I’m very curious about this subject, and I’m sure people have tried it before, but I was just wondering if this could be a better method of introducing diploid species to established tetraploid line than crossing the diploids directly with the tetras? If so, are there any remontant hexaploids out there?
Can Alba Maxima cross with diploids to create tetraploids?
No, but only because it’s a canina. You need to learn what that means.
Beauty and the bastards - Wissemann.pdf (690 KB)
Theoretically, though, a hexaploid could indeed be crossed against a diploid to produce a tetraploid. Whether there are any remontant hexaploids is an interesting question. The person who would know best would be David Zlesak, perhaps he’ll weigh in.
All these Canina family are pretty extraordinary in their make up and you have to be aware what their septet formulae is before using them. It depends on this septet arrangement whether you use it as a pollinator or seed parent.
Alba 4+2
R. canina 4+1
R rubiginosa 4+1
R. glutinosa 5+1
R. mollis 3+1
R. glauca 3+1
R. pomifera 3+1
Andrew,
As Warren pointed out Albas have 4 sets of chromosomes in the egg and 2 sets in the pollen. The two extra sets in the egg don’t pair up and they only get passed along in the egg, not in the pollen. Using diploid pollen on an alba would get you something akin to a triploid with 2 extra sets of chromosomes just hanging around not pairing up with any of the other three. They will still have an influence on the seedling though. Alba pollen is the same as tetraploid pollen and has been used that way by a number of breeders including myself. So using Alba pollen on a diploid will get you triploid offspring the same as doing a diploid x tetraploid cross would. So to answer your question, this really isn’t a better method to get traits from diploid species into the established tetraploids.
I don’t know of any remontant hexaploid roses out there. But you’re right, crossing a diploid with a hexaploid could get you tetraploid offspring. I tried this once by crossing R.blanda x R.Moyesii “Geranium”. It turns out that Geranium is virtually sterile and I didn’t get any offspring from this cross. I did get some seedlings though, but they turned out to be OP seedlings. But you have to remember that even if you were successful in getting a hexaploid x diploid cross to work, the resulting tetraploid offspring will have 3 sets of chromosomes from the hexaploid and only one set from the diploid. Those are worse odds than if you just crossed the tetraploid with a diploid and got triploid offspring with a 2 to 1 ratio. So crossing a diploid with a hexaploid probably isn’t going to be a better or faster route to get diploid species traits into an established tetraploid line.
Andrew,
After crunching the numbers, the tetraploid offspring of the diploid x hexaploid cross will produce gametes with the diploid chromosomes 50% of the time, all of them tetraploid gametes. The tripoid offspring of the diploid x tetraploid cross will also produce gametes with the diploid chromosomes 50% of the time. But with 33% of them diploid gametes and 67% of them tetraploid gametes. So the overall numbers are the same the mix is different.
Alba 4+2
R. canina 4+1
R rubiginosa 4+1
R. glutinosa 5+1
R. mollis 3+1
R. glauca 3+1
R. pomifera 3+1
So it sounds like the most straight forward way to get to regular tetraploid states with these, is to use Alba pollen on a tetraploid, done, and use the pollen of the others on a slutty diploid, then use chromosome doubling chemicals on the seedlings. To hopefully avoid the unusual chromosome bindings.
Thank you everyone for the great advice, needless to say I will not be ordering an Alba Maxima, and Don thank you for that informative pdf!! David has sent me a detailed and informative email on what I need to know.
Totally unrelated to chromosome and ploidy talk, has anyone seen Austin’s new “Royal Jubilee” for this year. I’m thinking of ordering one; looks like it might be the closest he’s gotten to a peony looking rose. Also, it’s one of only two roses I’ve seen listed under his new “English Alba Hybrid” classification. I’m curious to see where and how far he will take his Alba hybrids.
Andrew I sent this one over to Europe last year, some people did n’t believe it was a rose, thinking it was a peony rose.
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Being aware of pentaploids in canina family, I did not know about tetraploids with asymmetric meiosis, would you please provide any research paper where this is investigated?
As a second question related to this, does recombination happen during meiosis between the 4 constant chromosomes and the other chromosomes that separate into the pollen? Or does no recombination happen between those chromosomes? I couldn’t find any literature on this.
Forget about the septet business, the concept of septets is an historic artifact, part of a theory that is now obsolete and distracting. We have a detailed understanding now of how inheritance works in roses.
This paper explains why canina are the Borg of the rose world and how their peculiar inheritance works.
Evolution by Reticulation: European Dogroses Originated by Multiple Hybridization Across the Genus Rosa
Also, I cannot find a link to this one but see
Wissemann V. 2006. Beauty and the bastards. Intensive hybridization controls the evolution of wild roses. B.I.F. FUTURA 21: 158-163.
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The old link is dead but luckily the second post in this thread, you attached the pdf and it downloads so still accessible 
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Deja vue all over again.
I knew this occurred from research I read a long time ago. We have a bunch of fertile Purple Pavement x Rosa pomifera that also have seedlings. It works out fine. In our case, the two Rosa pomifera came from ForestFarm, so selection for seedlings seems to hold true as a “3+1” as far as we know.
One fact must be mentioned: there was no theory. Hurst presented mounds of data and his analyses there of. His “septet scheme”, as he called it, was a “working hypothesis”. His words.
After establishing the framework, he set working out the details with extensive breeding experiments. Many Rosa species are slow to mature and flower, and the necessity of continuing to the second and third generations, meant that many years would be required to reach any definite conclusions. Sadly, he died before he could publish his monograph.
Artifact? I would call his work “monumental”. How many botanists have ever compared hundreds of species according to a list of about 100 traits? Fifty of these were found to be relevant.
Distraction? Take a look at what has been accomplished by breeders of wheat and other small grains. Wheat has chromosomes in groups of seven. Just like roses. Common bread wheat, Triticum vulgare, is a hexaploid built up with complete sets of chromosomes from three distinct species. Just like Rosa moyesii.
Blackhurst (1948) pollinated Rosa rubiginosa by various species. He managed to prove two things.\
- He could not get his facts straight.
- Differential pairing of chromosomes cannot – BY ITSELF – account for the peculiar meiosis of the Caninae species.
The first possible explanation (or basis for a fuller explanation) comes from the wheat breeders.
http://bulbnrose.x10.mx/Heredity/RileyPairing.html
Simply stated, hexaploid bread wheat behaves more like a diploid with x = 21 chromosomes. But when one of those chromosomes is missing a small, specific segment, some of the other chromosomes form groups of 2, 3 and rarely 4. Thus, there is genetic regulation that limits pairing of homeologous chromosomes, while allowing homologous parings.
It is useful to remember that not all chromosome pairings are equally productive. Homologous pairs can crossover and shuffle their genes to some extent. Homeologous pairs to not crossover so much, so whatever big chunk of chromosome you get will be pretty much “sent in stone” for a long time.
Near the beginning of the 20th century, some iris fanciers heard of Mendel, and imagined it would be a simple matter to combine the bright yellow of Iris variegata, with the more attractive form and graceful branching of I. pallida. It took a long while to get the yellow color without the zif-zag stalks of the same species.
Same thing with Rosa foetida. Some lines opened turnipy white in cold weather. Some had short buds that turned whenever the yellow was expressed. And some lines had red pigment marring the yellow petals. And let’s not forget about blackspot. Some of these problems might have been avoided from the beginning by getting the Foetida yellow into a species with similar chromosome that would all more crossovers. Percy Wright’s ‘Hazeldean’ might have been a great help if it had turned up much earlier (before Wright was born".
Furthermore, the Caninae section still has some goodies that might be of interest, but which are not transmitted through the pollen. It’s a pity that Blackhurst (1948) failed to mention whether any of his Rubiginosa hybrids inherited the leaf-fragrance. There must be genes involved, and they must be on one or more chromosomes.
When Caninae species are pollinated by “regular” diploids or tetraploids, meiosis is scrambled and there is much elimination.
Heslop-Harrison (1954/55)
Next, by the aid of lantern slides, he described the cytology of the roses, stressing the peculiarities of the Caninae and the Spinosissimae. From that he led up to experimental work with the hybrids between > R. spinosissima > on the one hand and > R. sherardi, R. rubiginosa > and > R. caesia > on the other. In all the hybrids reared F1 generations were obtained which manifested a certain degree of fertility, and the resulting F2 lots leant strongly toward the > R. spinosissima > parent when reared to maturity. In addition, many F2 plants remained herbaceous, and perished after a height of 2 cm. had been reached.
Professor Heslop Harrison emphasized that the F1 lots, whilst conforming, in a general sort of way, cytologically to the usual Caninae pattern, in their later meiotic stages on the female side showed important anomalies. As a result, amongst the seedlings, orthoploid plants were secured carrying chromosome complements of 14, 28, 35 and 42. Thus it was clear that a new polyploid series had been evolved by a distinctly novel mechanism. Further, amongst the seedlings there were encountered aneuploid plants with chromosome numbers 2n=24, 2n=32 and so on.
Apparently, in development a fairly heavy mortality rate takes place, leaving F2 plants, as far as present results indicate, possessing, like > R. spinosissima> , a balanced set of 28 chromosomes. These plants display a regular heterotype division like > R. spinosissima > and a normal homotype division, and are quite fertile. Further, this same fertility is manifested in the F3 and F4 generations.
That the surviving offspring were generally similar to R. spinosissima, suggests that the most nearly homologous chromosomes in the seed parent were preserved, while the others were lost. Other species should capture a different set.
And with the right chromosomal “bait”, we might be able to snag the red-tinged leaves of R. glauca.
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I have a 3rd generation R. glauca hybrid. Tetraploid, repeating, modern. No red whatsoever. In fact, gone by 2nd generation. What one gets in terms of many traits in the dog clan once overcoming the genetic hurdle is not as straightforward as a basic modern x modern cross. At least in my experience. It is possible to retain it, I suppose (if I knew how the trait worked genotypically), but it sounds like a pain to retrieve and then retain each generation.
I have asked commercial wholesale professionals on more than one occasion of foliage aesthetics. I brought up Dortmund because its a fan favorite of Master Gardeners for its holly-like foliage alone. They said it has absolutely no sway in commercial selection whatsoever. That definitely made me a bit sad to hear. I had intended to bring about a double-flowered version of Summer Wind with even greater apple scent, but it seemed like an uphill battle at that point. Getting anything modern out of Rosa primula, let alone retaining the unique smell, felt near impossible so I gave up that ghost as well.
Blackhurst (1948) failed to mention whether any of his Rubiginosa hybrids inherited the leaf-fragrance. There must be genes involved, and they must be on one or more chromosomes.
Rosa glutinosa passed on pine scented leaves to progeny with Mousseau du Japon for me though terpenes derive from different pathways than do the esters that give apple scent. I used to have a wall chart where I could trace such connections. I wonder if there an internet equivalent somewhere.
Anyway, my point is just to suggest that caninas can indeed be useful breeders when it comes to foliage.
My 2nd gen. Rosa glutinosa have the scented foliage. In fact, sometimes more so than the species, but I have lost it easily in the next generation. I find it hard to use, although I am still persisting, because the species flower is so miniscule, that getting flower/plant size balance has been a problem that I am still working out. I did post a yellow seedling from it, which was exciting in terms of a first, but the concept needs more work to be better.
I agree that the foliage is the most useful part of the dog group, but maybe for different reasons. It’s resistances to secondary diseases most other species do not readily resist has been really amazing. I also think the roots are of major interest. They pass on an amazing own root ability without suckers. In combination with Rosa wichurana descendants, this has been very helpful. In terms of those that wish to avoid Rosa wichurana types, it is also helpful.
Hi
Your glauca hybrids sound interesting. Do you find any traits from the R. glauca in the 3rd generation? I have been crossing the glauca hybrid ‘Carmenetta’ of Preston with various hulthemia hybrids (good hip set) and with some mix of striped roses. I have been using ‘Carmenetta’ as a mother and I figured that I would retain the foliage color more easily that way. In the first generation (ca 60 plants), I have very few plants with glaucous leaves and now I am keeping the lot in the hope that some of them will retain some hardiness. Normally, I am quite obsessed with ploidy but in these crosses I am just observing what happens. But my guess is that my first generation has a canina meiosis (3+2) and I do wonder what I should do if I find a plant that I would like to work on further, if I should use it as a mother or a father? … I am probably quite ahead of me as none has flowered yet.
Did you use your R. glauca as a mother plant or a father plant? If you used it as a father, do you think the triploidy in the first generation created some problems with further hybridization?
Hjörtur
So the path that this seedling followed was [Modern tetraploid floribunda x (tetraploid x (Rosa glauca x tetraploid))]. Once breaking the uneven caninae meiosis threshold is crossed, some of the origin traits do not follow along. Losing the maternal block of chromosomes that seem to cause the uneven caninae meiosis seems to do this, at least from my perception. The 2nd and 3rd generation are fully fertile.
In the 2nd and 3rd generations, the most astounding things is the amazing root vigor, willingness to root, and root outwards well. I cannot test the hardiness beyond my temperate rainforest climate, but I do know it was unphased by heat stress. It is likely hardier than the floribunda seed parent. It also passed on downy resistance. The floribunda seed parent passes on downy quite readily, and it was easily bred out.
I would use yours as a father. Selfing it wont be of much help as an attempt to retain glauca traits you may want to reinforce. You can lose alleles you may want to retain, and there is no way to know if you lost them or not in this cross type.
In your case, if you want to reinforce the glaucous trait, you may be able to take the eventual repeat blooming tetraploid porudct of your labors, and then use that to breed back to Rosa glauca, and begin again. Of course, there is no guarantee you will pick up the foliage well enough to create another eventual modern tetraploid product. We know it is likely NOT intrinsically tied to the female block causing the uneven meiosis. Rosa x ‘Mohawk’ seems to imply that Rosa glauca can pass on glaucous foliage to 1st and 2nd generations. Even if Mohawk is a self, the product would be from male donor Rosa glauca recombination.
Mohawk, as a dwarf, is a massively missed opportunity. It may be a once-bloomer, but hardy roses in that size are exceedingly rare. It could possibly be an easier route for breeders for glaucous foliage, since the tendency of “climbing” has been culled out. Cross it onto a double, repeating flori of china-type rebloom. Select for foliage and size. Keep many of them in a row. Allow them to OP and self. Rinse, repeat until desired outcome lol.
One aspect about the glaucous foliage in Rosa glauca is that we dont particularly know how it works in roses genotypically. It could be polygenic, since there are red-leaf roses (not that rare) and basic glaucous foliage (semi-rare). I can think of several basic glaucous roses, but most of them are non-repeating, so that would present a problem for bridging such a trait to see if theyre compatible. Rosa pomifera is glaucous, for example, but once-blooming and with the red. Rosa pomifera x Europeana could be interesting to see for the sake of experiencing whether or not the two foliage traits can easily combine to appear the same separately.