Browsing by Author "Danquah, Agyeman"

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    Determination of inheritance of aphid resistance in cowpeagenotypes and identification of single sequence repeatmarkers linked to resistance genes
    (Wiley Online Library, 2021-10-10) Ouedraogo, Adelaїde P.; Danquah, Agyeman; Tignegre, Jean-Baptiste
    An understanding of the mode of inheritance is fundamental to plant breeding. The choice of an appropriate selection method considers the number of genes involved and their modes of action. In plant breeding, markers can overcome the false resistance that may arise from greenhouse screening. The goal of this study was to facilitate the better use of cowpea genotypes resistant to aphids. Specifically, we sought to determine the number of genes involved in the ability of cowpeas to survive aphid infestation and identify single sequence repeat (SSR) markers linked to aphid resistance genes. Two pairs of parents (Tiligre × KVX295-124-2-99 and Tiligre × IT97K556-6) were used to generate two F2 populations. Each of these populations was screened with aphids to determine the mode of inheritance of resistance to aphids in cowpeas. SSR markers were used to screen parent, F1, and F2 individuals to locate polymorphic markers and markers linked to the genes involved in resistance to aphids. The results showed that the ability to survive under aphid infestation in KVX295-2-124-99 and IT97K556-6 is controlled by two nonallelic genes. The markers MA61 and MA70 were found linked to aphid resistance in cowpea.
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    Genetic parameter estimation and selection in advanced breeding population of white Guinea yam
    (Taylor & Francis, 2021-03-01) Norman, Prince Emmanuel; Tongoona, Pangirayi B.; Danquah, Agyeman
    White Guinea yam (Dioscorea rotundata Poir.) is an important tuber crop grown extensively in tropical regions of West African yam belt. Tuber yield, dry matter content, and tolerance to yam mosaic virus are key traits used for identification and selection of superior varieties for commercial deployment. In this study, we estimated genetic parameters for fresh tuber yield, tuber dry matter content, and quantitative field tolerance to yam mosaic virus in 49 clones grown in multi-environment trials (METs). We conducted genomic prediction involving 6337 single nucleotide polymorphisms (SNPs) and phenotypic field evaluation of data collected on the three traits from four sites. Additive genetic and non-genetic factors contributed significantly to phenotypic variation of studied yam traits in METs but to varying degrees. The non-genetic effects were relatively high for most of the measured traits. Narrow-sense heritability values were low (<0.30) for all studied traits. Further analysis of the performance of the clones at test sites with additive main effects and multiplicative interaction (AMMI) analysis exhibited significant genotype by environment interactions (GEI) for the three traits. The AMMI identified TDr10/00412, TDr11/00055, and TDr09/00135 clones with lowest mean trait stability index and outstanding performance for fresh tuber yield (t ha−1), tuber dry matter, and mosaic virus resistance across sites. The elite clones identified could serve as useful source of alleles for the genetic improvement of the crop and possibly considered for release to farmers.
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    Genomic and Phenotypic Diversity of Cultivated and Wild Tomatoes with Varying Levels of Heat Tolerance
    (MDPI, 2021-03-29) Ayenan, Mathieu Anatole Tele; Danquah, Agyeman; Agre, Paterne A.
    Assessment of genetic variability in heat-tolerant tomato germplasm is a pre-requisite to improve yield and fruit quality under heat stress. We assessed the population structure and diversity in a panel of three Solanum pimpinellifolium (wild tomatoes) and 42 S. lycopersicum (cultivated tomatoes) lines and accessions with varying heat tolerance levels. The DArTseq marker was used for the sequencing and 5270 informative single nucleotide polymorphism (SNP) markers were retained for the genomic analysis. The germplasm was evaluated under two heat stress environments for five yield and flower related traits. The phenotypic evaluation revealed moderate broad-sense heritabilities for fruit weight per plant and high broad-sense heritabilities for fruit weight, number of inflorescences per plant, and number of flowers per inflorescence. The hierarchical clustering based on identity by state dissimilarity matrix and UPGMA grouped the germplasm into three clusters. The cluster analysis based on heat-tolerance traits separated the germplasm collection into five clusters. The correlation between the phenotypic and genomic-based distance matrices was low (r = 0.2, p < 0.05). The joint phenotypic and genomic-based clustering grouped the germplasm collection into five clusters well defined for their response to heat stress ranging from highly sensitive to highly tolerant groups. The heat-sensitive and heat-tolerant clusters of S. lycopersicum lines were differentiated by a specific pattern of minor allele frequency distribution on chromosome 11. The joint phenotypic and genomic analysis revealed important diversity within the germplasm collection. This study provides the basis for efficient selection of parental lines to breed heat-tolerant varieties.