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Crop Biotech Update

Overexpression of a Gene from Pepper Affects Xanthophyll Production in GE Tomato

February 4, 2011

Xanthophylls are yellow pigments produced by plant chloroplast which absorb light and disperse excess light during photosynthesis. Chromoplast, another pigment producing plastids, has also evolved to produce pigments to attract pollinators. In tomato, chromoplasts in the petals produce more xanthophylls than those in fruits. Caterina D'Ambrosio and other scientists from Metapontum Agrobios, Italy inserted CrtR-b2 (carotene beta hydroxylase 2) from pepper to tomato to induce production of more xanthophyll precursors.

Results of their study indicate that the plastid-containing tissues of hemizygous transgenic plants have increased amounts of xanthophylls compared with the control. For instance, the leaves produced more violaxanthin (orange pigment), four times higher than usual. Ripe fruits also contained excess violaxanthin and significant amounts of esterified xanthophylls.

On the other hand, homozygous transgenic plants had reduced transcript content in the tissues, especially in the petals, due to the occurrence of post-translational gene silencing. This study suggests that tomato fruits can also accumulate xanthophylls like its petal and pepper fruits. This study could also serve as a model for other studies on alteration in the production of beta-carotene-derived xanthophylls to further elucidate molecular mechanisms in carotenoid metabolism in tomato.

Read the abstract of this study at http://www.springerlink.com/content/9w8460128q021x16/.