Li Bingbing, Lu Xuqiang, Gebremeskel Haileslassie, Zhao Shengjie, He Nan, Yuan Pingli, Gong Chengsheng, Mohammed Umer, Liu Wenge
Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, Henan, China.
Front Plant Sci. 2020 Jan 22;10:1689. doi: 10.3389/fpls.2019.01689. eCollection 2019.
Seed coat color is an important trait highly affecting the seed quality and flesh appearance of watermelon (). However, the molecular regulation mechanism of seed coat color in watermelon is still unclear. In the present study, genetic analysis was performed by evaluating F, F and BC populations derived from two parental lines (9904 with light yellow seeds and Handel with black seeds), suggesting that a single dominant gene controls the black seed coat. The initial mapping result revealed a region of interest spanning 370 kb on chromosome 3. Genetic mapping with CAPS and SNP markers narrowed down the candidate region to 70.2 kb. Sequence alignment of the three putative genes in the candidate region suggested that there was a single-nucleotide insertion in the coding region of in 9904, resulting in a frameshift mutation and premature stop codon. The results indicated that named was the candidate gene for black seed coat color in watermelon. In addition, gene annotation revealed that encoded a polyphenol oxidase (PPO), which involved in the oxidation step of the melanin biosynthesis. This research finding will facilitate maker-assisted selection in watermelon and provide evidence for the study of black seed coat coloration in plants.
种皮颜色是一个重要性状，对西瓜的种子品质和果肉外观有很大影响。然而，西瓜种皮颜色的分子调控机制仍不清楚。在本研究中，通过对来自两个亲本系（浅黄色种子的9904和黑色种子的Handel）的F1、F2和BC群体进行评估，进行了遗传分析，结果表明一个单一显性基因控制黑色种皮。初步定位结果显示在3号染色体上有一个跨度为370 kb的感兴趣区域。利用CAPS和SNP标记进行遗传定位，将候选区域缩小到70.2 kb。对候选区域中三个推定基因的序列比对表明，9904中一个基因的编码区存在单核苷酸插入，导致移码突变和提前终止密码子。结果表明，命名为的该基因是西瓜黑色种皮颜色的候选基因。此外，基因注释显示该基因编码一种多酚氧化酶（PPO），其参与黑色素生物合成的氧化步骤。这一研究发现将有助于西瓜的分子标记辅助选择，并为植物黑色种皮着色的研究提供证据。
