NYT: Israeli academics determine gene for producing furanocoumarins in grapefruit

Via the New York Times: 

...High levels of furanocoumarins interfere with human liver enzymes, among other processes. In their presence, medications can build up to unhealthy levels in the body. And grapefruits and some related citrus fruits are full of them.

But there is no such warning for other kinds of citrus, such as mandarins and other oranges. Citrus researchers at the Volcani Center in Israel reported Wednesday in the journal The New Phytologist that, by crossing mandarins and grapefruit, they’ve uncovered genes that produce furanocoumarins in some citrus fruits. It’s a finding that opens the possibility of creating grapefruit that doesn’t require a warning label.

Scientists had worked out the compounds’ structures and pieced together a basic flowchart of how they are made years ago, said Yoram Eyal, a professor at the Volcani Center. But the precise identities of enzymes catalyzing the process — the proteins that snip off a branch here, or add a piece there — remained mysterious. He and his colleagues knew that one way to identify them was to breed citrus high in furanocoumarins with those without. If the offspring of such a cross had varying levels of the substances, it should be possible, by digging into their genetics, to pinpoint the genes for the proteins.

...When they examined the offspring of a mandarin and a grapefruit, the researchers saw something remarkable. Fifty percent of the young plants had high levels of furanocourmains, and 50 percent had none. That particular signature meant something very specific, in terms of how the ability to make these substances is inherited.

“We saw there was only one gene that could have controlled it,” said Livnat Goldenberg, a Volcani Center researcher who is the lead author of the new study.

...The researchers soon identified the gene controlling the production of furanocoumarins in leaves and fruit, which produces an enzyme called 2-oxoglutarate-dependent dioxygenase, or 2OGD for short. Mandarins, it turns out, have a mutated form of this gene that keeps the enzyme from functioning properly. This version cropped up in all the mandarin and orange varieties the researchers checked, explaining why they do not cause the same problems as grapefruit in people taking prescription medications. In these plants, furanocoumarin production is paused.

This is one of those things where 1) it's hilarious that it's taken up to 2025 to determine the gene for furanocoumarin production in grapefruit and 2) it will be really interesting to see if this innovation (pharma-safe grapefruit) is eventually commercialized.