Determining the Fate of Hybridized Genomes in the Allopolyploid Brassica napus

Polyploidy is widely acknowledged as a widespread mechanism in the evolution and speciation of the majority of flowering plants. Allopolyploid forms through interspecific hybridization and whole genome duplication. While allopolyploids may display increased vigor relative to their progenitors, they can also face challenges to fertility following hybridization. Genetic changes in allopolyploids result from recombination between the hybridized subgenomes, which can influence phenotype and ultimately determine fitness of future generations. To study dynamic changes that follow allopolyploid formation, Brassica napus lineages were derived by hybridizing Brassica oleracea and Brassica rapa. Two lineages of B. napus were analyzed for genetic and phenotypic changes in the S2, S7, and S12 generations. Although these lineages were genetically identical at the time of hybridization, divergence was apparent by the S2 generation. There was a significant increase in sequence loss across generations within both lineages. Four of six generations from both lineages displayed no significant differences to each other in sequence loss relative to the parental generation. In both lineages, there was a bias towards losing sequences from the B. olereacea subgenome. Some individual plants showed novel phenotypes; however, there was no correlation between the examined genetic changes and selected phenotypes.

Name thesis:degree_name

MS in Biological Sciences

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2010

Author dc:creator

• Wang, Tina Y

Contributors dc:contributor

• Edward Himelblau

• allopolyploids
• genetic changes
• hybridization
• phenotypes
• Genetics and Genomics
• Molecular Genetics
• Plant Breeding and Genetics

Identifier

10.15368/theses.2010.126

OAI identifier oai:identifier

oai:digitalcommons.calpoly.edu:theses-1375