Abstract: In this study, the phytoene synthase gene （PSY,PjPSY2） from the fruits of thePanax japonicusand conducted bioinformatics analysis and functional validation were cloned. The results showed that the open reading frame of thePjPSY2gene was 945 bp, encoding a protein with typical phytoene synthase structural characteristics, and exhibiting high homology with other known plantPSYgenes. RT-PCR analysis showed that thePjPSY2gene had been integrated into the genome of wild-typeArabidopsis thalianaand was expressed at the transcriptional level at significantly higher levels than in wild-type plants. Analysis of five carotenoid components and their contents preliminarily confirmed that thePjPSY2gene affects fruit coloration inP. japonicusby regulating the biosynthesis of carotenoids. This study provides a foundation for a deeper understanding of the molecular characteristics and functions ofPjPSY2gene inP. japonicusfruits, and the results offer a scientific basis for the genetic improvement and breeding ofP. japonicus.

Key words: Panax japonicus, phytoene synthase, bioinformatics, fruit colour, carotenoid synthesis