Phytoene synthase 1 (PSY1) and capsanthin-capsorubin synthase (CCS) are two major genes responsible for fruit color variation in pepper (Capsicum spp.). However, the role of PSY2 remains unknown. We used a systemic approach to examine the genetic factors responsible for the yellow fruit color of C. annuum ‘MicroPep Yellow’ (MY) and to determine the role of PSY2 in fruit color. We detected complete deletion of PSY1 and a retrotransposon insertion in CCS. Despite the loss of PSY1 and CCS function, both MY and mutant F₂ plants from a cross between MY and the ‘MicroPep Red’ (MR) accumulated basal levels of carotenoids, indicating that other PSY genes may complement the loss of PSY1. qRT-PCR analysis indicated that PSY2 was constitutively expressed in both MR and MY fruits, and a color complementation assay using Escherichia coli revealed that PSY2 was capable of biosynthesizing a carotenoid. Virus-induced gene silencing of PSY2 in MY resulted in white fruits. These findings indicate that PSY2 can compensate for the absence of PSY1 in pepper fruit, resulting in the yellow color of MY fruits.

中文翻译：

---

番茄红素合酶2可以补偿辣椒果实中PSY1的缺失，从而控制其颜色。

番茄红素合酶1（PSY1）和辣椒红素-辣椒素合酶（CCS）是导致辣椒（Capsicum spp。）果实颜色变化的两个主要基因。但是，PSY2的作用仍然未知。我们使用了系统的方法来检查导致C. annuum'MicroPep Yellow'（MY）的黄色果实颜色发生的遗传因素，并确定PSY2在果实颜色中的作用。我们检测到CCS中PSY1的完全缺失和反转录子插入。尽管PSY1和CCS功能丧失，MY和突变体F ₂MY和'MicroPep Red'（MR）之间杂交的植物积累了基础水平的类胡萝卜素，这表明其他PSY基因可能弥补了PSY1的损失。qRT-PCR分析表明PSY2在MR和MY水果中均组成性表达，并且使用大肠杆菌进行的颜色互补测定显示PSY2能够生物合成类胡萝卜素。MY中病毒引起的PSY2基因沉默导致白色果实。这些发现表明，PSY2可以弥补辣椒果实中PSY1的缺失，从而导致MY果实呈黄色。