Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, 450009, China.
College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China.
Theor Appl Genet. 2018 Apr;131(4):947-958. doi: 10.1007/s00122-018-3050-5. Epub 2018 Jan 23.
A 159 bp deletion in ClFS1 gene encoding IQD protein is responsible for fruit shape in watermelon. Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is known for its rich diversity in fruit size and shape. Fruit shape has been one of the major objectives of watermelon breeding. However, the candidate genes and the underlying genetic mechanism for such an important trait in watermelon are unknown. In this study, we identified a locus on chromosome 3 of watermelon genome controlling fruit shape. Segregation analysis in F and BC populations derived from a cross between two inbred lines "Duan125" (elongate fruit) and "Zhengzhouzigua" (spherical fruit) suggests that fruit shape of watermelon is controlled by a single locus and elongate fruit (OO) is incompletely dominant to spherical fruit (oo) with the heterozygote (Oo) being oval fruit. GWAS profiles among 315 accessions identified a major locus designated on watermelon chromosome 3, which was confirmed by BSA-seq mapping in the F population. The candidate gene was mapped to a region 46 kb on chromosome 3. There were only four genes present in the corresponding region in the reference genome. Four candidate genes were sequenced in this region, revealing that the CDS of Cla011257 had a 159 bp deletion which resulted in the omission of 53 amino acids in elongate watermelon. An indel marker was derived from the 159 bp deletion to test the F population and 105 watermelon accessions. The results showed that Cla011257 cosegregated with watermelon fruit shape. In addition, the Cla011257 expression was the highest at ovary formation stage. The predicted protein of the Cla011257 gene fitted in IQD protein family which was reported to have association with cell arrays and Ca-CaM signaling modules. Clear understanding of the genes facilitating the fruit shape along with marker association selection will be an effective way to develop new cultivars.
一个 159bp 的缺失负责西瓜果实形状的 ClFS1 基因编码 IQD 蛋白。西瓜（Citrullus lanatus (Thunb.) Matsum. & Nakai）以其丰富的果实大小和形状多样性而闻名。果实形状一直是西瓜育种的主要目标之一。然而，这种重要性状的候选基因和潜在遗传机制在西瓜中尚不清楚。在这项研究中，我们确定了控制西瓜果实形状的染色体 3 上的一个位点。来自两个自交系“Duan125”（长果）和“Zhengzhouzigua”（圆果）杂交后代的 F 和 BC 群体的分离分析表明，西瓜果实形状由单个位点控制，长果（OO）对圆果（oo）不完全显性，杂合子（Oo）为椭圆形果实。在 315 个品种的 GWAS 图谱中确定了一个主要的标记位点，该标记在 F 群体的 BSA-seq 图谱中得到了证实。候选基因被定位到参考基因组 3 号染色体上 46kb 的区域。在该区域，参考基因组中只有四个基因。在这个区域测序了四个候选基因，结果表明 Cla011257 的 CDS 有一个 159bp 的缺失，导致长果中缺失 53 个氨基酸。从 159bp 的缺失中衍生出一个插入缺失标记来测试 F 群体和 105 个西瓜品种。结果表明 Cla011257 与西瓜果实形状共分离。此外，Cla011257 的表达在子房形成阶段最高。Cla011257 基因的预测蛋白属于 IQD 蛋白家族，该家族被报道与细胞阵列和 Ca-CaM 信号模块有关。对促进果实形状的基因的深入了解以及与标记的关联选择将是开发新品种的有效途径。
