Abstract：
Noncoding polymorphism frequently associates with phenotypic variation, but causation and mechanism are rarely established. Noncoding single-nucleotide polymorphisms (SNPs) characterize the major haplotypes of the Arabidopsis thaliana floral repressor gene FLOWERING LOCUS C (FLC). This noncoding polymorphism generates a range of FLC expression levels, determining the requirement for and the response to winter cold. The major adaptive determinant of these FLC haplotypes was shown to be the autumnal levels of FLC expression. Here, we investigate how noncoding SNPs influence FLC transcriptional output. We identify an upstream transcription start site (uTSS) cluster at FLC, whose usage is increased by an A variant at the promoter SNP-230. This variant is present in relatively few Arabidopsis accessions, with the majority containing G at this site. We demonstrate a causal role for the A variant at -230 in reduced FLC transcriptional output. The G variant upregulates FLC expression redundantly with the major transcriptional activator FRIGIDA (FRI). We demonstrate an additive interaction of SNP-230 with an intronic SNP+259, which also differentially influences uTSS usage. Combinatorial interactions between noncoding SNPs and transcriptional activators thus generate quantitative variation in FLC transcription that has facilitated the adaptation of Arabidopsis accessions to distinct climates.
摘要：
非编码多态性经常与表型变异相关，但是因果关系和机制很少建立。非编码单核苷酸多态性（SNP）表征拟南芥花阻遏基因FLOWERINGLOCUSC（FLC）的主要单倍型。这种非编码多态性产生一系列FLC表达水平，确定冬季寒冷的要求和响应。这些FLC单倍型的主要适应性决定因素显示为FLC表达的秋季水平。这里,我们研究了非编码SNP如何影响FLC转录输出。我们确定了FLC的上游转录起始位点（uTSS）簇，其使用通过启动子SNP-230处的A变体而增加。此变体存在于相对较少的拟南芥种质中，在这个网站上，大多数包含G。我们证明了-230处的A变体在降低的FLC转录输出中的因果作用。G变体与主要转录激活因子FRIGIDA(FRI)冗余地上调FLC表达。我们证明了SNP-230与内含子SNP259的累加相互作用，这也不同地影响了uTSS的使用。因此，非编码SNP和转录激活因子之间的组合相互作用在FLC转录中产生了定量变化，这促进了拟南芥对不同气候的适应。
