Tahitian vanilla is an interspecific hybrid
It looks like the origins of Tahitian vanilla (Vanilla tahitiensis), long a mystery, have been resolved:
Tahitian Vanilla Originated in Maya Forests, Says Botanists (Science Daily)
It's not terribly shocking that the origin is Central America, given that the historical record supported the idea of going from Guatemala to Taihiti, via the Philippines. What was suprising, to me anyway, was the fact that it turns out to be an interspecific hybrid (maybe this wasn't a shocker to vanilla botanists, but my vanilla knowledge is kind of limited) between V. planifolia, the species currently cultivated for most vanilla production, and V. odorata, a species not know to have ever been cultivated. Taihitian vanilla is distinct in that it possesses the compound heliotropin, which no doubt came from the odorata parent, and gives the beans their unusually floral aroma.
The story reminds me a little of that of the cultivated strawberry, the interspecific hybrid coming into prominence far from its ancestors native lands, but of course in this case the hybridization likely occurred long before they went to Taihiti, probably in some Mayan garden. If and when the data gets published, it would be interesting to see how distant a hybrid the genetic evidence suggests this is. Given that vanilla is commonly propagated vegetatively (vanilla is an orchid, and orchids are known for being a pain to germinate, requiring the presence of specific mycorrhizal fungi), the Taihitian vanilla we grow today could conceivably be the original genotype resulting from the initial hybridization. I'd be interested to know if the odorata and planifolia chromosomes play nice and pair with each other, or if this is actually an alloploid of some kind...
(I suppose one could make a case that vanilla isn't a fruit, but I'm known for being a little flexible with my defnition around here, and it is technically the fruit that is consumed. Basically my definition is: if you eat it, and it's not an agronomic crop, and it's not a vegetable, then it's a fruit (and I've been known to be a tad flexible on the vegetable thing, too). Mostly I just thought it was a cool article.)
Update: I found the actual article, which appears to be freely available here. So there are a few answers to my questions above:
F1 hybrid?: Almost, but probably not quite
Polyploid?: Some yes (4x), some no (2x)
Single genotype: Nope.
They looked at both a nuclear region and a chloroplast region (which allows them to conclude that V. planifolia is the maternal parent in all cases).
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