| TECHNOLOGY |
The characteristic yellow-orange color of Cheez Whiz comes from a natural plant pigment, the carotenoid bixin. Known in crude extract as annatto, bixin is isolated from the seeds of the tropical plant Bixa orellana. Researchers have now determined how the shrub synthesizes bixin from another carotenoid, lycopene, and are planning to use that knowledge to engineer bixin-producing tomatoes. the group hypothesized that the structural similarity between bixin and saffron meant a similar biosynthetic pathway. They used DNA probes crafted from the genes of other plants to look for similar sequences in B. orellana. They found the enzyme pathway they were looking for: a dioxygenase to convert lycopene to bixin aldehyde, then an aldehyde dehydrogenase to produce norbixin, and finally a methyltransferase to yield bixin. The researchers transferred the relevant B. orellana genes into bacteria preengineered to produce lycopene and were able to detect bixin production. But it takes two to four years to grow B. orellana and harvest the seed. Author proposes engineering tomato plants, which yield lycopene-rich fruit in a matter of months, to produce bixin as well. Bacteria wouldn't be as useful for bixin production in industrial quantities, because they cannot store large amounts of the chemical. However it's produced, bixin would likely be one of the first natural pigments to enter the arena of genetically modified products.
Inserting three genes into tomatoes will be challenging--it will likely require inserting each gene into one tomato, then combining them through cross-breeding. Authorhopes to have bixin-producing tomatoes within two years.
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