The double flower is a highly important breeding trait that affects the ornamental value in many flowering plants. To get a better understanding of the genetic mechanism of double flower formation in Dianthus chinensis, we have constructed a high-density genetic map using 140 F2 progenies derived from a cross between a single flower genotype and a double flower genotype. The linkage map was constructed using double-digest restriction site-associated DNA sequencing (ddRAD-seq) with 2353 single nucleotide polymorphisms (SNPs). Quantitative trait locus (QTL) mapping analysis was conducted for 12 horticultural traits, and major QTLs were identified for nine of the 12 traits. Among them, two major QTLs accounted for 20.7% and 78.1% of the total petal number variation, respectively. Bulked segregant RNA-seq (BSR-seq) was performed to search accurately for candidate genes associated with the double flower trait. Integrative analysis of QTL mapping and BSR-seq analysis using the reference genome of Dianthus caryophyllus suggested that an SNP mutation in the miR172 cleavage site of the A-class flower organ identity gene APETALA2 (DcAP2L) is responsible for double flower formation in Dianthus through regulating the expression of DcAG genes.

中文翻译：

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在石竹中定位与双花表型相关的基因DcAP2L。

双花是非常重要的育种特性，会影响许多开花植物的观赏价值。为了更好地了解石竹双花形成的遗传机制，我们使用140个F2子代构建了高密度遗传图谱，该子代来自单花基因型和双花基因型之间的杂交。使用具有2353个单核苷酸多态性（SNP）的双消化限制性位点相关的DNA测序（ddRAD-seq）构建连锁图。对12个园艺性状进行了数量性状基因座（QTL）定位分析，并为12个性状中的9个确定了主要QTL。其中，两个主要的QTL分别占花瓣总数变化的20.7％和78.1％。进行散装分离子RNA-seq（BSR-seq）以精确搜索与双花性状相关的候选基因。利用石竹参考基因组进行的QTL定位和BSR-seq分析的综合分析表明，A类花器官同一性基因APETALA2（DcAP2L）的miR172切割位点的SNP突变是通过调节石竹的双花形成的原因DcAG基因的表达。