The color of watermelon flesh is an important trait determined by a series of carotenoids. Herein, we used Cream of Saskatchewan (pale yellow flesh) and PI 186490 (white flesh) as parental materials for an F₂ segregation and initial mapping using the bulked segregant analysis sequencing (BSA-seq) strategy. The BSA results revealed a flesh color-related QTL that spans approximately 2.45 Mb on chromosome 6. This region was preliminarily positioned in a 382-kb segment, and then narrowed down into a 66.8-kb segment with 1260 F₂ individuals. A total of nine candidate genes were in the fine mapping interval, but only Cla007528 (encoding chlorophyllase) had non-synonymous mutations and was significantly expressed between the parental materials throughout flesh development. We also checked the expression patterns of the carotenoid metabolic pathway genes based on RNA-seq data and qRT-PCR validation. Three genes in the xanthophyll cycle (CICHYB, CINCED-1 and CINCED-7) exhibited differential expression patterns between the two parental lines at different flesh color formation stages. ClPSY1, CIPDS, CIZDS, CICHXE, CICRTISO and CILCYB also exhibited clearly different expression patterns accompanied by carotenoid accumulation.

西瓜果肉的颜色是由一系列类胡萝卜素决定的一个重要性状。在此，我们使用萨斯喀彻温奶油（淡黄色果肉）和 PI 186490（白果肉）作为使用批量分离分析测序 (BSA-seq) 策略进行 F ₂分离和初始映射的亲本材料。BSA结果显示在6号染色体上有一个跨越约2.45 Mb的肉色相关QTL。该区域初步定位在一个382-kb的片段，然后缩小到一个66.8-kb的片段，有1260个F ₂个体。共有 9 个候选基因处于精细定位区间，但只有Cla007528（编码叶绿素酶）具有非同义突变，并且在整个果肉发育过程中在亲本材料之间显着表达。我们还根据 RNA-seq 数据和 qRT-PCR 验证检查了类胡萝卜素代谢途径基因的表达模式。叶黄素循环中的三个基因（CICHYB、CINCED-1和CINCED-7）在不同肉色形成阶段的两个亲本系之间表现出差异表达模式。ClPSY1、CIPDS、CIZDS、CICHXE、CICRTISO和CILCYB也表现出明显不同的表达模式，伴随着类胡萝卜素的积累。