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Broadening genetic diversity in canola (Brassica napus) germplasm using the B. oleracea var. alboglabra C-genome
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- Author / Creator
- Bennett, Rick A
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Genetic diversity in spring canola (Brassica napus L., AACC genome, 2n=38) cultivars is narrow. Limited effort has been made to utilize genetic diversity from the diploid species B. oleracea (CC genome, 2n=18), apparently due to the difficulty of producing B. napus × B. oleracea hybrids as well as lack of canola quality traits in seeds of this species. This Ph.D. research investigates the potential of genetic diversity of the C-genome of B. oleracea for the improvement of spring oilseed B. napus. Inbred lines were developed from F1 and BC1 plants of canola B. napus × B. oleracea var. alboglabra interspecific crosses through pedigree breeding. These populations were assessed for seed quality, effectiveness of selection based on morphological traits, genetic diversity using simple sequence repeat (SSR) markers, and ploidy levels using flow cytometry and cytological analysis of meiotic chromosomes. Heterotic potential of the F8 lines were evaluated, and compared with two populations derived from winter × spring and spring × spring B. napus crosses. In addition, an early flowering F5 line was used to generate a doubled haploid population for phenotypic and genetic analysis of the early flowering allele(s) of B. oleracea introgressed into B. napus. Erucic acid content in the B. napus × B. oleracea interspecific plants depended on genotype at the C-genome locus (C+C+, C+C0, C0C0) as well as dosage effect of the zero-erucic allele from B. napus A-genome; and F2 segregation deviated significantly from the 3:1 ratio based on disomic segregation of C-genome erucic acid alleles. Low glucosinolate plants were achieved from a relatively small segregating population, due to simpler segregation of high and low glucosinolate alleles in C-genome only. Surprisingly, all inbred lines resulting from self-pollination of F2 and BC1 plants stabilized to B. napus type – none were found to have B. oleracea ploidy. On a population basis, hybrid yield of the inbred lines of B. napus × B. oleracea and winter × spring crosses did not deviate significantly from the tester parent Hi-Q; however, a number of lines displayed significant mid- and high-parent heterosis. No correlation was found between genetic distance of the inbred lines from Hi-Q and mid- or high-parent heterosis for seed yield. Two publicly available SSR markers, sR10417 and Ol13-G05, previously mapped to the B. napus chromosome N12, were found to be associated with the early flowering allele of B. oleracea introgressed into B. napus. In addition, two SSR markers, SSR-617 and SSR-129, were strongly associated with a QTL for high glucosinolate content originating from the C-genome of B. oleracea, presumably residing on the B. napus chromosome N19. The findings from this Ph.D. research project suggested that it is feasible to introgress genetic diversity from the C-genome of B. oleracea into a canola quality and euploid B. napus background; and this diversity has great potential for improving yields of hybrid canola, as well as introducing alleles for improvement of specific traits such as earliness of flowering.
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- Graduation date
- Fall 2012
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.