Elevation of the provitamin A content of transgenic tomato plants


Tomato products are the principal dietary sources of lycopene and major source of β-carotene, both of which have been shown to benefit human health. To enhance the carotenoid content and profile of tomato fruit, we have produced transgenic lines containing a bacterial carotenoid gene (crtI) encoding the enzyme phytoene desaturase, which converts phytoene into lycopene. Expression of this gene in transgenic tomatoes did not elevate total carotenoid levels. However, the β-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 repressed. The alteration in carotenoid content of these plants did not affect growth and development. Levels of noncarotenoid isoprenoids were unchanged in the transformants. The phenotype has been found to be stable and reproducible over at least four generations.

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Figure 1: Carotenoid biosynthesis showing the diversity of desaturases.
Figure 2: Uniform distribution of CRTI protein among different fruit tissues.
Figure 3: Northern blot analysis of crtI primary transformants.
Figure 4: Inheritance and expression of crtI in 20 progeny plants.


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Financial support was principally from the European Community BIOTECH Programme (#B102 CT-930400, as part of the project of Technological Priority 1993–1996). We thank Rachel Drake for helpful discussions. Zeneca Agrochemicals is gratefully acknowledged for the provision of labatory and greenhouse space. We thank Karen Bacon for maintenance of the plants.

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Correspondence to Peter M. Bramley.

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Römer, S., Fraser, P., Kiano, J. et al. Elevation of the provitamin A content of transgenic tomato plants. Nat Biotechnol 18, 666–669 (2000). https://doi.org/10.1038/76523

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