Chromosomal Evolution, Genetic Diversity, and Speciation Mechanisms in Polyploid Tragopogon (Asteraceae)

多倍体或全基因组复制是开花植物进化的主要力量，许多开花植物物种是通过杂交和多倍体相结合的过程起源的。染色体的变化可能通过多倍体中基因的丢失和复制而产生遗传多样性，并可能促进物种形成，但在年轻的自然发生的多倍体植物中，染色体进化的程度尚不清楚。本文将利用分子细胞遗传学方法研究向日葵属植物的染色体和基因组的变化。这些物种是最近形成的(在过去的80年里)，并通过亲本物种的不同种群的杂交而重复形成。此外，两个多倍体的合成品系都已在实验室中培育出来。因此，Tragopogon提供了一个独特的机会来比较年轻的天然和合成多倍体植物的染色体变异。这个项目将解决新的多倍体中染色体变异的程度，无论发生的变化类型是否受某些“规则”的支配，以及这种变异在自然种群中的影响。多倍体在开花植物(300,000个或更多物种的群体)中很常见。此外，世界上所有的主要农作物和最严重的杂草都是多倍体的。因此，表征多倍体形成后不久发生的过程对于了解大多数植物物种的基因组至关重要，从而对于我们保护植物生物多样性并可持续地从中受益的能力至关重要。结合DNA序列分析，该项目将为在染色体、基因组和遗传水平上的多倍化过程提供新的见解。

Polyploidy, or whole genome duplication, is a major force in flowering plant evolution, with many flowering plant species having originated through the combined processes of hybridization and polyploidy. Chromosomal changes may generate genetic diversity via loss and duplication of genes in polyploids and may promote speciation, but the extent of chromosomal evolution in young, naturally occurring polyploid plants is unknown. Molecular cytogenetic methods will be used to investigate chromosomal and genomic changes in Tragopogon mirus and T. miscellus of the sunflower family. These species formed recently (in the past 80 years) and repeatedly through hybridization of different populations of the parental species. Furthermore, synthetic lines of both polyploids have been produced in the lab. Tragopogon therefore provides a unique opportunity to compare chromosomal variation in young natural and synthetic polyploid plants. This project will address the extent of chromosomal variation in new polyploids, whether or not certain "rules" govern the types of changes that occur, and the effect of this variation in natural populations. Polyploidy is common in flowering plants (a group of 300,000 or more species). Furthermore, all of the world's major crops and most serious weeds are polyploid. Therefore, characterizing the processes that take place shortly after polyploid formation is crucial for understanding the genomes of most plant species, and thus for our ability to conserve plant biodiversity and sustainably benefit from it. In conjunction with DNA sequence analyses, this project will provide new insight into the process of polyploidization at the chromosomal, genomic, and genetic levels.