University of Khartoum

Fine Mapping of Quantitative Trait Loci (QTLs) Associated with Striga Resistance using Molecular Markers and Introgression of resistance genes into Sorghum (Sorghum bicolor (L.) Moench) in Sudan

Fine Mapping of Quantitative Trait Loci (QTLs) Associated with Striga Resistance using Molecular Markers and Introgression of resistance genes into Sorghum (Sorghum bicolor (L.) Moench) in Sudan

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Title: Fine Mapping of Quantitative Trait Loci (QTLs) Associated with Striga Resistance using Molecular Markers and Introgression of resistance genes into Sorghum (Sorghum bicolor (L.) Moench) in Sudan
Author: Rasha Ali Mohammed Ahmed, Ali
Abstract: Witchweed (Striga sp.), is a devastating parasitic weed in sub-Saharan Africa and parts of Asia. It's control is difficult and can only be achieved through integrated management strategies, that depend mainly on host plant resistance. Genetic mapping of Quantitative Trait Loci (QTLs) associated with Striga resistance is an important step towards developing Striga resistant genotypes. The objectives of this study were fine mapping of Striga resistance genes from sorghum variety N13 in the course of incorporating superior levels of Striga resistance in agronomically elite genetic backgrounds by marker-assisted backcrossing and identify superior Striga resistant lines. For this purpose, five QTLs associated with Striga resistance were identified and mapped in sorghum variety N13. For fine mapping 218 Simple Sequence Repeats (SSR) markers were used. SSRs (169) and Diversity Arrays Technology (DArT) markers (544) were identified, of these markers 45.9% were polymorphic of which 41 were in close vicinity to Striga resistance QTL regions and thus used for genotyping. Moreover, 21 SSRs and 175 DArT markers in close association with Striga resistance QTLs were mapped. A saturated linkage map was constructed with 278 markers spanning a distance of 2362.4 cM. Striga resistances QTLs were saturated with 2-7 markers each and mapped markers were used to introgress Striga resistance QTLs from N13 into three favored sorghum varieties (Tabat, Wad Ahmed and AG8) but susceptible to Striga. Backcross populations BC3F4 (31) and BC4F1 (218), were generated. Standard variety trials were carried out for ten Striga resistant superior lines which were then advanced for multi-location testing in naturally or artificially Striga infested plots. Four lines with 3- 4 QTLs, T1BC3F4, AG6BC3F4, AG2BC3F4 and W2BC3F4, were released for commercial use based on Striga resistance and agronomic eliteness. Under field conditions the increase in yield observed for the released varieties was in the range of 180%- 298% over their recurrent parents. Twenty Striga resistant lines with two or more major QTLs were also selected for regional evaluation. This research is an excellent example of adopting and implementing marker assisted selection (MAS) to generate improved cultivars combining agricultural eliteness with high level of Striga resistance.
Description: 145page
URI: http://khartoumspace.uofk.edu/handle/123456789/13549
Date: 2015-06-17


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