and demonstrated the effectiveness of integrating SSR and SNP markers for trait mapping and marker‐assisted breeding.Item Toxicity of Jatropha Seed Oil to Callosobruchus maculatus (Coleoptera: Bruchidae) and its Parasitoid, Dinarmus basalis (Hymenoptera: Pteromalidae)(Journal of Applied Sciences Research 4(8): 945-95, 2008) Boateng, B.A.; Kusi, F.The susceptibility of C. maculatus and D. basalis to Jatropha seed oil was evaluated under laboratory conditions. The adults of C. maculatus and D. basalis had the same susceptibility to Jatropha seed oil but the parasitoid was relatively more susceptible than its host at all treatment levels. The oil was also repellent to C. maculatus but its persistency declined from 15 to 60 days in storage. The eggs of C. maculatus were comparatively more susceptible to the Jatropha seed oil than those of the parasitoid due to the protection afforded by the grain. However, the larvae and pupae of C. maculatus showed a relatively lower susceptibility to the oil. It is possible to incorporate the oil in a well designed pest management programme taking advantage of the short persistency of the oil on grains and its relatively ineffectiveness against the C. maculatus pupae developing inside the grain.