Cowpea Breeding Programs Research Articles

Genetic analysis for forage yield and quality characters in cowpea (Vigna unguiculata L. Walp)

This study was carried out to determine the combining ability of forage yield, its components and quality traits among crosses derived from nine selected cowpea parents. About 36 crosses were generated from diallel crosses, excluding reciprocals. These crosses and nine parents were evaluated for combining ability for forage yield, its components and quality traits. The results indicated that parent 85-5E was the best combiner for green fodder yield, dry matter yield, leaf length, leaf breadth, number of leaves per plant, number of branches per plant, crude protein content and in-vitro dry matter digestibility. Similarly, parent FOS 1 proved to be the best combiner for vine length, number of leaves per plant, number of branches per plant, crude protein content and in-vitro dry matter digestibility. The crosses involving FOS 1 x CL 398, CL 391 x C 88, FOS 1 x C 74, CL 396 x CL 391 and FOS 1 x C 88 were the best specific combiner for green fodder yield and most of its components traits. The ratio of gca/sca values was greater than unity for most of the forage and quality traits, inferring that additive gene action played an important role in their inheritance. In contrast, for traits like vine length, dry matter yield, crude protein content, and in-vitro dry matter digestibility, the above-said ratio was less than unity, indicating non-additive gene action played an important role. So, to utilize both additive and non-additive gene effects, modification of conventional breeding methods such as bi-parental breeding or reciprocal recurrent selection will be the better choice for initiating any cowpea breeding program.

Genetic variability in exotic cowpea (Vigna unguiculata L.) genotypes

Genetic variability plays a crucial role in hybridization and the development of crops with desirable traits. This study, conducted at the Regional Agricultural Research Station of the Bangladesh Agricultural Research Institute in Chattogram, focused on assessing genetic diversity, correlations, and path coefficients related to yield and other traits in 31 cowpea genotypes. The experiment, designed as a randomized complete block with three replications, revealed significant differences among the genotypes for all traits measured, as confirmed by analysis of variance. While most traits showed minimal differences between phenotypic and genotypic variances, plant height and yield per plant were more significantly influenced by environmental factors. The coefficients of variation were low for days to first flowering, days to 50% flowering, days to maturity, and days to harvesting; moderate for seeds per plant; and high for other traits. Plant height, thousand-seed weight, and yield per plant exhibited high heritability and substantial genetic advance, suggesting that direct selection for these traits would be effective due to their additive genetic control. The correlation analysis indicated significant positive relationships between yield per plant and several flowering and maturity traits at both the genotypic and phenotypic levels. Path analysis identified plant height, days to 50% flowering, days to harvesting, seeds per plant, pods per plant, and thousand-seed weight as having positive direct effects on yield per plant, implying that selection for these traits could enhance cowpea yield. Among the evaluated genotypes, E25 stood out as the highest yielding with 533.33 g yield per plant, early maturity at 84 days after sowing, moderate thousand-seed weight (124.33 g), seeds per plant (13.87), and plant height (103.33 cm), making it a promising candidate for hybridization. This research provides valuable insights for cowpea breeding programs, highlighting the importance of selecting specific traits like plant height, flowering time, and thousand-seed weight to develop high-yielding, resilient cowpea varieties adaptable to diverse agricultural conditions. Asian J. Med. Biol. Res. 2024, 10(4), 148-156

Evaluation and identification of high yielding and stable cowpea genotypes using GGE biplot and joint regression analysis for varietal development in East and Southern Africa

Malawi, Mozambique, and Tanzania's cowpea breeding programs have been collaborating on pre-breeding trials in different locations, focusing on key traits such as grain yield. However, there is a lack of information regarding the nature of genotype-environment interaction patterns among these environments. The study was conducted to assess and identify high-yielding and stable cowpea genotypes for the development of improved varieties in these three countries. Thirty genotypes were evaluated in ten environments using an incomplete block design with three replications. Grain yield data was analyzed using genotype (G) × genotype-environment interaction (GGE) biplot and joint regression analysis. The joint analysis of variance showed highly significant differences (P < 0.001) for the main effects of genotypes and environment, as well as their interaction effects. This suggested that the environments assessed were distinct and that the genotypes exhibited varying performances in response to environmental variations. The environmental indices showed that only four environments were favorable for high grain yield, and overall, Guariba was the topmost yielder (1973.5 kg ha−1) across all environments. The analysis identified IT10K-817-7 and MWcp08 as superior and stable genotypes, making them highly desirable and potentially recommended across test environments for their expected ability to achieve economically viable yields. Overall, Chitedze Research Station in Malawi and Nametil Research Station in Mozambique were both discriminating and representative, indicating that they are good test environments for selecting best-performing genotypes that can perform well across a wide range of conditions. These environments can be recommended as the best environments for future cowpea genotype evaluations targeting the release of varieties in the three countries (Malawi, Mozambique and Tanzania) where the METs were carried out.

Genetic Variability Studies for Identification of High Yielding Genotypes with High Protein Content in Grain Cowpea [Vigna unguiculata (L.) Walp.

Background: Cowpea is a major legume crop which has high protein content and provides a powerful tool to combat malnutrition due to its highly nutritional value. Identification of superior genotypes will aid in cowpea breeding program. Genetic variability is the foremost requirement in a breeding population for the selection of high yielding genotypes. To develop a new high yielding variety, it is important to study the genetic variability present in it so that proper and efficient selection could be done and most promising genotypes could be identified. Methods: Keeping this in mind, studies on genetic variability in grain cowpea was done utilizing 40 diverse exotic and indigenous cowpea genotypes which were evaluated for ten quantitative characters for two consecutive years 2020 and 2021. The experiment was planted in randomized block design with 3 replications at Pantnagar. Data was recorded on ten characters. Result: Mean squares were found to be highly significant for all the characters. Cluster analysis revealed five genetically diverse clusters. Cluster I had 8 genotypes, cluster II had 9 genotypes, cluster III consisted of 12 genotypes, cluster IV had 6 genotypes and Cluster V consisted 5 genotypes. Cluster I had the greatest intra-cluster distance (2.500) whereas cluster V had the smallest intra-cluster distance (1.701). In the cluster V, one of the genotype Pant Lobia-2 exhibited the highest mean values for all the characters. The highest GCV and PCV was recorded by number of pods per plant (28.87, 29.19) followed by yield (q/ha) (28.72, 29.04). The higher value of phenotypic component compared to the corresponding genotypic component suggest that there was an environmental influence on the performance of the genotypes. Correlation studies revealed positive correlation between pod length, pods per cluster, seeds per pod and yield quintal per hectare. Path coefficient analysis showed the significant positive direct relationship between plant height, peduncle length, pod length, number of pods per cluster, number of pods per plant and number of seeds per pod with yield quintals per hectare. The results of the study showed that, out of the 40 genotypes evaluated, Pant Lobia-2 exhibited the best performance. It has attractive red bold seeds with 31% protein content. Therefore it can be used in grain cowpea breeding program.

Canonical correlations between morphoagronomic and production traits in traditional cowpea varieties based on genotypic values

Obtaining information about the main morphoagronomic and yield components, as well as their interrelationships, is of utmost importance in cowpea breeding programs, aiming at the selection of superior genotypes. The analysis of canonical correlations allows us to predict and describe the relationship between groups of characters, allowing the indirect selection of superior genotypes. The objective of this work was to verify relationships between morphological characters and production components through the analysis of canonical correlations using genotypic values obtained via mixed REML/BLUP models in traditional cowpea varieties. The experiment was conducted in a randomized block design with three replications and 12 treatments. Traditional varieties were characterized and evaluated during the germination, seedling, flowering and harvest stages with data obtained from plants, pods and seeds. Using the genotypic correlation matrix, two sets of characteristics were established, Group I, formed by production components and Group II, formed by morphoagronomic characters. A second correlation analysis was performed to verify associations between morphoagronomic and seed traits (seed length, width and thickness). It was found that dependence between the groups evaluated and intergroup associations can be established, which allows the study of cause-effect and the practice of indirect selection between groups of variables studied. An increase in pod length, hundred-grain mass and seed size is achieved through the selection of early maturing plants, with greater width of the apical leaflet and length of the hypocotyl.

Genetic progress in cowpea [Vigna unguiculata (L.) Walp.] stemming from breeding modernization efforts at the International Institute of Tropical Agriculture.

Genetic gain has been proposed as a quantifiable key performance indicator that can be used to monitor breeding programs' effectiveness. The cowpea breeding program at the International Institute of Tropical Agriculture (IITA) has developed and released improved varieties in 70 countries globally. To quantify the genetic changes to grain yield and related traits, we exploited IITA cowpea historical multi-environment trials (METs) advanced yield trial (AYT) data from 2010 to 2022. The genetic gain assessment targeted short duration (SD), medium duration (MD), and late duration (LD) breeding pipelines. A linear mixed model was used to calculate the best linear unbiased estimates (BLUE). Regressed BLUE of grain yield by year of genotype origin depicted realized genetic gain of 22.75 kg/ha/year (2.65%), 7.91 kg/ha/year (0.85%), and 22.82 kg/ha/year (2.51%) for SD, MD, and LD, respectively. No significant gain was realized in 100-seed weight (Hsdwt). We predicted, based on 2022 MET data, that recycling the best genotypes at AYT stage would result in grain yield gain of 37.28 kg/ha/year (SD), 28.00 kg/ha/year (MD), and 34.85 kg/ha/year (LD), and Hsdwt gain of 0.48g/year (SD), 0.68g/year (MD), and 0.55g/year (LD). These results demonstrated a positive genetic gain trend for cowpea, indicating that a yield plateau has not yet been reached and that accelerated gain is expected with the recent integration of genomics in the breeding program. Advances in genomics include the development of the reference genome, genotyping platforms, quantitative trait loci mapping of key traits, and active implementation of molecular breeding.

Genetic Variability and Interrelationships of Grain, Cooking, and Nutritional Quality Traits in Cowpea: Implications for Cowpea Improvement

Grain quality, cooking quality, and nutritional quality traits are some of the major attributes that enhance the uptake and utilization of improved cowpea varieties. Therefore, there is a need for a better understanding of the genetic variation and inter-relationships among these quality traits in cowpeas to integrate them into cowpea breeding programs. This study was conducted to determine genetic variability among 306 cowpea genotypes for grain quality, cooking quality, and nutritional quality traits and to understand the interrelationships among these traits for exploitation in breeding programs. The results showed highly significant differences (p &lt; 0.001) among genotypes for grain quality, cooking quality, and nutritional quality traits. The mean performance for these quality traits was also very variable. These results suggest that genetic variability exists in the cowpea genotypes studied, which can be exploited in breeding programs aimed at developing high-performing varieties for the said traits. Significant (p &lt; 0.001) positive correlations were detected for protein content with iron and zinc. On the other hand, nutritional quality traits did not exhibit any association with grain quality or cooking quality traits. Cooking quality traits were also shown to be significantly and positively correlated with grain quality traits. This study has identified several genotypes with desirable quality-related traits that could be used in crossing programs to generate improved varieties with consumer-preferred traits to improve the food, income, and nutritional status of many smallholder farmers that largely depend on cowpeas.

Understanding specific gender dynamics in the cowpea value chain for key traits to inform cowpea breeding programs in Malawi, Mozambique and Tanzania.

Cowpea is an important food and nutrition security crop in Malawi, Mozambique and Tanzania and it is mainly produced by women farmers mainly on a subsistence scale. The majority of these farmers use local varieties despite the availability of improved varieties in the region. Low acceptability and adoption of improved varieties have also hampered cowpea breeding efforts. The low adoption, especially among women farmers, has been attributed to the failure by breeding programs to involve farmers in the process of designing and developing improved varieties with a view to meeting their priorities and preferences. Despite women constituting the majority of cowpea farmers in these countries, no comprehensive gender analysis on cowpea value chain had been instituted to understand the traits that are gender and youth responsive and how to incorporate them in the product profiling so that the developed varieties benefit men, women and youth. The main objective of the gender study was, therefore, to identify preferred traits by different gender groups within the whole cowpea value chain to inform cowpea breeding programs in the three countries. The study employed quantitative and qualitative methods to elucidate preferences, including value chain mapping, a quantitative survey of farmers, focus group discussions and key informant interviews targeting farmers/consumers, traders, policymakers and processors. Results showed that the top-ranking traits in order of importance across the countries and gender were; (1) high grain yield, (2) good grain taste, (3) early maturity time, (4) large grain size, (5) good leaf taste and (6) short cooking time. It was further noted that different gender groups preferred almost similar traits though minor variations were noted in terms of prioritization of these traits. These results have had two major influences on our cowpea breeding program: firstly, the breeding program changed the way it prioritizes traits to include ones that reflect the needs of men, women and the youth in the cowpea value chain. Secondly, our breeding objectives are closely aligned to gender differences in the target population of farmers and other users, by incorporating key priority traits that address the needs of both men and women, including the youth. That is to say, product targets and specific product profiles are more gender sensitive. Since the breeding work is ongoing, the expectation is that the development of improved varieties resulting from this gender sensitive process will translate into higher adoption levels of these varieties (compared with previous releases), which might have ripple effects on food, nutrition and income security in the region.

Morphological diversity, correlation studies, and multiple-traits selection for yield and yield components of local cowpea varieties

Abstract The evaluation of the diversity in the cowpea local varieties (CLVs) allows the efficient use of genetic resources for cultivar development. This study aimed to evaluate the diversity of CLVs based on observation of morphological characteristics and to identify the relationship among morphological traits and potential varieties as donor genes to improve yield potential. The CLVs were collected from five provinces in Indonesia during 2017–2018. The evaluation of the performance of CLVs’ morphological characteristics was carried out in the Indonesian Legumes and Tuber Crops Research from March to July 2019. The observed data were 43 agronomic characters which consist of qualitative and quantitative characters. There is a high variation in stem pigmentation and seed color in 214 CLVs. There were nine qualitative characters with no variation. Most quantitative characters showed significant variation among CLVs. The clustering of 214 CLVs results in five clusters in which some CLVs maintain valuable characteristics that could be used in the breeding program. The number of pods per plant, number of racemes per plant, and 100 seed weight were useful for indirect selection in the yield improvement. Based on the genotype by trait biplot, the CLV 112, 191, and 111 could be used as donor parents for seed size improvement and the CLV 169 could be used as a donor parent for the yield potential improvement in the cowpea breeding program. Four cowpea genotypes can be recommended for commercial release or used as potential breeding material in cowpea cultivar development programs. The new findings of this study could provide a basis for the genetic improvement of cowpea.

Characterization of terminal flowering cowpea (Vigna unguiculata (L.) Walp.) mutants obtained by induced mutagenesis digs out the loss-of-function of phosphatidylethanolamine-binding protein

Cowpea (Vigna unguiculata (L.) Walp) is one of the major food legume crops grown extensively in arid and semi-arid regions of the world. The determinate habit of cowpea has many advantages over the indeterminate and is well adapted to modern farming systems. Mutation breeding is an active research area to develop the determinate habit of cowpea. The present study aimed to develop new determinate habit mutants with terminal flowering (TFL) in locally well-adapted genetic backgrounds. Consequently, the seeds of popular cowpea cv P152 were irradiated with doses of gamma rays (200, 250, and, 300 Gy), and the M1 populations were grown. The M2 populations were produced from the M1 progenies and selected determinate mutants (TFLCM-1 and TFLCM-2) from the M2 generation (200 Gy) were forwarded up to the M5 generation to characterize the mutants and simultaneously they were crossed with P152 to develop a MutMap population. In the M5 generation, determinate mutants (80–81 days) were characterized by evaluating the TFL growth habit, longer peduncles (30.75–31.45 cm), erect pods (160°- 200°), number of pods per cluster (4–5 nos.), and early maturity. Further, sequencing analysis of the VuTFL1 gene in the determinate mutants and MutMap population revealed a single nucleotide transversion (A-T at 1196 bp) in the fourth exon and asparagine (N) to tyrosine (Y) amino acid change at the 143rd position of phosphatidylethanolamine-binding protein (PEBP). Notably, the loss of function PEPB with a higher confidence level modification of anti-parallel beta-sheets and destabilization of the protein secondary structure was observed in the mutant lines. Quantitative real-time PCR (qRT-PCR) analysis showed that the VuTFL1 gene was downregulated at the flowering stage in TFL mutants. Collectively, the insights garnered from this study affirm the effectiveness of induced mutation in modifying the plant’s ideotype. The TFL mutants developed during this investigation have the potential to serve as a valuable resource for fostering determinate traits in future cowpea breeding programs and pave the way for mechanical harvesting.

Assessing the effects of 24-epibrassinolide and yeast extract at various levels on cowpea’s morphophysiological and biochemical responses under water deficit stress

BackgroundDue to the factor of water deficit, which has placed human food security at risk by causing a 20% annual reduction in agricultural products, addressing this growing peril necessitates the adoption of inventive strategies aimed at enhancing plant tolerance. One such promising approach is employing elicitors such as 24-epibrassinolide (EBR) and yeast extract, which are potent agents capable of triggering robust defense responses in plants. By employing these elicitors, crops can develop enhanced adaptive mechanisms to combat water deficit and improve their ability to withstand drought condition. This study investigates the impact of different levels of EBR (0, 5, 10 µm) and yeast extract (0 and 12 g/l) on enhancing the tolerance of cowpea to water deficit stress over two growing seasons.ResultsThe findings of this study demonstrate that, the combined application of EBR (especially 10 µm) and yeast extract (12 g/l) can increase seed yield (18%), 20-pod weight (16%), the number of pods per plant (18%), total chlorophyll content (90%), and decrease malondialdehyde content (45%) in cowpea, compared to plants grown under water deficit stress without these treatments. Upon implementing these treatments, impressive results were obtained, with the highest recorded values observed for the seed yield (1867.55 kg/ha), 20-pod weight (16.29 g), pods number per plant (9), and total chlorophyll content (19.88 mg g−1 FW). The correlation analysis indicated a significant relationship between the seed yield, and total chlorophyll (0.74**), carotenoids (0.82**), weight of 20 seeds (0.67**), and number of pods (0.90**). These traits should be prioritized in cowpea breeding programs focusing on water deficit stress.ConclusionsThe comprehensive exploration of the effects of EBR and yeast extract across various levels on cowpea plants facing water deficit stress presents a pivotal contribution to the agricultural domain. This research illuminates a promising trajectory for future agricultural practices and users seeking sustainable solutions to enhance crops tolerance. Overall, the implications drawn from this study contribute significantly towards advancing our understanding of plant responses to water deficit stress while providing actionable recommendations for optimizing crop production under challenging environmental conditions.

A Genome-Wide Association Study Reveals Region Associated with Seed Protein Content in Cowpea.

Cowpea (Vigna unguiculata L. Walp., 2n = 2x = 22) is a protein-rich crop that complements staple cereals for humans and serves as fodder for livestock. It is widely grown in Africa and other developing countries as the primary source of protein in the diet; therefore, it is necessary to identify the protein-related loci to improve cowpea breeding. In the current study, we conducted a genome-wide association study (GWAS) on 161 cowpea accessions (151 USDA germplasm plus 10 Arkansas breeding lines) with a wide range of seed protein contents (21.8~28.9%) with 110,155 high-quality whole-genome single-nucleotide polymorphisms (SNPs) to identify markers associated with protein content, then performed genomic prediction (GP) for future breeding. A total of seven significant SNP markers were identified using five GWAS models (single-marker regression (SMR), the general linear model (GLM), Mixed Linear Model (MLM), Fixed and Random Model Circulating Probability Unification (FarmCPU), and Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK), which are located at the same locus on chromosome 8 for seed protein content. This locus was associated with the gene Vigun08g039200, which was annotated as the protein of the thioredoxin superfamily, playing a critical function for protein content increase and nutritional quality improvement. In this study, a genomic prediction (GP) approach was employed to assess the accuracy of predicting seed protein content in cowpea. The GP was conducted using cross-prediction with five models, namely ridge regression best linear unbiased prediction (rrBLUP), Bayesian ridge regression (BRR), Bayesian A (BA), Bayesian B (BB), and Bayesian least absolute shrinkage and selection operator (BL), applied to seven random whole genome marker sets with different densities (10 k, 5 k, 2 k, 1 k, 500, 200, and 7), as well as significant markers identified through GWAS. The accuracies of the GP varied between 42.9% and 52.1% across the seven SNPs considered, depending on the model used. These findings not only have the potential to expedite the breeding cycle through early prediction of individual performance prior to phenotyping, but also offer practical implications for cowpea breeding programs striving to enhance seed protein content and nutritional quality.

Agro-morphological characterization of selected varieties of vegetable cowpea [Vigna unguiculata (L.) Walp.] in Burkina Faso

Vegetable Cowpea (Vigna unguiculata) is one of the neglected legumes in Burkina Faso, and as a result, its genetic diversity remains poorly known. The main aim of this study was to know its genetic variability through an agro-morphological characterization. Twenty vegetable cowpea varieties were evaluated at the Kamboinsé Environmental, Agricultural and Training Research Center following a three-replication Fischer block design under rainfed conditions. Fifteen quantitative and nine qualitative variables were collected and subjected to various statistical analyses. Analysis of variance was significant for the variables 50% flowering, vegetable cowpea date, number of pods obtained per plant, number of seeds per pod, fresh pod weight, fresh pod yield, pod length, plant height, seed length and chlorophyll content. Strong correlations were also reported between the various variables. The observed diversity is structured in three morphological groups viz., Group 1 consists of individuals with early flowering, high chlorophyll content and the number of pods obtained per plant. Group 2 brings together the varieties of average agronomic performance for pod length, the number of pods per plant, number of days at 95% maturity, fresh pod weight, yield of fresh pods and group 3 of varieties with long pods, early green date, high pod weight and good fresh pod yield. Among the tested varieties, the varieties IT83S-872 (30 pods), IT84S-2246 (27 pods), Baguette (25 pods), IT83S-818 (26 pods), and IT85F-2682 (24 pods) stood out for their high pod production. In addition, the varieties of vegetable cowpea baguette, baguette grimpant, Telma, and IT83S-911 showed the best performance in terms of early vegetable cowpea date stage, longest pods, highest pod weight and best yield of fresh pods. The high genetic variability level within the tested varieties could be exploited in future green cowpea breeding programmes.

Parâmetros genéticos e índices de seleção de genótipos de feijão-caupi para produção de grãos verdes

ABSTRACT Cowpea is a legume that is grown worldwide and used for different purposes, especially as green grains. However, considering the low availability of cowpea cultivars for green grain production, selecting genotypes that have better traits for this purpose is necessary. In this context, the objective of this study was to estimate genetic parameters and evaluate different selection indices for identifying superior cowpea genotypes and subsidizing cowpea breeding programs focused on green grain production. A field experiment was conducted at the Center of Agricultural Sciences of the Federal University of Ceará (UFC), Ceará, Brazil. The treatments consisted of 42 cowpea genotypes from the Active Germplasm Bank of the UFC. Fourteen traits were used for characterization. The experiment was conducted in an augmented block design with four controls. The data obtained were subjected to analysis of variance, and genetic parameters, correlations, and selection indices were determined. The traits days to flowering (DFL), days to fruiting (DFR), green pod weight (GPW), green pod width (GW), green pod length (GPL), green pod thickness (GPT), number of grains per pod (NGP), and green grain thickness (GGT) showed heritability higher than 70%, indicating that selection in an early generation is favorable. The genetic correlations between the trait pairs DFL×DFR, GPW×GPL, and GW×GGT were higher than the phenotypic and environmental correlations. Genotypes CE-228, CE-688, CE-994, CE-165, CE-796, and BRS-Paraguaçu showed simultaneous superiority for the evaluated traits and are the most appropriate for green grain production.

Seleção de genótipos de feijão-caupi para caracteres nutricionais

ABSTRACT Cowpea is a worldwide consumed legume due to its high nutrient concentrations. Selecting genotypes with high nutrient concentrations can contribute to developing biofortified cultivars. This study aimed to evaluate the nutritional potential and indicate genotypes of Vigna unguiculata for genetic improvement based on nutritional traits. Forty-three cowpea genotypes belonging to the Active Germplasm Bank of the Federal University of Ceará were used in the study. The analyses of dry matter, ash, ether extract, proteins, and minerals (phosphorus, potassium, calcium, magnesium, sulfur, sodium, copper, iron, zinc, manganese, and boron) were performed in triplicate. The data were subjected to analysis of variance, means comparison test, genetic parameters, nutritional quality indexes, and the sum of ranks. Genetic variances predominated concerning environmental variation for the nutrient concentrations of cowpea can be transmitted to future generations. The CE-0151, CE-0189, CE-0207, CE-0228, CE-0248, CE-0542, CE-0685, CE-0686, CE-0796, CE-0997, and CE-1002 genotypes are indicated for selection for continuing the biofortified cowpea breeding program.

Transcriptome Analysis of Differentially Expressed Genes Associated with Salt Stress in Cowpea (Vigna unguiculata L.) during the Early Vegetative Stage.

Cowpea (Vigna unguiculata (L.), 2n = 22) is a tropical crop grown in arid and semiarid regions that is tolerant to abiotic stresses such as heat and drought. However, in these regions, salt in the soil is generally not eluted by rainwater, leading to salt stress for a variety of plant species. This study was conducted to identify genes related to salt stress using the comparative transcriptome analysis of cowpea germplasms with contrasting salt tolerance. Using the Illumina Novaseq 6000 platform, 1.1 billion high-quality short reads, with a total length of over 98.6 billion bp, were obtained from four cowpea germplasms. Of the differentially expressed genes identified for each salt tolerance type following RNA sequencing, 27 were shown to exhibit significant expression levels. These candidate genes were subsequently narrowed down using reference-sequencing analysis, and two salt stress-related genes (Vigun_02G076100 and Vigun_08G125100) with single-nucleotide polymorphism (SNP) variation were selected. Of the five SNPs identified in Vigun_02G076100, one that caused significant amino acid variation was identified, while all nucleotide variations in Vigun_08G125100 was classified as missing in the salt-resistant germplasms. The candidate genes and their variation, identified in this study provide, useful information for the development of molecular markers for cowpea breeding programs.

Genetic Diversity and Population Structure of Cowpea (Vigna unguiculata (L.) Walp.) Landraces from Portugal and Mozambique.

Cowpea (Vigna unguiculata (L.) Walp.) is currently a legume crop of minor importance in Europe but a highly relevant staple crop in Africa and the second most cultivated legume in Mozambique. In Portugal and Mozambique, cowpea's phenotypic and genetic variation has been maintained locally by farmers in some areas. We used the molecular markers SSR, SilicoDArT and SNP to analyze the genetic diversity and population structure of 97 cowpea accessions, mainly from Portugal (Southern Europe) and Mozambique (Southern Africa). As far as we know, this is the first time that the genetic variation and the relationship between cowpea landraces collected in Portugal with those originated in Mozambique is reported. Despite the shared historical past, the Portuguese landraces did not share a common genetic background with those from Mozambique, and two different gene pools were revealed. Knowledge of the genetic structure of cowpea landraces offers an opportunity for individual selection within landraces adapted to particular eco-physiological conditions and suggests the existence of a valuable gene pool for exploitation in future Portugal-PALOP (Portuguese-speaking African countries) cowpea breeding programs.

Seleção de linhagens superiores de feijão-caupi derivadas de cultivares locais para a região semiárida brasileira

Abstract The objective of this work was to select superior cowpea lines derived from local cultivars for the semiarid region of southeastern Piauí, Brazil. A total of 38 genotypes (36 lines and two commercial cultivars) were evaluated in a randomized complete block design, with two replicates, in the municipality of Ipiranga do Piauí, in the state of Piauí. The following traits were evaluated: number of days to the onset of flowering, pod length, number of grains per pod, weight of 100 grains, commercial grain quality, and grain yield. Deviance analyzes were performed using the restricted maximum likelihood and best unbiased predictor approach, the parameters and genetic values were estimated, and simultaneous selection was carried out via the sum of ranks index. The likelihood ratio test showed a significant difference between the evaluated genotypes. Lines 36, 5, 24, 8, 2, 23, 29, 28, 34, 6, 19, 11, 7, and 20 are superior for the set of evaluated traits and, therefore, are the most promising to compose the advanced trial of the cowpea breeding program and to generate cultivars for family farmers in the semiarid region of southeastern Piauí.

Phenotypic Diversity of Cowpea (Vigna unguiculata L. Walp) Based on Shorter Cooking Time and Canning Quality Traits

Cowpea is a leguminous crop rich in protein. Despite its nutritional quality, the crop is underutilized due to its prolonged cooking time requiring energy to make it palatable. This study investigated the adaptation capacity, cooking time and canning quality of a panel of 94 accessions of cowpea obtained from the International Institute of Tropical Agriculture IITA, Ibadan and Rumukoro Market Port Harcourt Nigeria. Seeds were planted at the Department of Crop and Soil Science Research Farm and Allu Town, University of Port Harcourt, Nigeria. The experimental design was randomized complete block design (RCBD) in three replicates for three seasons (early wet, late wet and dry season). Agronomic Parameters such as plant height, number of leaves, number of branches, leave length, leave width, and the flowering date was collected at two weekly intervals after weeks of planting. The cooking evaluation was carried out using a digital cooker (Tower Product), while canning quality was evaluated using a cost-effective sealer. Results obtained showed that cowpea adapted to the three seasons with optimal performance observed in the late wet season. The cooking results showed that TVU-2, TVU-8, TVU-9, TVU-13, TVU, 21, TVU29, TVU-36, TUV-38, iron white, akara bean, iron brown and honey bean had short cooking time while TVU-2, TVU-13, TVU-26, TVU-37, TVU-38, TVU-45, TVU-50 and TVU-51 had good canning quality. It is recommended that the selected accessions for better agronomic and culinary quality traits can be used for cowpea breeding programmes.

Breeding implications of nodulation performance and root structure under natural inoculation for soil fertility enhancement and sustainable cowpea production

Nitrogen deficiency is the most limiting abiotic stress factor affecting the grain yield of cowpea (Vigna unguiculata L.) in sub-Saharan Africa (SSA) countries. Breeding for high-yielding potential in association with high nitrogen fixation performance is the principal objective of cowpea breeding programs to improve both the productivity and production of this orphan crop in the region. Therefore, the present study was undertaken to determine the diversity of genotypes for nodulation capacity in two environments and to understand the root architecture and morphology of genotypes as well as grain yield and yield-related traits in 324 cowpea genotypes. The experiment was conducted in two different environments during the 2017 cropping season. The experiments were laid out in 18 × 18 simple lattice design. Grain yield exhibited highly significant and positive genotypic correlations with stem diameter, basal root length of 1st whorls, basal root branching density, taproot length and adventitious root length, demonstrating that selection of cowpea genotypes based on these traits could be effective to capitalize on grain yield under low nitrogen conditions. Days to flowering, days to maturity, stem diameter, 1st whorl angle, basal root length of 1st whorls, basal root branching density, taproot length, adventitious root diameter and adventitious root length had significant and positive genotypic correlations with days to maturity. The first ten principal components (PC) explained 65.13% of the total variation. Stem diameter, taproot width, and taproot length traits were important contributors to the variability in the first PC. The highest inter-cluster distance (D2) was recorded between clusters III and IV. However, clusters II and V recorded the minimum inter-cluster distance (78.96 units). The range of intra-cluster distance was 24.22–5,112.92 units, indicating that the high genetic distance displayed within and between clusters has to be exploited via crossing and selecting the most divergent parents for future cowpea improvement. Five clusters of cowpea genotypes were evident, and within the clusters, the genotypes had good nodulation potential with high grain yield traits, which could significantly contribute to SSA food and nutritional security. Moreover, it can contribute to resilience and improve crop production and sustainability under marginal environmental conditions.