Department of Plant Biology, University of Georgia, Miller Plant Sciences Bldg., Athens, GA 30602, USA.
Theor Appl Genet. 2012 Sep;125(5):897-907. doi: 10.1007/s00122-012-1881-z. Epub 2012 May 12.
The identification of genes underlying the phenotypic transitions that took place during crop evolution, as well as the genomic extent of resultant selective sweeps, is of great interest to both evolutionary biologists and applied plant scientists. In this study, we report the results of a molecular evolutionary analysis of 11 genes that underlie fatty acid biosynthesis and metabolism in wild and cultivated sunflower (Helianthus annuus). Seven of these 11 genes showed evidence of selection at the nucleotide level, with 1 (FAD7) having experienced selection prior to domestication, 2 (FAD2-3 and FAD3) having experienced selection during domestication, and 4 (FAB1, FAD2-1, FAD6, and FATB) having experienced selection during the subsequent period of improvement. Sequencing of a subset of these genes from an extended panel of sunflower cultivars revealed little additional variation, and an analysis of the genomic region surrounding one of these genes (FAD2-1) revealed the occurrence of an extensive selective sweep affecting a region spanning at least ca. 100 kb. Given that previous population genetic analyses have revealed a relatively rapid decay of linkage disequilibrium in sunflower, this finding indicates the occurrence of strong selection and a rapid sweep.
鉴定在作物进化过程中发生的表型转变所涉及的基因，以及由此产生的选择清除的基因组范围，这对进化生物学家和应用植物科学家都非常感兴趣。在这项研究中，我们报告了对野生和栽培向日葵（Helianthus annuus）脂肪酸生物合成和代谢所涉及的 11 个基因的分子进化分析结果。这 11 个基因中有 7 个在核苷酸水平上显示出选择的证据，其中 1 个（FAD7）在驯化前经历了选择，2 个（FAD2-3 和 FAD3）在驯化过程中经历了选择，4 个（FAB1、FAD2-1、FAD6 和 FATB）在随后的改良过程中经历了选择。从扩展的向日葵品种中对这些基因的一部分进行测序，发现几乎没有额外的变异，对其中一个基因（FAD2-1）周围的基因组区域的分析表明，发生了广泛的选择清除，影响了至少大约 100kb 的区域。鉴于先前的群体遗传分析表明，向日葵中连锁不平衡的衰减相对较快，这一发现表明存在强烈的选择和快速的清除。
