Improved soybean cultivars have been adapted to grow at a wide range of latitudes, enabling expansion of cultivation worldwide. However, the genetic basis of this broad adaptation is still not clear. Here, we report the identification of GmPRR3b as a major flowering time regulatory gene that has been selected during domestication and genetic improvement for geographic expansion. Through a genome-wide association study of a diverse soybean landrace panel consisting of 279 accessions, we identified 16 candidate quantitative loci associated with flowering time and maturity time. The strongest signal resides in the known flowering gene E2, verifying the effectiveness of our approach. We detected strong signals associated with both flowering and maturity time in a genomic region containing GmPRR3b. Haplotype analysis revealed that GmPRR3b^H6 is the major form of GmPRR3b that has been utilized during recent breeding of modern cultivars. mRNA profiling analysis showed that GmPRR3b^H6 displays rhythmic and photoperiod-dependent expression and is preferentially induced under long-day conditions. Overexpression of GmPRR3b^H6 increased main stem node number and yield, while knockout of GmPRR3b^H6 using CRISPR/Cas9 technology delayed growth and the floral transition. GmPRR3b^H6 appears to act as a transcriptional repressor of multiple predicted circadian clock genes, including GmCCA1a, which directly upregulates J/GmELF3a to modulate flowering time. The causal SNP (Chr12:5520945) likely endows GmPRR3b^H6 a moderate but appropriate level of activity, leading to early flowering and vigorous growth traits preferentially selected during broad adaptation of landraces and improvement of cultivars.

改良的大豆品种已适应在广泛的纬度上生长，从而使种植范围扩大到全世界。但是，这种广泛适应的遗传基础仍不清楚。在这里，我们报告鉴定GmPRR3b作为主要的开花时间调控基因，已在驯化和遗传改良期间选择以进行地理扩展。通过对由279个种质组成的多种大豆地方品种组成的全基因组关联研究，我们确定了16个与开花时间和成熟时间相关的候选定量基因座。最强的信号存在于已知的开花基因E2中，验证我们方法的有效性。我们在包含GmPRR3b的基因组区域中检测到与开花和成熟时间相关的强信号。单倍型分析表明，GmPRR3b ^H6是主要的形式GmPRR3b已经近现代品种选育过程中被使用。mRNA谱分析表明，GmPRR3b ^H6表现出节律性和光周期依赖性表达，并在长时间条件下被优先诱导。GmPRR3b ^H6的过表达增加了主茎节数和产量，而使用CRISPR / Cas9技术敲除GmPRR3b ^H6则延迟了生长和花期过渡。GmPRR3b^H6似乎是多个预测的生物钟基因的转录阻遏物，包括GmCCA1a，其直接上调J / GmELF3a来调节开花时间。因果SNP（Chr12：5520945）可能赋予GmPRR3b ^H6中等但适当的活性水平，从而导致在早熟的地方品种广泛适应和品种改良期间优先选择的早期开花和旺盛的生长性状。