背景回顾：Phenotypic evolution is usually attributed to changes in protein function or gene transcription. In principle, mutations that affect protein abundance through enhancing or attenuating protein translation also could be an important source for phenotypic evolution. 

提出问题：However, these types of mutations remain largely unexplored in the studies of phenotypic variation in nature. 

主要发现：Through fine-scale genetic mapping and functional interrogation, we identify a single nucleotide substitution in an anthocyanin-activating R2R3-MYB gene causing flower color variation between a pair of closely related monkeyflower (Mimulus) species, the hummingbird-pollinated Mimulus cardinalis, and self-pollinated Mimulus parishii. 

结果：This causal mutation is located in the 5′ untranslated region and generates an upstream ATG start codon, leading to attenuated protein translation and reduced flower coloration in the self-pollinated species. 

结论：Together, our results provide empirical support for the role of mutations affecting protein translation, as opposed to protein function or transcript level, in natural phenotypic variation.

 摘 要 

表型演化通常归因于蛋白功能或基因转录的变化。总体上，能够增强或减弱蛋白翻译的突变，从而影响蛋白丰度，这些突变也可能是表型演化的重要来源。然而，在有关自然界表型变异的研究中，这类突变在很大程度上尚未被探索。通过精细的遗传图谱和功能实验，作者鉴定到了一个花色苷激活因子R2R3-MYB基因的单核苷酸替换，导致了一对近缘猴面花物种之间的花色变异，即蜂鸟授粉的红花猴面花（Mimulus cardinalis）和自花授粉的Mimulus parishii。该原因突变位于5′非翻译区，并产生一个上游ATG起始密码子，导致自花授粉物种中蛋白翻译减弱以及花瓣着色减弱。总之，本文的研究结果揭示了在自然表型变异中，影响蛋白翻译而非蛋白功能或转录水平的突变同样发挥了非常重要作用。

** 袁耀武 **