Browsing by Author "Kinyua, Miriam"

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    Genetic Diversity of Cassava Mutants, Hybrids and Landraces Using Simple Sequence Repeat Markers
    (SCIENCEDOMAIN international, 2014-10-11) Arunga, Ester E.; Chepkoech, Emmy; Kinyua, Miriam; Kiplagat, Oliver; Kimno, Stephen
    Aims: Cassava (Manihot esculenta Crantz) is a crop with largely unexplored and unexplained potentially valuable genetic variability. The knowledge and understanding of the extent of genetic variation of cassava germplasm is important for conservation and improvement. Objective: The current study was to investigate the genetic divergence of cassava mutants, hybrids and landraces using simple sequence repeat (SSR) markers. Methodology: Genetic diversity of ten cassava genotypes was determined using 14 SSR markers. Results: Findings from this study showed that the dendrogram based on UPGMA cluster analysis revealed that SSR data indicated the existence of high divergence among the accessions. The cophenetic matrices obtained showed that SSR data marker type was r = 0.91. Conclusion: The wider genetic diversity observed using SSR markers would be valuable for efficient management of germplasm and for effective utilization of materials in breedingprogrammes to produce hybrids of desirable characteristics. The extensive genetic diversity is important to coming generations so that it copes with unpredictable environmental changes and human needs.
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    Genetic Diversity of Cassava Mutants, Hybrids and Landraces Using Simple Sequence Repeat Markers
    (SCIENCEDOMAIN international, 2014-10-11) Arunga, Ester E.; Chepkoech, Emmy; Kinyua, Miriam; Kiplagat, Oliver; Kimno, Stephen
    Aims: Cassava (Manihot esculenta Crantz) is a crop with largely unexplored and unexplained potentially valuable genetic variability. The knowledge and understanding of the extent of genetic variation of cassava germplasm is important for conservation and improvement. Objective: The current study was to investigate the genetic divergence of cassava mutants, hybrids and landraces using simple sequence repeat (SSR) markers. Methodology: Genetic diversity of ten cassava genotypes was determined using 14 SSR markers. Results: Findings from this study showed that the dendrogram based on UPGMA cluster analysis revealed that SSR data indicated the existence of high divergence among the accessions. The cophenetic matrices obtained showed that SSR data marker type was r = 0.91. Conclusion: The wider genetic diversity observed using SSR markers would be valuable for efficient management of germplasm and for effective utilization of materials in breeding programmes to produce hybrids of desirable characteristics. The extensive genetic diversity is important to coming generations so that it copes with unpredictable environmental changes and human needs.
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    Genetic diversity of determinate French beans grown in Kenya based on morpho-agronomic and simple sequence repeat variation
    (Academic Journals, 2015-08) Arunga, Esther E.; Kinyua, Miriam; Ochuodho, Julius; Owuoche, James; Chepkoech, Emy
    French bean (Phaseolus vulgaris L.) in Kenya is cultivated predominantly in the Central, Eastern and Rift Valley provinces. Despite its importance as an export commodity, there has been little breeding effort devoted to its improvement and no much focus on gaining an understanding of the genetic diversity of the germplasm used in cultivation. The present objective was to evaluate the genetic diversity of a set of 36 Kenyan French bean accessions, based on a combination of morpho-agronomic and simple sequence repeat markers (SSRs). For the former, 20 morpho-agronomic traits were measured in two growing seasons, while for the latter; the germplasm was genotyped at 26 SSR loci. The accessions varied significantly (P≤ 0.05) with respect to pod diameter, pod length, pod number per plant, pod weight per plant and seed weight, but not with respect to the number of days taken to reach flowering, leaf length, leaf width or plant height. There was a large influence of season over flowering time, pod diameter, pod length, plant height and seed weight, and a significant (P≤ 0.05) interaction between accession and season for pod diameter, pod length, pod weight per plant, number of pods per plant and seed weight. The variation in the morpho-agronomic traits split the 36 accessions into four clusters. Shannon-Weaver diversity indices for qualitative, pseudo-qualitative and four selected quantitative traits ranged from 0.23 to 0.88. Of the 26 SSR primer pairs, which successfully amplified all 36 DNAs, 18 were informative, producing a mean of 2.17 alleles per SSR locus and a PIC value between 0.17 and 0.41. The level of gene diversity ranged from 0.19-0.50 (mean 0.36). The low observed mean heterozygosity reflected the predominantly autogamous habit of French bean. The modest amount of genotypic variation uncovered can be attributed to the effect of intensive selection for pod quality. A phylogeny based on the informative SSR loci revealed three major clusters, each representing a different pod diameter class. Combining the morpho-agronomic and DNA-based markers in this assessment of germplasm provides a way of taking advantage of the best features of both marker types that can be useful for identification of French bean varieties and applications of molecular markers to breeding.