Abstract: To investigate the function of tomato dxs gene and confirm it can facilitate the accumulation of the downsteam metabolites, the coding sequence of dxs gene ( ledxs) was cloned from tomato by reverse-transcrip tion polymerase chain reaction (RT-PCR) , and constructed into the prokaryotic exp ression vector pTrcLeDXS. The lycopene biosynthetic pathway in E. coli strain XL1-Blue was reconstructed by transforming with pAC-LYC carrying the three key enzymes, crtE, crtB and crt I, in the lycopene pathway. This engineered XL-2 Blue was transformed with pTrcLeDXS. Then the engineerd bacteria was used to construct the color complementation p late and detect the content of lycopene after been fermented. The engineered XL1-Blue harboring pAC-LYC and pTrcLeDXS became red because of the p roduction of lycopene. And after 21 h cultivation,the lycopene p roductivity reached 605.25μg·L^-1. The results demonstrate that ledxs can facilitate the carotenoid pathway flow to lycopene biosynthesis, and p rove the function of ledxs by color comp lementation. The lycopene p roductivity of the engineered bacteria could meet the requirement of industrial p roduction and can be used for fermentation to produce lycopene.

Key words: Tomato, DXS, Cloning, Lycopene, Color comp lementation, Fermentation