菊类植物基因组多倍化和重复基因功能分化的系统发育基因组学研究

基因组多倍化通过染色体环境的整体复制产生大量重复基因，是产生新基因和新功能的进化源泉。重复基因在进化过程中发生的功能分化可以促进生殖隔离和物种形成，有利于增加后代类群的生物多样性和环境适应性。菊类植物是真双子叶植物的主要类群之一，它具有高度的生物多样性和广泛的地理分布，包含多种重要作物、药材和耐受极端环境的植物。菊类植物多个类群在进化过程中发生过全基因组重复，因此是研究多倍化促进物种形成和物种分化的良好材料。在本项目中，我们将从菊类植物的物种谱系出发选择若干代表性物种，筛选一批包含丰富信息位点的低拷贝核基因，为研究全基因组重复提供稳定的系统发育关系框架。进一步使用比较基因组学和系统发育基因组学方法发现菊类进化过程中经历的多倍化事件，从转录调控、关键位点突变和自然选择压力等角度研究重复基因在后代物种中发生的新功能化和亚功能化，为揭示基因组多倍化促进物种形成和植物适应逆境的分子机制提供依据。

Polyploidization or whole genome duplication doubles the whole chromosome environment and results in a great many duplicated genes in genomes of descendants. These gene duplicates are considered as major driving force for evolution of novel gene functions and for improvement of evolutionary adaptation. Potential functional divergence among gene duplicates benefits biodiversity due to reproductive isolation. As one of the two major groups in core eudicots, asterids own many species that widely spread around the globe, including crops, herbal plants and many species living in extreme environments. Asterids, of which many groups are known to exhibit polyploidization events during their evolution, are considered as good materials for studies on speciation and differentiation. In this project, we will select typical species among different clades of asterids, to reconstruct a phylogenetic tree of asterids by using low-copy nucleic genes containing sufficient informative sites. In addition, we will investigate the potential polyploidization events during the evolution of asterids by using comparative genomic and phylogenomic analyses. This study will reveal neo-functionalization and sub-functionalization of duplicated genes in offspring genomes of asterids by considering effects of transcription regulation, causal mutations and nature selection, and will provide molecular clues for understanding how whole genome duplication promotes speciation and environmental adaptation.