Peanut genomics is very challenging due to its inherent problem of genetic architecture. Blockage of gene flow from diploid wild relatives to the tetraploid; cultivated peanut, recent polyploidization combined with self pollination, and the narrow genetic base of the primary genepool have resulted in low genetic diversity that has remained a major bottleneck for genetic improvement of peanut. Harnessing the rich source of wild relatives has been negligible due to differences in ploidy level as well as genetic drag and undesirable alleles for low yield. Lack of appropriate genomic resources has severely hampered molecular breeding activities, and this crop remains among the less-studied crops. The last five years, however, have witnessed accelerated development of genomic resources such as development of molecular markers, genetic and physical maps, generation of expressed sequenced tags (ESTs), development of mutant resources, and functional genomics platforms that facilitate the identification of QTLs and discovery of genes associated with tolerance/resistance to abiotic and biotic stresses and agronomic traits. Molecular breeding has been initiated for several traits for development of superior genotypes. The genome or at least gene space sequence is expected to be available in near future and this will further accelerate use of biotechnological approaches for peanut improvement.

Peanut is an important and nutritious agricultural commodity and a livelihood of many small-holder farmers in the semi-arid tropics (SAT) of world which are facing serious production threats. Integration of genomics tools with on-going genetic improvement approaches is expected to facilitate accelerated development of improved cultivars. Therefore, high-resolution genotyping and multiple season phenotyping data for 50 important agronomic, disease and quality traits were generated on the ‘reference set’ of peanut. This study reports comprehensive analyses of allelic diversity, population structure, linkage disequilibrium (LD) decay and marker-trait association (MTA) in peanut. Distinctness of all the genotypes can be established by using either an unique allele detected by a single SSR or a combination of unique alleles by two or more than two SSR markers. As expected, DArT features (2.0 alleles/locus, 0.125 PIC) showed lower allele frequency and polymorphic information content (PIC) than SSRs (22.21 alleles /locus, 0.715 PIC). Both marker types clearly differentiated the genotypes of diploids from tetraploids. Multi-allelic SSRs identified three sub-groups (K = 3) while the LD simulation trend line based on squared-allele frequency correlations (r2) predicted LD decay of 15–20 cM in peanut genome. Detailed analysis identified a total of 524 highly significant MTAs (pvalue >2.1×10–6) with wide phenotypic variance (PV) range (5.81–90.09%) for 36 traits. These MTAs after validation may be deployed in improving biotic resistance, oil/ seed/ nutritional quality, drought tolerance related traits, and yield/ yield components.

a b s t r a c tGroundnut (Arachis hypogaea L.) is susceptible to pre-and post-harvest infections by Aspergillus spp. Aflatoxin B 1 (AFB 1 ), is the contaminant produced by the fungus in infected grains posing a threat to human and animal health. This paper reports of a study undertaken in Malawi to determine the occurrence and distribution of Aflatoxigenic Aspergilli in the soil and AFB 1 contamination in groundnuts. A total of 1397 groundnut samples collected from farm homesteads, local markets, warehouses and shops in 2008 and 2009 were analyzed for AFB 1 contamination using the enzyme linked immunosorbent assay (ELISA), and A. Aspergilli population densities in 1053 soil samples collected from the same sites were estimated using serial dilutions plated on A. Aspergilli medium. Farmer socioeconomic profile information was also collected to determine relationships to AFB 1 contamination. The results revealed 46% and 23% of the total samples, from 2008 to 2009, respectively, had AFB 1 contamination levels greater than 4 ppb, and those above 20 ppb were 21% for 2008 and 8% for 2009, respectively. Fitted smooth curve relationships show that there is a clear increase in the chance of groundnut contamination when the population density of A. Aspergilli in the soil increased beyond 3000 (log (cfu) > 8). The measured level of A. Aspergilli in soil varied by location, as well as ecologies within location. Low-altitude ecologies, which were warmer and experienced low precipitation levels, had the highest densities of A. Aspergilli, whereas cooler high-altitude ecologies had the lowest density of these fungi. Similarly high AFB 1 contamination, was recorded across the country with 11e28% of all samples collected from the warm low to mid-altitude ecologies recording contamination !20 ppb and low contamination (2e10% of samples) in the mid to high altitude cool ecologies. From a crop management perspective, this study also suggests that both less experienced and older farmers were more likely to produce groundnuts contaminated with aflatoxin. These findings have implications in the design of intervention strategies to avoid short-and long-term human health effects from aflatoxin exposure.

Intermittent drought is the most important yield limiting factor affecting groundnut (Arachis hypogaea L) production in rain-fed regions of Sub-Saharan Africa and Asia.Improvement of crop adaptation to drought is needed and this starts by having a thorough assessment of a large and representative set of germplasm. In this study, 247 lines belonging to the reference collection of groundnut were assessed under well-watered (WW) and intermittent water stress (WS) conditions in India and Niger for two years, following similar experimental protocols. The WS treatment reduced pod yield (31-46%), haulm yield (8-55%) and the harvest index (1-10%). Besides a strong treatment effect, yield differences within locations and years, were attributed to both genotypic and genotype-by-treatment interactions. Pod yield under WW and WS conditions were closely related in both years (Patancheru, r 2 = 0.42 and r 2 = 0.50; Sadore, r 2 = 0.22 and r 2 = 0.23). By contrast, within location and treatment, pod and haulm yields were affected predominantly by genotype-by-year (G x Y) effects, especially under WS. Within treatment across locations and years, pod and haulm yields were mostly ruled by genotypic effects, which allowed identifying a group of entries with contrasting pod yield across locations under WS. However, genotype and genotype by environment (GGE) biplot analyses distinguished India from Niger, suggesting that the selection remains environment-specific and also revealed dissimilarity between years in Niger. A close relationship was observed between yield and pod growth rate (r 2 = 0.51), and partition (r 2 = 0.33) under WS conditions, whereas no significant relationship was found between yield under WS and SCMR, or specific leaf area (SLA). These results showing a close interaction between the environmental conditions and the genotypic response to intermittent drought shows the necessity to carefully choose environments that truly represent target environments. This is an important result in the current breeding context of marker-assisted recurrent selection or genome-wide selection. This work opens also new ways for the breeding of drought tolerant groundnut, by bringing new highly contrasting lines currently used for crossing and deciphering drought adaptation traits to better understand GxE interactions, while it challenges the relevance of long-time used surrogates such as SCMR or SLA.

Rising food and nutritional insecurity threatens the livelihoods of millions of poor people, particularly in sub‐Saharan Africa. Vegetable and legume production and consumption are a potent mechanism for small‐scale, disadvantaged farmers to obtain the required nutrients in their diets and to generate much‐needed income through trade. Vegetables and legumes are key sources of nutrients and health‐promoting phytochemicals, providing higher micronutrient contents and a wider spectrum of essential compounds to meet nutritional and health needs than other food sources. Diversifying diets with vegetables and legumes is a cheaper, surer, and more sustainable way to supply a range of nutrients to the body and combat malnutrition and associated health problems than other approaches that target only a single or a few nutritional factors. Furthermore, vegetables and legumes often accompany staple crops in meals, and most staple crops are less palatable without vegetable or legume accompaniments. As a growing world population demands more and higher quality foods, and as environmental problems such as soil degradation, water scarcity, biodiversity loss, and climate change become more acute, the need for innovative vegetable and legume research solutions to improve food and nutritional security cannot be overemphasized.