Conservation priorities for African Vigna species: Unveiling Angola’s diversity hotspots

Abstract

• It is widely recognized that the conservation of the Crop Wild Relatives (CWR) in their wild habitats is fundamental to ensure the continuous supply of novel genetic material, crucial for future crop improvement. Vigna unguiculata (cowpea) and V. subterranea (bambara groundnut) are amongst the most significant African legumes as sources of food and fodder. In this study we investigated the diversity of Vigna species in Angola, to identify hotspot areas for their in situ conservation, and thus underpin future food security in Sub-Saharan Africa. Based on four criteria (i.e. potential utilization for crop improvement, threat status, ethnobotanical value, and geographical distribution) we prioritize Vigna CWR for conservation actions in Angola. Our results reveal that 28 Vigna species occur in Angola, two of which are endemic (V. mendesii and V. ramanniana). These species are unevenly distributed across the country, with greater dominance in the central-north and western areas, where four hotspot areas (Saurimo, Serra da Chela, N’dalatando, and Huambo) are identified. However, significant gaps in the current in situ conservation strategies are highlighted by our results, since the CWR diversity hotspots remain unprotected and only nine of the 28 Vigna species are recorded in protected areas. Moreover, in light of the fact that only one accession of Vigna collected in Angola exists in genebanks globally at present, we recommend a targeted seed collecting programme to support future management and ex situ conservation of plant genetic resources in Angola. Our study calls attention to the fact that Angola, together with Zambia, has the highest Vigna species richness in Sub-Saharan Africa, and provides new data and tools for the sustainable use of these species in crop improvement.