InsideScience: Asian Origins of Wine Grapes

Interesting article in InsideScience:
[url]
https://www.insidescience.org/news/toda ... stern-asia[/url]
On the Asian origins of wine grapes. I think the folklore is that they originated as domestication of wild grapes.
Tom

Thank you, Tom.

It's more than folklore to suggest that today's wine grapes originated as wild grapes. But that was only ever in terms of genetic origin - no one thought each current wine variety was found in the forrest did they?

The only issues are where the grapes were domesticated, and how they were spread and hybridised. I think a lot of what is described in the InsideScience article was known already - namely that all vinifera varieties have genetic origins in west Asia. But I think it is new to assert that there is a single variety that they all descend from.

It's great that the article links to the research paper. There is a lot more detail there. I'll see what I can glean from it when I have a proper computer screen in front of me, and more time.

It wouldn't surprise me to find that all cultivated V. vinifera are descended from a single ancestor. Wild vines are dioecious--separate male and female plants. Most plants are hermaprhoditic--both stamens and pistil on the same flower. In vines, stamen and pistil development are controlled by two separate key genes. A mutation in one of these genes disables pistil development, resulting in a plant with only male flowers. A mutation in the other gene disables stamen development, resulting in a female plant. Apparently being dioecious confers some sort of selective advantage, because all wild vines are that way.

But at some point a rare cross-over event occurred, resulting in a vine with hermaphroditic flowers. This would be a big advantage for cultivation as the grower doesn't have to devote land area to male plants that produce no fruit. So likely what happened with Vitis vinifera in ancient times was a repeat of what happened in Concord, MA in 1849, where a farmer planted one of the native Vitis labrusca vines that turned out to be hermaphroditic. That vine was the ancestor of all Concord grape vines.

-Paul W.

But at some point a rare cross-over event occurred, resulting in a vine with hermaphroditic flowers.

It's not such a rare event. According to Patrick McGovern (I'm not sure what his source is) "about 5-7%" of wild vines are hermaphrodite.

Having said that, it must be less common to find a hermaphrodite wild vine that is also suitable for cultivation for winemaking.

McGovern also points out that it is not easy to identify hermaphrodite vines by eye, so early winemakers would not be in a position to go scouring through forrests to seek them out. It would rather be the luck of the draw among the vines they tried cultivating.

The Hermaphrodite Hypothesis has it more like 2 -3 % of a wild vine population were hermaphrodite plants. As pointed out by Paul it was this small percentage of a wild vine population that started man with domesticating the grape vines. If male plant were chosen, they would bear no fruit and be abandoned. If female plant was chosen, the vine would produce fruit only if a male plant was nearby, otherwise the plant would appear to be sterile and also abandoned

Salute

At least for the wild Vitis labrusca and related species here in New England, the female vines don't produce fruit every year. For cultivation you'd want vines that not only are hermaphroditic but produce fruit every year.

-Paul W.

I fully understand the point about needing hermaphrodite vines for cultivation. It's just that I would not call 5-7%, or even 2-3%, exactly "rare". But that is just semantics.

Regardless, I am curious about this "Hermaphrodite Hypothesis", and how it leads to 2-3%. A google did not reveal anything useful.

Isn't the obvious way to establish the proportion of hermaphrodite vines to estimate it by counting? I know Patrick McGovern was doing wild vine field work in western Asia, so it it quite possible that he did the counting himself.

Hi Steve,
I believe Dr Jose Vouillamoz, might of "coined the phrase"

Salute

Hi Steve,
I believe Dr Jose Vouillamoz, might of "coined the phrase"

That seems to be the case. But the hypothesis does not in itself "have" the percentage as 2-3%. Jose simply states "circa 2 - 3%" in the same way as Patrick does "about 5 to 7 percent".
https://littlewine.co/blogs/editorial/g ... stication1

As no great claims to accuracy were made in either case, the two are not entirely incompatible.

(Edit: I've just inserted "not" into my first sentence, which I had intended to be there all along, and I have also tried to make the point of the sentence easier to follow)

The percentage might also vary depending on which wild vine population you are studying.

Are there any conjectures as to why vines are dioecious when so many other plants are hermaphroditic? There must be some selective pressure preventing the species from reverting to being hermaphroditic.

-Paul W.

The percentage might also vary depending on which wild vine population you are studying.

Incidentally, I have just noticed that Patrick and Jose collaborated in doing field work to study wild vines in eastern Turkey, so it seems likely that the two percentage estimates were based on the same data. Without asking them, I guess we'll never know.

Are there any conjectures as to why vines are dioecious when so many other plants are hermaphroditic? There must be some selective pressure preventing the species from reverting to being hermaphroditic.

My conjecture is that plants might like to be dioecious for genetic diversity. And presumably the advantage of being hermaphroditic is ease of fertilisation, even in the wild. But that doesn't explain why vines and other plants tend to swing in different directions.

I have just read the Nature Communications article more closely
https://www.nature.com/articles/s41467-021-27487-y.pdf

Though much of the detail went over my head, it seemed to me that the "single domestication event" it mentions is not intended to imply that there is a single variety from which all modern wine grapes have descended. The "event" was people in a fertile-crescent region starting to domesticate wild grapes. The word "single" is meant to distinguish that domestication hypothesis from an alternative one where "cultivated grapes have at least two origins, one in the East and the other in the West, and western wine grapes may have had their origin in an independent event of domestication from western sylvestris".

To put it another way, the "event" was the domestication of the species, not of a single variety. I suppose you could argue that the whole spieces originated in a single variety, like all humans have Eve as an ancestor, but that is a different issue.

Certainly there is no mention of a single "grand-daddy" variety, and the emphasis of the article is looking at the process of eastern wine grapes being hybridised with wild varieties in the West. As I think I said above, we already knew that in broad-brush terms, but I guess the article confirms it and provides more detail.

Frankly, I think the InsiderScience article is wrong to write "new research confirms that every popular wine grape shares an ancestor". If the research does confirm it, it is hidden in the details of the genetic analyses, and not given the attention it deserves.

"Single event" meaning "single period of domestication" makes a lot of sense.

The science and technical trade press is notorious for misinterpretation. I was interviewed once for a trade press article and I was shocked to see how different what they printed was from what I said. It is very likely that InsideScience has misunderstood things.

-Paul W.

Vinifera vines are not always hermaphodite. It's just that those that are not, aren't cultivated.

All vine species (genus Vitis) are dioecious (separate male and female plants). Hermaphroditic vines apparently account for 2%-7% of the wild V. vinifera population.

If you think the sex situation for vines is complicated, check out fig trees.

-Paul W.

Vinifera vines are not always hermaphodite. It's just that those that are not, aren't cultivated.

Actually, Peter.... Picolit is sterile. Needs to be interplanted w/ Verduzzo or something.
Tom

If winemaking could have an east/west origin, is it not possible that an eastern stone age primitive cultivated grape has ties with ties with western cultivated grape?

Salute

If winemaking could have an east/west origin, is it not possible that an eastern stone age primitive cultivated grape has ties with ties with western cultivated grape?

Not sure exactly what you are asking, but the current evidence points to a single origin for vine cultivation, which was in the fertile crescent (AKA the east, from a European perspective). Then those cultivated varieties spread west, and were hybridised with European wild varieties. So there seems to be no cultivated grapes that are soley European in origin, but there are some that are 100% eastern.

(In all this we are of course talking about Eurasia. There must be another story to tell about what happened the other side of the Atlantic)

Picolit is sterile. Needs to be interplanted w/ Verduzzo or something.

It's more that picolit is not fully hermaphroditic. Its pollen tends to be infertile. So the variety is for agricultural purposes female-only. It needs to be interplanted with a variety that has fully fertile pollen.

-Paul W.

Picolit is sterile. Needs to be interplanted w/ Verduzzo or something.

It's more that picolit is not fully hermaphroditic. Its pollen tends to be infertile. So the variety is for agricultural purposes female-only. It needs to be interplanted with a variety that has fully fertile pollen.

-Paul W.

OK, but there are other examples of female-only vinifera flowers"
"Vitis vinifera L. can be divided into two subspecies, V. vinifera subsp. vinifera, the cultivated grapevine, and its wild ancestor, V. vinifera subsp. sylvestris. Three flower types have been described: hermaphrodite and female in some varieties of vinifera, and male or female flowers in sylvestris."
https://www.sciencedirect.com/science/a ... 3820304672

Vinifera vines are not always hermaphodite. It's just that those that are not, aren't cultivated.

Actually, Peter.... Picolit is sterile. Needs to be interplanted w/ Verduzzo or something.
Tom

Sure, there are exceptions. But Picolit is not widely grown and there's very little of it

OK, but there are other examples of female-only vinifera flowers"
"Vitis vinifera L. can be divided into two subspecies, V. vinifera subsp. vinifera, the cultivated grapevine, and its wild ancestor, V. vinifera subsp. sylvestris. Three flower types have been described: hermaphrodite and female in some varieties of vinifera, and male or female flowers in sylvestris."

I'm sure V. vinifera vinifera has also produced plants with male-only flowers. But those would have been tossed out and not cultivated. One can deal with female-only varieties by inter-planting them with hermaprhoditic varieties.

-Paul W.

I'm sure V. vinifera vinifera has also produced plants with male-only flowers. But those would have been tossed out and not cultivated. One can deal with female-only varieties by inter-planting them with hermaprhoditic varieties.

-Paul W.

Why can you not inter-plant with male-only sylvestris or vinifera vines?

But I can see why you WOULD not - when you can use grape-bearing hermaphrodites.

Of course you could interplant with male-only vines. But why give up that real estate when you could interplant with a hermaphroditic variety that yields grapes you can vinify? OK, so maybe the wine from the interplanted variety can't go into your AOC wine offering, but you can sell it off as plonk and recoup some of your investment in it.

-Paul W.