Abstract Chromoplast differentiation during flesh development in different watermelon varieties was observed by optical and transmission electron microscopy. Carotenoid analyses by LC–MS/MS revealed that red-fleshed watermelon mainly accumulated lycopene, which eventually shaped into a crystalloid chromoplast near maturation, while the accumulation of other carotenoids led to the formation of globular chromoplasts. Expressions of three phytoene synthase genes (ClPSY) and seven plastid lipid-associated genes (ClPAP) in different flesh development stages were analyzed. Based on our results, the expression of ClPSY1 was consistent with the accumulation of phytofluene and total carotenoids, while that of ClPAP (Cla014416) was consistent with ClPSY1. CDS and promoter sequence variations of ClPSY1 and Cla014416 may be the main reason for the significant expression levels based on gene and promoter cloning.

中文翻译：

---

西瓜中 ClPAP 和 ClPSY1 的表达与有色体分化、类胡萝卜素积累和果肉颜色形成相关

摘要 通过光学显微镜和透射电子显微镜观察了不同西瓜品种在果肉发育过程中的色体分化。LC-MS/MS 对类胡萝卜素的分析表明，红肉西瓜主要积累番茄红素，最终在接近成熟时形成晶体状有色体，而其他类胡萝卜素的积累导致球状有色体的形成。分析了三个八氢番茄红素合酶基因（ClPSY）和七个质体脂质相关基因（ClPAP）在不同果肉发育阶段的表达情况。根据我们的结果，ClPSY1 的表达与植物氟和总类胡萝卜素的积累一致，而 ClPAP (Cla014416) 的表达与 ClPSY1 一致。