Genome-Wide Association Study Revealed SNP Alleles Associated with Seed Size Traits in African Yam Bean (Sphenostylis stenocarpa (Hochst ex. A. Rich.) Harms).

Seed size is an important yield and quality-determining trait in higher plants and is also crucial to their evolutionary fitness. In African yam bean (AYB), seed size varies widely among different accessions. However, the genetic basis of such variation has not been adequately documented. A genome-wide marker-trait association study was conducted to identify genomic regions associated with four seed size traits (seed length, seed width, seed thickness, and 100-seed weight) in a panel of 195 AYB accessions. A total of 5416 SNP markers were generated from the diversity array technology sequence (DArTseq) genotype-by-sequencing (GBS)- approach, in which 2491 SNPs were retained after SNP quality control and used for marker-trait association analysis. Significant phenotypic variation was observed for the traits. Broad-sense heritability ranged from 50.0% (seed width) to 66.4% (seed length). The relationships among the traits were positive and significant. Genome-wide association study (GWAS) using the general linear model (GLM) and the mixed linear model (MLM) approaches identified 12 SNP markers significantly associated with seed size traits across the six test environments. The 12 makers explained 6.5-10.8% of the phenotypic variation. Two markers (29420334|F|0-52:C>G-52:C>G and 29420736|F|0-57:G>T-57:G>T) with pleiotropic effects associated with seed width and seed thickness were found. A candidate gene search identified five significant markers (100026424|F|0-37:C>T-37:C>T, 100041049|F|0-42:G>C-42:G>C, 100034480|F|0-31:C>A-31:C>A, 29420365|F|0-55:C>G-55:C>G, and 29420736|F|0-57:G>T-57:G>T) located close to 43 putative genes whose encoding protein products are known to regulate seed size traits. This study revealed significant makers not previously reported for seed size in AYB and could provide useful information for genomic-assisted breeding in AYB.

The first report of bean common mosaic virus (BCMV) infection of African yam bean (Sphenostylis stenocarpa) in Nigeria.

BACKGROUND: African yam bean (Sphenostylis stenocarpa) is an underutilized crop that has the potential to contribute to sustainable food security. In October 2021, more than 90% African Yam Bean (AYB) plants showed typical virus symptoms of mosaic and necrosis in the grain legumes field of the Institute of Agricultural Research and Training (IAR&T), Nigeria. METHODS AND RESULTS: Subsequently, leaf samples were collected and tested by ELISA and PCR to identify the virus species. Anti-BCMV and anti-potyvirus antibodies both gave positive results when symptomatic leaves were tested, and PCR using primers designed to the coat protein gene of BCMV amplified a band of the expected size (469 bp). The sequence of the PCR product was deposited in GenBank with the accession No. OL763314. The nucleotide sequence of the coat protein gene had 99% identity with BCMV isolate TN2 (KY044818). The identities of the nucleotide and amino acid sequence of the partial CP gene of the isolated virus relative to those of other potyviruses were 82.96-99.12% and 87.33-100%,, respectively. Phylogenetic analyses of the partial CP-nucleotide sequences grouped the isolate from this study (BCMV-IART-AYB) and BCMV-TN2 in the same cluster with other BCMV strains of the peanut stripe (PSt) and the blackeye cowpea (BlC) strains. CONCLUSIONS: In this study, we identified Bean commom mosaic virus (BCMV) infecting AYB for the first time in Nigeria and show that it has high nucleotide and amino acid identity with an Isolate of cowpea-infecting BCMV in India and China respectively than isolate in Nigeria.

Genetic diversity and population structure of an African yam bean (Sphenostylis stenocarpa) collection from IITA GenBank.

African yam bean, AYB (Sphenostylis stenocarpa), is an underutilized legume of tropical Africa. AYB can boost food and nutritional security in sub-Saharan Africa through its nutrient-rich seeds and tubers. However, inadequate information on germplasm with desirable agro-morphological traits, including insufficient data at the genomic level, has prevented the full exploitation of its food and breeding potentials. Notably, assessing the genetic diversity and population structure in a species is a prerequisite for improvement and eventual successful exploitation. The present study evaluated the population structure and genetic diversity of 169 accessions from the International Institute of Tropical Agriculture (IITA) collection using 26 phenotypic characters and 1789 single nucleotide polymorphism (SNP) markers. The phenotypic traits and SNP markers revealed their usefulness in uniquely distinguishing each AYB accession. The hierarchical cluster of phenotypes grouped accessions into three sub-populations; SNPs analysis also clustered the accessions into three sub-populations. The genetic differentiation (FST) among the three sub-populations was sufficiently high (0.14-0.39) and significant at P = 0.001. The combined analysis revealed three sub-populations; accessions in sub-population 1 were high yielding, members in sub-population 2 showed high polymorphic loci and heterozygosity. This study provides essential information for the breeding and genetic improvement of AYB.

Predictive genotype-phenotype relations using genetic diversity in African yam bean (Sphenostylis stenocarpa (Hochst. ex. A. Rich) Harms).

BACKGROUND: African Yam Bean (AYB) is an understudied and underutilized tuberous legume of tropical West and Central African origin. In these geographical regions, both seeds and tubers of AYB are important components of people's diets and a potential target as a nutritional security crop. The understanding of the genetic diversity among AYB accessions is thus an important component for both conservation and potential breeding programs. RESULTS: In this study, 93 AYB accessions were obtained from the International Institute of Tropical Agriculture (IITA) genebank and genotyped using 3722 SNP markers based on Restriction site-Associated DNA sequencing (RAD-Seq). Genetic data was analysed using multiple clustering methods for better understanding the distribution of genetic diversity across the population. Substantial genetic variability was observed in the present set of AYB accessions and different methodologies demonstrated that these accessions are divided into three to four main groups. The accessions were also analysed for important agronomic traits and successfully associated with their genetic clusters where great majority of accessions shared a similar phenotype. CONCLUSIONS: To our knowledge, this is the first study on predicting genotypic-phenotypic diversity relationship analysis in AYB. From a breeding perspective, we were able to identify specific diverse groups with precise phenotype such as seed or both seed and tuber yield purpose accessions. These results provide novel and important insights to support the utilization of this germplasm in AYB breeding programs.

Sphenostylis stenocarpa Seed Extract Attenuates Dyslipidemia in Testosterone Propionate-induced Benign Prostatic Hyperplasia in Rats.

BACKGROUND AND OBJECTIVE: Benign Prostatic Hyperplasia (BPH) is a prevalent disease among older men caused by abnormal proliferation of the prostatic cells. Findings indicate an association between dyslipidemia and BPH. This study aimed at evaluating the effect of ethanol extract of Sphenostylis stenocarpa seed on the lipid profile of rats with testosterone propionate-induced BPH. MATERIALS AND METHODS: A total of 25 male Wistar rats randomized into five groups of five rats each were used. BPH was induced in the rats by subcutaneous injection of testosterone propionate in olive oil for 28 days. The test rats (after BPH induction) were treated with ethanol extract of the plant seed at doses of 200 and 400 mg kg-1 b.wt. The concentrations of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triacylglycerol were evaluated on the sera of the rats. RESULTS: The BPH control rats (model group) showed a significant (p<0.05) increase in concentrations of total cholesterol, LDL-C, triacylglycerol, with a significant decrease in HDL-C compared to the normal control. Oral administration of the seed extract to the rats significantly reversed these dyslipidemia indicators when compared to the model group. CONCLUSION: This study has shown that ethanol extract of S. stenocarpa seed ameliorated dyslipidemia in testosterone propionate-induced BPH in rats. This suggests that the plant seed may be useful in the prevention of cardiovascular disease.

Influence of extrusion cooking on physicochemical properties and starch digestion kinetics of Sphenostylis stenocarpa, Cajanus cajan, and Vigna subterranean grains.

Thermal degradation of sugars and amino acids, and depolymerization of macromolecules such as starch, proteins and fibre occasioned by high-temperature short-time extrusion cooking modify the physicochemical and functional properties of raw materials. High-temperature short-time extrusion cooking holds promise for the expanded use of non-conventional ingredients as food/feed due to its practicality, increased productivity and efficiency, and ability to retain thermally degradable nutrients during cooking. However, little is known about the effect of the high-temperature short-time extrusion cooking process on the physicochemical properties and starch digestibility of lesser-known grain legumes such as African yam beans (Sphenostylis stenocarpa), Pigeon pea (Cajanus cajan), and Bambara peanut (Vigna subterranean). In this study, we investigate the effect of high-temperature short-time extrusion cooking and extrusion cooking temperature; low (100°C) vs high (140°C) temperatures in a single screw extruder, on hydration characteristics, viscoamylolytic properties, in vitro starch digestibility and digestion kinetics of these grain legumes. We show that water holding capacity and swelling power increased (p < 0.05) with increasing extrusion temperature for Sphenostylis stenocarpa and Vigna subterranean but not Cajanus cajan extrudates. Significant effects of extrusion cooking (i.e unextruded vs 100°C and unextruded vs 140°C) and extrusion temperatures (i.e. 100°C vs 140°C) were observed in peak, trough, final and setback viscosities of all extrudates. Starch digestibility and digestion characteristics were modified with increase in extrusion temperature, however, no effect of extrusion temperatures (i.e. 100°C vs 140°C) on starch digestion kinetics was observed for Sphenostylis stenocarpa and Vigna subterranean except for hydrolysis index (34.77 vs 40.77%). Nutritional and physiological implications of extruded grain legumes in monogastric animal feeding were also highlighted. The Information presented herein will influence expanded use of extruded grain legumes as feed ingredients for intensive monogastric animal feeding.

Evaluation of fermented African yam bean flour composition and influence of substitution levels on properties of wheat bread.

The composition (proximate, amino acids, in vitro protein digestibility [IVPD]), antinutritional factors (ANFs), functional properties, and antioxidant activity of fermented African yam bean flour (FAYBF) were determined in this study, and the effect of substituting FAYBF on the properties (nutritional, physical, and functional) of bread was investigated. Fermentation significantly (P ≤ 0.05) increased the levels of nutrients, IVPD, total phenolic content (TPC), and antioxidant activity in the flour, with significant (P ≤ 0.05) reduction in ANFs. The water absorption capacity (WAC) and oil absorption capacity (OAC), and swelling capacity of the flour increased after fermentation, while bulk density decreased. Substitution of wheat flour with FAYBF increased WAC and OAC, while peak viscosity decreased. Composite breads had higher nutritional, IVPD, TPC, and antioxidant activity than 100% wheat bread. The study demonstrates that FAYBF could be explored for the preparation of wheat-based bread, with reduced gluten levels. PRACTICAL APPLICATION: Bread is a staple food and this study can assist in increasing the utilization of neglected leguminous crops as well as addressing the challenge of malnutrition, prevalent in developing countries.

Selecting Yield and Nutritional Traits in Sphenostylis stenocarpa Landraces for Food Improvement.

BACKGROUND: Sphenostylis stenocarpa is an underexploited African indigenous food crop that is enriched in nutritional quality. OBJECTIVE: Exploring the robust genetic base of this landrace can help to maximize the benefit of the agricultural sector on the economy through production that is enhanced by packaging and patent. This as well will increase the quality of food production and promote African campaign on food sustainability. METHODS: Upon this, this research made use of multiple statistics to identify S. stenocarpa yield and nutritional trait relatedness that supported selection for maximum yield and nutritional trait output. Yield and related traits including protein and oil contents of twenty-three Sphenostylis stenocarpa landraces were studied under a four year planting seasons in Teaching and Research farm of Landmark University, Nigeria. RESULTS: Trait variances from Landrace × Year (L × Y) interaction, Principal Component and Cluster analyses were evaluated and the variation patterns were identified. Some vegetative (maturity phase, height and branching) and yield traits (Pod traits, seed yield and oil content) correlated significantly (P < 0.05) in the L × Y interactions. This suggests the usefulness of these traits in improving S. stenocarpa grain and oil quality yield. Tuber and nodule yield including protein content did not differ significantly in the variance table. CONCLUSION: The result indicates that one location trial is insufficient to determine such trait performance. The first four PCs that accounted for 51 percent of the total variations were traceable to branching, maturity date, pod numbers, seed and oil content as main contributors to yield.

Morphological, structural and functional properties of starch granules extracted from the tubers and seeds of Sphenostylis stenocarpa.

Sphenostylis stenocarpa (Hochst. ex A. Rich.) Harms, is a legume widely recognized in Africa for its edible starchy tuber and seeds. In the present morphological, structural and functional properties of starch extracted from the tubers and seeds of a same accession of this plant were characterized and compared. With smaller and more angular granules, tuber starch displayed higher resistance toward amylolysis and gelatinization than seed starch. The amylolysis of seed starch resulted in fragmented granules with typical layered structures of growth rings. During their hydrothermal treatments, both tuber and seed starches showed condensed ghosts even at 95°C. This high resistance toward hydrothermal degradation was considered as the basis of the typical pasting properties of these two materials. Both seed and tuber starch exhibited A-type crystalline pattern. Under non-oxidative combustion tuber starch presented a degradation peak at 310°C while seed starch was degraded around 302°C.

Structural and physicochemical characterization of Sphenostylis stenocarpa (Hochst. ex A. Rich.) Harms tuber starch.

Several characteristics of African Yam Bean tuber starch (AYB) were studied and compared with that of a well-known native potato starch (P). The diameter of AYB granules ranged from 5.7µ to 49µ with a median at 19.5µ. During its pasting, AYB exhibited a low peak of viscosity in accordance with its low granules swelling and disintegration capacity. The gelatinization temperature of AYB was 75.2°C while that of P was 60.4°C. AYB was observed to be more stable during thermo-gravimetrical Analysis. Its degradation peak was observed at 308°C while that of P was 303°C. The X-ray diffraction analysis revealed that AYB belongs to the A-type crystalline group instead of C-type as claimed for several legumes starches. The stability of AYB and its capacity to structure starch-water systems make this resource an interesting ingredient for new food and non-food products.

Formulation and Evaluation of Oral Dissolving Films of Amlodipine Besylate Using Blends of Starches With Hydroxypropyl Methyl Cellulose.

BACKGROUND: Natural polymers serve as cheap, non-toxic, biocompatible excipients in oral drug delivery. These advantages inform their uses in the design of drug dosage forms. OBJECTIVES: The aim of the study was to prepare and evaluate oral dissolving films of amlodipine besylate, an anti-hypertensive drug, using starch/polymer blends. MATERIAL AND METHODS: Bambara nut (BAM) and the African yam bean (AYB) starches were individually blended with hydroxypropyl methyl cellulose (HPMC). The material and rheological properties of the blends were determined. Amlodipine besylate was incorporated by dispersion and films were prepared by solvent evaporation method and evaluated for mechanical and drug release properties. RESULTS: The BAM/HPMC blends had higher viscosity values than the corresponding AYB/HPMC blends. All the blends gave a Hausner ratio above 1.25 and Carr's index above 22. Blends of ratio 1 : 1 and 2 : 1 produced good films and were subsequently evaluated. All films disintegrated within 15 mins but had poor folding endurance. BAM/HPMC (1 : 1) and AYB/ /HPMC (2 : 1) released all of the drug content within 30 min. The ranking for dissolution profile was AYB/HPMC (2 :1 ) > BAM/ /HPMC (1 :1 ) > BAM/HPMC (2 : 1) > AYB/HPMC (1 : 1). The type and ratio of starch in the blend influenced the drug release pattern of the films. CONCLUSIONS: Starch/HPMC blend ratios of 1 : 1 and 2 : 1 were found suitable for the formulation of oral dissolving film of amlodipine besylate with good disintegration time and drug release profile.

Sphenostylisins A-K: bioactive modified isoflavonoid constituents of the root bark of Sphenostylis marginata ssp. erecta.

Sphenostylisins A-C (1-3), three complex dimeric compounds representing two novel carbon skeletons, along with an additional eight new compounds, sphenostylisins D-K (4-11), were isolated from the active chloroform-soluble extract of the root bark of Sphenostylis marginata ssp. erecta using a bioactivity-guided isolation approach. The structures were elucidated by means of detailed spectroscopic analysis, including NMR and HRESIMS analysis, and tandem MS fragmentation was utilized to further support the structures of 1-3. The absolute configuration of sphenostylisin C (3) was established by electronic circular dichroism analysis. Plausible biogenetic relationships between the modified isoflavonoids 1-11 are proposed, and a cyclization reaction of 9 was conducted to support one of the biogenetic proposals made. All of these pure isolates were evaluated against a panel of in vitro bioassays, and among the results obtained, sphenostylisin A (1) was found to be a very potent NF-κB inhibitor (IC50 = 6 nM).

Phytoassessment of a waste engine oil-polluted soil exposed to two different intervals of monitored natural attenuation using African yam bean (Sphenostylis stenocarpa).

The present study comparatively investigated the phytotoxic effects of waste engine oil (WEO)-polluted soil exposed to monitored natural attenuation up to 5 and 14 months respectively. Soil was previously polluted with WEO at 0, 1, 2.5, 5 and 10% w/w oil in soil. Although, there was significant reduction in heavy metal concentration of soil as well as total hydrocarbon contents, performance of Sphenostylis stenocarpa was greatly retarded when sown at 5 months after pollution (MAP), with death of all seedlings except in the control. However, growth and yield performances were significantly (p > 0.05) enhanced at 14 MAP. Computation of hazard quotient showed that ecological risk factor initially posed by the presence of heavy metals in the soil at 5 MAP was significantly (p > 0.05) reduced to safe levels at 14 MAP.

Evaluation of the effect of processing methods on the nutritional and anti-nutritional compositions of two under-utilized Nigerian grain legumes.

The nutritional and anti-nutritional compositions of African Yam Bean (AYB) and Lima bean flours under different processing methods were determined. Nutritional and anti-nutritional properties studied include moisture content, crude protein, crude fibre, ash content, ether extract, carbohydrate, tannin, protease inhibitor and phytate. The moisture content of AYB flours ranged from 9.31 to 9.61% while that of lima beans ranged from 9.32 to 9.56%. There is a significant different among the samples when the unprocessed AYB (control) and the processed AYB were compared. The same trend was also observed with lima bean flours. However, some nutrient did not show significant variations with processing. It was observed that samples of soaked/de-hulled AYB have the least protease inhibitor of 0.73 mg/100 g and it is significantly different from the unprocessed samples. Soaked/de-hulled flours of both AYB and lima beans have the most percentage decrease in anti-nutritional content. Lima bean flours were observed to have higher anti-nutritional content than AYB. The percentage decrease of anti-nutritional factors in the samples is proportionally higher than that of the nutrients. The nutritional and anti-nutritional compositions of the samples suggest that processed African Yam Bean (AYB) and Lima bean flours would have useful application in fabricated foods.

Effect of peptide size on antioxidant properties of African yam bean seed (Sphenostylis stenocarpa) protein hydrolysate fractions.

Enzymatic hydrolysate of African yam bean seed protein isolate was prepared by treatment with alcalase. The hydrolysate was further fractionated into peptide sizes of <1, 1-3, 3-5 and 5-10 kDa using membrane ultrafiltration. The protein hydrolysate (APH) and its membrane ultrafiltration fractions were assayed for in vitro antioxidant activities. The <1 kDa peptides exhibited significantly better (p < 0.05) ferric reducing power, diphenyl-1-picryhydradzyl (DPPH) and hydroxyl radical scavenging activities when compared to peptide fractions of higher molecular weights. The high activity of <1 kDa peptides in these antioxidant assay systems may be related to the high levels of total hydrophobic and aromatic amino acids. In comparison to glutathione (GSH), the APH and its membrane fractions had significantly higher (p < 0.05) ability to chelate metal ions. In contrast, GSH had significantly greater (p < 0.05) ferric reducing power and free radical scavenging activities than APH and its membrane fractions. The APH and its membrane fractions effectively inhibited lipid peroxidation, results that were concentration dependent. The activity of APH and its membrane fractions against linoleic acid oxidation was higher when compared to that of GSH but lower than that of butylated hydroxyl toluene (BHT). The results show potential use of APH and its membrane fractions as antioxidants in the management of oxidative stress-related metabolic disorders and in the prevention of lipid oxidation in food products.

The proximate, mineral, and toxicant compositions of four possible food security crops from southeastern Nigeria.

The proximate, nutritional, and antinutritional compositions of the raw, cooked, and roasted samples of four Nigerian indigenous seeds-Sphenostylis stenocarpa, Pentaclethra macrophylla, Mucuna flagellipes, and Citrullus colocynthis-were evaluated. Also estimated were zinc and divalent cation bioavailability of the seeds using millimolar ratios/kg dry weight of [calcium]/[phytate], [phytate]/[zinc], [calcium][phytate]/[Zn], and [phytate]/[total phosphorus]. The results obtained revealed that the seeds of P. macrophylla and C. colocynthis had high protein and lipid levels. All the seeds were also found to have high energy value and low moisture content. Mineral analysis showed the presence of Na, K, Ca, and Mg in appreciable quantities and Zn, I, Fe, and Se in minute quantities. Antinutritional analyses indicated the presence of traces of tannin, oxalate, phytate, saponin, and cyanide in the samples. The various processing techniques had significant (P ≤ .05) effects on the measured parameters. The calculated [Ca][phytate]/[Zn] molar ratios revealed that these seeds had values above the critical level of 0.5 mL/kg, thus indicating reduced bioavailability of zinc. In view of the high nutrient contents, low antinutritional contents after processing, and their superabundance, these seeds could be cheap nutrient sources. The implications of these findings with regards to food security are enormous.

Pretreatment of African yam bean (Sphenostylis stenocarpa): effect of soaking and blanching on the quality of African yam bean seed.

The effect of pretreatment (soaking in sodium salts and blanching) on hydration coefficient (HC), chemical composition, texture, and color of African yam bean (AYB) was investigated. Soaking in water and in salt solutions increased the HC and about 90% of final HC values were attained at 12 and 4 hr of soaking for whole and dehulled beans, respectively. Protein content was slightly increased by soaking and blanching while ash and fat contents were reduced. Generally, a combination of dehulling and wet-processing reduced firmness of the beans more than soaking or blanching of the whole beans. Antioxidant activity was lowest (3260 TE(3)100 g) in cream-colored beans and highest (16,600 TE/100 g) in brown-colored beans. The tannin contents of unprocessed cream-colored beans and dehulled wet-processed marble variety were not significantly different (p > 0.05). The levels of tannins in the marble variety were reduced by blanching for 40 min (19.2%), soaking for 12 hr (16.0%), dehulling (72.0%), dehulling and blanching (88.8%). The whiteness of bean flours was increased significantly by dehulling, slightly by wet-processing of marble variety, and reduced significantly by wet-processing of cream-colored beans.

Effect of heat treatment on the proximate composition, energy values, and levels of some toxicants in African yam bean (Sphenostylis stenocarpa) seed varieties.

The effects of heat treatments on the proximate composition, energy content, and levels of some antinutritional factors in brown and marble-colored African yam bean (AYB) seed flours were investigated. In raw brown and marble-colored AYB seed flours; moisture content, dry matter, crude protein, crude fat, ash, total carbohydrate and caloric value did not differ significantly at the 5% level. Autoclaving and cooking slightly increased the moisture level. Crude protein, crude fat, and ash contents were decreased by autoclaving and were further decreased by cooking. The decrease was not, however, considerable for the AYB that is not eaten raw and whose full nutritional potential as a legume can be derived only when heat treated, as previous reports have indicated for legume seeds. The levels of the toxicants were generally higher in the raw brown AYB compared to the marble-colored, and were generally reduced by both autoclaving and cooking. In the most commonly available and consumed marble-colored AYB, autoclaving at 121 degrees C, 15 psi for 20 min decreased cyanogenic glycosides by 46%, oxalate by 48.9%, tannin by 15.0%, saponin by 14.8% and trypsin inhibitors by 61.3% while cooking for 3.5 hours in tap water decreased these toxic factors by 66.5%, 70.3%, 72.2%, 48.7%, and 86.0%, respectively. The results indicate that for raw samples, varietal difference did not significantly affect nutrient composition though the toxicants were generally higher in the brown AYB than the marble-colored. Autoclaving decreased both nutrient value and the level of toxicants in the two seed types; values were further reduced by cooking. Of the toxicants, trypsin inhibitor was found to be the most heat-labile and of the heat treatment methods, cooking to tenderness is recommendable.