ghanaopendata/ghanaian-research-english huggingface dataset:
Genetic studies of aphids (Aphis craccivora Koch) resistance in cowpea

Cowpea aphid (Aphis craccivora) is a serious pest in legume that causes significant grain yield losses. Chemical control measures are the most widely known form of control to this pest. However, breeding for resistance to this insect is very important because of its compatibility with other pest control methods; environment and eliminate dependence on environmentally toxic chemicals that resource poor subsistence farmers cannot afford. Breeding for cowpea aphid resistance was studied in crosses involving two resistant (Hewale and Asomdwee) and two susceptible (Asetenapa and Videza) genotypes. Crosses were made to generate direct and reciprocal F1 generations and direct and reciprocal F2 generations. All plants in each generation were evaluated for aphid resistance on the field using Randomized Complete Block Design. Each plant was infested with cowpea aphid two weeks after planting and the number of aphid colonies and damage scored between 0 – 5. The results showed most of the direct and reciprocal F1 generations to be resistant to the cowpea aphid and the F2 segregating generations were intermediate between the resistant and susceptible parents but were skewed towards the resistant parent. Results also showed that the resistance in Hewale and Asomdwee were controlled by a single gene and the F2 generation conformed to the 3 resistant and 1 susceptible after a χ2 test. Reciprocal differences were not detected in the crosses suggesting the absence of maternal effect. Negative heterosis over mid-parent was observed for aphid resistance score. It is possible to improve cowpea aphid resistance in susceptible cowpea lines in a hybridization programme.

Source: KNUST
Genetic study of extra-early maturity in cowpea (Vigna unguiculata(L.) Walp.)

Three field experiments were conducted to investigate the genetic basis of extra-early maturity in cowpea by incorporating extra-early maturity genes from a land race (Sanzi) into locally adapted improved medium maturity cultivar (Padi-Tuya). Ten progenies derived from the cross were evaluated using RCBD with three replications. The genotypes showed highly significant (p<0.01) variability for days to 50% flowering, days to first flower initiation, days to 90% pod maturity and days to first pod maturity. No significant differences (p>0.05) were observed in F 1 and RF 1 progenies suggesting the absence of maternal effect on the inheritance of extra-early maturity in cowpea. Broad sense heritability varied from 75% to 99% while narrow sense heritability was 74% to 99%, indicating the importance of both additive and non additive variances implying that selection for improvement in the F 2 will be effective in improving early maturity in cowpea. The observed ratio (3:1) for F2 and BC1 indicating the inheritance of extra-early maturity in cowpea is dominant or partial dominant over late maturity and therefore influenced by monogenic dominance and recessive epistasis. Negative heterosis over mid-parent observed for early maturity parameters indicates the inheritance of early maturity was towards the extra-early parent (Sanzi). The additive-dominance model revealed that both additive and non-additive gene effects contributed significantly to the inheritance of the trait studied suggesting the potential for further improvement through hybridization and selection procedures. Seed coat colour pattern was maternally inherited and various segregation colour patterns were observed in the F2 and RF2 . The seed coat colour colour pattern observed in the segregation populations could not fit in any of the modification in Medelian ratios suggesting the trait is quantitatively inherited.

Source: KNUST
Genetic studies on the inheritance of disease resistance, fruit yield and quality in tomatoes (Lycopersicon esculentum Mill)

Interspercific crosses involving the wild tomato variety Cherry, Lycopersicon esculentum var. cerasiforme and the commercial cultivars; NR1, NR 2, NR 44 and NR 46 were made. Vegetative characteristics, disease resistance and fruit qualities of the F1, F2, B1 and B2 generations were studied. Days to visible bud stage, number of branches per plant at anthesis, plant height, number of flowers per truss, number of fruits per truss, days to maturity, average fruit diameter, average fruit weight, total fruit weight, number of fruits per plant, total fruit yield, disease reaction were the characters studied. Diseases encountered in the field included damping-off, seedling blight, wilt, die back and viral diseases. In general, Cherry was found to be highly tolerant to many diseases and to drought when compared to the commercial parents. With the exception of seedling blight, which was observed to be controlled by duplicate dominant epistatic genes since the F2 ratio of healthy to diseased plants was 15:1, other fungal diseases were observed to be controlled by a single dominant gene since the F2 ratio of healthy to diseased plants was 3:1. F, hybrids were observed to be as good as the Cherry in disease tolerance and vigour. Cherry had higher mean values than the NR-lines for all the characters except average fruit diameter, average fruit weight and total fruit weight per plant. The hybrids especially F1, B1, B2 and some F2 were observed to be close to the wild Cherry in most of the characters. The major problem with the use of Cherry in these crosses was on the size of the fruits which was below marketable size. However, fruit size of F1s was improved through the use of commercial cultivars as donor parents (males) in a backcross to produce B2 progenies. Fresh fruits picked at colour break and stored in the laboratory to fully ripen stage were analysed for pH, soluble solids contents, citric acid, total sugars, vitamin C and colour. Cherry had higher soluble solids content, total sugars, citric acids and vitamin C than the commercial cultivars and its colour was as good as the other genotypes. All these qualities were passed on to the progenies. Heritability (in narrow sense) estimates for the vegetative, yield and fruit quality traits were high indicating that all these traits influenced by additive genes and as such progress can be made through selection for such traits. In order to develop stable varieties with high disease tolerance, acceptable fruit sizes and good fruit quality, it is suggested that single plant selection followed by backcrosses using the commercial varieties as recurrent parents may be followed.

Source: KNUST
Genetic Susceptibility and Predictors of Paradoxical Reactions in Buruli Ulcer

Buruli ulcer is an infectious disease of skin, subcutaneous fat and sometimes bone, mainly affecting children in West Africa. It is considered as one of the Neglected Tropical Diseases but the disease occurs also in moderate climates like South East Australia and Japan where it may also affect adults. Once a patient has started antibiotic treatment, lesions may increase in size even if the antimicrobial treatment is effective; this is highly confusing for doctors and patients as they may think that treatment actually fails. The cause of Buruli ulcer is Mycobacterium ulcerans, related to other mycobacteria that cause disease in man, like leprosy and tuberculosis. Using data from two different studies in West Africa, we show that these paradoxical reactions are associated with trunk localization and that they occur more often in larger lesions. The chance to develop these reactions appeared partly inherited: carrying the homozygous ins/ins genotype of 3’UTR TGTG 285 polymorphism in the SLC11A1 gene increased the risk of paradoxical reactions. Vitamin D is important for the immune defense against infections by mycobacteria. Vitamin D blood concentrations were not associated with paradoxical reactions; patients generally did well, and we did not need corticosteroid immune suppression to overcome these reactions.

Source: KNUST
Genetic variation and genotype × environment interaction in yams (Dioscorea spp.) for root colonization by arbuscular mycorrhiza

Root colonization by arbuscular mycorrhiza (AM) enhances nutrient acquisition by plants and could benefit the production of yam (Dioscorea spp.). The variation in AM colonization in yam genotypes was evaluated in two experiments at four locations (Ibadan, Onne, Abuja and Ubiaja) in different agroecologies of Nigeria in 2004 and 2005. Twenty-seven genotypes of D. rotundata and 28 of D. alata were investigated in a randomized complete block design with three replicates. Arbuscular mycorrhizal fungi colonized all yam genotypes. Root length colonization ranged from 24 to 95% in D. rotundata and from 21 to 95% in D. alata. Colonization was observed to be high in locations with lower soil available P but was not precluded by relatively high soil acidity. Highly significant (P< 0.001) effects were observed in D. rotundata for genotype and location, as well as genotype × location, location × year and in D. alata for genotype, location and year. The location × genotype × year interaction was significant (P < 0.05) in both experiments. The broad sense heritability estimates for AM colonization were 0.60 in D. rotundata and 0.87 in D. alata. Further analysis of genotype × environment interactions using a GGE biplot for the two-year data showed that the most stable genotypes for AM colonization across locations were TDr 93-32 (D. rotundata) and TDa 98/01183 (D. alata). The highest percentage AM colonization mean were found in TDr 93-32 (D. rotundata) and TDa 01/00204 in (D. alata). Generally, the highest mean colonization values were obtained at Abuja and Ubiaja. The results of this study reveal that AM colonization in yam is host-dependent and influenced by the environment

Source: KNUST
Genomic and epidemiological characteristics of SARS-CoV-2 in Africa

ince late 2019, the coronavirus disease 2019 (COVID-19) outbreak, caused by SARS CoV-2, has rapidly evolved to become a global pandemic. Each country was affected but with a varying number of infected cases and mortality rates. Africa was hit late by the pan demic but the number of cases rose sharply. In this study, we investigated 224 SARS-CoV 2 genome sequences from the Global Initiative on Sharing Avian Influenza Data (GISAID) in the early part of the outbreak, of which 69 were from Africa. We analyzed a total of 550 muta tions by comparing them with the reference SARS-CoV-2 sequence from Wuhan. We clas sified the mutations observed based on country and region, and afterwards analyzed common and unique mutations on the African continent as a whole. Correlation analyses showed that the duo variants ORF1ab/RdRp 4715L and S protein 614G variants, which are strongly linked to fatality rate, were not significantly and positively correlated with fatality rates (r = -0.03757, P = 0.5331 and r = -0.2876, P = 0.6389, respectively), although increased number of cases correlated with number of deaths (r = 0.997, P = 0.0002). Fur thermore, most cases in Africa were mainly imported from American and European coun tries, except one isolate with no mutation and was similar to the original isolate from Wuhan. Moreover, unique mutations specific to countries were identified in the early phase of the outbreak but these mutations were not regional-specific. There were common mutations in all isolates across the continent as well as similar isolate-specific mutations in different regions. Our findings suggest that mutation is rapid in SARS-CoV-2 in Africa and although

Source: KNUST
The genetics of maturity and its correlated traits and stability analysis in maize (zea mays l.) (a) identification of genomic regions controlling maturity and its correlated traits in b73 x unadapted mexican maize population. (b) evaluation of genotype by environment interactions in maize.

This study was conducted to (i) apply biotechnological approaches. viz simple sequence repeats (SSR) primers and restriction fragment length polymorphism (RFLP) probes with classical breeding procedures to identify genes important in adapting exotic maize germplasm, and (ii) understand the mode of inheritance of maturity in adapted by unadapted F2 maize population. Two hundred and eleven (211) S1 families developed from a cross between adapted Corn Belt maize inbred line (B73) and an unadapted maize population and their testcrosses were evaluated at two planting dates and two locations, respectively, in 1995. Maturity was quantitatively inherited, and few factors were responsible for its expression in maize. Earliness was dominant to lateness. Fingerprinted DNA isolates from each family with SSR primers and RFLP probes revealed that, putative quantitative trait loci associated with maturity were located on seven of the ten chromosomes. Phi085, Phi 113, Phi014, Pigmentation umc59, umc168 and bnl5.09 were associated with maturity. The gene effects of the markers were a combination of additive and dominance. Ear and plant height were also quantitatively inherited and were linked to Pigmentations umc59, umc34, csu5, phi014, bnl5.09 and bnl7.49. Pigmentation, csu25, phi0l4, bnl7.49 and umcl09 were also associated days to anthesis, grain moisture at harvest and grain yield in testcrosses. The use of molecular markers in conjunction with classical breeding methods was an efficient approach to understanding the mode of inheritance of maturity in maize.

Source: KNUST
Genetic variation and genotype × environment interaction in yams (Dioscorea spp.) for root colonization by arbuscular mycorrhiza

Root colonization by arbuscular mycorrhiza (AM) enhances nutrient acquisition by plants and could benefit the production of yam (Dioscorea spp.). The variation in AM colonization in yam genotypes was evaluated in two experiments at four locations (Ibadan, Onne, Abuja and Ubiaja) in different agroecologies of Nigeria in 2004 and 2005. Twenty-seven genotypes of D. rotundata and 28 of D. alata were investigated in a randomized complete block design with three replicates. Arbuscular mycorrhizal fungi colonized all yam genotypes. Root length colonization ranged from 24 to 95% in D. rotundata and from 21 to 95% in D. alata. Colonization was observed to be high in locations with lower soil available P but was not precluded by relatively high soil acidity. Highly significant (P< 0.001) effects were observed in D. rotundata for genotype and location, as well as genotype × location, location × year and in D. alata for genotype, location and year. The location × genotype × year interaction was significant (P < 0.05) in both experiments. The broad sense heritability estimates for AM colonization were 0.60 in D. rotundata and 0.87 in D. alata. Further analysis of genotype × environment interactions using a GGE biplot for the two-year data showed that the most stable genotypes for AM colonization across locations were TDr 93-32 (D. rotundata) and TDa 98/01183 (D. alata). The highest percentage AM colonization mean were found in TDr 93-32 (D. rotundata) and TDa 01/00204 in (D. alata). Generally, the highest mean colonization values were obtained at Abuja and Ubiaja. The results of this study reveal that AM colonization in yam is host-dependent and influenced by the environment.

Source: KNUST
Genomic Arrangement of Nod Gene Sequences of Bradyrhizobium Isolates from TGx Soybean Genotypes in Relation to Bradyrhizobium USDA110

Soybean nodulates with specific rhizobia and usually requires inoculation with Bradyrhizobium japonicum strains. Several varieties (e.g., Malayan and Orba) introduced to Africa (Pulver et al., 1982;) were however adequately nodulated in soils that had no previous inoculation with B. japonicum while cultivars from North America were poorly nodulated. The freely nodulating soybean genotypes, termed promiscuous, however, had poor agronomic characteristics. The International Institute of Tropical Agriculture (IITA) selected soybean genotypes that combined the free nodulating traits of the promiscuous genotypes and the improved agronomic characteristics of the North American genotypes. The resultant TGx genotypes, widely cultivated in western and eastern Africa have poor yields due to ineffective nodulation (Okereke and Eaglesham, 1992). This observation led to the suggestion that the TGx soybean genotypes would benefit from B. japonicum inoculation. It is therefore important that the genetic relatedness of the indigenous rhizobia nodulating these soybean genotypes to recommended inoculum strains (e.g., B. japonicum USDA 110) needs to be elucidated. A total of 258 Bradyrhizobium

Source: KNUST
Genotype environment interaction (GXE): effects on some major agronomic and rheological properties of cassava (Manihot esculenta, Crantz)

Work was carried out to assess tuber yield, flour, gari and starch yields and their rheological properties in four elite varieties of cassava namely NKZ-009, NKZ-015, DMA-002 and WCH-037 selected from Brong Ahafo collections by Safo-Kantanka et al. (2000). Two sets of on-farm and on-station experiments were carried out. On-farm studies involved the four elite varieties grown at 18 locations in two years in the Transition and Forest ecozones. The on-station studies compared the performance of the above elite varieties with four improved varieties namely Abasafitaa, Ajisiafi and Gblemoduade which are IITA-based varieties developed by CSIR-Crops Research Institute and Tek-bankye which was developed by the Faculty of Agriculture, Kwame Nkrumah University of Science and Technology at two locations in two years. Data were collected on root tuber yield, harvest index, dry matter content, cooking quality, flour, gari and starch yields. Rheological data were collected on solubility, swelling power and water-binding capacity of flour and starch, and swelling capacity and pH of gari. The results from both experiments showed significant genotype x environment (GXE) interaction for all the traits studied. The age at harvest for maximum tuber yield did not coincide with that of flour, gari and starch yields. The performance of DMA-002 and WCH-037 was significantly better than the NKZ-lines for the agronomic traits but not significantly different for the rheological properties. The performance of the elite varieties was not significantly different from the released ones in any trait studied. Farmers seemed to have selected for varieties with high dry matter content since dry matter for the elite varieties was higher than the IITA-based improved varieties. However, dry matter did not have direct relationship with flour and gari yield. The presence of GXE interactions introduced complications into evaluation and selection for both agronomic and rheological characteristics among the cassava cultivars.

Source: KNUST
Genotype by environment interaction and grain yield stability of extra-early maize (Zea mays L.) Hybrids Evaluated at Three Locations in Ghana

In Ghana, genotype by environment interaction effect on maize grain yield is usually significant due to considerable variation in soil and weather conditions at growing sites. A proper understanding of the effects of G x E interactions on variety evaluation and cultivar recommendations is vital. It was with this aim that this study was conducted to evaluate forty-four extra-early maize hybrids obtained from the International Institute of Tropical Agriculture (IITA) and a local check hybrid to identify stable and high-yielding hybrids with superior agronomic performance for commercial production in Ghana during the 2011 growing season. These hybrids were evaluated at Ejura, Fumesua and Kpeve; representing the forest transition, forest and transition zones of Ghana. The effects of genotype (G), location (L) and G × L were found to be highly significant (P < 0•01) for grain yield. The variations among the genotypes (G) were the largest components of variance (79.16 %) for grain yield, whereas the locations effects and G × L accounted for 7.04 % and 7.37 %, respectively. The genotype main effect plus genotype × environment interaction biplot explained 0.97 of total variations in the sum of squares for grain yield. The GGE biplot procedure provided results in terms of stability and performance of the hybrids. This method identified the hybrids TZEEI 5 x TZEEI 4, TZEEI 1 x TZEEI 22, TZEEI 20 x TZEEI 19, TZEEI 31 x TZEE I8 and TZEEI 13 x TZEEI 22 as the high yielding and stable. TZEEI 11 x TZEEI 22, TZEEI 5 x TZEEI 50, TZEEI 8 x TZEEI 51 and TZEEI 8 x TZEEI24 are low yielding but stable. TZEEI 2 x TZEEI 11 and TZEEI 15 x TZEEI 8 was high yielding and the least stable and TZEEI 13 x TZEEI 12 and TZEEI 26 x TZEEI 24 had both low yielding and low stability. It identified Ejura, located in the forest transition zone, as the ideal testing environment for these set of hybrids.

Source: KNUST
Genotype by environment interaction and grain yield stability of sorghum (sorghum bicolor) hybrids evaluated at three locations in northern Ghana

Sorghum (Sorghum bicolor (L) Moench) is a staple food crop for millions of poor people in the semi-arid tropics and is adapted to a wide range of environmental conditions. In Ghana where there is large variation in environment it may be expected that genotype by environment interaction may also be higher. In such situation, one cultivar may have higher yield in some environments while the second cultivar may excel in the other. Variation in soil and weather condition across sorghum growing environments has led to significant genotype by environment effect on sorghum yields. Therefore, the evaluation of sorghum genotypes for stability of performance under varying environmental condition becomes an important aspect in sorghum hybrid evaluation. It was with this idea that this study was conducted to evaluate four sorghum hybrids, two commercial sorghum varieties and a local check obtained from the Savanna Agricultural Research Institute to identify stable and high yielding sorghum genotypes for commercial production during 2014 growing season in Ghana. The genotypes were evaluated at three locations in Northern Ghana at Nyankpala, Damongo and Manga. These were significant (P < 0.01) genotype (G), location (L) and genotype by location interaction (GLI) effect for grain yield. The contributions of the total variance accounted for by the genotypes were highest being (42%) for grain yield. The location effect and genotype by location (G × L) accounted for (23%) and (13%) respectively. The GGE biplot analysis showed that G1 (XSW2134) was high yielding and most stable, G2 (XSW256) was high yielding but least stable and G4 (Marcia) was low yielding and least stable. Damongo which is located in the Guinea savannah zone would be appropriate in selecting superior genotype.

Source: KNUST