Main conclusion Bambara groundnut has the potential to be used to contribute more the climate change ready agriculture. The requirement for nitrogen fixing, stress tolerant legumes is clear, particularly in low input agriculture. However, ensuring that existing negative traits are tackled and demand is stimulated through the development of markets and products still represents a challenge to making greater use of this legume.

The International Institute of Tropical Agriculture maintains the world’s largest collection of cowpea germplasm of over 15,000 accessions. A sub-set of 298 lines from the loosely composed mini core collection of 370 landraces were genotyped based on genotyping by sequencing (GBS). Ward’s minimum variance hierarchical cluster analysis, model-based ancestry analysis and discriminant analysis of principal component (DAPC) were carried out on this sub-set. Three clusters were identified by the different clustering methods. Principal component analysis further supported the three clusters especially when accessions are scattered along the axes of the first two principal components. The first two principal components explained a total of 22.30% of the variation. Cluster one comprises 115 accessions from the largest number of countries and has the highest gene diversity, heterozygosity and polymorphic information content (PIC) values. Cluster two is made up of 102 accessions, 90 percent of which are from West and Central Africa. Analysis of molecular variance shows that the most variation is among accessions and lowest among clusters. No cluster is made exclusively of accessions from a single country. Based on SNP markers, the sub set of cowpea mini core germplasm collection used in this study encompasses the diversity in the crop.

African yam bean (Sphenostylis stenocarpa (Hochst ex. A. Rich.) Harms) is an annual legume with the capacity to produce bean seeds in a pod and produce tubers with varying seed patterns and colors. It is suggested to have the potential to significantly boost food security in sub-Saharan Africa due to its considerable nutritional qualities but still yet underutilized. Many farmers show limited interest in its production owing to limited knowledge of its nutritional profile, income generation capacity for small-holder farmers’, processing, and other related utilization concerns. This study evaluated the proximate and antinutrient composition of processed and unprocessed seeds of African yam bean (Sphenostylis stenocarpa (Hochst ex. A. Rich.) Harms.). Seeds were harvested from the experimental research field consisting of 50 accessions at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. They were divided into two portions; the first was processed by oven drying at 60°C for 24 hours and the second was left raw. There were significant differences (P<0.05) in the levels of proximate and antinutrient in the forms in which the samples were analyzed. TSs104 had the highest protein content of 25.08%, while the lowest was TSs68 (20.50%). However, in the unprocessed seed, protein content ranged between 24.93% (TSs38) and 19.13% (TSs11). Both processed and unprocessed seeds had high carbohydrate contents. In processed seeds, TSs9 (62.93%) had the highest percentage and TSs1 (29.64%) recorded the lowest. In unprocessed seed, the percentage ranged between 67.36% (TSs4) and 54.23% (TSs38). The observed variation may suggest possible suitability of seed for various end-use products and targeted breeding programs for crop improvements. In sub-Saharan Africa, this lesser-known legume could be adapted as a promising food crop in combating protein-energy malnutrition.

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.

The narrow base of genetic diversity characteristic of cowpea can be attributed to it being self-pollinating, evolving from narrow wild germplasm and exhibiting very limited gene flow between wild and cultivated types. Backcrossing to introduce simply inherited desirable traits and utilization of improved breeding lines and varieties as parents in crossing programs further narrowed the genetic base of cowpea varieties. In most cowpea breeding programs, genes for resistance and market traits were pyramided into lines characterized by high levels of acceptance to farmers and consumers. Besides predisposing widely distributed improved varieties to genetic vulnerability, a narrow base of genetic variation may be contributing to the plateauing in cowpea grain yield, which compromises genetic gains. Cross compatible wild relatives have not been used in variety development because breeders shy away from them due to their tiny seed size, unattractive seed coat color and texture, pod shattering, and susceptibility to viruses. A number of wild cowpea relatives, both within and outside section Catiang of Vigna species, have been evaluated for their reaction to cowpea insect pests and diseases. Vigna vexillata lines were resistant to the legume pod borer (Maruca vitrata), the cowpea weevil (Callosobruchus maculatus), and Striga gesnerioides but are cross incompatible with cultivated cowpea. Some lines among the cross compatible wild relative V. unguiculata ssp. dekindtiana were found to be resistant to aphid in the seedling stage, while others showed good levels of drought and heat tolerance. Molecular markers are being generated to identify quantitative trait loci (QTL) with effects on some desirable attributes in cowpea. Modern breeding tools, including transgenics, can be applied for the improvement of cowpea, bypassing the natural barriers of traditional breeding. Transgenic cowpea with Bt gene cry1Ab showing resistance to M. vitrata has been released in Nigeria. Genome editing, a powerful emerging tool, can also be used for developing improved cowpea varieties with durable resistance to pests and diseases.