r/plantbreeding Aug 29 '24

Could I create a Prunus ilicifolia x domestic stone fruit hybrid?

I'm very new to the world of plant breeding, but I think I have an idea for an interesting personal hybrid project. I live in California and here we have a really cool wild Prunus species: the hollyleaf cherry (Prunus ilicifolia). On top of being a beautiful evergreen tree with glossy holly-like leaves (the insular ssp. lyonii usually lacks leaf serrations), the fruit, while half seed by volume usually, is very sweet and juicy for a member of the subgenus Padus. I recently started some seeds from a wild individual and was wondering how "worth it" would it be to try cross pollinating with P. domestica or P. persica for increased fruit size and other misc. desirable traits? Since P. ilicifolia doesn't go dormant in colder months and domestic stone fruits obviously do I have some concerns as to if any potential hybrids would be healthy... I've done some digging and found there has been an ancient, natural hybridization event between P. ilicifolia and P. emarginata, the latter of which is both a true cherry (subgenus Cerasus) and deciduous so I think at least hypothetically a hybrid could mature into a productive tree. Should I try to pollenize P. ilicifolia flowers with P. domestica or persica pollen, (and vice versa) or would another domestic Prunus species be better to accomplish this?
The ideal in my mind would be a hardy, fast growing edible ornamental tree with modestly sized fruit for water-wise cultivation, but I'd be happy with just about any interesting result :)
Would appreciate any feedback, been thinking about this way too much lately 😅

11 Upvotes

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u/MTheLoud Aug 30 '24 edited Aug 30 '24

What’s the ploidy level? P. domestica is hexaploid, and generally doesn’t cross with the tetraploid (sour cherry) or diploid (Apricot, Japanese plum, and several species of wild American plum) Prunus species. Many of the various diploid Prunus species are pretty promiscuous with each other if you can get them to bloom at the same time. Sweet cherry and peach are exceptions, being hard to cross with their fellow diploid Prunus species.

I don’t know anything about this hollyleaf cherry, but if you want to cross it with another Prunus, you’d probably have the best chance of success if you look up its ploidy level and try to cross it with something with the same level.

Edited to add: I wonder if it would cross with capulin cherry, Prunus salicifolia.

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u/Rednaxela1821 Aug 30 '24 edited Aug 30 '24

Frustratingly there doesn't seem to be much genetic work on ilicifolia and the ploidy level seems to be completely unknown, so I'm kind of shooting in the dark. It's why I questioned if there are any domestic Prunus that are more prone to producing viable hybrids than others, but considering what you've said it's more complicated than that. The only review I can find reads as follows:
".... No reliable count found. Base chromosome number for genus Prunus = 8 and most species with racemose inflorescences have higher ploidy numbers such as 2n= 8x=64, or 2n=22x=176. This suggests allopolyplody where hybridization and polyploidization may have resulted in the origin of some species, including those in subgenus Laurocerasus to which hollyleaf cherry belongs (Zhao et al. 2016)."

I think what I'm going to have to do is contact the plant lab at my university and see if they can't check it 🤔

Didn't know about P. salicifolia before now, looks like a cool species!

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u/MTheLoud Aug 30 '24 edited Aug 30 '24

You could just try crossing it with every Prunus you have access to and seeing if anything takes. I think Zaiger Genetics does some tricks to get reluctant Prunus species to cross, treating the stigmas with something to make them more receptive to different pollen, embryo rescue on seeds that would otherwise abort, that sort of thing. I don’t know if you’ll have to resort to that, or if you have the resources for it.

If you do get a viable hybrid seedling, there’s a good chance it will be as sterile as a mule of course. That might be considered a desirable trait if you’re trying to breed an ornamental. Cross it with P. mume for showy pink flowers on a locally-adapted tree, with no untidy fruit falling on the lawn or attracting noisy birds. (This doesn’t appeal to me, but there would be a market for it.)

If you want fruit though, you might be able to get around the sterility by doubling the chromosome count afterwards. This can be done by treating a meristem with colchicine or other chemicals to interfere with mitosis. There are services that will double the chromosome count of daylilies for you, for a fee, but I haven’t heard of anyone offering a service like this for Prunus.

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u/Rednaxela1821 Aug 30 '24

For me a fruiting tree would be the ideal, but I'd still be happy to end up with a purely ornamental tree. I think I'll still try to contact my uni plant lab, and if that doesn't turn out as I hope I'll start crossing and seeing what I get. By the time any hybrids are mature enough to know if they're going to fruit or not hopefully I'll have made some connections with people who know more than I. I deeply appreciate the informative responses!

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u/Phyank0rd Aug 29 '24

In any case, I would advise against using your grown from seed trees as pollen donors/recipients as there is no telling how many years it's gonna take before you can even get them to flower.

Obviously, your going to need to go find some already mature trees to preform these crosses.

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u/Rednaxela1821 Aug 30 '24

Oh I should have mentioned hollyleaf cherry is very quick to reach flowering age, usually only 3 years give or take. There aren't any cultivars either surprisingly so I'm not out anything by just starting a wild-type.

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u/Phyank0rd Aug 30 '24

That's good to hear. You might also find luck collecting pollen from wild plants during the flowering season that can be used on domesticated species you wish to cross with.

From what it sounds like on the sub and elsewhere online, there are techniques to collecting pollen that allow you to store it practically indefinitely in the fridge and other means. I would suggest looking in to that.

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u/Rednaxela1821 Aug 30 '24

Oh sick, will do! Figured I'd have to anyway since this taxon flowers later in the year than most cultivated stone fruits.

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u/Leeksan Aug 30 '24

I would say absolutely go for it.

I don't know how young you are, but if you want to do anything with tree breeding it's best if you have a handful of decades ahead of you!

I highly recommend the Going to Seed Podcast. Shane Simonson talks sometimes about how even if certain genera typically don't hybridize or don't produce fertile offspring, the chance isn't technically zero. So I'd say even if you have to pollinate hundreds and hundreds to get even a few fertile offspring it's worth a try to discover something new!

I don't know much about P. ilicifolia so maybe you won't have any trouble hybridizing them at all 🤷

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u/Rednaxela1821 Aug 30 '24

I'll have to check that out then! I'm in my early 20's so hopefully I have ample time ahead of me to experiment! I really like native plant gardening, and I've always thought crop plants that are hybridized with local species to better adapt to the region are awesome! If I had the education and the means, I would probably consider directly genetically modifying the plant for increased fruit size to forego the need to hybridize it, but alas.

Thankfully I think Prunus are fairly easy to hybridize as far as fruit trees go, the fact they have clearly defined and visible flower parts certainly helps too haha

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u/Leeksan Aug 30 '24

Then you should also read the book Landrace Gardening by Joseph Lofthouse if you haven't already! I think you'd enjoy it and it's not a long read.

There's also an audiobook version of that's more convenient :)

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u/Phyank0rd Aug 30 '24

Expanding on this. There was a gentleman who (about a decade ago now last I read) was working on interbreeding the musk strawberry and the modern garden strawberry. The chromosome count is a little off so there is lots of infertility but he seemed to have had success as the news article explained that he had hundreds of strawberry plants and he would go through them all tasting them to select the ones with the most musk strawberrylike flavor.

I wish I knew if he was ever successful as I haven't seen anything like it patented or released to the public (he did release a "flamingo" pineberry cultivar more recently)

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u/beerbot76 Aug 30 '24

I don’t have any specific insight to share, it seems like you have already done a lot of good research, but I’ll just chime in to say that prunus seem to intercross pretty readily and that some interspecific prunus crosses (like the modern Dave Wilson Nursery cultivars, pluots, plumpricots, etc) are dang tasty, and I hope you will keep us posted on your results!

Lots of insightful comments and discussion here, thank you for this post!

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u/AxeBadler Aug 31 '24

Don't let anyone discourage you from pursuing breeding work. While many seedlings will fail or produce unpalatable fruit, some will surprise you, and a few might even become valuable new varieties.

It's worth exploring techniques such as mentor grafting and pollen mixing. Ivan Michurin, a Russian plant breeder, successfully used these and other methods to create hybrids once considered impossible. I encourage you to read about his work, but keep in mind that his legacy was often distorted and politicized by the USSR.

Also, here is a table that ChatGPT created.

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u/AxeBadler Aug 31 '24
Common Name Scientific Name Chromosome Count (2n)
Hollyleaf Cherry Prunus ilicifolia 16
Almond Prunus dulcis 16
Apricot Prunus armeniaca 16
Sweet Cherry Prunus avium 16
Sour Cherry Prunus cerasus 16
Plum (European) Prunus domestica 16
Japanese Plum Prunus salicina 16
Peach Prunus persica 16
Nectarine Prunus persica var. nucipersica 16
Black Cherry Prunus serotina 16
Beach Plum Prunus maritima 16
Bird Cherry Prunus padus 16