Elevation of the provitamin A content of transgenic tomato plants

Tomato products are the principal dietary sources of lycopene and major sou rce of beta-carotene, both of which have been shown to benefit human health . To enhance the carotenoid content and profile of tomato fruit, we have pr oduced transgenic lines containing a bacterial carotenoid gene (crtl) encod ing the enzyme phytoene desaturase, which converts phytoene into lycopene, Expression of this gene in transgenic tomatoes did not elevate total carote noid levels. However, the beta-carotene content increased about threefold, up to 45% of the total carotenoid content, Endogenous carotenoid genes were concurrently upregulated, except for phytoene synthase, which was represse d. The alteration in carotenoid content of these plants did not affect grow th and development. Levels of noncarotenoid isoprenoids were unchanged in t he transformants, The phenotype has been found to be stable and reproducibl e over at least four generations.