I only skimmed the video, but wasn’t he mostly just talking about melons, not wild plants? He mentioned the domestication of watermelons, yeah, but he also said it took thousands of years. Doesn’t strike me as easy.
But to your question: the main thing is to have a wild plant that already produces large, good tasting fruit in reasonable quantities on a plant that has easy cultural requirements. The feijoa is a pretty good example. It’s only been cultivated since the 1920s, so a hundred years, but it’s already got some well-developed cultivars and varieties. But, well, wild feijoa are already pretty close to what you’d want anyway in a domesticated plant: hardy, productive, few pests, nice shrubby form, good sized fruits that are easy to pick and taste good. Finger lime
But plants like that are really few and far in-between, especially in temperate regions (the tropics are way better and there are hundreds if not thousands of tropical fruits that could easily be domesticated, but that’s a different story).
The other avenue seems to be wild plants that are closely related to already domesticated fruits. Shipova comes to mind. It’s a cross between the domestic European pear and the quasi-domesticated whitebeam. Whitebeam are a kind of edible but not all that great fruit, but once crossed with pear, you get Shiova, which is apparently pretty nice.
Similar work has been done with grapes. There are numerous wild American grapes that were crossed with European grapes. While the main goal was to breed disease resistance into European grapes, but as a nice side effect we got some hybrids that preserved the American grape flavors which some people appreciate, all while also considerably improving fruit characteristics.
Then there are semi-domesticated plants where the wild plants are actually already somewhat manmade. This can sometimes overlap with the other categories (I’d be shocked if feijoa wasn’t already cultivated to some extent before the Spanish arrived). The somewhat trendy Amaranth fits this category, though it’s not a fruit. Many, if not most, wild species of Agave are similarly not actually wild–they are hybrids, intentional or accidental, created by native peoples in the relatively recent past. As a result, Agave taxonomy is an unmitigated nightmare where everything is all mixed up and confusing. Finger lime is likely another example, and similarly benefits from being closely related to other citruses and is easily hybridized with them.
Then you have wild plants that are edible and could theoretical be domesticated given enough time and effort. Black tupelo trees produce an edible berry. You might could make different selections from the wild population for sweetness, flavor, and size, and then combine those selections and slowly breed better and better tupelo berries. Eventually, you might even end up with a decent sized berry that tastes good. Good luck in doing that in less than a thousand years though, since tupelo take a decade to start fruiting from seed, and their fruits are described as thin, oily, and bitter to sour tasting anyway. Probably the best bet would be to combine several different species of Tupelo in the hopes of getting a five hundred year head-start.
To my mind, the second category is where there is the most realistic potential. For almost every domestic species, there are a half dozen wild relatives. The hybridization can be difficult, often requiring modern technology, but oftentimes after that first step things get much easier. Hybrid persimmons were only developed thanks to some mad Soviet scientists trying embryo-rescue and tissue-culture techniques over and over until they finally made a breakthrough. After that first initial cross though, it’s pretty easy to breed the hybrids back to either parent. That’s not always the case, but it is often enough to be workable.
The list of potential hybrids and backcrosses is staggering. Some of them are already being worked on, many not. You’ve got maypops crossed with more subtropical and tropical passion fruits–that’s a pretty active field right now. There are a bunch of people crossing wild citruses like trifoliate with edible citruses, mostly in an attempt to breed cold hardy citrus. Of course hybrid persimmon breeding is really hot right now, especially on this forum. Some professional work has been done on grapes, but honestly a lot more could be done. There are so, so many wild grape species and only a few have been used much. Doubly so for Rubus and Ribes. There are dozens to hundreds of species in each of those genera, and only a few are actually domesticated. Most of the blackberry varieties on the West Coast are the descendants of a wild Asian blackberry crossed with European blackberry and a bit of American dewberry genetics. That’s cool, but what about crosses with dewberry again to really get that flavor, or crosses with the somewhat unique tasting New Mexican raspberry or the salmonberry? We crossed European Ribes with a native species in California and got the Jostaberry, but to my knowledge we’ve never crossed European Ribes with clove currant, or with prickly currant, with the extremely tough and drought-tolerant squaw currant or with the heat and humidity tolerant Georgia currant.
There’s a user here on the forum who is working on crossing purpleleaf plum with edible plums and who has a fine collection of improved Chickasaw plums and hybrids of various American species and Japanese plums such as some of the Auburn university releases. Plums are one area where only a fraction of the possible work has been done. There’s something like 50 different plum species, only three or four of which are domesticated. That’s a massive, massive pool of genetic material. And similar things can be said about cherries. And apples and their relatives, and pears and their relatives.
A whole new branch of commercial blueberries resulted from the domestication of rabbiteye type blueberries, and yet another, quite promising, branch came from crosses classic northern highbush blueberries with southern species of blueberry. But there are so, so many more species of blueberry and potential crosses. Want a blueberry that ripens in the fall? There’s genetic potential for that. Black blueberries? Plenty of possibilities for that. Ground cover blueberry plants? Might be some ploidy issues but nothing automatically impossible.
Goumi is just now seeing some popularity, and the newer selections of goumi are pretty decent. But the harvest window is pretty short. If only goumi had relatives that ripen in the summer, relatives that ripen in the fall, and relatives that ripen in the dead of winter… And maybe relatives with larger fruit. As it turns out, it has all of those, because the genus it is in is enormous, dozens of species.
We managed to cross two species of persimmon, which was a great achievement. But did you know that genus has over 700 species in it? Most are tropical, yes, but two are temperate, and at least two more are subtropical…
Breeding cold hardiness into domestic species is another pretty significant area of work. I mentioned citrus already, where two or three wild or wild-ish species, the trifoliate, ichang papeda, and taiwanica citruses, together with the already domesticated kumquats and various mandarins such as Changsha, all can provide some degree of cold hardiness when crossed with regular citrus. And for exceptionally dry areas, Australian desert lime is a wild citrus with unbelievable drought tolerance and a decent bit of cold hardiness too, so I can’t imagine how crosses involving it, trifoliate, and some edible citrus won’t eventually make for good fruit trees in places like western Texas.
There’s a fairly close relative of avocado native to Mexico that’s growing just fine in Raleigh NC, zone 7. Other, not quite as closely related, species are native to the Carolinas and hardy into the warmer parts of zone 6.
There are relatives of Chinese yangmei that are native to Russia and Canada. Can they be hybridized? No one knows, we haven’t tried it yet.
There is an edible banana species that fruits and flowers in the warmer parts of zone 7, but the fruit are pretty poor quality and aren’t worth trying to eat. Banana genetics get complicated, and seedless genes are almost a must-have, but still, seems like something a well-educated and passionate amateur breeder could pull off in a lifetime.
There’s a species of Annona hardy to 9a or 8b. There’s a whole lot of the US that’s now in those zones or warmer. There are guava species, good tasting ones at that, that are just as hardy or perhaps a little more. Some Eugenias can take temperatures down into the upper teens. Almost all of these are basically wild species, but are in genera that have some exceptionally good fruit. Indeed, some Annonas often make it into lists of the best tasting fruit on earth.
Certain pepper species are root-hardy into upper zone 8. And the solanum genus has an enormous variety of different fruiting plants, some of which are also surprisingly hardy. There’s a bit of work being done on them, but not all that much considering just how massive the genus is.
Papaya has some cold-tolerant relatives. And baring that, some of the smaller, much sweeter varieties of papaya ripen up in just a few months. Just breeding those varieties of papaya to mature faster and flower in long-day periods would be all it takes for folks to start growing papayas as summer annuals just like how we grow tomatoes and peppers.
There are Cinnamon genus species hardy to zone 8, and two star-anise species that, while poisonous, are hardy into zone 7, and native too. Chinese nutmeg-yew has edible nuts, its close American relative the Florida nutmeg-yew has been grown, successfully, in Michigan.
The list goes on and on and on.
I know a lot of folks get excited when they learn that such and such a weed is actually edible if you boil it twice and leave it in the sun to dry after treating it with slacked lime. But, well, we frankly don’t benefit much about yet another marginally palatable green. There’s so much more rewarding breeding work that could be done instead of one more person growing a patch of Jerusalem artichokes that they’ll rarely eat anyway. But a lot of this work is difficult, and all of it takes a long time. Worse, most of these crosses would only have much of a chance at success if non-traditional breeding methods are used to at least get things going. But, for example, tissue culture isn’t actually that hard if you’ve got a good dedicated set up, there are even YouTube tutorials and channels for DIY tissue culture. So, just for example, a few hundred hobbyist fruit growers doing their own pollen freezing and embryo rescues for outlandish and daring crosses seems entirely realistic, and were that to happen, I suspect we’d see all kinds of new and interesting fruit pop up, and much, much sooner than if we just stick to trying to domesticate single species of truly wild (and therefore mediocre usually) plants via manual selection.
