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

本研究将探讨全基因组复制在显花植物Tolmiea属的进化后果。当一个后代最终拥有两个父母所有染色体的副本时，就会发生复制。基因组复制经常发生在开花植物（300，000多个物种）中，可能有助于它们的成功。大多数农作物是最近一次或多次复制事件的结果，包括小麦、棉花、玉米、马铃薯和甘蔗。因此，对虎耳草属（虎耳草科）的研究不仅在农业上而且在生物多样性研究上都具有重要意义。menziesii直接起源于该属的单二倍体，T. diplomenziesii.目前的研究发现，二倍体和同源四倍体Tolmiea在非生物生态位偏好和生理水分胁迫反应方面存在分歧。与其他生态生理学调查，本研究将描述同源多倍体的作用发挥了基因表达模式的分歧，使用一个共同的花园实验，包括多个人口和多个水胁迫处理。这项研究将：1）提供对天然同源多倍体与其二倍体亲本相比基因表达的全基因组模式的见解，2）评估基因表达水平对存在和不存在水分胁迫的变化和响应性，以及3）使用合成多倍体系来确定这些变化是多倍体的直接影响还是随后进化的结果。本研究将增加我们对同源多倍体引起的基因表达变化的理解，并将为未来的育种管理和同源多倍体作物的改良提供有价值的信息。

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.