Shi Xiaowen, Chen Chen, Yang Hua, Hou Jie, Ji Tieming, Cheng Jianlin, Veitia Reiner A, Birchler James A
Division of Biological Sciences, University of Missouri, Columbia, MO, USA.
Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO, USA.
Methods Mol Biol. 2020;2093:161-171. doi: 10.1007/978-1-0716-0179-2_12.
Dosage effects in plants are caused by changes in the copy number of chromosomes, segments of chromosomes, or multiples of individual genes. Genes often exhibit a dosage effect in which the amount of product is closely correlated with the number of copies present. However, when larger segments of chromosomes are varied, there are trans-acting effects across the genome that are unleashed that modulate gene expression in cascading effects. These appear to be mediated by the stoichiometric relationship of gene regulatory machineries. There are both positive and negative modulations of target gene expression, but the latter is the plurality effect. When this inverse effect is combined with a dosage effect, compensation for a gene can occur in which its expression is similar to the normal diploid regardless of the change in chromosomal dosage. In contrast, changing the whole genome in a polyploidy series has fewer relative effects as the stoichiometric relationship is not disrupted. Together, these observations suggest that the stoichiometry of gene regulation is important as a reflection of the mode of assembly of the individual subunits involved in the effective regulatory macromolecular complexes. This principle has implications for gene expression mechanisms, quantitative trait genetics, and the evolution of genes depending on the mode of duplication, either segmentally or via whole-genome duplication.
植物中的剂量效应是由染色体拷贝数、染色体片段或单个基因倍数的变化引起的。基因通常表现出剂量效应，即产物的量与存在的拷贝数密切相关。然而，当染色体的较大片段发生变化时，会释放出全基因组的反式作用效应，这些效应以级联效应调节基因表达。这些效应似乎是由基因调控机制的化学计量关系介导的。对靶基因表达既有正向调节也有负向调节，但后者是多数效应。当这种反向效应与剂量效应相结合时，可能会发生基因补偿，即无论染色体剂量如何变化，其表达都与正常二倍体相似。相比之下，在多倍体系列中改变整个基因组产生的相对效应较少，因为化学计量关系没有被破坏。总之，这些观察结果表明，基因调控的化学计量作为参与有效调控大分子复合物的各个亚基组装模式的反映是很重要的。这一原理对基因表达机制、数量性状遗传学以及取决于复制模式（片段复制或全基因组复制）的基因进化都有影响。
