Browsing by Author "Msiska, Ulemu Mercy"

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    Identification and mapping of quantitative trait loci associated with soybean rust (Phakopsora pachyrhizi) resistance in genotype UG 5
    (African Journal of Biotechnology, 2018) Gebremedhn, Hailay Mehari; Msiska, Ulemu Mercy; Weldekidan, Miesho Belay; Abate Asmamaw, Fentaw; Winnifred, Akech; Onziga, Dramadri Isaac; Lapaka Odong, Thomas; Rubaihayo, Patrick; Tukamuhabwa, Phinehas
    Soybean rust, Phakopsora pachyrhizi, is one of the most serious and widespread foliar diseases of soybean causing high yield losses world-wide. The objective of this study was to identify and map quantitative trait loci (QTLs) resistant to soybean rust in genotype UG 5. Ninety-seven F2 mapping plants, obtained from a cross between Wondersoya and UG 5, were used for this study. Quantitative trait locus analysis using QTL IciMapping software identified three putative QTLs associated with soybean rust (SBR) on chromosomes 6, 9 and 18 with logarithms of odds (LOD) scores ranging from 3.47 to 8.23 and phenotypic variance explained by the QTLs ranging from 18.3 to 25.6%. The putative QTL detected on chromosome 9 is novel and has not been reported elsewhere. The putative QTLs identified in this study could help to facilitate SBR resistance breeding towards efficient marker assisted selection approach and gene pyramiding leading to the development of durable resistance.
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    Inheritance of soybean resistance to soybean rust in Uganda’s soybean germplasm
    (International Journal of Agronomy and Agricultural Research, 2018) Gebremedhn, Hailay Mehari; Belay Weldekidan, Miesho; Msiska, Ulemu Mercy; Asmamaw, Fentaw Abate; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, Patrick
    Understanding the genetic mechanisms of soybean rust resistance is important for effective selection and breeding procedures. This study was hence conducted to determine the combining ability and gene action controlling soybean rust using a 10x10 half diallel mating design. The F2 segregating populations along with their parents were evaluated for rust severity and sporulation level at two reproductive stages (R4 and R6) in screen house and field conditions during the second season of 2016 and first season of 2017 at MUARIK using an alpha lattice design replicated thrice. Significant differences were observed among the parents and F2 generations for both disease severity and sporulation level. General and specific combining abilities were highly significant. The GCA/SCA ratio (1.50-2.30) and the Baker’s ratio (0.75-0.82) showed the predominance of additive gene action in the inheritance of soybean rust resistance. The broad-sense (0.94-0.99) and narrow-sense (0.73-0.82) heritability estimates indicated the possibility of improving resistance to soybean rust through selection in the early generations. UG 5, Maksoy 3N, Maksoy 4N and Maksoy 5N had negative GCA effects. The F2 populations derived from these parents crossed with Wonder soya and Nam 2 had also negative SCA effects. The use of these parents and F2 populations can, therefore, increase the response to selection for improving resistance to soybean rust.
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    New sources of cowpea genotype resistance to cowpea bruchid Callosobruchus maculatus (F.) in Uganda
    (International Journal of Agronomy and Agricultural Research, 2018) Belay Miesho, Weldekidan; Gebremedhin, Hailay Mehari; Msiska, Ulemu Mercy; Mohammed, Khalid Elsiddig; Malinga, Geoffrey Maxwell; Sadik, Kassim; Lapaka Odong, Thomas; Rubaihayo, Patrick; Kyamanywa, Samuel
    Cowpea bruchid Callosobruchus maculatus (F.) is a major constraint to cowpea production throughout subsaharan Africa. The identification of sources of C. maculatus resistance and their incorporation into breeding programs would be a beneficial strategy to combat the devastation caused by the bruchid in stored cowpea. We evaluated 145 cowpea genotypes from Uganda and introductions from Kenya and Nigeria for resistance to bruchids. The mean number of eggs and number of holes, percentage pest tolerance, percentage weight loss, bruchid developmental period, bruchid growth and Dobie susceptibility index were significantly different among the 145 genotypes. Based on Dobie susceptibility index value, there were 18 resistant, 114 moderately resistant and 13 susceptible genotypes. Dobie’s susceptibility index correlated negatively with insect development period and percentage pest tolerance, and positively with number of eggs, growth index, number of holes and weight loss. The study identified new sources of cowpea from the studied genotypes that could be used by cowpea breeders to develop cultivars with relatively high resistance to cowpea bruchid. However, further investigations and identifcation of biochemicals that are responsible for cowpea seed resistance to bruchid are recommended.