Quantitative traits may be controlled by many loci, many alleles at each locus, and subject to genotype-by-environment interactions, making them difficult to map. One example of such a complex trait is shoot branching in the model plant Arabidopsis, and its plasticity in response to nitrate. Here, we use artificial selection under contrasting nitrate supplies to dissect the genetic architecture of this complex trait, where loci identified by association mapping failed to explain heritability estimates. We found a consistent response to selection for high branching, with correlated responses in other traits such as plasticity and flowering time. Genome-wide scans for selection and simulations suggest that at least tens of loci control this trait, with a distinct genetic architecture between low and high nitrate treatments. While signals of selection could be detected in the populations selected for high branching on low nitrate, there was very little overlap in the regions selected in three independent populations. Thus the regulatory network controlling shoot branching can be tuned in different ways to give similar phenotypes.

中文翻译：

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人工选择揭示了拟南芥中枝条分枝的复杂遗传结构及其对硝酸盐供应的响应。

数量性状可能由许多基因座、每个基因座上的许多等位基因控制，并且受到基因型与环境相互作用的影响，使得它们难以绘制图谱。这种复杂性状的一个例子是模式植物拟南芥的枝条分枝及其对硝酸盐反应的可塑性。在这里，我们在对比硝酸盐供应下使用人工选择来剖析这种复杂性状的遗传结构，其中通过关联图谱识别的基因座未能解释遗传力估计。我们发现对高分枝选择的一致反应，以及其他性状（例如可塑性和开花时间）的相关反应。用于选择和模拟的全基因组扫描表明，至少有数十个基因座控制这一性状，低硝酸盐处理和高硝酸盐处理之间具有独特的遗传结构。虽然可以在低硝酸盐高分枝选择的群体中检测到选择信号，但在三个独立群体中选择的区域中几乎没有重叠。因此，控制枝条分支的调控网络可以以不同的方式进行调整，以产生相似的表型。