Wide hybridization between different species/genera

I love making crosses between different species and/or genera. How about you? Any of you involved in that sort of thing? How about crosses between domesticated species and their wild ancestors?

Great to hear of the continuing success on these projects and the interesting types emerging from the efforts!

In case it's of interest to the hybridization enthusiast, the somewhat technical article in the link below reinforces the notion that neighboring plants, sometimes rather divergent ones, are contributing to genetic variation in saved seeds via hybridization and subsequent acquisition of genes and chromosomes.  Suddenly I'm envisioning yet MORE weeds, not less, in the garden to foster this possibility.

http://www.plantphysiol.org/content/plantphysiol/173/1/65.full.pdf

Thanks John: I have been a follower of the work of Alan Kapuler for some years. He introduced me to an idea that I think of as "kinship gardening", growing things together that are somewhat distantly related, in hopes that every once in a great while they might find a way to hybridize.

I sure am in the muck up to my eyeballs with inter-species hybrids. Just today I planted  two different inter-species squash hybrids right next to each other. Hoping to get some offspring that are: [moschata X maxima] X [argyrosperma X moschata]. I might even attempt hand pollination to make this cross, even though I set it up to encourage bee-pollination. I'm also intending to attempt to cross pepo into [moschata X maxima] this summer.

I'll be watching the tomatoes closely for any hybrids that are [S lycopersicon X S habrochaites] X [S lycopersicon X S pennelliii]. I stopped trying to keep peruvianum complex tomatoes as separate species. They all got lumped together and inter-crossed. Eventually I may identify some hybrids between Solanum habrochaites and Solanum pennellii.

Other inter-species hybrids that I am working on  are perennial wheat, perennial rye, perennial watermelon, corn, cactus, various bean crosses. When I was breeding sunroots, I kept watch for crosses between H tuberosum and H annuus. That would have a lot of potential!

I find your work exciting, Joseph! My approach is plant everything together, save the best seeds this year. Or drop the newly sewn seed tray of fwo different types, sfamp feet and swear, scrape it up off the floor back into tray, plant out resulting mix and ses what happens.  Volunteer crossing!  I just hope to get varieties of beens and tomatoes that suit our horrid soil on a north east facig old neglected paddock that we ars trying to drag back to production.  I do keep my flint and sweet corns separate though. Am I right to do so?

Mandy Launchbury-Rainey wrote:I do keep my flint and sweet corns separate though. Am I right to do so?

I like to keep my sweet corn and the flint corn separate for use in the kitchen.

One of my favorite corn varieties has flint, flour, sweet, pop, and wild corn all growing together. I don't use it in the kitchen though. I use it for plant breeding, and to feed the chickens.

Joseph Lofthouse wrote:I love making crosses between different species and/or genera. How about you? Any of you involved in that sort of thing? How about crosses between domesticated species and their wild ancestors?

Unfortunately, the only thing I can lay (accidental) claim to is having planted some Chenopodium amaranticolor in my garden that went rogue, crossed with the lambsquarter already present as a weed, and formed clear hybrids.  The upshot is the generation of large-leafed lambsquarter with varying shades of purple through pink.  All of it very edible and now more succulent as a possible consequence of the hybridization.  And no planting needed.....all emerge as volunteers each spring.  Still working on a more annualized swiss chard.....but the end product is a ways down the road.

Joseph Lofthouse wrote:I love making crosses between different species and/or genera. How about you? Any of you involved in that sort of thing? How about crosses between domesticated species and their wild ancestors?

Haven't had a chance to try this, but I have been curious: we know that Queen Anne's lace is just a carrot reverted to the wild (Daucus carota). I have hear of people re-domesticating it through careful selection over the years. Now, parts of North America have their own native species, Daucus pusilla. I have long been curious as to whether this, too, can be domesticated into a garden carrot.

That's a interesting question. When I lived in California for a few years the first few months I was there I was weeding non-natives out of around some natives. One of the natives I found was a Daucus pusillus plant. Not much to it. Just a small annual flower.

In case this didn't get linked earlier.   Really interesting discussion on the extent of wild genome introgression on the improvement of crop plants.

As a summarizing statement, consistent with what Joseph and the others have been observing over the years, --  "... it is important to stress out that adaptive introgression has higher opportunities to occur in (i) traditional farming systems where landraces are used and farmers select seed stocks over generations and (ii) low input systems where wild resistance traits could favor crop fitness (crop higher fitness). In intensive systems with no nutrient/water limitation and use of pesticides (i.e. more typical large-scale monocultures), it would be more difficult to identify and thus select for wild advantageous alleles."  [from the article.....my clarification added in the last set of parentheses]

https://www.frontiersin.org/articles/10.3389/fpls.2019.00004/full

I'm working on [domestic watermelon x citron melon]  hybrids.

https://www.experimentalfarmnetwork.org/project/24

I'm tinkering with crossing tepary beans with other Phaseolus beans. Kind of expanding on Carol Deppe's discovery that led to her "Beefy Resilient Grex".

What I'd love to try is crossing Theobroma with something like okra, to make an annual chocolate source :) But that's going to have to wait until my greenhouse is built so I can grow the cacao plants.

Ellendra Nauriel wrote:I'm tinkering with crossing tepary beans with other Phaseolus beans. Kind of expanding on Carol Deppe's discovery that led to her "Beefy Resilient Grex".

The best information that we have regarding the origins of Carol's Beefy Resilient Grex, is that the black "tepary" bean that she started with was not a tepary bean at all, but a common bean that has been mis-named in the seed industry for decades. As a result of our investigation, seed companies are updating their catalogs to call Black Mitla by it's proper species.

I think that it would be valuable to make acutifolius X vulgaris hybrids, but Black Mitla wouldn't be an appropriate starting point. We are having good success with vulgaris X coccineus crosses with vulgaris as the mother of the cross.

Joseph Lofthouse wrote:

Ellendra Nauriel wrote:I'm tinkering with crossing tepary beans with other Phaseolus beans. Kind of expanding on Carol Deppe's discovery that led to her "Beefy Resilient Grex".

The best information that we have regarding the origins of Carol's Beefy Resilient Grex, is that the black "tepary" bean that she started with was not a tepary bean at all, but a common bean that has been mis-named in the seed industry for decades. As a result of our investigation, seed companies are updating their catalogs to call Black Mitla by it's proper species.

I know there's been a lot of debate about that. And I've seen a lot of people talking about how easily Black Mitla crosses with other common beans. But what I haven't seen (or else it was there and I missed it) was how easily does it cross with true tepary beans?

Even if it can't be used as a bridge between the species, there are other ways to cross them. Life happened the last few years, putting my experiments on hold. But I'm hoping to try again next year.

I grew Lofthouse scarlet runners packed for 2017, scarlet runners from some other source (no seed back), and Dakota Bumble Bean together in a tiny patch this year. I thought I had recalled that Dakota Bumble Bean was an interspecies hybrid but the variety description just says Jacobs cattle as an ancestor. Wonder if any crosses will show up.

Also decided recently I want to grow 5 species of Camassia together in the hopes of hybrids.

It's easy to spot crosses between common beans and runner beans. Just watch the common bean patch for (somewhat washed out) scarlet flowers. The cross pretty much only works if common bean is the mother.

Another easy way to spot crosses even earlier is to watch the cotyledons. Runner bean cotyledons stay underground. Common bean cotyledons are high in the air. Hybrids are near ground level.

I read about Burbank's attempt to hybridize Raspberry with Strawberry.

Link here: http://bulbnrose.x10.mx/Heredity/Burbank/Burbank_raspXstraw.html

He succeeded in making the hybrids, but they were all kinds of sterile: when the flowers finally took, they formed tiny drupelets with hollow seeds, no embryos.

Tried it a few times back in 2015, with an intuitive twist: rather than combine a diploid raspberry with an octaploid strawberry (as he likely did), I went full diploid: Reine des Vallees Alpine Strawberry with Caroline Red Raspberry. As with Burbank, strawberry was the pollen donor (despite raspberry pollen being easier to harvest and strawberry seed easier to sprout). Maybe it was the heat, or perhaps I should've tried more frequently on a daily basis, but the flowers (which I isolated) didn't take.

I've put a pin on the project for the time being, though I still have the plants. Among the things I'll try next time around: Mentor Pollination (sterilizing pollen from the pistil parent and mixing it with the pollen donor's pollen – the sterile pollen should be chemically reactive with the pistil despite being unable to fertilize, opening the way for the fertile pollen of the intended male parent), and maybe switching the parents around (male raspberry on female strawberry).

Besides that, I'd love to cross Medlar with several other Pomme fruit, and I'm fascinated with Somatic Hybrids (though it's not something I can do at home). I'd like to make a somatic hybrid between Ulluco and Madeira vine; I wouldn't mind crossing them the old-fashioned way, but Ulluco is notoriously difficult to flower, and even worse to fertilize.

Caesar S.   Don't know if 'embryo rescue' would be of help here?    Was surprised to find out how far back in history the technique had been used.

https://en.wikipedia.org/wiki/Embryo_rescue

On a parallel note, I'm fond of artichokes.....and need someone to figure out a wide hybrid between domesticated artichoke and Canada thistle   (!!..  ;-)  )  
Imagine all of that Canada thistle vim and vigor producing abundant, tasty artichokes.....Now THAT would be a game changer on the northern Plains.

Embryo rescue is excellent! I've seen papers on hybrids achieved through that method, including Garlic x Onion and hybrid Yams. Now if only they released those hybrids to the permies, that'd be great.

With that said, Burbank's hybrid had no further embryo to rescue, and Ulluco x Anredera brings its own problems. First, I'd have to get Ulluco to flower (challenging enough if in a temperate climate, which I'm not), then assuming Anredera was flowering at the same time, I'd need to successfully cross pollinate and hope the flower holds fruit (with Ulluco's poor track record, I'd sooner pollinate Anredera as the female parent). I think Ulluco x Anredera would be more readily achieved as a Somatic Hybrid. As for Strawberry x Raspberry, at least the initial hybrid has proof of concept; if a chromosome-paired hybrid like I'm planning still came out sterile, my next line of attack would be chromosome doubling with oryzalin or colchicine... A bit above my resources, but doable in a home environment. I'd also think of adding diploid hip roses to the mix (R. pomifera, R. roxburghii), since they're the closest relatives of strawberries and raspberries.

Speaking of roses, Father Schoener allegedly crossed R. pomifera with a Spitzenberg Apple, and successfully got a hybrid tree to bear fruit! Shame it was lost, together with so many of his roses. I wouldn't consider that hybrid intuitive, given the different subfamilies and the differing fruit structure (the hybrid was supposedly a pomme, like the apple). Indeed, my theory is that rose hips are essentially inside-out raspberries (as figs might be seen as inside-out mulberries); and strawberries have achenes, like rose hips, which are structurally equivalent to raspberry drupelets (while the strawberry's accessory-fruit is equivalent to the raspberry torus/core – the outer part in a rose hip).

Link to Schoener: http://bulbnrose.x10.mx/Roses/breeding/Schoener/SchoenerCD1938.html

If going the traditional non-somatic route, I'd highly recommend the mentor pollination for your artichoke hybrid. I've heard it can do wonders for crossing otherwise uncrossable distant relatives within a family. I think it was pioneered by Michurin, or was otherwise a favored technique of his, and he successfully made a 4-genus hybrid ("Titan": Sorbus x Aronia x Malus x Pyrus), among many others.

Keep us posted if you make the attempt, I'd be very interested in such a vigorous artichoke myself.

I just received some seeds of a Perennial Bean hybrid: Phaseolus lunatus x polystachios (¿P. x lunastachios?) an accession originally from Colombia. I also received some pure P. polystachios seeds. This will make for some fun breeding experiments.

I have been thinking that a figXmulberry cross would be really interesting.  Fig pollination is difficult though. I’m not sure how it could be done.

Ken W Wilson wrote:I have been thinking that a figXmulberry cross would be really interesting.  Fig pollination is difficult though. I’m not sure how it could be done.

Graft-hybridization might be an option...

Basically how it works, is the cell walls get damaged during grafting, and a nucleus from scion and from stock each get incorporated into a new fused cell. If that cell happens to become an apical bud, then you have a new tetraploid species. Sure the odds are low, but overall, it's just a numbers game.

Ken W Wilson wrote:I have been thinking that a figXmulberry cross would be really interesting.  Fig pollination is difficult though. I’m not sure how it could be done.

If you try it, I think you might have more success with caprifig pollen on a unisexual female mulberry. With that said, I think they're a bit too distantly related for pollen to have an impact (¿unless you use mentor pollination?), which leads me to...

Joseph Lofthouse wrote:
Graft-hybridization might be an option...

Basically how it works, is the cell walls get damaged during grafting, and a nucleus from scion and from stock each get incorporated into a new fused cell. If that cell happens to become an apical bud, then you have a new tetraploid species. Sure the odds are low, but overall, it's just a numbers game.

I think grafting between the two has been tried and failed, but don't quote me on that. At any rate, with your suggested method, I think we might have a better statistical chance of success combining them in-vitro. It's exactly the same thing in either case, a "Somatic Hybrid", only in the case of the graft, it's left up to chance, where in-vitro the result is guaranteed (if they're compatible). Plus, you might end up with several combinations of nuclear + cytoplasmic genomes, some of which may be more viable than others.

Please keep us up to date on your diploid raspberry x strawberry hybrid. I think you are on to something with keeping the ploidy number the same.

I would love for someone to make an avocado x mango hybrid someday. Even if it was a somatic hybrid. I think it would be interesting to try combining one haploid genome of each species and as a separate experiment try combining a full genome of each species in one cell. I think a mango-avacado combination might be surprisingly good.

Joseph Lofthouse wrote:

The best information that we have regarding the origins of Carol's Beefy Resilient Grex, is that the black "tepary" bean that she started with was not a tepary bean at all, but a common bean that has been mis-named in the seed industry for decades. As a result of our investigation, seed companies are updating their catalogs to call Black Mitla by it's proper species.

Things like that happen. For a long time, the "wonderberry" was sold as Solanum X burbankii, believed to be a hybrid created by Luther Burbank. Turns out it isn't; it is a good species, Solanum retroflexum, thought to be native to South Africa, and Burbank probably intended to use it as a parent in his hybridization experiments. Wikipedia gives the following bit of information pertinent to this discussion:

the supposed hybrid combination would not be viable due to different ploidy of S. guineense and S. villosum.

Ploidy means the number of chromosomes. If a given species has, say 12 chromosomes (six pairs), then the triploid form would have 18 chromosomes (and be sterile, because it has six pairs and six unpaired), and the tetraploid would have 24 (12 pairs). In general, a viable hybrid needs to have compatible numbers of chromosome pairs in each parent -- so a 12-chromosome species probably could not hybridize with, say, a 14-chromosome species -- one gamete would have 6 chromosomes, the other 7, and the odd one out could not form a pair.

Andrew Barney wrote:Please keep us up to date on your diploid raspberry x strawberry hybrid. I think you are on to something with keeping the ploidy number the same.

I would love for someone to make an avocado x mango hybrid someday. Even if it was a somatic hybrid. I think it would be interesting to try combining one haploid genome of each species and as a separate experiment try combining a full genome of each species in one cell. I think a mango-avacado combination might be surprisingly good.

The alpine strawberries are currently flowering, I'm waiting on the raspberry... It'll be a few months at least, since I trimmed it back to the main stem and finally put it in the ground.

I forgot to mention, strawberries and raspberries (and roses) have the same haploid number of 7, so the chromosomes should match up evenly at the same ploidy level (no guarantee though, as in the "Triangle of U", you might end up with allodiploids). Apples (and other Malinae), on the other hand, have a haploid number of 17, so pairing them up with the previous taxa would be quite complicated.

As for Mango x Avocado, the extreme genetic distance guarantees that, barring a miracle, a normal hybrid would never take. I'm not sure if a somatic hybrid would have any viability at that distance, but it could be a worthwhile experiment. I predict extreme issues with cytoplasmic compatibility, though, if viable.

Gastronomically, the closest you might get to a fruity avocado might be Safou fruit, which is similarly fatty, but said to have an acidic component in its flavor.

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Jason Hernandez wrote:

Joseph Lofthouse wrote:

The best information that we have regarding the origins of Carol's Beefy Resilient Grex, is that the black "tepary" bean that she started with was not a tepary bean at all, but a common bean that has been mis-named in the seed industry for decades. As a result of our investigation, seed companies are updating their catalogs to call Black Mitla by it's proper species.

Things like that happen. For a long time, the "wonderberry" was sold as Solanum X burbankii, believed to be a hybrid created by Luther Burbank. Turns out it isn't; it is a good species, Solanum retroflexum, thought to be native to South Africa, and Burbank probably intended to use it as a parent in his hybridization experiments. Wikipedia gives the following bit of information pertinent to this discussion:

the supposed hybrid combination would not be viable due to different ploidy of S. guineense and S. villosum.

Ploidy means the number of chromosomes. If a given species has, say 12 chromosomes (six pairs), then the triploid form would have 18 chromosomes (and be sterile, because it has six pairs and six unpaired), and the tetraploid would have 24 (12 pairs). In general, a viable hybrid needs to have compatible numbers of chromosome pairs in each parent -- so a 12-chromosome species probably could not hybridize with, say, a 14-chromosome species -- one gamete would have 6 chromosomes, the other 7, and the odd one out could not form a pair.

I'm not very familiar with the ploidy counts for the greater Solanum nigrum species complex, but while I don't doubt the validity and existence of S. retroflexum, I think applying that name to the Wonderberry might be mislabeling it. Burbank gives a detailed account of his process in breeding the wonderberry in "Luther Burbank: His Methods And Discoveries". Maybe the parent species he used were mislabeled? Nevertheless, they were two noticeably different species, carefully emasculated and crossed repeatedly until he achieved the resulting wonderberry, which was intermediate in character between the parents.

I certainly won't stake my life on the claim, and a mistake, mislabeling event, or stray pollen granule, could have affected the situation at any point... But I feel inclined to believe Mr. Burbank, that the Wonderberry (originally Sunberry?) is an actual hybrid.

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Some pic of my Phaseolus x lunastachios, next to some Winged Beans, in active growth:

Andrew Barney wrote:Please keep us up to date on your diploid raspberry x strawberry hybrid. I think you are on to something with keeping the ploidy number the same.

I would love for someone to make an avocado x mango hybrid someday. Even if it was a somatic hybrid. I think it would be interesting to try combining one haploid genome of each species and as a separate experiment try combining a full genome of each species in one cell. I think a mango-avacado combination might be surprisingly good.

Another problem with this is the different botanical families. Strawberry and raspberry are both in the Rose family, so they are fairly close. Mango is in the Cashew family, whereas avocado is in the Laurel family. I do not know of any successful interfamily crosses.

Jason Hernandez wrote:Another problem with this is the different botanical families. Strawberry and raspberry are both in the Rose family, so they are fairly close. Mango is in the Cashew family, whereas avocado is in the Laurel family. I do not know of any successful interfamily crosses.

Guineafowl hybrids are usually considered interfamilial, depending on the classification scheme. There are no known interordinal hybrids, and the distance between Avocados and Mangos runs far deeper than even that... Different major branches of the Angiosperm clade. Both Mesangiosperms, but the Avocado is a Magnoliid, whereas the Mango is an Eudicot.

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The lunastachios hybrid bean vines seem a bit underdeveloped, with little vining going on, but they're already flowering! Pale yellow, an occasional white flower which might be sun bleached. There's also a minor aphid infestation, curtesy of the local ants, but otherwise everything is dandy, and I expect to see seeds within a month or so.

*Note - To reiterate, I did not breed these beans, I acquired them. I think they were originally bred in Colombia.

I'm working on crossing Buffalo Gourd with Malabar Gourd; the desired end result is an edible, perennial, drought tolerant winter squash, with giant tap roots full of edible starch and bitter leaves that deter pests and grazing animals. Ideally it could grow in dryland pasture, avoid being grazed early in the year, then take over once the grasses went dormant and yield squash with no further work.

So far, no luck. I'm going to be experimenting with grafting them together this year to see if I can speed things up.

Interesting to see everyone's projects.

The cross I'll be working on this year will be between Melothria pendula and Melothria sphaerocarpa with the aim of developing a relatively large-fruited perennial cucumber, not unlike a perennial lemon cucumber. There's not a lot of info on M. sphaerocarpa, though it's grown as a seed crop in Africa and is supposed to have bitter flesh (no clue if that's for mature fruit only, or immature fruit as well.) I'm not sure what ploidy looks like for these species, so no clue what the chances for a successful cross are. M. pendula produces blueberry-sized fruit (essentially a small perennial cucamelon) and M. sphaerocarpa is about tennis ball sized and larger. I'd be happy if I could end up with a perennial vine with 1-inch or larger fruits with good flavor.

I would work with Cucumis picrocarpus if I could find any seeds online... Native to Australia and very similiar to C.melo
Also some things closely related to cucumbers / melons. C. hystrix, C. sativus var. hardwickii, Cucumis debilis, C. setosus, C. silentvalleyi, C. indicus. Hard to find much information on some of these though...
I have been trying to obtain wild Cucumis melo types, sometimes a seller lists one and then I have to hurry and buy it because I probably won't see it again.

I grew a wild type C melo one year. Ended up throwing away my entire year's seed and breeding work, because the fruit was poisonous, and I couldn't take the risk that it had shed poison pollen into the patch.

I am planning on growing the wild types a distance away, probably hand pollinating to domesticated types.  Might hand pollinate a few domestics as well to ensure the parents still reproduce properly. Shouldn't be too difficult since I only grow small areas of melon.

Joseph Lofthouse wrote:
Other inter-species hybrids that I am working on  are perennial wheat, perennial rye, perennial watermelon, corn, cactus, various bean crosses. When I was breeding sunroots, I kept watch for crosses between H tuberosum and H annuus. That would have a lot of potential!

@Joseph, how do you breed a perennial that is typically propagated as an annual? I'm new to plant breeding, just a mere baby, so forgive me if this is newbie stuff! I'm just fascinated that turning an annual into a perennial is even a possibility!

R. Beaty wrote:@Joseph, how do you breed a perennial that is typically propagated as an annual? I'm new to plant breeding, just a mere baby, so forgive me if this is newbie stuff! I'm just fascinated that turning an annual into a perennial is even a possibility!

The basic procedure is to cross closely related varieties or species that have desirable traits. For example, a large seeded annual rye was crossed with a small seeded wild grass with perennial roots. Then the offspring were selected for large seeds, AND perennial roots. Oh, and the domesticated rye is easily de-hulled, while the wild rye held on tenaciously to it's hulls. So selection was done among the offspring for easy threshing and de-hulling. Then, when it got to my place, it was further screened for winter hardiness, since the original selection was done in the maritime northwest with it's gentle winters.

Bok choi, and turnips are the same species. Bok choi was selected to be an annual. Turnips were selected to be biennial. It might be fabulous to cross them, and re-select for a biennial bok choi that wouldn't go to seed so quickly.

With the promiscuous tomatoes. I'm combining the disease resistance of the wild tomatoes with the better fruit quality of the domestic tomatoes. And while I'm at it, I'm selecting for the highly out-crossing traits of the promiscuous tomatoes, to get rid of the inbreeding that causes lots of trouble for domestic tomatoes.

@Joseph Lofthouse

Thank you so much for sharing - this is fascinating! I have several other questions:

-How do you identify perennial roots in a related species? Is it via observation, or reading certain references?

-You mentioned selecting for hardiness in harsher winters for the specific species in your example. Is it possible to slowly, after multiple generations of selective breeding, develop a variety that will survive - or even thrive - in a climate quite different from the one from which its fore-parents came? For example, if there is a species that thrives in a hot, dry climate, is it possible to slowly select a variety that could survive in a cool, humid climate? Even more particularly, I've heard that maize doesn't do well in the Sahel of Africa, and that to date, there are still no varieties that do well there (I'd have to dig deeper to find out if this is true, that there are no varieties at all). Is it conceivable that such a variety of maize could be bred?

Thank you!