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UBC Theses and Dissertations

Expression of duplicated genes in a polyploid plant in response to abiotic stress Dong, Shaowei


Polyploidy, or genome doubling, is an important process in plant evolution that has effects on phenotypes, such as changes in flowering time. Allopolyploidy can result in considerable genetic changes including alterations to genome structure, DNA methylation patterns, and gene expression. Although the expression of duplicated genes in polyploid plants has been extensively studied, little is known about the effects of abiotic stress conditions on homeologous gene expression. In this thesis, I examined the expression of 30 homeologous gene pairs in response to five abiotic stress treatments, using a single strand conformation polymorphism (SSCP) assay in allotetraploid Gossypium hirsutum. Twenty-two genes showed stress-induced changes in the expression ratio of the two homeologs, and eight genes showed reciprocal expression changes in response to different abiotic stress treatments, suggesting quantitative subfunctionalization. I also examined the expression of ten homeologous gene pairs in response to three abiotic stress treatments in a synthetic Gossypium allotetraploid. Eight genes showed stress-induced expression changes. Comparison of the expression changes showed that there was little correspondence in the stress-induced homeolog expression patterns between the natural and synthetic Gossypium polyploids. The results of this study indicate that abiotic stress conditions can have considerable effects on expression of homeologous genes. Some of those expression changes might help plants survive abiotic stresses.

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