African yam bean, AYB (Sphenostylis stenocarpa Hochst. ex. A. Rich Harms), is a tuberous legume of tropical Africa. AYB has the potential to significantly boost food security due to its considerable nutritional qualities. However, the crop is underutilized. To efficiently utilize AYB genetic resources for its improvement, it is necessary to understand the crop's diversity. This study investigated the amplification ability of 36 cowpea simple sequence repeat (SSR) primers across AYB genomic DNA, extracted from 67 accessions. Thirteen (36%) of the cowpea SSRs showed transferability in AYB. Eight of these SSRs amplified above 60% of AYB accessions and generated 55 polymorphic fragments with an average of 6.9 per primer. Polymorphic information content ranged from 0.6691 to 0.8857 with an average of 0.7791. This study also assessed the genetic diversity within 67 AYB accessions using eight cowpea (Vigna unguiculata L. Walp)-derived SSR primers. The result revealed a high level of genetic diversity with simple matching coefficient ranging from 0.458 to 1.000. A dendrogram depicting three main clusters was generated based on unweighted pair group method with arithmetic average. Cluster 1 was the most diverse with a dissimilarity range of 0.517–1.000. The level of genetic diversity revealed in this study indicates that the studied AYB germplasm can be exploited for genetic improvement. Additionally, the transferable markers will aid AYB genome research and also make possible the comparative mapping between AYB and cowpea.

African yam bean (AYB) is an affordable protein source capable of diversifying the food base in sub-Saharan Africa. However, research efforts made towards the crop's improvement and in expanding production are limited. This study characterized 169 AYB accessions at Jimma, Ethiopia, using 31 phenotypic characters. The analysis of variance revealed highly significant (P < 0.01) differences for days to 50% flowering, days to first flowering, leaf area, number of seeds per pod, pod length, seed thickness, total seed weight, petiole length and significant (P < 0.05) difference for terminal leaf length. Accession TSs62B produced the highest number of seeds per pod (17.65) and recorded the highest 100 seed weight (25.30 g), while 3A was the earliest to flower at an average of 84.50 d. Principal component analysis (PCA) of qualitative traits attributed 77.6% of observed variations to the first five principal components, of which the first two PC axes accounted for 53.6% of total variations. Cluster analysis and PCA biplot distinctly grouped the accessions into two major groups, cluster I had the highest number of accessions (108). The analytical approaches used confirmed considerable diversity across the germplasm with a distance matrix ranging from 0.37 to 0.85. The extent of diversity reflected in the current study provides breeders the baseline information to design breeding strategies, which might help identify materials for release as variety or parental lines for hybridization programmes.

African yam bean, an underutilized legume usually cultivated for its edible tubers and seeds, is known for its nutrition-rich qualities; however, the crop’s level of consumption is low. The underutilization of the crop could be attributed to several constraints, including long cooking hours of up to 24 hours. Cooking time is an important food trait; it affects consumers’ choices, nutrients content, and anti-nutrient conditions. Additionally, foods requiring long cooking hours are non-economical in terms of energy usage and preparation time. The prolonged cooking time associated with AYB places enormous limitations on the invaluable food security potentials of the crop. Therefore, the availability of AYB grains with a short cooking time could lift the crop from its present underused status. To efficiently develop AYB grains with reduced cooking time, information on the crop’s cooking variables is a prerequisite. This review presents available information on variations in cooking time, cooking methods, and processing steps used in improving cooking time and nutrient qualities in AYB. Likewise, the review brings to knowledge standard procedures that could be explored in evaluating AYB’s cooking time. This document also emphasizes the molecular perspectives that could pilot the development of AYB cultivars with reduced cooking time.

African yam bean has immense food and nutrition potential and is resilient to adverse environmental conditions. Despite its potential, the crop is underutilized, which could be attributed to seed hardness (requiring about 6–24 hours of cooking time); and the abundance of antinutrient factors (tannin, phytate, and oxalate). This study evaluated the physical (seed hardness, cooking time) and chemical compositions (crude protein, tannin, phytate, and oxalate) of 93 AYB accessions grown in Ethiopia. The seed hardness of each accession was determined by the compression force and compression time using Texture Analyzer, whereas cooking time was ascertained using Mattson Bean Cooker. The accession’s crude protein level, tannin, oxalate, and phytate were investigated from flour samples using standard laboratory procedures. Highly significant ( P < 0.01 ) differences were observed for cluster means of compression force, cooking time, and oxalate. The accessions were grouped into three clusters: cluster-II was prominent with 42 accessions, while cluster-I had the least (25). The mean values for compression force ranged from 50.05 N ± 10.25 (TSs-423) to 278.05 N ± 13.42 (TSs-378) whereas compression time varied from 0.35 secs ± 0.02 (TSs-334) to 5.57 secs ± 6.12 (TSs-62B). Cooking time ranged from 127.50 mins ± 2.12 (TSs-82A) to 199.50 mins ± 10.61 (TSs-138B); crude protein ranged from 15.41% ± 0.11 (TSs-269) to 24.51% ± 0.22 (TSs-446). Tannin ranged from 0.61 mg/g  ± 0.02 (TSs-47) to 9.62 mg/g ± 0.03 (TSs-334) likewise, phytate ranged from 0.28 ± 0.01 (TSs-137) to 7.01 ± 0.10 (TSs-3). Accessions TSs-55; TSs-82 showed the lowest oxalate content of 0.21% ± 0.01; 0.21% ± 0.00, respectively. Similarly, TSs-352; TSs-47 revealed the most abundant tannin content of 0.70 ± 0.00 and 0.70 ± 0.07. The correlation analysis revealed a low positive and significant ( P < 0.05 ) association (r = 0.24) between protein and phytate content.

African yam bean, AYB (Sphenostylisstenocarpa), is an underutilized legume of tropical Africa. AYB can boost food and nutritional security in sub-Saharan Africa through its nutrient-rich seeds and tubers. However, inadequate information on germplasm with desirable agro-morphological traits, including insufficient data at the genomic level, has prevented the full exploitation of its food and breeding potentials. Notably, assessing the genetic diversity and population structure in a species is a prerequisite for improvement and eventual successful exploitation. The present study evaluated the population structure and genetic diversity of 169 accessions from the International Institute of Tropical Agriculture (IITA) collection using 26 phenotypic characters and 1789 single nucleotide polymorphism (SNP) markers. The phenotypic traits and SNP markers revealed their usefulness in uniquely distinguishing each AYB accession. The hierarchical cluster of phenotypes grouped accessions into three sub-populations; SNPs analysis also clustered the accessions into three sub-populations. The genetic differentiation (FST) among the three sub-populations was sufficiently high (0.14–0.39) and significant at P = 0.001. The combined analysis revealed three sub-populations; accessions in sub-population 1 were high yielding, members in sub-population 2 showed high polymorphic loci and heterozygosity. This study provides essential information for the breeding and genetic improvement of AYB.