Abstract: Two nectarine cultivars，CN9（white-fleshed）and its yellow-fleshed mutant CN9Y，were used as materials to investigate carotenoids metabolism and genes expression. Qualitative and quantitative levels of carotenoids were analyzed by using HPLC，the expression of genes related to carotenoid accumulation were detected via real-time qPCR method. The results showed that the total carotenoid and β-carotene content of CN9Y nectarine were 5.7 and 19.6 times higher than that of CN9 respectively in calyxes. Carotenoid metabolism genes of both biosynthesis and degradation showed significant higher expression level in CN9Y calyxes than in CN9，except DXS and LCY-E. In petals，the total carotenoid content was similar between CN9 and CN9Y，but their carotenoid composition contents were different. The gene expression levels of DXS，HDR，PDS，LCY-E，CHY-B and CCD1 were higher in CN9Y petals than in CN9，but ZDS，NCED1 and CCD4 were lower in CN9Y than in CN9. In leaves，the carotenoid compositions of CN9 and CN9Y were all dominated by β-carotene，violaxanthin，cis-9-violaxanthin and lutein，the total carotenoid content was similar between CN9 and CN9Y during early fruit development stage，but CN9Y obviously increased after fruits matured，however，CN9 was still stabilized. During 55–80 d after flowering，only the expression level of CCD4 was in accordance with carotenoid accumulation，it is suggested that the difference of CCD4 expression level may lead to the difference of carotenoid accumulation in leaves between the two materials in later stage.

Key words: nectarine, mutant, white-flesh, yellow-flesh, carotenoid, gene