Background: Understanding factors influencing the expression of a trait is key in designing a breeding program. Genotype by environment interaction has great influence on most quantitative traits. Promiscuous nodulation is a trait of importance for soybean production in Africa, because of the soil bacteria Bradyrhizobium japonicum not being indigenous in most African soils. Most soybean cultivars require B. japonicum for nodulation leading to the need for seed inoculation before sowing soybean in Africa. Few cultivars have capability to nodulate with Bradyrhizobia spp. that are different from B. japonicum and native in African soils. Such cultivars are termed "promiscuous cultivars. " Field experiments were conducted in six locations in Uganda for two seasons, to investigate the extent of environmental influences on the nodulation ability of promiscuous soybean genotypes. Results:Additive main effect and multiplicative interaction effects showed highly significant environment and genotype by environment (G × E) interaction effects on all nodulation traits. G × E interaction contributed more to the total variation than genotypes. The genotypes Kabanyolo I and WonderSoya were the most stable for nodules' dry weight (NDW), which is the nodulation trait the most correlated with grain yield. Genotype UG5 was the most stable for nodules' number (NN), and Nam II for nodules' effectiveness (NE). The genotype NamSoy 4M had the highest performance for NN, NFW, and NDW, but was less stable. WonderSoya had the highest NE. Genotype and genotype by environment analysis grouped environments into mega-environments (MEs), and four MEs were observed for NDW, with NamSoy 4M the winning genotype in the largest ME, and Kasese B the ideal environment for that nodulation trait. Conclusion:This study provides information that can guide breeding strategies. The low genetic effect that led to high environmental and G × E interaction effects raised the need for multi-environments testing before cultivar selection and recommendation. The study revealed genotypes that are stable and others that are high performing for nodulation traits, and which can be used as parental lines in breeding programs.

Kersting’s groundnut is an important source of protein and essential nutrients that contribute to food security in West Africa. However, the crop is still underexploited by the populations and under-researched by the scientific community. This study aimed to investigate the genetic diversity and population structure of 217 Kersting’s groundnut accessions from five origins using 886 DArTseq markers. Gene diversity was low and ranged from 0.049 to 0.064. The number of private alleles greatly varied among populations (42–192) and morphotypes (40–339). Moderate to very high levels of selfing and inbreeding were observed among populations (s=56–85%, FIS=0.389–0.736) and morphotypes (s=57–82%, FIS=0.400–0.691). Moreover, little to very high genetic differentiations were observed among populations (0.006≤FIS≤0.371) and morphotypes (0.029≤FIS≤0.307). Analysis of molecular variance partitioned 38.5% of the genetic variation among and 48.7% within populations (P<0.001). Significant isolations by distance were detected between populations (R2=0.612, P=0.011) and accessions (R2=0.499, P<0.001). Discriminant analysis of principal components and neighbour joining consistently distinguished eight distinct clusters. These data provide a global picture of the existing genetic diversity for Kersting’s groundnut and will guide the choice of breeding strategies to increase production.

Cowpea [Vigna unguiculata (L.) Walp] is a globally important food security crop.However, it is susceptible to pest and disease; hence, constant breeding efforts based on its diversity are required for its improvement. The present study aims to investigate the genetic diversity, population structure, and linkage disequilibrium (LD) among 274 cowpea accessions from different origins. A total of 3,127 single nucleotide polymorphism (SNP) markers generated using diversity array technology (DArT) was used. Population structure, neighbor-joining clustering, and principal component analyses indicated three subpopulations within the germplasm. Results of STRUC-TURE analysis and discriminant analysis of principal components (DAPC) were complementary in assessing the structuration of the diversity among the germplasm, with the grouping of the accessions improved in DAPC. Genetic distances of 0.005-0.44 were observed among accessions. Accessions from western and central Africa, eastern and central Africa, and Asia were predominant and distributed across all subpopulations. The subpopulations had fixation indexes of 0.48-0.56. Analysis of molecular variance revealed that within subpopulation variation accounted for 81% of observed genetic variation in the germplasm. The subpopulations mainly consisted of inbred lines (inbreeding coefficient = 1) with common alleles, although they were from different geographical regions. This reflects considerable seed movement and germplasm exchange between regions. The LD was characterized by low decay for

Food and nutritional insecurity constitute a main challenge in most Sub-Sahara African countries. Efforts to provide diets with sufficient nutrients such as proteins, carbohydrates, vitamins and essential minerals should include the introduction of new vegetable and legume crops. Vegetable soybean "edamame", is a nutritious vegetable legume well known and consumed in Asia and America, but underutilized in Africa. This review paper aims at documenting the existing information on edamame and analyzing the potentials for its use in Sub-Saharan Africa. The analysis of the existing literature revealed that vegetable soybean provides great advantages in term of production because of good market value of the fresh pods having a good market value and high demand on both local and international markets. Then, the consumption of edamame can also really contribute to reducing nutritional deficiencies in children and even adults, through its great nutritional content and good health benefits. Therefore, edamame is a good crop to promote in Africa. The promotion of edamame requires many research activities starting from evaluation of agro-ecological adaptation, determination of consumers' preferences and genetic improvement based on farmers, processors and consumers' needs, in order to sustain a seed system for the crop.

Formal public sector soybean breeding in Africa spans over four decades, and it was initiated by the International Institute of Tropical Agricultural (IITA). As the demand of soybean continues to outstrip production, strategic projects such the Tropical Legume (TL) were initiated, in which the main goal was to enhance the productivity of soybean in the farmers' fields in Sub-Saharan Africa. One of the strategies to enhance the productivity of soybean in the farmers' fields is through developing and deploying improved soybean varieties in the target countries. Through the TL I and TL II projects, a number of varieties were released in the target countries, Kenya, Nigeria, Malawi and Mozambique by employing participatory variety selection (PVS). This review provides highlights of the achievements made by IITA breeding programme and insights of what needs to be done to enhance yield improvement for soybean in Africa using demand-driven breeding approaches.

Background: Genetic diversity in a germplasm is crucial for continuous improvement of crop varieties. A panel of 274 cowpea ( Vigna unguiculata L.) accessions of unknown genetic diversity was assembled from diverse sources. This study used 3127 SNP markers, generated with the diversity array technology (DArT), to assess genetic diversity, population structure and linkage disequilibrium (LD) in the assembled germplasm. Results: The population structure analysis inferred three subpopulations within the germplasm, which was confirmed by Neighbour-Joining (NJ) clustering and principal component analysis (PCA). Low genetic distances (0.005 to 0.44) were observed between accessions. Accessions from Africa; West and Central Africa (113 accessions), East and Central Africa (93 accessions), and Asia (53 accessions) were predominant in the germplasm; and distributed across all subpopulations. High fixation indexes (0.48≤F ST ≤0.56) were obtained for the inferred subpopulations. AMOVA revealed a very large contribution of within subpopulations variation to the observed genetic variation in the germplasm. However, the expected heterozygosity (He) was higher than the observed heterozygosity (Ho), indicating high proportion of inbred lines in the germplasm. Linkage Disequilibrium (LD) was observed in the germplasm, which showed a low decay at longer physical distance between markers in the genome. Conclusions: Significant genetic structuration exists in the assembled cowpea germplasm which shows that there is a potential for improvement of the crop. The subgroups consisted mainly of inbred lines which, although from different geographical regions shared alleles in common reflecting high movement of seeds and exchange of germplasm between regions. The presence of linkage disequilibrium in the germplasm paves a way for prospective whole genome-wide association studies in cowpea for quality attributes and important agronomic traits.

Identification of genes associated with bruchid resistance variations in cowpea accessions would help breeders to generate new cowpea cultivars with improved resistance and quality. In this work, 107 cowpea collections from various areas in six countries were phenotyped for their responses to Callosobruchus maculatus and genotyped with Single Nucleotide Polymorphism (SNP) markers. Six multi-locus models Genome Wide Association Study (mrMLM, FASTmrMLM, pKWmEB, pLARmEB, FASTmrEMMA and ISISEM-BLASSO) were used to associate the genotype data to phenotypic cowpea resistance traits: Percentage of Bruchid Emergence (PBE); Percentage of Weight Loss (PWL); Median Development Period (MDP); Dobie Susceptibility Index (DSI); Number of Egg Laid (NEL) and Mean Number of Hole (MNH).Out of 14 QTNs, three were associated with more than one trait and were associated with 11 candidate genes located within 10-30 kb of the QTNs. These candidate genes exhibit functionalities associated with cowpea resistance mechanisms. All these results could contribute to the gene networks in resistant cowpea varieties.The result of this study could also increase our knowledge of genetic resistance of cowpea to bruchids and could be useful for molecular breeding.

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