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SummaryComparative analysis of preferences and key criteria for selecting cowpea (Vigna unguiculata L. Walp.) varieties was conducted using the data collected from farmers’ participatory varietal selection (FPVS) activities conducted over 3 years with a total of 2401 farmers (1230 male and 1171 female) in 13 villages in Tougouri department in northern region and Tiéfora department in southern region of Burkina Faso in West Africa. Over the 3 years, farmer criteria for variety selection remained basically stable, but some variations among the regions and years were noticed. Grain yield was the most common and the most important criterion for farmers’ choice in both regions. Farmers in Tougouri (north) put more emphasis on early maturity (90%) and drought resistance (19.7%) as selection criteria than farmers in Tiéfora (south). Farmers in Tiéfora placed statistically significant importance on seed colour and plant type, while farmers in Tougouri did not, and for these selection criteria, there were only slight differences between genders in both areas. Results of stepwise multiple regression indicated that maturity and seed colour in the north, and seed size and seed colour in the south were the most important selection factors for farmers to select cowpea varieties. Improved varieties should have sufficiently good yield to be accepted, but other favoured traits may differ by target region as a reflection of local and regional market demands as well as deep-rooted cultural preferences. Understanding local and regional differences in selection criteria for cowpea varieties is necessary to improve the acceptance of newly released improved varieties. Preferences identified in the participatory activities could inform further development of cowpea breeding strategies for north and south regions of Burkina Faso.

SUMMARYThe low yield of pearl millet largely due to the low adoption of improved varieties substantiates the application of client-oriented plant breeding for pearl millet. Hence to enhance adoption, new varieties must correspond to farmers’ preferences and respond to the constraints prevailing in the production environments, participatory rural appraisals were conducted in two agro-ecological zones (Sahel and North-Sudan) to determine farmers’ preferences in the choice of varieties and to identify constraints to pearl millet production. The study revealed that the major production constraints are hierarchically drought, Striga, head miner, bird and downy mildew. Compact panicle, large grain size and non-bristle panicle were the most preferred traits in pearl millet across agro-ecological zones. Very long panicle and early maturity crop cycle were more preferred in the Sahel zone whereas, in the North-Sudan zone medium panicle length and medium maturity cycle were more preferred by farmers. Traits largely rejected by farmers were small grain size, narrow, loose and bristled panicle. Very few investigations were done to understand the raison of the low adoption of improved technologies in pearl millet. This study identified the major criteria of new pearl millet variety adoption by farmers. It is expected that breeding program must integrate these criteria in new pearl millet variety profiling to enhance adoption.

Multi-parent advanced generation inter-cross (MAGIC) populations are an emerging type of resource for dissecting the genetic structure of traits and improving breeding populations. We developed a MAGIC population for cowpea (Vigna unguiculata L. Walp.) from eight founder parents. These founders were genetically diverse and carried many abiotic and biotic stress resistance, seed quality and agronomic traits relevant to cowpea improvement in the United States and sub-Saharan Africa, where cowpea is vitally important in the human diet and local economies. The eight parents were inter-crossed using structured matings to ensure that the population would have balanced representation from each parent, followed by single-seed descent, resulting in 305 F8 recombinant inbred lines each carrying a mosaic of genome blocks contributed by all founders. This was confirmed by single nucleotide polymorphism genotyping with the Illumina Cowpea Consortium Array. These lines were on average 99.74% homozygous but also diverse in agronomic traits across environments. Quantitative trait loci (QTLs) were identified for several parental traits. Loci with major effects on photoperiod sensitivity and seed size were also verified by biparental genetic mapping. The recombination events were concentrated in telomeric regions. Due to its broad genetic base, this cowpea MAGIC population promises breakthroughs in genetic gain, QTL and gene discovery, enhancement of breeding populations and, for some lines, direct releases as new varieties.

Molecular-assisted backcrossing (MABC) was used to introgress drought tolerance, Striga and root-knot nematode resistance QTLs into a farmer-preferred widely grown cowpea landrace adapted for intercropping in Burkina Faso. Two backcross populations were developed using two drought tolerant donor lines IT93K-503-1 (nematode resistant) and IT97K-499-35 (Striga resistant) and the drought sensitive landrace Moussa Local as the recurrent parent. A set of 184 genomewide EST-derived SNP markers spanning an average of 2-cM intervals and flanking known trait positions was employed for genotyping the backcross progenies using the cowpea KASP genotyping platform. BC1F1 individual plants that were heterozygous for SNPs associated with drought tolerance, Striga and/or nematode resistance (foreground SNPs) and carried as many recurrent-parent alleles as possible at other SNP loci (background SNPs) were selected for the next backcross cycle. This process was repeated to produce BC3F1 families of each donor population. The six best families from the two donors based on marker aided selection and preliminary yield performance under well-watered and water-restricted field trials and Striga resistance screening were selfed to increase seed (BC3F2) for further yield tests. This study demonstrated the high efficiency of using SNP markers in foreground and background marker selection in a MABC scheme to improve a widely grown cowpea variety by adding drought tolerance and biotic stress resistance traits. Key words: Molecular-assisted backcrossing (MABC), drought tolerance, Striga, root-knot nematode, QTLs, EST-derived SNP markers, cowpea.

Development and analysis of Multiparent Advanced Generation Inter-Cross (MAGIC) populations have been conducted with several crop plants to harness the potential for dissecting the genetic structure of traits and improving breeding populations. We developed a first MAGIC population for cowpea (Vigna unguiculataL. Walp.) from eight founder parents which are genetically diverse and carry many abiotic and biotic stress resistance, seed quality and agronomic traits relevant to cowpea improvement in sub-Saharan Africa (SSA) where cowpea is vitally important in the human diet and in local economies. The eight parents were inter-crossed using structured matings to ensure the population would have balanced representation from each of the founder parents, followed by single-seed descent, resulting in 365 F8 recombinant inbred lines (RILs) each carrying a mosaic of genome blocks contributed from all founders. This was confirmed by SNP genotyping with the cowpea Illumina 60K iSelect BeadArray. Following filtering to eliminate duplicates, sister lines and accidental selfing events, a core set of 305 F8 RILs was chosen as the primary population. The F8 lines were on average 99.74% homozygous while also diverse in agronomic traits including flowering time, growth habit, maturity, yield potential and seed characteristics across environments. Trait-associated SNPs were identified for most of the parental traits. Loci with major effects on photoperiod sensitivity and seed size were also verified by genetic mapping in biparental RIL populations. The distribution of recombination frequency varied considerably between chromosomes, with recombination hotspots distributed mostly in the telomeric regions. Due to its broad genetic base, this cowpea MAGIC population promises breakthroughs in genetic gain and high-resolution genetic mapping for gene discovery, enhancement of breeding populations and, for some lines, direct releases as new varieties.

Summary Cowpea (Vigna unguiculata L. Walp.) is a legume crop that is resilient to hot and drought-prone climates, and a primary source of protein in sub-Saharan Africa and other parts of the developing world. However, genome resources for cowpea have lagged behind most other major crops. Here we describe foundational genome resources and their application to analysis of germplasm currently in use in West African breeding programs. Resources developed from the African cultivar IT97K-499-35 include a whole-genome shotgun (WGS) assembly, a bacterial artificial chromosome (BAC) physical map, and assembled sequences from 4,355 BACs. These resources and WGS sequences of an additional 36 diverse cowpea accessions supported the development of a genotyping assay for 51,128 SNPs, which was then applied to five biparental RIL populations to produce a consensus genetic map containing 37,372 SNPs. This genetic map enabled the anchoring of 100 Mb of WGS and 420 Mb of BAC sequences, an exploration of genetic diversity along each linkage group, and clarification of macrosynteny between cowpea and common bean. The SNP assay enabled a diversity analysis of materials from West African breeding programs. Two major subpopulations exist within those materials, one of which has significant parentage from South and East Africa and more diversity. There are genomic regions of high differentiation between subpopulations, one of which coincides with a cluster of nodulin genes. The new resources and knowledge help to define goals and accelerate the breeding of improved varieties to address food security issues related to limited-input small-holder farming and climate stress. This article is protected by copyright. All rights reserved.

There have been reports of breakdown of striga resistance in previously resistant cowpea cultivars in Burkina Faso. This could be attributed to new striga races emerging or to an increase in the aggressiveness of current striga races. Therefore, cowpea genotypes were evaluated in fields infested with S. gesnerioides at three striga hot spots in Burkina Faso and in pots under artificial infestation with striga races SR 1, SR 5 and SR Kp to identify new, adapted and striga-resistant sources. Cowpea genotypes showed differential reactions for striga resistance over sites and for striga races in pot experiments, indicating differences in the races involved, and SR Kp was reported as a new race. Resistant sources conferring site-specific or multiple striga-race resistance were identified. Genotypes 58-57, Sanga 2, IT84S-2049, IT98K-205-8, IT93K-693-2, KVx771-10, KVx775-33-2, KVx61-1, Gorom local, Mouride and Melakh conferred resistance to all three striga races. These genotypes are potential donor parents for breeding new, adapted and striga-resistant genotypes. Cowpea landraces including Moussa local and Niaogo local with farmers' preferred traits were susceptible and need improvement for striga resistance.

SUMMARYCowpea (Vigna unguiculata L. Walp.) is a legume crop that is resilient to hot and drought-prone climates, and a primary source of protein in sub-Saharan Africa and other parts of the developing world. However, genome resources for cowpea have lagged behind most other major crop plants. Here we describe foundational genome resources and their application to analysis of germplasm currently in use in West African breeding programs. Resources developed from the African cultivar IT97K-499-35 include bacterial artificial chromosome (BAC) libraries and a BAC-based physical map, assembled sequences from 4,355 BACs, as well as a whole-genome shotgun (WGS) assembly. These resources and WGS sequences of an additional 36 diverse cowpea accessions supported the development of a genotyping assay for over 50,000 SNPs, which was then applied to five biparental RIL populations to produce a consensus genetic map containing 37,372 SNPs. This genetic map enabled the anchoring of 100 Mb of WGS and 420 Mb of BAC sequences, an exploration of genetic diversity along each linkage group, and clarification of macrosynteny between cowpea and common bean. The genomes of West African breeding lines and landraces have regions of marked depletion of diversity, some of which coincide with QTL that may be the result of artificial selection or environmental adaptation. The new publicly available resources and knowledge help to define goals and accelerate the breeding of improved varieties to address food security issues related to limited-input small-holder farming and climate stress.

Resistance mechanisms to the pod-sucking bug (PSB) Clavigralla tomentosicollis Stal, in cowpea genotype IT86D-716, were studied in field and laboratory. Non-preference was evaluated on three cowpea varieties (IT86D-716, Moussa local and KVx396-4-5-2D) through measuring differences in population parameters and extent of damage under field and laboratory conditions. Antibiosis was evaluated based on development parameters of C. tomentosicollis when reared on pods of the aforementioned varieties. The variety IT86D-716 consistently exhibited both non-preference and antibiosis resistance mechanisms to C. tomentosicollis. A chemical analysis of the pods was conducted to identify compounds conferring antibiosis. Several compounds including cyanogenic heterosides, flavonoids, tannins and trypsin inhibitors were present in pods of IT86D-716. Evidence suggests that antibiosis due to these compounds may contribute to the resistance to PSB. In the case of antibiosis, 5-day long exposures were adequate to observe nymphal mortality. Based on this finding, a fast, reliable and low-cost screening of pods can be carried out in the laboratory for identification of lines that are C. tomentosicollis resistant.

Le niebe est une denree de base en Afrique subsaharienne. L’objectif de ce travail est d’identifier des lignees a haut rendement, tolerantes a la secheresse et resistantes a la race 1 de S. gesnerioides . Des lignees issues de la selection recurrente et des varietes temoins ont ete evaluees au Centre Ouest (condition maximale d’humidite) et au Nord (condition de stress hydrique) du Burkina Faso en 2014. Tous les genotypes ont montre une resistance a la race 1 de Striga et plusieurs lignees ont reussi a produire plus de 1300 kg/ha sur les deux sites. L’Analyse en Composantes Principales realisee sur la base des caracteres quantitatifs a permis d’identifier deux groupes. Le groupe 1 est compose par des individus precoces a rendement modere (Nafi, Gorom local, KVX˗61˗1 et Komcalle). Le groupe 2 est constitue par les genotypes extra precoces a rendement modere (C2˗6˗3, C2˗18˗2, C2˗27˗2, IT97K-499-35 et Yiis yande). © 2017 International Formulae Group. All rights reserved. Mots cles: Niebe, Striga gesnerioides , stress hydrique, rendement English Title: Evaluation of 15 genotypes of rain-fed cowpea [ Vigna unguiculata (L.) Walp.] In northern and central-western Burkina Faso English Abstract Cowpea is a staple food in sub-Saharan Africa. The objective of this work is to identify high yielding, drought tolerant and race 1 resistant lines of S. gesnerioides . The breeding lines of including some varieties were evaluated in field trial under drought stressed and non-stressed conditions in 2014. Results show that the breeding lines showed complete resistance to race 1 of Striga and many improved varieties are capable of producing over 1300 kg grain/ha. Biplot displays indicated that the genotypes could be grouped into two categories according to their cycle and yielding ability as indicated below: moderate yielding-early maturing (Nafi, Gorom local, KVX˗61˗1 et Komcalle) and moderate yielding extra-early maturing (C2˗6˗3, C2˗18˗2, C2˗27˗2, IT97K-499-35 et Yiis yande). © 2017 International Formulae Group. All rights reserved. Keywords: Cowpea, Striga gesnerioides , drought, yield

This chapter summarizes recent advances in genomic resources, technologies, breeding platforms, and molecular markers that are being used to expedite delivery of cowpea cultivars with resistance to important biotic stresses. The genomic resources available in cowpea include high-throughput single nucleotide polymorphism (SNP) genotyping platforms, a high-density consensus genetic map with more than 1,100 markers, a whole genome sequence assembly, bacterial artificial chromosomes (BACs), and a physical map anchored to the genetic map. Markers linked to important biotic resistance traits, including resistance to foliar and flower thrips, Fusarium wilt, root-knot nematode, bacterial blight, ashy stem blight (Macrophomina), Striga, and viruses are described, together with tools developed to integrate SNP genotypes, genetic maps, and trait information to guide breeding. A genetic transformation system has been developed for cowpea and breeding lines developed with resistance to cowpea weevil and Maruca pod borer. Some examples of initial work in evaluating and optimizing marker-assisted backcross and marker-assisted pedigree breeding are described. Major challenges that must be overcome to allow for the adoption of modern marker-assisted breeding (MAB) in cowpea include human and precision phenotyping capacity issues. Further, as essentially all cowpea breeding is being conducted by the public sector with modest resources, efficient strategies are needed to minimize running costs.

Highly specific seed market classes for cowpea and other grain legumes exist because grain is most commonly cooked and consumed whole. Size, shape, color, and texture are critical features of these market classes and breeders target development of cultivars for market acceptance. Resistance to biotic and abiotic stresses that are absent from elite breeding material are often introgressed through crosses to landraces or wild relatives. When crosses are made between parents with different grain quality characteristics, recovery of progeny with acceptable or enhanced grain quality is problematic. Thus genetic markers for grain quality traits can help in pyramiding genes needed for specific market classes. Allelic variation dictating the inheritance of seed size can be tagged and used to assist the selection of large seeded lines. In this work we applied 1,536-plex SNP genotyping and knowledge of legume synteny to characterize regions of the cowpea genome associated with seed size. These marker-trait associations will enable breeders to use marker-based selection approaches to increase the frequency of progeny with large seed. For 804 individuals derived from eight bi-parental populations, QTL analysis was used to identify markers linked to 10 trait determinants. In addition, the population structure of 171 samples from the USDA core collection was identified and incorporated into a genome-wide association study which supported more than half of the trait-associated regions important in the bi-parental populations. Seven of the total 10 QTLs were supported based on synteny to seed size associated regions identified in the related legume soybean. In addition to delivering markers linked to major trait determinants in the context of modern breeding, we provide an analysis of the diversity of the USDA core collection of cowpea to identify genepools, migrants, admixture, and duplicates.

Agricultural migration and land insecurity in the Bwaba territory of Burkina Faso The Bwaba territory which has remained under-populated for a long time started to experience a prodigious population growth in the 70s with migratory overflows. The immigrants, mostly Moose peasants from the central and northern parts of Burkina Faso, were attracted by the rich natural potentialities (good rainfall and fertile soils) and by the region being under-populated. The growth of the population, cotton planting and the mechanization of agriculture will increase the need for farming lands to an extent such that access to land has become a major issue in some areas. The evolution of that issue in the Bwaba territory has now led to land insecurity for the immigrants. This situation which deteriorates the social relationship between the immigrants and the indigenous populations is likely to have an impact on the agricultural productivity which chiefly depends on the immigrants. The study of the land issue focuses on the social dimension related to land resources. The present study which has been conducted at both regional and local levels shows the global nature of the problem. Demographic and sociological factors, as well as the farming methods and legal matters ought to be taken into consideration in its analysis. The resolution of land insecurity must be included in a regional management policy which takes all the productive capacity of the space into account., Longtemps resté sous-peuplé, le pays bwa du Burkina Faso connaît, à partir de la décennie 1970, un accroissement démographique prodigieux dû essentiellement aux migrations de colonisation agricole. Ces migrations, suscitées par les potentialités naturelles certaines (bonne pluviométrie, sols fertiles) et par le sous-peuplement de la région, sont principalement le fait des Mossi du Centre et du Nord du Burkina. Cet apport important de la population, la culture du coton et la pratique de la mécanisation agricole vont accroître les besoins en terres de culture à telle enseigne que dans certaines régions du Bwamu, le foncier devient un enjeu majeur. La dynamique foncière qui prévaut dans le Bwamu aujourd'hui conduit à une insécurité foncière des migrants. Cette situation détériore les relations sociales entre autochtones et allochtones et pourrait compromettre le dynamisme agricole de la région qui, du reste, repose en grande partie sur les colons. L'étude de la question foncière privilégie ici la dimension sociale du rapport aux ressources foncières. Menée aux niveaux régional et local, cette étude essaie de montrer le caractère global de la question qui demande que soient intégrés dans l'analyse des aspects démographiques, sociologiques, le système de culture, les considérations juridiques, etc. La résolution de l'insécurité foncière doit s'insérer dans une politique d'aménagement régional qui prenne en compte toutes les possibilités productives de l'espace., Drabo Issa. Migration agricole et insécurité foncière en pays bwa du Burkina Faso. In: Espace, populations, sociétés, 2000-1. Mélanges (II) - Miscellanies (II) pp. 43-55.

The stay-green phenomenon is a key plant trait with wide usage in managing crop production under limited water conditions. This trait enhances delayed senescence, biomass, and grain yield under drought stress. In this study we sought to identify QTLs in cowpea (Vigna unguiculata) consistent across experiments conducted in Burkina Faso, Nigeria, Senegal, and the United States of America under limited water conditions. A panel of 383 diverse cowpea accessions and a recombinant inbred line population (RIL) were SNP genotyped using an Illumina 1536 GoldenGate assay. Phenotypic data from thirteen experiments conducted across the four countries were used to identify SNP-trait associations based on linkage disequilibrium association mapping, with bi-parental QTL mapping as a complementary strategy. We identified seven loci, five of which exhibited evidence suggesting pleiotropic effects (stay-green) between delayed senescence, biomass, and grain yield. Further, we provide evidence suggesting the existence of positive pleiotropy in cowpea based on positively correlated mean phenotypic values (0.34< r