Resilience Traits in Underutilised Crops: Drought Tolerance in Bambara Groundnut

Climate change represents one of the greatest challenges facing humankind. In particular, how to grow more food, of better nutritional value with fewer inputs for a rapidly increasing population? Many factors reduce crop yields, including both biotic and abiotic stresses. Abiotic stress alone is estimated to account for potential yield loss of more than 50% in average for most of the major crops, with soil water-deficit being the most detrimental. Consequently, resilience traits preserved in underutilised crops deserved to receive more research focus. As a good example, Bambara groundnut (Vigna subterranea [L.] Verdc, an indigenous Africa legume) has the potential to be one of the components of food security, nutritionally complement with cereal diets for chronic malnutrition. More importantly, it tolerates and produces yields in harsh environments. A better understanding of the adaptation mechanisms that have evolved in this crop to cope with water deficit would be beneficial to crop breeding and improvement programmes. The lack of ex ante sequence information is a major current constraints (and has been a common problem in underutilised crop generally, although the recent 100 African crop genomes initiative is an important step; http://news.ucdavis.edu/search/news_detail.lasso?id=10804). To overcome this bottleneck, we have been attempting to develop tools to translate genetic information from major crops to underutilised crops. We have focused on the resources available in common bean (Phaseolous Vulgaris) and soybean (Glycine max) because they are the closest relatives to Bambara groundnut with sequenced genomes (estimated five to 20 million years divergence, respectively). The effect of mild drought in Bambara groundnut at flowering stage was evaluated by cross-species microarray analysis and a small pilot scale Massively Parallel Signature Sequencing (MPSS) analysis, coupled with crop physiological measurements. The transcriptomic profiles derived from a segregating population of a controlled cross and a number of contrasting landraces generated in response to reduced water availability is providing a preliminary insight into the underlying mechanisms of tolerance to drought in Bambara groundnut. This understanding will be used to enhance breeding efforts in Bambara groundnut to realise its potential to contribute to food security in regions that experience transient and persistent drought.