Association Studies and Legume Synteny Reveal Haplotypes Determining Seed Size in Vigna unguiculata.

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

Genome Resources for Climate‐Resilient Cowpea, an Essential Crop for Food Security

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 the 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 4355 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 bi‐parental 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

Migration agricole et insécurité foncière en pays bwa du Burkina Faso

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

Appui à l'élaboration de stratégies de développement de la filière niébé au Burkina Faso

Rapport

Appui à la définition de stratégies de développement des filières agro-sylvo-pastorales et halieutiques sélectionnées dans les régions d'intervention du PADAB II: "Goulots d'étranglement et actions pilotes"

Rapport

Innover pour développer les marchés: le cas de la conservation du niébé au Burkina Faso

International audienceLe niébé est une culture vivrière pourvoyeuse de revenus en milieu rural au Burkina Faso. Ses marchés se développent: zones de production, grandes villes, exportations régionales. Un des goulots d'étranglement de la filière est la difficulté de conserver le produit pour des raisons techniques et financières. La recherche appliquée a mis au point un emballage qui permet de diminuer les pertes et de normaliser le conditionnement du produit. La communication examinera cette innovation sous les angles de son intérêt à opérer les ajustements de l'offre et de la demande sur des marchés volatiles et de l'enjeu de l'intégration à ces marchés de l'agriculture familiale

Association Studies and Legume Synteny Reveal Haplotypes Determining Seed Size in Vigna unguiculata.

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

Regards croisés sur le risque lié à la qualité sanitaire du cresson à Antananarivo (Madagascar)

Actes en ligne : https://agritrop.cirad.fr/557847/International audienceAvantageuse par certains côtés, l'agriculture urbaine présente plusieurs risques, notamment liés à la qualité des eaux d'irrigation et aux pratiques des agriculteurs. La communication témoigne du cas d'Antananarivo, capitale de Madagascar, où le cresson cultivé dans les bas fonds de la ville progresse et contribue de façon importante à l'alimentation des habitants. Les scientifiques ont mesuré la qualité du milieu (eaux, sols) et de la plante (différents stades de la filière). Les consommateurs sont conscients des risques sanitaires qu'ils encourent et les affrontent. Leur savoir?faire (choix du produit, lavage, cuisson) est efficace et indispensable pour la gestion de ces risques en situation de défaillance des institutions publiques et de faible segmentation du marché par rapport à la qualité