Cowpea has the potential to make a significant contribution to food and nutritional security and ... more Cowpea has the potential to make a significant contribution to food and nutritional security and poverty reduction in West and Central Africa. Constraints to be addressed include poor access to inputs including seeds, pest control, and product markets for widespread distribution of improved varieties, and integrated pest management technologies to reduce crop losses and improve product quality. The collaborative project between IITA and IFAD (International Fund for Agricultural Development) over a decade has enhanced cowpea production and grain quality through PRONAF, a technologically strong and effective participatory research development and capacity building with NARES and IFAD-funded development projects. PRONAF has made a substantial contribution to developing and disseminating sustainable, improved cowpea innovations in West and Central Africa. Target countries include Benin, Burkina Faso, Cameroon, Ghana, Mali, Niger, and Nigeria. In addition to innovations, capacity buildin...
This study determined the gene effects involved in the inheritance of pod length and other yield-... more This study determined the gene effects involved in the inheritance of pod length and other yield-related traits and relationships among traits in crosses between two cowpea lines (TVu 2280 and TVu 2027) and a yard-long bean (TVu 6642) line with long pods. Plants of six generations (P1, P2, F1, F2, BC1P1, and BC1P2) derived from TVu 2280 × TVu 6642 and TVu 2027 × TVu 6642 were evaluated under field conditions. Data collected on 14 yield components of each cross were used for generation mean analysis. Gene effects and their magnitudes varied with the crosses; digenic epistatic gene effects were detected for 10 traits in TVu 2280 × TVu 6642 and 11 traits in TVu 2280 × TVu 6642. Only additive gene effect was significant for pod length in TVu 2280 × TVu 6642 while additive, dominant, and two of the three digenic epistatic gene effects were significant in TVu 2027 × TVu 6642. Models that incorporated only significant additive, dominant, and digenic epistasis were adequate for all 14 trait...
Genetic linkage map was constructed within the cultivated gene pool of cowpea from F10 recombinan... more Genetic linkage map was constructed within the cultivated gene pool of cowpea from F10 recombinant inbred population of 94 individuals. The recombinant population was derived from a cross between the breeding lines Kanannado and 88DM-345 which were developed in Nigeria. Kanannado is day sensitive while 88DM-345 is day neutral. Twenty-three AFLP primer combinations were tested on the inbred lines and the parentals generating 141 marker loci. A total of 96 AFLP marker loci identified 11 linkage groups spanning 2551.6 cM with an average distance of 231.9 cM. Average marker density was 26.58 per marker loci. Linkage groups ranged from 17.2 to 1137.8 cM and included 3–35 marker loci, respectively. A total of 4330 crossing-over with an average of 2.0 per cM was observed. The average number of crossing-over per individual over the genome was 4.5 per chromosome per individual.
The Tropical Legumes III project aims to reduce food insecurity in drought-prone areas of Sub Sah... more The Tropical Legumes III project aims to reduce food insecurity in drought-prone areas of Sub Saharan Africa (SSA) and South Asia (SA), through improved productivity and production of four major grain legumes – chickpea, common bean, cowpea and groundnut. This is being sone by conducting research under three complementary research and delivery pillars: support for the development and release of farmer-preferred varieties; strengthening of the legume breeding capacity of partner CGIAR centers (ICRISAT, IITA and CIAT), and national partners Burkina Faso, Ghana, Mali, Nigeria, Ethiopia, Tanzania and Uganda; and establishment of sustainable seed delivery systems that service the needs of small-holderfarmers. Significant achievements have been recorded. Breeding program assessments have been completed in all countries and improvement plans developed for execution. New seed varieties (163) have been released and are fast replacing the old ruling seed varieties in all target countries. Thi...
Flower bud thrips (Megalurothrips sjostedti) is one of the most damaging pests to cowpea in Afric... more Flower bud thrips (Megalurothrips sjostedti) is one of the most damaging pests to cowpea in Africa and varietal resistance is one of the effective approaches to minimize the pest damage. Study was conducted to assess variability among 117 genotypes in addition to two resistant (Sanzisabinli and TVu 1509) and one susceptible (Vita7) checks at Cinzana and N’Tarla locations under natural and artificial infestations of thrips. Parameters such as total number of pods per plant and damage scoring were used to assess the test entries. Genotypes CIPEA82672, Suivita2, TVu 1509 and Sanzisabinli were found highly tolerant, Diaye and TVu7677 moderately tolerant whilst nine genotypes were found tolerant to thrips attacks. CIPEA82672 and Suivita2 had higher grain yield than the resistant checks. Year by genotype, year by location and year by location by genotype interactions were significant for most traits. Genotype by genotype by environment (GGE) effect on yield showed CIPEA82672 most stable a...
Optimization of a breeding program for increased genetic gain requires quality assurance (QA) and... more Optimization of a breeding program for increased genetic gain requires quality assurance (QA) and quality control (QC) at key phases of the breeding process. One vital phase in a breeding program that requires QC and QA is the choice of parents and successful hybridizations to combine parental attributes and create variations. The objective of this study was to determine parental diversity and confirm hybridity of cowpea F1 progenies using KASP (Kompetitive Allele-Specific PCR)-based single nucleotide polymorphism (SNP) markers. A total of 1,436 F1 plants were derived from crossing 220 cowpea breeding lines and landraces to 2 elite sister lines IT99K-573-1-1 and IT99K-573-2-1 as male parents, constituting 225 cross combinations. The progenies and the parents were genotyped with 17 QC SNP markers via high-throughput KASP genotyping assay. The QC markers differentiated the parents with mean efficiency of 37.90% and a range of 3.4–82.8%, revealing unique fingerprints of the parents. Ne...
Both cowpea and yard-long bean belong to Vigna unguiculata ssp. unguiculata but have diverged thr... more Both cowpea and yard-long bean belong to Vigna unguiculata ssp. unguiculata but have diverged through human induced evolution in sub-Saharan Africa and Asia, respectively. To map the quantitative trait loci (QTLs) for yield associated traits and derive new lines that may combine the attributes of both types, we developed a F2:3 mapping population derived from a cross between cowpea line TVu2185 and yard-long bean line TVu6642. Using DArT markers, a total of 30 QTLs accounting for 1.8–13.0% phenotypic variation was detected for pod and seed traits. Some novel major QTLs for peduncle number per plant (qPeN2.2), pod length (qPoL3), seed breadth (qSB4), length (qSL7.2) and thickness (qST9) identified on chromosomes 2, 3, 4, 7 and 9, respectively, are particularly interesting and need to be validated. Moreover, we confirmed previously reported QTLs for pod length (qPoL8) and 100-seed weight (qSW8) on chromosome 8 and for seed number per pod (qSN9.2) on chromosome 9 suggesting usefulness for marker-assisted-selection purpose. Notably, some QTLs for these traits were clustered especially on chromosomes 5, 7, 8, 9 and 10 indicating the presence of the same QTL or linked loci in these regions. Moreover, the involvement of epistasis was observed for trait expressions, but compared with the main effect QTLs, the phenotypic effects of epistatic-QTLs detected were much less. The present QTL analysis may provide a useful tool for breeders to formulate efficient breeding strategy for introgression of the desirable alleles for yield related traits in cowpea using molecular markers.
SummaryComparative analysis of preferences and key criteria for selecting cowpea (Vigna unguicula... more 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 criter...
Cowpea (Vigna unguiculata L.) is an important protein-rich grain legume and fodder crop grown acr... more Cowpea (Vigna unguiculata L.) is an important protein-rich grain legume and fodder crop grown across the semi-arid zones of the tropics below the Saharan desert and similar agro-ecological zones of eastern and southern Africa and the world. Drought, heat, low fertility soils, pests and diseases are key factors causing traditional varieties in Africa to yield much lower than their potential. Collaborative breeding programs are being aimed to develop improved cowpea cultivars for Africa. Marker-assisted backcrossing is being applied to accelerate introgression of known resistance genes into local cultivars, including resistance to the parasitic weed Striga, several fungal and bacterial diseases, nematodes and insect pests. Marker-assisted recurrent selection (MARS) is being evaluated in four countries in Africa using four populations, each derived from a cross between elite parents carrying traits relevant to each target environment. Following QTL discovery at F3 - F4 generations, mem...
Proceedings of the National Academy of Sciences, 2009
Consensus genetic linkage maps provide a genomic framework for quantitative trait loci identifica... more Consensus genetic linkage maps provide a genomic framework for quantitative trait loci identification, map-based cloning, assessment of genetic diversity, association mapping, and applied breeding in marker-assisted selection schemes. Among “orphan crops” with limited genomic resources such as cowpea [ Vigna unguiculata (L.) Walp.] (2 n = 2 x = 22), the use of transcript-derived SNPs in genetic maps provides opportunities for automated genotyping and estimation of genome structure based on synteny analysis. Here, we report the development and validation of a high-throughput EST-derived SNP assay for cowpea, its application in consensus map building, and determination of synteny to reference genomes. SNP mining from 183,118 ESTs sequenced from 17 cDNA libraries yielded ≈10,000 high-confidence SNPs from which an Illumina 1,536-SNP GoldenGate genotyping array was developed and applied to 741 recombinant inbred lines from six mapping populations. Approximately 90% of the SNPs were techn...
Cowpea has the potential to make a significant contribution to food and nutritional security and ... more Cowpea has the potential to make a significant contribution to food and nutritional security and poverty reduction in West and Central Africa. Constraints to be addressed include poor access to inputs including seeds, pest control, and product markets for widespread distribution of improved varieties, and integrated pest management technologies to reduce crop losses and improve product quality. The collaborative project between IITA and IFAD (International Fund for Agricultural Development) over a decade has enhanced cowpea production and grain quality through PRONAF, a technologically strong and effective participatory research development and capacity building with NARES and IFAD-funded development projects. PRONAF has made a substantial contribution to developing and disseminating sustainable, improved cowpea innovations in West and Central Africa. Target countries include Benin, Burkina Faso, Cameroon, Ghana, Mali, Niger, and Nigeria. In addition to innovations, capacity buildin...
This study determined the gene effects involved in the inheritance of pod length and other yield-... more This study determined the gene effects involved in the inheritance of pod length and other yield-related traits and relationships among traits in crosses between two cowpea lines (TVu 2280 and TVu 2027) and a yard-long bean (TVu 6642) line with long pods. Plants of six generations (P1, P2, F1, F2, BC1P1, and BC1P2) derived from TVu 2280 × TVu 6642 and TVu 2027 × TVu 6642 were evaluated under field conditions. Data collected on 14 yield components of each cross were used for generation mean analysis. Gene effects and their magnitudes varied with the crosses; digenic epistatic gene effects were detected for 10 traits in TVu 2280 × TVu 6642 and 11 traits in TVu 2280 × TVu 6642. Only additive gene effect was significant for pod length in TVu 2280 × TVu 6642 while additive, dominant, and two of the three digenic epistatic gene effects were significant in TVu 2027 × TVu 6642. Models that incorporated only significant additive, dominant, and digenic epistasis were adequate for all 14 trait...
Genetic linkage map was constructed within the cultivated gene pool of cowpea from F10 recombinan... more Genetic linkage map was constructed within the cultivated gene pool of cowpea from F10 recombinant inbred population of 94 individuals. The recombinant population was derived from a cross between the breeding lines Kanannado and 88DM-345 which were developed in Nigeria. Kanannado is day sensitive while 88DM-345 is day neutral. Twenty-three AFLP primer combinations were tested on the inbred lines and the parentals generating 141 marker loci. A total of 96 AFLP marker loci identified 11 linkage groups spanning 2551.6 cM with an average distance of 231.9 cM. Average marker density was 26.58 per marker loci. Linkage groups ranged from 17.2 to 1137.8 cM and included 3–35 marker loci, respectively. A total of 4330 crossing-over with an average of 2.0 per cM was observed. The average number of crossing-over per individual over the genome was 4.5 per chromosome per individual.
The Tropical Legumes III project aims to reduce food insecurity in drought-prone areas of Sub Sah... more The Tropical Legumes III project aims to reduce food insecurity in drought-prone areas of Sub Saharan Africa (SSA) and South Asia (SA), through improved productivity and production of four major grain legumes – chickpea, common bean, cowpea and groundnut. This is being sone by conducting research under three complementary research and delivery pillars: support for the development and release of farmer-preferred varieties; strengthening of the legume breeding capacity of partner CGIAR centers (ICRISAT, IITA and CIAT), and national partners Burkina Faso, Ghana, Mali, Nigeria, Ethiopia, Tanzania and Uganda; and establishment of sustainable seed delivery systems that service the needs of small-holderfarmers. Significant achievements have been recorded. Breeding program assessments have been completed in all countries and improvement plans developed for execution. New seed varieties (163) have been released and are fast replacing the old ruling seed varieties in all target countries. Thi...
Flower bud thrips (Megalurothrips sjostedti) is one of the most damaging pests to cowpea in Afric... more Flower bud thrips (Megalurothrips sjostedti) is one of the most damaging pests to cowpea in Africa and varietal resistance is one of the effective approaches to minimize the pest damage. Study was conducted to assess variability among 117 genotypes in addition to two resistant (Sanzisabinli and TVu 1509) and one susceptible (Vita7) checks at Cinzana and N’Tarla locations under natural and artificial infestations of thrips. Parameters such as total number of pods per plant and damage scoring were used to assess the test entries. Genotypes CIPEA82672, Suivita2, TVu 1509 and Sanzisabinli were found highly tolerant, Diaye and TVu7677 moderately tolerant whilst nine genotypes were found tolerant to thrips attacks. CIPEA82672 and Suivita2 had higher grain yield than the resistant checks. Year by genotype, year by location and year by location by genotype interactions were significant for most traits. Genotype by genotype by environment (GGE) effect on yield showed CIPEA82672 most stable a...
Optimization of a breeding program for increased genetic gain requires quality assurance (QA) and... more Optimization of a breeding program for increased genetic gain requires quality assurance (QA) and quality control (QC) at key phases of the breeding process. One vital phase in a breeding program that requires QC and QA is the choice of parents and successful hybridizations to combine parental attributes and create variations. The objective of this study was to determine parental diversity and confirm hybridity of cowpea F1 progenies using KASP (Kompetitive Allele-Specific PCR)-based single nucleotide polymorphism (SNP) markers. A total of 1,436 F1 plants were derived from crossing 220 cowpea breeding lines and landraces to 2 elite sister lines IT99K-573-1-1 and IT99K-573-2-1 as male parents, constituting 225 cross combinations. The progenies and the parents were genotyped with 17 QC SNP markers via high-throughput KASP genotyping assay. The QC markers differentiated the parents with mean efficiency of 37.90% and a range of 3.4–82.8%, revealing unique fingerprints of the parents. Ne...
Both cowpea and yard-long bean belong to Vigna unguiculata ssp. unguiculata but have diverged thr... more Both cowpea and yard-long bean belong to Vigna unguiculata ssp. unguiculata but have diverged through human induced evolution in sub-Saharan Africa and Asia, respectively. To map the quantitative trait loci (QTLs) for yield associated traits and derive new lines that may combine the attributes of both types, we developed a F2:3 mapping population derived from a cross between cowpea line TVu2185 and yard-long bean line TVu6642. Using DArT markers, a total of 30 QTLs accounting for 1.8–13.0% phenotypic variation was detected for pod and seed traits. Some novel major QTLs for peduncle number per plant (qPeN2.2), pod length (qPoL3), seed breadth (qSB4), length (qSL7.2) and thickness (qST9) identified on chromosomes 2, 3, 4, 7 and 9, respectively, are particularly interesting and need to be validated. Moreover, we confirmed previously reported QTLs for pod length (qPoL8) and 100-seed weight (qSW8) on chromosome 8 and for seed number per pod (qSN9.2) on chromosome 9 suggesting usefulness for marker-assisted-selection purpose. Notably, some QTLs for these traits were clustered especially on chromosomes 5, 7, 8, 9 and 10 indicating the presence of the same QTL or linked loci in these regions. Moreover, the involvement of epistasis was observed for trait expressions, but compared with the main effect QTLs, the phenotypic effects of epistatic-QTLs detected were much less. The present QTL analysis may provide a useful tool for breeders to formulate efficient breeding strategy for introgression of the desirable alleles for yield related traits in cowpea using molecular markers.
SummaryComparative analysis of preferences and key criteria for selecting cowpea (Vigna unguicula... more 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 criter...
Cowpea (Vigna unguiculata L.) is an important protein-rich grain legume and fodder crop grown acr... more Cowpea (Vigna unguiculata L.) is an important protein-rich grain legume and fodder crop grown across the semi-arid zones of the tropics below the Saharan desert and similar agro-ecological zones of eastern and southern Africa and the world. Drought, heat, low fertility soils, pests and diseases are key factors causing traditional varieties in Africa to yield much lower than their potential. Collaborative breeding programs are being aimed to develop improved cowpea cultivars for Africa. Marker-assisted backcrossing is being applied to accelerate introgression of known resistance genes into local cultivars, including resistance to the parasitic weed Striga, several fungal and bacterial diseases, nematodes and insect pests. Marker-assisted recurrent selection (MARS) is being evaluated in four countries in Africa using four populations, each derived from a cross between elite parents carrying traits relevant to each target environment. Following QTL discovery at F3 - F4 generations, mem...
Proceedings of the National Academy of Sciences, 2009
Consensus genetic linkage maps provide a genomic framework for quantitative trait loci identifica... more Consensus genetic linkage maps provide a genomic framework for quantitative trait loci identification, map-based cloning, assessment of genetic diversity, association mapping, and applied breeding in marker-assisted selection schemes. Among “orphan crops” with limited genomic resources such as cowpea [ Vigna unguiculata (L.) Walp.] (2 n = 2 x = 22), the use of transcript-derived SNPs in genetic maps provides opportunities for automated genotyping and estimation of genome structure based on synteny analysis. Here, we report the development and validation of a high-throughput EST-derived SNP assay for cowpea, its application in consensus map building, and determination of synteny to reference genomes. SNP mining from 183,118 ESTs sequenced from 17 cDNA libraries yielded ≈10,000 high-confidence SNPs from which an Illumina 1,536-SNP GoldenGate genotyping array was developed and applied to 741 recombinant inbred lines from six mapping populations. Approximately 90% of the SNPs were techn...
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