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Title: Strategies to broaden the genetic base of cereal crops
Author: Chikuni, Marlene
ISNI:       0000 0004 2671 9566
Awarding Body: The University of Reading
Current Institution: University of Reading
Date of Award: 2009
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Broadening the genetic base of crops is an on-going process. This study examined allelic diversity in 52 maize landraces from 12 African countries to determine places of greater genetic diversity. Eight chloroplast loci generated 21 alleles which gave 42 haplotypes. Analysis of molecular variance indicated that 70% of the variation was within accessions and 30% of the variability was partitioned among accessions within groups. A negative correlation obtained from Mantel test results indicated that the landraces shared similar alleles regardless of geographic distance and hence similar allelic frequencies which translated into the low allelic richness (1.33 alleles/locus) observed. Principal Component Analysis indicated that all haplotypes were subsets of South African maize accessions and in addition, the British were responsible for the spread of maize within Africa. An assessment of the CCA microsatellite repeat in the grain colour gene (yl) showed that the yellow accessions originated from the white accessions but there were no distinct geographic groupings. These results indicate that maize landraces from South Africa can enhance efforts to broaden the genetic base of maize varieties in Africa. The second major goal of the study centered on investigating spontaneous gene transfer in wheat double haploids. Three hundred and ninety two microsatellite markers were maize as an inducing parent. As expected, most of the markers (95.9%) gave positive amplification in maize. Significantly, no markers amplified any maize specific products in the DH wheat varieties suggesting that there was no or if any, negligible introgression of maize DNA into DH wheat varieties. Results from this study suggest that interspecific crosses may not be a viable option for targeted introduction of alien germplasm into improvement programmes of wheat and other crops.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available