Dissertation Research: The evolutionary significance of autopolyploidy in Tolmiea (Saxifragaceae)

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This research will investigate the evolutionary consequences of whole-genome duplication in the flowering plant genus Tolmiea. Duplication occurs when an offspring ends up with two copies of all of the chromosomes of its parents. Genome duplications have occurred frequently within the flowering plants (300,000+ species), and likely contributed to their success. Most agricultural crops are the result of one or more recent duplication events, including wheat, cotton, corn, potato, and sugarcane. Thus, the research will be of broad importance in agriculture as well as the study of biodiversity.Tolmiea (Saxifragaceae) contains one polyploid, T. menziesii that arose directly from the single diploid in the genus, T. diplomenziesii. Ongoing work found divergence both in abiotic niche preference and physiological water stress responses between diploid and autotetraploid Tolmiea. In concert with other ecophysiological investigations, this research will characterize the role autopolyploidy has played in the divergence of gene expression patterns using a common garden experiment consisting of multiple populations and multiple water-stress treatments. This study will: 1) provide insights into genome-wide patterns of gene expression in a natural autopolyploid compared to its diploid parent, 2) evaluate the variation and responsiveness of gene expression levels to the presence and absence of water-stress, and 3) use synthetic polyploid lines to determine whether these changes are the immediate effect of polyploidy or the result of subsequent evolution. This study will increase our understanding of gene expression changes resulting from autopolyploidy, and will provide valuable information for future breeding management and improvement of autopolyploid crops.