Tracing Tahitian vanilla

Normal 0 false false false MicrosoftInternetExplorer4

Scientists have ascertained the pedigree of Tahitian vanilla, the orchid whose rarity and rich, sweet flavor distinguishes it from the widely used commercial vanilla. The discovery of the plant’s heritage could set off a custody battle between nations, researchers say.

The new analysis, reported in the August American Journal of Botany, places Tahitian vanilla’s origin in Central America, although today the plant is grown only in French Polynesia and doesn’t exist in the wild.

“I am concerned that this altogether could dispossess Polynesia of a patrimonial genetic resource,” comments Pascale Besse, a plant geneticist at the joint research center PVBMT Cirad and University of Reunion. Now that Tahitian vanilla’s parents have been identified, people could create “Tahitian” vanilla anywhere, diluting its value in the luxury and gourmet markets, Besse says. But that flavor doesn’t arise from genes alone, she adds, and the Tahitian environment may be central to the orchid’s distinctive bouquet.

As with wine and coffee, environmental factors, such as climate or soil quality, and processing methods are important, she says.

The pods or “beans” of Tahitian vanilla (Vanilla tahitensis) are much richer in oils known as oleoresins and have a fruitier scent than Vanilla planifolia, the species that provides roughly 95 percent of the vanilla beans sold worldwide each year, says economic botanist Pesach Lubinsky of the University of California, Riverside, who led the new study.

Scientists had established that Vanilla planifolia is native to Mesoamerica, but the heritage of Vanilla tahitensis remained a riddle. The 50 to 100 species in the orchid genus Vanilla are found all over the globe, but only the Western Hemisphere species bear fragrant pods, Lubinsky says.

“Only the New World species are aromatic — that was a big clue. If we are looking for its ancestors, let’s look in the New World,” he says.

Most hypotheses about Tahitian vanilla’s origins implicated good old V. planifolia. But there were two contenders for the other parent. V. pompona, which Tahitian vanilla tends to smell like, and V. odorata, which Tahitian vanilla tends to looks like.

To investigate, Lubinsky and colleagues examined DNA from chloroplasts, the plant’s light-harvesting factories, and from the nuclei of several species of vanilla. The chloroplast genome is passed on only by mothers; it doesn’t tango with paternal DNA the way nuclear DNA does. Tahitian vanilla’s chloroplast DNA was indeed identical to V. planifolia, confirming plain vanilla as its mom. The nuclear DNA was a mixture of V. planifolia and V. odorata, as would be expected from a hybrid, the researchers report.

Tahitian vanilla was probably born between 1350 and 1500, says Lubinsky, perhaps bred intentionally by farmers in the lowlands of Central America and then used as a flavoring in chocolate. “For my money, that’s where Tahitian vanilla originated — in some Maya forest garden,” he says. “It’s pretty clear its first use was by the ancient Maya who were drinking chocolate.”

“Vanilla is the secret of chocolate,” says Lubinsky, author of an analysis in the current issue of Economic Botany on the origins and dispersal of commercial vanilla.

Because the new finding demonstrates a Mesoamerican origin of what is now a solely French Polynesian crop, it does raise an interesting genetic resources dilemma regarding what nation owns rights to the plant’s genes, Lubinsky says.

Today, to safeguard the crop, growable plant parts of V. tahitensis are not allowed to be imported or exported from Tahiti. “It would be disastrous for Tahiti if other places started producing this vanilla,” Lubinsky says.