Department of Plant Biology and Genome Center, University of California, Davis, CA 95616, USA.
New Phytol. 2010 Apr;186(1):194-206. doi: 10.1111/j.1469-8137.2010.03198.x.
Two fundamental types of polyploids are known: allopolyploids, in which different parental chromosome sets were combined by ancestral hybridization and duplication; and autopolyploids, which derive from multiplication of the same chromosome set. In autopolyploids, changes to the nuclear environment are not as profound as in allopolyploids, and therefore the effects of genome doubling on gene regulation remain unclear. To investigate the consequences of autopolyploidization per se, we performed a microarray analysis in three equivalent lineages of matched diploids and autotetraploids of Arabidopsis thaliana. Additionally, we compared the expression levels of GFP transgenes driven by endogenous enhancer elements (enhancer traps) in diploids and autotetraploid of 16 transgenic lines. We expected that true ploidy-dependent changes should occur in independently derived autopolyploid lineages. By this criterion, our microarray analysis detected few changes associated with polyploidization, while the enhancer-trap analysis revealed altered GFP expression at multiple plant life stages for 25% of the lines tested. Genes on individual traps were coordinately regulated while endogenous gene expression was not affected except for one line. The unique sensitivity of enhancer traps to ploidy, in contrast to the observed stability of genes, could derive from lower complexity of regulatory pathways acting on traps versus endogenous genes.
异源多倍体，其中不同的亲本染色体组通过祖先杂交和复制组合在一起；和同源多倍体，它们来自同一染色体组的倍数增加。在同源多倍体中，核环境的变化不如异源多倍体那样深刻，因此基因组加倍对基因调控的影响仍不清楚。为了研究同源多倍化本身的后果，我们在拟南芥的三个同源的二倍体和同源四倍体的等效谱系中进行了微阵列分析。此外，我们比较了由内源增强子元件（增强子陷阱）驱动的 GFP 转基因在 16 个转基因系的二倍体和同源四倍体中的表达水平。我们期望真正的倍性依赖性变化应该发生在独立衍生的同源多倍体谱系中。根据这一标准，我们的微阵列分析检测到与多倍体化相关的变化很少，而增强子陷阱分析显示在 25%的测试线中，多个植物生命阶段的 GFP 表达发生了改变。单个陷阱上的基因被协调调节，而内源基因表达除了一条线外不受影响。与观察到的基因稳定性相比，增强子陷阱对倍性的独特敏感性可能源于作用于陷阱与内源基因的调控途径的复杂性较低。
