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Genetics of Russian wheat aphid (Diuraphis noxia) resistance in bread wheat (Triticum aestivum L.) accession CItr 2401

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dc.contributor.advisor Tsilo, T. J.
dc.contributor.advisor Tolmay, V. L. Sikhakhane, Thandeka Nokuthula 2017-08-07T06:30:55Z 2017-08-07T06:30:55Z 2017-01
dc.identifier.citation Sikhakhane, Thandeka Nokuthula (2017) Genetics of Russian wheat aphid (Diuraphis noxia) resistance in bread wheat (Triticum aestivum L.) accession CItr 2401, University of South Africa, Pretoria, <>
dc.description.abstract The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is one of the important insect pests of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and other grasses. To date, there are four RWA biotypes identified in South Africa. The virulent biotypes emerged, partly due to climate change and new genetic variations within populations of RWA; hence there is a need to improve host-plant resistance, as an effective control measure. Bread wheat (Triticum aestivum L.) accession Cereal Introduction (CItr) 2401 is known to be resistant to all RWA biotypes worldwide. The goal of this study was to use a backcrossed near-isogenic line (NIL) BC5F5 mapping population, developed from a cross between CItr 2401 and susceptible Kavkaz, to identify and validate single nucleotide polymorphism (SNP) markers linked to the resistance phenotype in CItr 2401. This was achieved by (i) conducting a preliminary study that evaluated the suitability of simple sequence repeat (SSR) markers previously reported in literature for discriminating stacked RWA resistance genes and, (ii) employing SNP markers for the first time in a RWA resistance study as a future alternative to the widely used SSR markers. None of the tested SSR markers showed potential use in marker-assisted selection (MAS). The mapping population was phenotypically evaluated for RWA resistance using the four South African biotypes, viz. RWASA1, RWASA2, RWASA3 and RWASA4. Analysis of variance (ANOVA) showed significant (P<0.001) differences of genotypes after confirming the normality of residuals and homogeneity of variance. The Illumina iSelect 9,000 wheat SNP platform was used to genotype the two crossing parents and a selection of 24 NIL genotypes from the mapping population. Eight SNP markers found to be linked to the phenotype were converted to breeder-friendly and high-throughput Kompetitive allele-specific polymerase chain reaction (KASP) markers. The designed KASP markers were validated on the two crossing parents, the 24 NIL sent for SNP genotyping, on the mapping population and on the preliminary study genotypes for their effectiveness. The KASP assays developed in this study will be useful for stacking the RWA resistance from CItr 2401 with other Dn genes effective against the RWA. en
dc.format.extent 1 online resource (xi, 116 leaves) : illustrations, tables
dc.language.iso en
dc.subject Gene stacking en
dc.subject Genotyping en
dc.subject KASP assay en
dc.subject Linkage mapping en
dc.subject Resistance en
dc.subject Russian wheat aphid en
dc.subject Sequencing en
dc.subject Simple sequence repeats en
dc.subject Single nucleotide polymorphism en
dc.subject Wheat en
dc.subject.ddc 633.119752
dc.subject.lcsh Plant molecular genetics -- South Africa en
dc.subject.lcsh Wheat -- South Africa -- Molecular genetics en
dc.subject.lcsh Russian wheat aphid -- Host plants -- South Africa en
dc.subject.lcsh Russian wheat aphid -- Biological control -- South Africa en
dc.subject.lcsh Wheat -- Diseases and pests -- Biological control -- South Africa en
dc.subject.lcsh Wheat -- Genetic engineering -- South Africa en
dc.subject.lcsh Wheat -- Insect resistance -- South Africa -- Genetic aspects en
dc.title Genetics of Russian wheat aphid (Diuraphis noxia) resistance in bread wheat (Triticum aestivum L.) accession CItr 2401 en
dc.type Dissertation en
dc.description.department Life and Consumer Sciences en M. Sc. (Life Sciences)

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