近日，德国马克斯·普朗克生物研究所Detlef Weigel、J. Grey Monroe等研究人员合作发现，拟南芥的突变偏向反映出自然选择。2022年1月12日，国际知名学术期刊《自然》在线发表了这一成果。

研究人员表示，自20世纪上半叶以来，进化论一直被突变的后果是随机发生的这一观点所主导。

研究人员通过对植物拟南芥新突变的大规模调查来检验了这一假设。与预期相反，研究人员发现突变在基因组的功能受限区域发生的频率较低——基因体内的突变频率减少了一半，基本基因的突变频率减少了三分之二。通过独立的基因组突变数据集，包括迄今为止进行的最大的拟南芥突变积累实验，研究人员证明表观基因组和物理特征可以解释全基因组范围内基因周围突变偏向模式的90%以上差异。观察到的基因周围的突变频率反过来又准确地预测了自然拟南芥的遗传多态性模式（r=0.96）。对等位基因频率的分析支持了突变偏倚是自然加入的基因周围序列进化模式的主要力量。

最后，研究人员发现受到较强净化选择的基因具有较低的突变率。该研究的结论是，与表观基因组相关的突变偏向减少了拟南芥中有害突变的发生，并挑战了突变是进化中无方向的力量这一普遍的范式。

附：英文原文

Title: Mutation bias reflects natural selection in Arabidopsis thaliana

Author: Monroe, J. Grey, Srikant, Thanvi, Carbonell-Bejerano, Pablo, Becker, Claude, Lensink, Mariele, Exposito-Alonso, Moises, Klein, Marie, Hildebrandt, Julia, Neumann, Manuela, Kliebenstein, Daniel, Weng, Mao-Lun, Imbert, Eric, gren, Jon, Rutter, Matthew T., Fenster, Charles B., Weigel, Detlef

Issue&Volume: 2022-01-12

Abstract: Since the first half of the twentieth century, evolutionary theory has been dominated by the idea that mutations occur randomly with respect to their consequences1. Here we test this assumption with large surveys of de novo mutations in the plant Arabidopsis thaliana. In contrast to expectations, we find that mutations occur less often in functionally constrained regions of the genome—mutation frequency is reduced by half inside gene bodies and by two-thirds in essential genes. With independent genomic mutation datasets, including from the largest Arabidopsis mutation accumulation experiment conducted to date, we demonstrate that epigenomic and physical features explain over 90% of variance in the genome-wide pattern of mutation bias surrounding genes. Observed mutation frequencies around genes in turn accurately predict patterns of genetic polymorphisms in natural Arabidopsis accessions (r=0.96). That mutation bias is the primary force behind patterns of sequence evolution around genes in natural accessions is supported by analyses of allele frequencies. Finally, we find that genes subject to stronger purifying selection have a lower mutation rate. We conclude that epigenome-associated mutation bias2 reduces the occurrence of deleterious mutations in Arabidopsis, challenging the prevailing paradigm that mutation is a directionless force in evolution.

DOI: 10.1038/s41586-021-04269-6

Source: https://www.nature.com/articles/s41586-021-04269-6