Natural variation in processability of individual Arabidopsis thaliana microRNAs. Arabidopsis thaliana

Like protein coding genes, loci that produce microRNAs (miRNAs) are generally considered to be under purifying selection, consistent with miRNA polymorphisms being able to cause disease. Nevertheless, it has been hypothesized that variation in miRNA genes may contribute to phenotypic diversity. Here we demonstrate that a naturally occurring polymorphism in the MIR164A gene interacts epistatically with an unlinked locus to affect leaf shape and shoot architecture in Arabidopsis thaliana. A single-base pair substitution in the miRNA complementary sequence alters the stability of the miRNA:miRNA* duplex. It thereby interferes with processing of the precursor and greatly reduces miRNA accumulation. We demonstrate that this is not a rare exception, but that natural strains of Arabidopsis thaliana harbor dozens of similar polymorphisms that affect processing of a wide range of miRNA precursors. Our results suggest that natural variation in miRNA processability due to cis mutations is a common contributor to phenotypic variation in plants. Overall design: sRNA sequencing transgenic A. thaliana

与蛋白质编码基因类似，编码微小核糖核酸（microRNAs，miRNAs）的基因座通常被认为处于纯化选择压力之下，这与miRNA多态性可引发疾病的结论相符。尽管如此，已有假说提出miRNA基因的变异或许会促成表型多样性。本研究证实，MIR164A基因中存在的一种自然多态性，可与一个非连锁基因座发生上位性互作，进而影响拟南芥（Arabidopsis thaliana）的叶片形态与地上部结构。该miRNA互补序列中的单碱基替换，会改变miRNA:miRNA*双链的稳定性，进而干扰前体的加工过程，并大幅降低miRNA的积累水平。本研究同时证实，此类现象并非罕见特例，拟南芥的自然株系中存在数十个类似的多态性位点，可影响众多miRNA前体的加工过程。研究结果表明，由顺式突变引发的miRNA加工能力的自然变异，是植物表型变异的常见诱因之一。整体实验设计：小核糖核酸（small RNA）测序 转基因拟南芥