Hawkins Jennifer S, Delgado Vivian, Feng Liang, Carlise Michael, Dooner Hugo K, Bennetzen Jeffrey L
Department of Biology, West Virginia University, Morgantown, WV, 26506, USA; Department of Genetics, The University of Georgia, Athens, GA, 30602, USA.
Plant J. 2014 Aug;79(3):375-84. doi: 10.1111/tpj.12537. Epub 2014 Jul 9.
Gene expression is a complex process, requiring precise spatial and temporal regulation of transcription factor activity; however, modifications of individual cis- and trans-acting modules can be molded by natural selection to create a sizeable number of novel phenotypes. Results from decades of research indicate that developmental and phenotypic divergence among eukaryotic organisms is driven primarily by variation in levels of gene expression that are dictated by mutations, either in structural or regulatory regions, of genes. The relative contributions and interplay of cis- and trans-acting regulatory factors to this evolutionary process, however, remain poorly understood. Analysis of eight genes in the Bz1-Sh1 interval of Zea mays (maize) indicates significant allele-specific expression biases in at least one tissue for all genes, ranging from 1.3-fold to 36-fold. All detected effects were cis-regulatory in nature, although genetic background may also influence the level of expression bias and tissue specificity for some allelic combinations. Most allelic pairs exhibited the same direction and approximate intensity of bias across all four tissues; however, a subset of allelic pairs show alternating dominance across different tissue types or variation in the degree of bias in different tissues. In addition, the genes showing the most striking levels of allelic bias co-localize with a previously described recombination hotspot in this region, suggesting a naturally occurring genetic mechanism for creating regulatory variability for a subset of plant genes that may ultimately lead to evolutionary diversification.
基因表达是一个复杂的过程，需要对转录因子活性进行精确的空间和时间调控；然而，单个顺式和反式作用模块的修饰可以通过自然选择来塑造，从而产生大量新的表型。数十年的研究结果表明，真核生物之间的发育和表型差异主要是由基因表达水平的变化驱动的，而这种变化是由基因的结构或调控区域的突变所决定的。然而，顺式和反式作用调控因子对这一进化过程的相对贡献和相互作用仍知之甚少。对玉米（Zea mays）Bz1-Sh1区间的八个基因的分析表明，所有基因在至少一种组织中都存在显著的等位基因特异性表达偏差，偏差范围从1.3倍到36倍。所有检测到的效应本质上都是顺式调控的，尽管遗传背景也可能影响某些等位基因组合的表达偏差水平和组织特异性。大多数等位基因对在所有四种组织中都表现出相同的偏差方向和近似强度；然而，一部分等位基因对在不同组织类型中表现出交替显性或在不同组织中的偏差程度有所变化。此外，表现出最显著等位基因偏差水平的基因与该区域先前描述的一个重组热点共定位，这表明存在一种自然发生的遗传机制，可为一部分植物基因创造调控变异性，最终可能导致进化多样化。
