Quantitative trait loci influencing days to flowering and plant height in cowpea, Vigna unguiculata (L.) Walp.

Cowpea (Vigna unguiculate (L.) Walp.) is a worldwide important multifunctional legume crop for food grain, vegetable, fodder, and cover crop. Nevertheless, only limited research has been conducted on agronomic traits. Here, we report quantitative trait locus (QTL) analysis of the days to flowering (DTF) and plant height (PH) using a dense SNP linkage map recently developed from a recombinant inbred line (RIL) population derived from a cross between Golden Eye Cream and IT98K-476-8. The population was phenotyped for DTF and PH through field and greenhouse trials under two environments. The QTLs controlling these traits were mapped using multiple-environment combined and individual trial phenotypic data. The combined data analysis identified one major QTL (qDTF9.1) for DTF, and one major QTL (qPH9.1) and a minor QTL (qPH4.1) for PH. qDTF9.1 and qPH9.1 were adjacent to each other on Chromosome 9 and each explained 29.3% and 29.5% of the phenotypic variation (PVE), respectively. The individual trial data analysis identified a minor QTL (qDTF2.1) on Chromosome 2 for DTF and two minor QTLs (qPH4.1 and qPH4.2) on Chromosome 4 for PH, while the major QTLs, qDTF9.1 and qPH9.1, were consistently identified in all trials conducted. Epistasis analysis revealed that qDTF9.1 interacted with one locus on Chromosome 4, contributed 50% of the PVE, and qPH9.1 interacted with one locus on each of Chromosomes 4 and 6, contributing 30% and 23% of the PVE, respectively, suggesting that epistasis plays an important role in the trait performance. These results, therefore, provide a deeper understanding of the genetic architecture of plant DTF and PH, and molecular tools necessary for cloning the genes and for enhanced cowpea breeding.

Genetic Variability, Heritability, and Clustering Pattern Exploration of Bambara Groundnut (Vigna subterranea L. Verdc) Accessions for the Perfection of Yield and Yield-Related Traits.

Bambara groundnut (Vigna subterranea L. Verdc.) is considered an emerging crop for the future and known as a crop for the new millennium. The core intention of this research work was to estimate the variation of landraces of Bambara groundnut considering their 14 qualitative and 27 numerical traits, to discover the best genotype fitted in Malaysia. The findings of the ANOVA observed a highly significant variation (p ≤ 0.01) for all the traits evaluated. There was a substantial variation (7.27 to 41.21%) coefficient value, and 14 out of the 27 numerical traits noted coefficient of variation (CV) ≥ 20%. Yield (kg/ha) disclosed positively strong to perfect high significant correlation (r = 0.75 to 1.00; p ≤ 0.001) with traits like fresh pod weight, dry pod weight, and dry seed weight. The topmost PCV and GCV values were estimated for biomass dry (41.09%) and fresh (40.53%) weight with high heritability (Hb) and genetic advance (GA) Hb = 95.19%, GA = 80.57% and Hb = 98.52%, GA = 82.86%, respectively. The topmost heritability was recorded for fresh pod weight (99.89%) followed by yield (99.75%) with genetic advance 67.95% and 62.03%, respectively. The traits with Hb ≥ 60% and GA ≥ 20% suggested the least influenced by the environment as well as governed by the additive genes and direct selection for improvement of such traits can be beneficial. To estimate the genetic variability among accessions, the valuation of variance components, coefficients of variation, heritability, and genetic advance were calculated. To authenticate the genetic inequality, an unweighted pair group produced with arithmetic mean (UPGMA) and principal component analysis was executed based on their measurable traits that could be a steadfast method for judging the degree of diversity. Based on the UPGMA cluster analysis, constructed five distinct clusters and 44 accessions from clusters II and IV consider an elite type of genotypes that produce more than one ton yield per hectare land with desirable traits. This study exposed an extensive disparity among the landraces and the evidence on genetic relatives will be imperative in using the existing germplasm for Bambara groundnut varietal improvement. Moreover, this finding will be beneficial for breeders to choose the desirable numerical traits of V. subterranea in their future breeding program.

Love on wings, a Dof family protein regulates floral vasculature in Vigna radiata.

BACKGROUND: The interaction among plants and their pollinators has been a major factor which enriched floral traits known as pollination syndromes and promoted the diversification of flowering plants. One of the bee-pollination syndromes in Faboideae with keel blossoms is the formation of a landing platform by wing and keel petals. However, the molecular mechanisms of elaborating a keel blossom remain unclear. RESULTS: By performing large scale mutagenesis, we isolated and characterized a mutant in Vigna radiata, love on wings (low), which shows developmental defects in petal asymmetry and vasculature, leading to a failure in landing platform formation. We cloned the locus through map-based cloning together with RNA-sequencing (RNA-seq) analysis. We found that LOW encoded a nucleus-localized Dof-like protein and was expressed in the flower provascular and vascular tissues. A single copy of LOW was detected in legumes, in contrast with other taxa where there seems to be at least 2 copies. Thirty one Dof proteins have been identified from the V. radiata's genome, which can be further divided into four Major Cluster of Orthologous Groups (MCOGs). We also showed that ectopic expression of LOW in Arabidopsis driven by its native promoter caused changes in petal vasculature pattern. CONCLUSIONS: To summarize, our study isolated a legume Dof-like factor LOW from V. radiata, which affects vasculature development in this species and this change can, in turn, impact petal development and overall morphology of keel blossom.

Symbiotic effectiveness and ecologically adaptive traits of native rhizobial symbionts of Bambara groundnut (Vigna subterranea L. Verdc.) in Africa and their relationship with phylogeny.

Bambara groundnut (Vigna subterranea L. Verdc.) is an indigenous, drought-tolerant, underutilized African food legume, with the ability to fix atmospheric N2 in symbiosis with soil bacteria called rhizobia. The aim of this study was to assess the morpho-physiological, symbiotic and phylogenetic characteristics of rhizobia nodulating Bambara groundnut in Ghana, Mali and South Africa. The morpho-physiologically diverse isolates tested were also found to exhibit differences in functional efficiency and phylogenetic positions. Based on Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR banding patterns, the isolates were grouped into eight major clusters. The concentrations of Ca, Na and K in soils had a significant (p ≤ 0.01) effect on the distribution of rhizobia. Though many isolates were symbiotically very effective, the effectiveness index varied markedly (p ≤ 0.05) among them. Moreover, the isolates also exhibited tolerance to a wide range of NaCl (0.5-7%), streptomycin (50-500 µg.ml-1), and kanamycin (25-150 µg.ml-1) concentrations. Additionally, these isolates could produce 0.02 to 69.71 µg.ml-1 of indole-3-acetic acid (IAA) in tryptophan-supplemented medium, as well as solubilize tri-calcium phosphate. Phylogenetic analysis of these rhizobial isolates using 16S rRNA, atpD, glnII, gyrB, recA and symbiotic (nifH and nodC) gene sequences revealed distinct and novel evolutionary lineages related to the genus Bradyrhizobium, with some of them being very close to Bradyrhizobium vignae, B. kavangense, B. subterraneum, B. elkanii and B. pachyrhizi.

Morpho-physiological characteristics of Vigna unguiculata [L.] Walp grown in a controlled environment using effluents from a beverage bottling company.

The use of industrial effluents for agricultural practices due to waste management properties, water scarcity, or cultural belief affects both the physiology and morphology of cultivated crops. This study reports the investigation of the agro-potentiality of the effluents from a beverage bottling company on cowpea (Vigna unguiculata) under a controlled environment. This greenhouse experiment was carried out within Obafemi Awolowo University. The effluents were applied at 0, 10, 20, 30, 40, and 50% concentrations using untreated (A) and treated (B) effluents separately in two groups. Physicochemical properties of the effluents were determined using standard methods. Exchangeable cations present in the effluents were investigated via the ammonium acetate exchange way. Morphological and yield parameters were measured in ten replicates. Transverse sections of the leaf, petiole, and stem were also investigated under a light microscopy. General linear model was used for statistical analysis with means compared using Tukey's HSD test at p < 0.05. The effluents had pH, electrical conductivity, and total dissolved solids in the range of 7.4-7.5, 599.0-693.0 µS/cm, and 395.0-455.0 mg/l, respectively. The exchangeable calcium and potassium concentrations in the effluents range 1067.00-1937.50 and 190.0-343.50 mg/l. Application of effluent A had no significant effect on number of pods per group, seeds per pod, leaf length, leaf width, and leaf area of cowpea (p > 0.05). There was a significant effect of effluent A on the number of leaves and shoot height (p < 0.05). The application of effluent B had a significant effect on the mean number of leaves and seeds per pod at higher (40-50%) concentrations (p < 0.05). Amendment with effluent B showed no significant effect on the mean shoot height, leaf length, width and area, pods per group, pod length, and girth size (p > 0.05). The frequency of guard cells was observed to decrease with increasing effluents (A and B) concentration on the abaxial epidermis. Likewise, a "black deposit" was observed in the vessels in the stem taken from group amended with effluent A at high concentrations (30-50%). No anatomical differences were observed in the petiole and leaf transverse sections of the control and amended subgroups. The untreated and treated effluents showed agro-potentiality. However, crops grown need to be monitored for the health impacts on man and animal, as risk of crop cellular disruption exist.

Retrieved 16S rRNA and nifH sequences reveal co-dominance of Bradyrhizobium and Ensifer (Sinorhizobium) strains in field-collected root nodules of the promiscuous host Vigna radiata (L.) R. Wilczek.

In the present study, the relative distribution of endophytic rhizobia in field-collected root nodules of the promiscuous host mung bean was investigated by sequencing of 16S ribosomal RNA (rRNA) and nifH genes, amplified directly from the nodule DNA. Co-dominance of the genera Bradyrhizobium and Ensifer was indicated by 32.05 and 35.84% of the total retrieved 16S rRNA sequences, respectively, and the sequences of genera Mesorhizobium and Rhizobium comprised only 0.06 and 2.06% of the recovered sequences, respectively. Sequences amplified from rhizosphere soil DNA indicated that only a minor fraction originated from Bradyrhizobium and Ensifer strains, comprising about 0.46 and 0.67% of the total retrieved sequences, respectively. 16S rRNA gene sequencing has also identified the presence of several non-rhizobial endophytes from phyla Proteobacteria, Actinobacteria, Bacteroides, and Firmicutes. The nifH sequences obtained from nodules also confirmed the co-dominance of Bradyrhizobium (39.21%) and Ensifer (59.23%) strains. The nifH sequences of the genus Rhizobium were absent, and those of genus Mesorhizobium comprised only a minor fraction of the sequences recovered from the nodules and rhizosphere soil samples. Two bacterial isolates, identified by 16S rRNA gene sequence analysis as Bradyrhizobium strain Vr51 and Ensifer strain Vr38, successfully nodulated the original host (mung bean) plants. Co-dominance of Bradyrhizobium and Ensifer strains in the nodules of mung bean indicates the potential role of the host plant in selecting specific endophytic rhizobial populations. Furthermore, successful nodulation of mung bean by the isolates showed that strains of both the genera Bradyrhizobium and Ensifer can be used for production of inoculum.

Aflatoxins, discolouration and insect damage in dried cowpea and pigeon pea in Malawi and the effectiveness of flotation/washing operation in eliminating the aflatoxins.

Aflatoxin contamination and biodeterioration were examined in 302 samples of dry cowpeas and pigeon peas that were randomly purchased from 9 districts of the Southern Region of Malawi during July and November 2015. Further, the impact of flotation/washing on aflatoxin levels on the pulses was elucidated. Aflatoxin analyses involved immunoaffinity column (IAC) clean-up and HPLC quantification with fluorescence detection (FLD) while legume biodeterioration assessments were done by visual inspection. Aflatoxins were frequently detected in cowpea (24%, max., 66 µg/kg) and pigeon pea (22%, max., 80 µg/kg) samples that were collected in the month of July. Lower aflatoxin incidence of 15% in cowpeas (max., 470 µg/kg) and 14% in pigeon peas (max., 377 µg/kg) was recorded in the November collection. Overall, aflatoxin levels were significantly higher in the pulses that were collected in November. However, there were no significant differences in the total aflatoxin (aflatoxin B1 (AFB1) + AFB2 + AFG1 + AFG2) levels between the two types of pulses. Remarkably, in 76.2% of the aflatoxin positive cowpea and in 41.7% of the aflatoxin positive pigeon pea samples, aflatoxin G1 concentration exceeded aflatoxin B1. Insect damage percentage averaged at 18.1 ± 18.2% (mean ± SD) in the cowpeas and 16.1 ± 19.4% in pigeon peas. Mean discolouration percentage (number of pulses) of the cowpeas and pigeon peas was found to be at 6.7 ± 4.9 and 8.7 ± 6.2%, respectively. Washing and discarding the buoyant fraction was highly efficient in reducing aflatoxin levels; only 5.2 ± 11.1% of the initial aflatoxin level was found in the cleaned samples. In conclusion, cowpeas and pigeon peas sold on the local market in Malawi may constitute a hazard especially if floatation/washing step is skipped.

Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth.

Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma.

Descrição de cultivares locais de feijão-caupi coletados na microrregião Cruzeiro do Sul, Acre, Brasil / Description of local cowpea cultivars from the microregion of Cruzeiro do Sul, Acre, Brazil

Local varieties of cowpea beans (Vigna unguiculata) are exposed to genetic erosion due to the introduction of commercial seeds. The aim of this study was to describe local germplasm of cowpea beans from Resex Alto Juruل and microrregion of Cruzeiro do Sul, Acre, Brazil. Two experiments were conducted either using the conventional agricultural system (in 2011), or in an alley cropping system (in 2012). The experimental was a randomized block design with nine treatments (cultivars) and three replicates per treatment. The plots were 12 m2 in size and rows were 0.45 m apart. Twenty qualitative and 21 quantitative characters were observed. The combined analysis of variance showed significant effects for genotype, agricultural system and for the interaction genotype/agricultural system. The qualitative trait with greater variation among genotypes were the commercial subclass according to the classification adopted by the Brazilian Ministry of Agriculture, followed by grain color, immature pod pigmentation, apical leaflet shape, leaf color and pod curvature. The plant habit, twinning tendency, pod attachment to peduncle and the pod wall thickness did not show differences. Among the quantitative traits, days to flowering and number of locules per pod did not differ between cultivars. Mean values for pod length, peduncle length, number of pods per peduncle and number of pods per plant were low. However, the germplasm collected showed good agronomic traits such as earliness, appropriate plant architecture, and adaptation to floodplain cultivation.

A distribuição de sementes comerciais ameaça erodir o germoplasma local em regiões tradicionais de plantio de feijões-caupi (Vigna unguiculata). O objetivo deste trabalho foi descrever as cultivares locais de feijão-caupi da Resex Alto Juruá e da microrregião Cruzeiro do Sul - AC. Foram conduzidos dois experimentos nos anos de 2011 e 2012, em sistema convencional e, em sistema de plantio em aleias, respectivamente. O delineamento experimental adotado nos experimentos foi de blocos ao acaso com nove tratamentos (cultivares), três repetições por tratamento, parcelas de 12 m2 e espaçamento de 0,45 m entre plantas e linhas. Foram observados vinte caracteres qualitativos e 21 quantitativos. A análise de variância conjunta dos experimentos apresentou significativo para genótipo, sistema de plantio e interação genótipo/sistema de plantio. A característica qualitativa com maior variação entre os genótipos foi subclasse comercial, seguida da cor do grão, pigmentação da vagem imatura, forma do folíolo apical, cor das folhas e curvatura da vagem. O hábito da planta, tendência a enrolar-se ao tutor, fixação da vagem ao pedúnculo e espessura de parede da vagem não apresentam diferenças. Dos caracteres quantitativos apenas número de dias até 50% das plantas em florescimento e número de lóculos/vagem não diferiram estatisticamente entre cultivares. Os valores médios para comprimento de vagem, comprimento do pedúnculo, número de vagens por pedúnculo e número de vagens por planta foram baixos, entretanto, o germoplasma coletado apresentou características valorizadas como ciclo precoce, arquitetura adequada da planta além da adaptação ao plantio em várzeas.