Bread wheat (Triticum aestivum L.) is an important cereal crop that provides over 20% of
the global calorie intake. With the world population constantly growing, yield production
must increase to meet food demands. Wheat plays a significant role on nutritional and food
security especially in rural areas, however, bread wheat grains are known to be inherently
deficient in micronutrients, particularly Fe and Zn, which makes them important
biofortification targets. To date, South African wheat genotypes have not been explored for
their nutritional micronutrient variation; hence there is a need to investigate the variation of
nutritional quality and its association with yield components. Bread wheat cultivars, TugelaDN and Elands were used in this study based on their known high yield potential, resistance
to insect pests and diseases as well as their good-to-excellent bread-making quality. The
goal of this study was to use a doubled haploid (DH) mapping population, developed from
a cross between cultivars Tugela-DN and Elands, to identify single nucleotide
polymorphism (SNP) and genotyping-by-sequencing (GBS)-based markers linked to high
nutritional quality and yield-related traits. This was achieved by (i) determining grain
micronutrient (Fe and Zn) concentration variation in 139 lines of a DH mapping population;
(ii) evaluating the mapping population for yield-related traits; (iii) determining the correlation
between micronutrient and yield-related traits among the genotypes; (iv) identifying SNP
GBS-based markers linked to the high minerals and yield-related traits. The analysis of
variance (ANOVA) showed significant (P<0.001) differences between genotypes for all
traits evaluated. A wide variation was observed for both GFeC and GZnC. The statistical
analysis revealed significant variation for Zn concentration (P < 0.001) among genotypes
and not significant Fe concentration. DArT-Seq was used to genotype Tugela-DN and
Elands cultivars and 139 DH genotypes. Quantitative trait loci (QTL) were detected using
SNP GBS-based markers on chromosome 2D, 5B, 5D, 6A, and 6B for GZnC, and on
chromosome 2D, 5B, 5D and 7D for GFeC. Most QTLs identified for GFeC and GZnC
shared the genomic interval and some of them also co-located with few yield-related traits.
The results of this study will contribute to breeding programmes to improve nutritional
quality of bread wheat and food security of the country. / Life and Consumer Sciences
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/26895 |
| Date | 02 1900 |
| Creators | Lephuthing, Mantshiuwa Christinah |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | application/pdf |
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