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

这项研究将调查开花植物属Tolmiea全基因组复制的进化后果。当后代拥有双亲所有染色体的两个副本时，就会发生复制。基因组复制在开花植物(300,000种)中经常发生，可能是它们成功的原因之一。大多数农作物是最近发生的一个或多个复制事件的结果，包括小麦、棉花、玉米、马铃薯和甘蔗。因此，这项研究在农业和生物多样性研究中具有广泛的意义。虎耳草(Tolmiea)包含一个多倍体Tolmiea，T.menziesii直接来自该属的单个二倍体T.diplomeziesii。正在进行的研究发现，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都存在差异。结合其他生态生理学研究，这项研究将通过一个由多个种群和多个水分胁迫处理组成的普通花园实验来表征同源多倍体在基因表达模式差异中所起的作用。这项研究将：1)提供天然同源多倍体与其二倍体亲本相比的全基因组基因表达模式，2)评估基因表达水平的变化和对有无水分胁迫的响应，以及3)使用合成多倍体品系来确定这些变化是多倍体的直接影响还是后续进化的结果。本研究将加深我们对同源多倍体引起的基因表达变化的理解，并将为今后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.