Dwarfism in crops is a useful breeding trait. In this study, we aimed to identify a candidate gene controlling semi-dwarfism in watermelon (Citrullus lanatus) using a combination of genetic mapping and quantitative trait loci (QTL)-seq. We evaluated phenotypes using an F₂ and F_2:3 population derived from a cross between a “Bush Sugar Baby” (BSB, semi-dwarf type) and a PCL-J1 (normal type) cultivar. Results indicated that a single recessive gene confers semi-dwarfism in BSB. We constructed a genetic map using 180 F₂ plants and 336 single-nucleotide polymorphisms (SNPs), detected using genotyping-by-sequencing, and mapped the semi-dwarfism locus, sdw-1, between the SNP markers linked by 9.6 cM (0.99 Mb) on Chr. 9. QTL analysis pointed to the same genomic location for sdw-1 using single-marker analysis. Further, based on the QTL-seq, we identified a significant genomic region for sdw-1 that matched with the sdw-1-flanking region in the genetic linkage map. This 1-Mb region was narrowed down by mapping three SNP markers developed from the QTL-seq data. The sdw-1 locus was mapped to the 0.44-Mb genomic region, which harbored 13 genes. One of the 13 genes, ClCG09G018320 (ATP-binding cassette (ABC) transporter B family member 19), showed the SNPs in its coding sequence, and cleaved amplified APS markers developed from those SNPs co-segregated with sdw-1 in fine mapping using 620 F₂ plants. Our results implied that a frameshift mutation in the ABC transporter gene and the resulting alteration in auxin transportation are the most likely to be responsible for semi-dwarfism in BSB.

作物中的侏儒症是有用的育种特性。在这项研究中，我们的目的是确定一个候选基因控制西瓜（半侏儒症西瓜使用遗传作图和数量性状基因座（QTL）的-SEQ的组合）。我们使用F ₂和F _2：3群体评估表型，这些群体来自“布什糖宝宝”（BSB，半矮型）和PCL-J1（正常类型）品种之间的杂交。结果表明，单个隐性基因赋予BSB半侏儒症。我们使用180个F ₂植物和336个单核苷酸多态性（SNP）构建了遗传图谱，并通过测序进行了基因分型，并绘制了半侏儒症基因座 sdw-1在Chr。上通过9.6 cM（0.99 Mb）链接的SNP标记之间。9. 使用单标记分析，QTL分析指向sdw-1的相同基因组位置 。此外，基于QTL-seq，我们确定了sdw-1的重要基因组区域  ，该区域与遗传连锁图中的sdw-1侧翼区域匹配 。通过映射从QTL-seq数据开发的三个SNP标记，可以缩小该1-Mb区域的范围。的 SDW-1 基因座映射到0.44-MB的基因组区域，其窝藏13个基因。这13个基因之一是ClCG09G018320（ATP结合盒（ABC）转运蛋白B家族成员19），显示了其编码序列中的SNP，并裂解了与sdw-1共分离的SNP产生的扩增APS标记  使用620 F ₂植物进行精细定位。我们的结果表明，ABC转运蛋白基因的移码突变和生长素转运的改变最可能是造成BSB半矮化的原因。