Phytoene synthase (PSY) is the first committed enzyme in carotenoid biosynthesis, which plays important role in ripen fruit colour. However, the roles of CaPSY genes are not explained detail in ripen pepper fruit colour. In this study, three CaPSY genes (CaPSY1, CaPSY2 and CaPSY3) were identified through basic local alignment search tool (BLAST) in pepper genome. Among them, CaPSY1 was predicted as putative candidate based on relative expression values using five developmental stages of fruit in Zunla-1 cultivar and also in ripen fruits of five contrasting pepper lines. The CaPSY1 was characterised functionally through virus-induced gene silencing (VIGS) in ripen fruits and overexpression in Arabidopsis thaliana (L.) Heynh. Silencing of CaPSY1 gene altered colour with increased lutein and decreased zeaxanthin content in pepper fruits. The transgenic Arabidopsis line CaPSY1 gene showed higher expression of PSY1 gene compared with WT and dwarf phenotype due to reduction of GA₃ (gibberellic acid) and higher abscisic acid (ABA) content. Our results confirmed that CaPSY1 gene involved in carotenoid metabolism in ripen pepper fruit and provide clue to develop bright red coloured pepper lines through breeding.

番茄红素合酶（PSY）是类胡萝卜素生物合成中的第一个重要酶，在成熟果实的颜色中起重要作用。但是，CaPSY基因的作用在成熟的辣椒果实颜色中未作详细解释。本研究通过辣椒基因组中的基本局部比对搜索工具（BLAST）鉴定了三个CaPSY基因（CaPSY1，CaPSY2和CaPSY3）。其中，基于相对表达值，使用Zunla-1品种的果实的五个发育阶段以及五个对比胡椒系的成熟果实中的相对表达值，将CaPSY1预测为候选候选。该CaPSY1通过成熟果实中的病毒诱导基因沉默（VIGS）和拟南芥（L.）Heynh中的过表达来进行功能鉴定。CaPSY1基因的沉默会随着辣椒果实中叶黄素的增加和玉米黄质含量的减少而改变颜色。与野生型和矮型相比，转基因拟南芥品系CaPSY1基因表现出较高的PSY1基因表达，这是由于GA ₃（赤霉素）的减少和脱落酸（ABA）含量的增加。我们的结果证实，CaPSY1基因参与成熟辣椒果实中的类胡萝卜素代谢，并为通过育种发展鲜红色辣椒系提供了线索。