Abstract:To explore the molecular mechanism of carotenoid accumulation and metabolism, two pepper ( Capsicum annuum L.) inbred lines named RF1601 ( the color of mature fruit is red) and PF1511 ( the color of mature fruit is purple) were used as materials in this study. The carotenoids in 5 different periods of fruits were extracted for quantitative analysis of lutein, capsanthin and beta carotene by HPLC. The expression of 7 genes related to carotenoid biosynthesis in these materials was also analyzed by the realtime PCR. The results showed that with the ripening of fruits, the contents of carotenoids in RF1601 and PF1511 increased gradually, reaching the highest value of 173. 0 and 37. 9 μg/g FW at the mature stage, respectively. The amount of lutein in RF1601 was about 3 times as much as that PF1511. Although capsanthin was unable to be detected at the juvenile stage of these materials, with the growing of the fruits, the qualities of capsanthin in RF1601 showed an overall upward trend, while it was still undetectable in the PF1511 throughout the whole period. Beta-carotene reduced to the minimum and then increased slowly. The expression of PSY, PDS, ZDS and LYC in RF1601 remained at a low level in the whole period, and CCS, the key gene of capsaicin synthesis, expressed at a high level at the mature stage. While PSY, PDS, ZDS and LYC in PF1511 were activated at the early stage and CCS almost kept silence throughout the whole period.