Barriers to gene flow between populations are an important determinant of genome evolution and play a fundamental role in speciation. The so-called 'barrier' or 'speciation genes' contribute to reproductive isolation by preventing successful interspecific mating, pre- or post-fertilization. Success of interspecific mating depends on the parental evolutionary distance, but also on the balance between the parental genomes. Insufficient dosage of maternal or paternal genomic factors in the gametes results in genomic stress for the developing embryo, involving epigenetic restructuring and gene misregulation. In interspecific crosses between the model plant Arabidopsis thaliana and its close wild relative Arabidopsis arenosa, high seed abortion (∼77 to 99%) is indicative of post-zygotic incompatibilities. Additionally, the endosperm of hybrid seed often fails to cellularize and important protein complexes involved in gene imprinting and gene regulation in development display a loss of misregulation that is dependent on parental dosage. The observed quantitative variation between different A. thaliana accessions in their ability to produce live seed with the close relative A. arenosa has led to the hypothesis that there are one or more genes that mediate this interspecific incompatibility. What are these genes and how do they interact to produce a deleterious outcome?
Specific Aims: The goal of my thesis is to use existing natural variation between A. thaliana ecotypes to characterize the genetic and molecular basis of hybrid incompatibility between diploid Arabidopsis species with the aims of:
I) Identifying genetic factors encoded by the maternal genome that mediate hybrid seed survival.
II) Investigating the downstream effects of hybridization through transcriptome analysis on hybrids that have varying degrees of seed survival.
III) Documenting the developmental consequences of imprinted factor misregulation.
|Commitee:||Brady, Siobhan M., Harada, John J., Kliebenstein, Daniel J.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 74/02(E), Dissertation Abstracts International|
|Subjects:||Molecular biology, Plant biology, Genetics|
|Keywords:||Arabidopsis, Hybrid incompatibility, Imprinting misregulation, Speciation, Transcriptome|
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