In a rapidly changing climate, flowering time (FL) adaptation is important to maximize seed yield in flax (Linum usitatissimum L.). However, our understanding of the genetic mechanism underlying FL in this multipurpose crop remains limited. With the aim of dissecting the genetic architecture of FL in flax, a genome-wide association study (GWAS) was performed on 200 accessions of the flax core collection evaluated in four environments. Two single-locus and six multi-locus models were applied using 70,935 curated single nucleotide polymorphism (SNP) markers. A total of 40 quantitative trait nucleotides (QTNs) associated with 27 quantitative trait loci (QTL) were identified in at least two environments. The number of QTL with positive-effect alleles in accessions was significantly correlated with FL (r = 0.77 to 0.82), indicating principally additive gene actions. Nine QTL were significant in at least three of the four environments accounting for 3.06–14.71% of FL variation. These stable QTL spanned regions that harbored 27 Arabidopsis thaliana and Oryza sativa FL-related orthologous genes including FLOWERING LOCUS T (Lus10013532), FLOWERING LOCUS D (Lus10028817), transcriptional regulator SUPERMAN (Lus10021215), and gibberellin 2-beta-dioxygenase 2 (Lus10037816). In silico gene expression analysis of the 27 FL candidate gene orthologous suggested that they might play roles in the transition from vegetative to reproductive phase, flower development and fertilization. Our results provide new insights into the QTL architecture of flowering time in flax, identify potential candidate genes for further studies, and demonstrate the effectiveness of combining different GWAS models for the genetic dissection of complex traits.

在快速变化的气候中，适应开花时间（FL）对于最大化亚麻（Linum usitatissimum L.）的种子产量非常重要。但是，我们对这种多用途作物中FL的遗传机制的理解仍然有限。为了剖析亚麻中FL的遗传结构，对四种环境中评估的200个亚麻核心种质进行了全基因组关联研究（GWAS）。使用70,935个经过策划的单核苷酸多态性（SNP）标记，应用了两个单基因座模型和六个多基因座模型。在至少两个环境中，共鉴定出与27个定量性状基因座（QTL）相关的40个定量性状核苷酸（QTN）。种质中具有正效应等位基因的QTL数量与FL显着相关（r  = 0.77至0.82），主要表示加性基因作用。在四个环境中的至少三个中，有九个QTL显着，占FL变异的3.06–14.71％。这些稳定的QTL跨越了27个拟南芥和与稻Oryza sativa FL相关的直系同源基因的区域，包括FLOWERING LOCUS T（Lus10013532），FLOWERING LOCUS D（Lus10028817），转录调节子SUPERMAN（Lus10021215）和Gibberellin 2-beta- dioxygenase 2（2）。）。在计算机基因表达分析中，直系同源的27个FL候选基因表明它们可能在从营养期到生殖期，花的发育和受精的过程中发挥作用。我们的结果为亚麻开花时间的QTL结构提供了新的见解，确定了潜在的候选基因有待进一步研究，并证明了结合不同GWAS模型进行复杂性状遗传解剖的有效性。