Abstract: Two nectarine cultivars，‘CN9’（white-fleshed）and its yellow-fleshed bud sport mutant ‘CN9Y’，were taken as materials to investigated carotenoids metabolism and genes expression. Qualitative and quantitative levels of carotenoids were analzed by HPLC，the expression levels of carotenoid biosynthetic genes were detected by real time qPCR method. The results included that no distinct difference in flesh color appeared between‘CN9’and its mutant during early development stage，while at the ripening stage，differences in flesh color became dramatic. At early development stage，the total carotenoid levels were similar in‘CN9’and‘CN9Y’fruits，dominated by the presence of β-carotene，violaxanthin，and lutein. The total carotenoid content was much higher in‘CN9Y’than in‘CN9’at the ripening stage，exhibiting higher quantities of violaxanthin，β-carotene，and zeaxanthin. Real-time quantitative expression analysis showed that the CCD4 transcript levels were dramatically higher at late ripening stages in‘CN9’with respect to‘CN9Y’. These results indicated that the difference in theexpression level of CCD4 between‘CN9’and its yellow-fleshed mutant is likely to be the major determinant of carotenoid accumulation levels.

Key words: nectarine, white-flesh, yellow-flesh, bud sport mutant, carotenoids, gene expression