Dissertation
Investigating the Molecular Basis of Heteromorphic Self-Incompatibility in Primula
Doctor of Philosophy (PhD), Washington State University
01/2017
Handle:
https://hdl.handle.net/2376/112451
Abstract
Plant breeding systems are fascinating responses to evolutionary forces and are critical to our propagation of agricultural crops. Heteromorphic self-incompatibility (HSI) is a system that has fascinated and puzzled scientists, including Charles Darwin, for over 150 years. In plants of the genus Primula two different floral morphs are found, named pin (L-morph) and thrum (S-morph). Pin flowers have a long style with the stigma positioned near the corolla tube mouth, and anthers halfway down the tube. Thrum flowers have reciprocal positioning of these organs. These differences in floral morphology are genetically linked to a self-incompatibility system that prevents self and intra-morph crosses. Together these traits work to promote out-crossing. Genetically, HSI is controlled by the S-locus, a supergene which segregates as a single genetic unit. Until recently the identity of the S-locus was unknown. In work presented here we sequenced regions of genomic DNA around suspected allelic S-locus markers (PvGLO) and were able to show that they instead represented distinct loci, one of which was specific to the thrum genome. We were also able to link this gene (PvGLO2) to the first identified S-locus gene (CYP734A50) which causes the short style in thrum. While previously thought to have two different alleles, we and others have shown that the S-locus is instead a dominant hemizygous insertion in the thrum genome, with no corresponding region in pin. We then used RNA-seq to examine differences in expression due to the presence of the S-locus at two floral development timepoints. We found differential expression of genes related to pollen development, among other processes, suggesting a developmental timing difference between the two morphs. Finally, we identified 19 Primula floral MADS-box genes, including PvGLO2, and characterized their expression in floral organs and protein-protein interactions. These data indicated that HSI does not affect floral MADS-box gene expression other than PvGLO2. Additionally, a possible mechanism is suggested in which PvGLO2 interacts differently with MADS-box genes than PvGLO1 which may lead to changes in downstream gene expression. To our knowledge, this work represents the most detailed characterization of MADS-box genes in an HSI species and in order Ericales.
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Details
- Title
- Investigating the Molecular Basis of Heteromorphic Self-Incompatibility in Primula
- Creators
- Benjamin Alan Burrows
- Contributors
- Andrew G McCubbin (Advisor)Eric H Roalson (Committee Member)Michael M Neff (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 169
- Identifiers
- 99900581716601842
- Language
- English
- Resource Type
- Dissertation