Single-Copy Sequence Evolution, Polyploidy and Phylogeny Reconstruction

9508630温德尔植物中常见的自然现象是染色体加倍或多倍体。超过三分之二的植物物种被怀疑在其进化史上经历了一轮或多轮染色体加倍，包括许多重要的经济物种，如小麦、马铃薯、棉花、大豆和甘蔗。染色体加倍与亲缘关系密切的物种之间的杂交高度相关。多倍体的一个后果是，所有的染色体，以及由此产生的基因，都会在新的基因组中复制，从而产生“遗传冗余”。有人假设，这种冗余会导致新的基因功能，因为每个基因的一个副本可以自由改变，而另一个副本保留了原来的功能。或者，可能其中一个复制副本因突变而丢失，或者两个副本都保持原来的功能。关于这些过程在自然界中的运作程度或它们的相对频率，我们知之甚少。爱荷华州立大学的乔纳森·温德尔博士正在解决这个问题，多倍体植物中复制的基因会发生什么？利用分子生物学工具和棉花属二倍体和多倍体模式系统，将分离、测序重复基因，并进行相互比较和非多倍体祖先类型的复制。许多不同类型的基因将从不同的染色体进行研究，目的是发现指导多倍体中重复基因命运的一般原理。这项研究的结果也将有助于指导用于密切相关物种和属的系统发育分析的核基因的选择。

9508630 Wendel A common natural phenomenon in plants is chromosome doubling or polyploidy. More than two-thirds of all plant species are suspected of having passed through one or more rounds of chromosome doubling during their evolutionary history, including many economically important species such as the wheat, potato, cotton, soybean, and sugar cane. Chromosome doubling is highly correlated with hybridization between closely related species. One consequence of polyploidy is that all chromosomes, and hence genes, become duplicated in the new genome, thereby creating "genetic redundancy". It has been hypothesized that this redundancy leads to new gene functions, because one copy of each gene is free to change while the other retains its original function. Alternatively, perhaps one of the duplicated copies is lost through mutation, or perhaps both copies maintain the original function. There is very little known about the extent to which these processes operate in nature or their relative frequency. Dr. Jonathan Wendel of Iowa State University is addressing the question, What happens to duplicated copies of genes in polyploid plants? Using tools of molecular biology and a model system of diploids and polyploids from the cotton genus, Gossypium, duplicated genes will be isolated, sequenced, and compared to each other as well as to copies from their non-polyploid ancestral types. Many different types of genes will be studied from different chromosomes with the aim of discovering general principles that guide the fate of duplicated genes in polyploids. Results from this research will also help guide the choice of nuclear genes used for phylogenetic analysis of closely related species and genera.