Ratios of diploids

hi group

I read a masters thesis on crossing reblooming and once blooming roses and recovering the recessive reblooming with diploids. I assumed rr X Rr would give half reblooming. The evidence in the thesis give ratio to be 1:8 or so. I have allowed this paper influence my breeding. I was not patient allowing the roses to rebloom 2nd year since I ripped them up.

This student uses Basye’s Thornless. He described this rose to be white from what I found in the literature -HMF that this rose is pink. I think that perhaps a tetraploid was used when like he crossed onto Old Blush would give these funny results as triploid F1s.

This thesis has baffled me and made serious impacts on how I did my crosses. I can only be thankful that I left a row of Rosa rugosa hybrids that the next season produced a 1:1 ratio.

Was he wrong? I guess that I have being only selecting for same year blooming.

Thanks Johannes


What is the title of the thesis?
What is the author’s name?
At what university was this thesis done?




I didn’t read the paper but an 8 to 1 ratio is not what I would have expected nor what I have observed. I was thinking the same thing in that the author may have used a tetraploid instead of a diploid which would skew his results. He may of also only counted the plants that bloomed the first year. If the seedlings had non-juvenile repeat bloom, like Rugosas have, then they might not bloom until their 2nd or 3rd year, so he wouldn’t have counted them.

I did reciprocal crosses with Metis and a repeat blooming third year plant last year. There are 11 seedlings with Metis as the pollen parent and 4 have bloomed already. That’s about 1/3 for juvenile repeat bloom. If I were to keep all of them until their third year I suspect there would be more that display non-juvenile repeat bloom.

Very interesting!

Coincidentally, Tom Silvers and I were recently discussing our shared interest in tropical fish when a case of surprisingly unexpected segregation came up.

In the common guppy fish (Poecilia reticulata), sex determination is usually the same as in most mammals: XX females, XY males. However, O. Winge (1932) reported on some crosses among some guppy strains that gave all or almost all female offspring. Among these he found an XX male. This led to a strain in which all members (male and female) were XX, and yet they gave approximately equal numbers of males and females. Clearly, there must be “genes” in other chromosomes that influence sex determination, and which may become aligned in such a way as to over-ride the “normal” role of the sex chromosomes.

Is something like this involved in Shupert’s results?

It is no secret that some reblooming roses are more enthusiastic about their rebloom than others. Repeated selection for free rebloom may have served to make rebloom vs once-bloom behave as neatly as sex determination in wild guppies. But if some science-minded breeder would raise seedlings from the reluctant rebloomers, we might not be so surprised by Shupert’s results.

For example, ‘Frau Karl Druschki’ is reported to be a vigorous once-bloomer on its own roots, but a freely reblooming dwarf when grafted to a suitable stock. And ‘Paul’s Lemon Pillar’ (Frau Karl Druschki x Maréchal Niel) is a once-bloomer. Both facts suggest that the relationship between once-bloom and rebloom is not as simple as we might like.

To all this I may add a comment from Viviand-Morel (1914), “I had occasion to cross the Polyantha Perle d’Or (Dubreuil) by the ordinary Bengal and obtained two huge Multifloras. The characters of the Bengal and the half-blood tea, of the Perle d’Or, had disappeared from the product.”

Maybe stray pollen interfered. But it is interesting that his cross also involved “the ordinary Bengal”, which I will assume is our ‘Old Blush’.


Here’s my take from my memory and talking with the student at ASHS meetings years ago and Dr. Byrne.

He did use the diploid R. wichurana in his crosses and not the tetraploid R. carolina hybrid. The cross was Old Blush x BT and some of those F1 hybrids were back crossed onto Old Blush. He did get a high ratio of seedlings that were once blooming. During the student’s (David S.) talk at ASHS he got me thinking. He ended his talk with a number of possibilities of this unexpected ratio. This is what popped into my mind as I heard him and later with some recent papers was confirmed and likely explains things. The major repeat bloom gene is linked to the gene for self incompatibility. I suggested that to David S. and suggested a way to test that would be to cross the F1’s as the female and backcross with Old Blush as the male and in that situation if one got the 1:1 that would help confirm basic linkage. Self-incompatibility is a “leaky” system and the genes may be a bit apart too allowing for them to recombine some for 1/8 repeaters instead of no repeat offspring.

As he puts pollen onto Old Blush from seedlings that are 1/2 Old Blush the gametes that segregated for the chromosomes with Old BLush self incompability alleles were being partially or completely blocked in favor of the gametes segregating to have the R. wichurana self incompat. allele. Those are different than Old Blush and those gametes are getting through. The repeat bloom allele happens to be on the same chromosome near the self incomp. allele and is going along for the ride. The gametes with the R. wich SI allele barring recombination should have the R. wich one time bloom allele. THe system is leaky so the 1/8 repeaters could be due to recombination or they just slipped through. I don’t think they did the cross the other direction to test this, but we do know now the genes are linked.


That’s also interesting, but the self-incompatibility of Rosa wichuraiana must be VERY leaky. Semeniuk (1971) selfed a non-recurrent specimen of R. wichuraiana and got 294 seeds: 226 germinated, all becoming non-recurrent plants. The reblooming form was also selfed: 494 seeds, all 373 that germinated were recurrent.

An F1 specimen was selfed, giving 121 once-bloomers, 37 rebloomers. That is not a perfect 3:1, but pretty close. At least it does not suggest any major disruption of segregation on the male side. Self-incompatility must be pretty weak for selfing to give so many viable seeds. Or, it must have been weak in the strain he was using.

The recurrent and non-recurrent selections were siblings raised from a variant R. wichuraiana that had been selfed.

‘Old Blush’ also gives self seedlings, according to Ralph Moore (1967). So, self-incompatibility is not very potent in this variety, either.

Hi Karl!

Great point. Temperature impacts SI quite a bit denaturing some of the proteins involved. In my cooler climate SI seems to be expressed more in some of the popular rugosas for instance compared to the same varieties grown further South. It would be interesting to do the follow up with the reciprocal cross David S. did to test the role of SI being the key component impacting what they experienced. My polys I like to work with are generally SI, however, when I had them in a warm greenhouse one June they set lots of seeds and the seedlings appeared to be selfs due to the phenotypes of the parents (thornless females growing next to thorny males gave all thornless seedlings, which is recessive, etc.). If there are records when the crosses were made and temperatures around that time, that may offer some insights too. Expression and impact of SI definitely varies due to genotype and environment.

David explanations are neat.

One could also consider that there is another explanation that fit another hypothesis about rebloom genetic control:
constant blooming being a failure of polygenic controled once blooming.
With different parents, as there is eventually more than one failure possible; different ratios are possible including those with more or less once bloomers than expected from the monogenic recessive hypothesis.

As pointed in some case there is the probability that OPs were Out Pollinations and not “mostly self pollinations”.

Self incompatibility in many diploids is quite strong at my place and many others.
I.e. being self incompatible The Fairy is often considered as sterile when with compatible pollen it is fully fertile.

Self-incompatibility is a complicated and confusing matter. Sometimes it can be weakened or eliminated by environmental conditions. There is also variation among specimens of a single species.

For instance, Stout (1922), discussing sterility in lilies, wrote, “The phenomena of incompatibility are well illustrated by the results obtained with L. regale, a splendid and beautiful lily recently introduced from China. Of the ten plants tested, nine were self-incompatible and one was self-compatible. Cross pollination between plants sometimes succeeded and sometimes failed.”

Leaky self-incompatibility was also responsible for the rapid development of cultivated Primulas. Ordinarily the plants result from crosses between “Pin” and “Thrum” breeding types. But “illegitimate” self-pollinations can occur, and be continued generation after generation, exposing recessive traits that would normally be hidden.

Weather can have a profound influence on fertility – both self- and cross. Plants that seem sterile (or nearly) may suddenly become fertile. It would be interesting to know how the weather in England in 1887 differed from normal.

The Garden, 1887
p. 194: Liliums seeding.—I have never known the different species of Lilies to bear seed so freely as this year. I have one seed pod on a plant of L. testaceum. As this Lily is supposed to be a hybrid, I wish to know if it often bears seed, as I have never known it do so before.—W. SHOOLBRED, St. Ann’s, Chepstow.
p. 394: Lilium testaceum seeding.—In answer to W. Shoolbred in THE GARDEN (p. 194), I once got a good seed-pod of this. It was exactly between Lilium candidum and L chalcedonicum. L candidum and L. testaceum both seeded under the same circumstance: the stems were cut off in flower and put into a pot of water in the open air. It is said if candidum is cut and the stems hung topsy-turvey they will seed .—F. MILES

Withers (1975) dealt specifically with Lilies, but also discussed research into self- and cross-incompatiblity in other plants. One note that may be of some interest: “Dr. Peter Valder of Sydney University has successfully crossed evergreen with deciduous rhododendrons by cutting off the style of the seed parent just in front of the ovary and then applying pollen from the pollen parent to the cut surface of the style. The pollen has germinated, and has had a much shorter journey to the ovules in the ovary, and successful fertilization and seed production has taken place.”

Lucien Reychler (1926) also experimented with pollen applied to the stumps of cut styles, and introduced directly into the ovary.

The shorter journey would reduce or eliminate whatever incompatibilty reactions may be occurring in the style.


Wandering slightly from the main topic, I’d like to mention some recent observations (this week). I’ve been collecting OP seeds of Rainbow KO for several years. With nitrate I can get germ up to 50% or so. Even with that I don’t get a huge lot of seedlings because each hip has only a couple seeds. Generally hips are scattered all round the bush, though more on the inside and near the ground. Last fall I noticed a rather striking clustering of hips on a couple branches on the north side of the bushes, which had not been pruned in spring. They were cut hard the previous summer (not spring but summer). The same treatment was given to double KO bushes right next to these 4 RKO.

Usually almost all OP of RKO look almost exactly like RKO. Rarely one gets something that seems nearer orange or salmon and very rarely yellow. Last season I found roughly half a dozen of these variants out of 500 or so seedlings. Incidentally, several of these are decently fertile when pollinated indoors with fresh pollen of unrelated plants.

In mid-Jan I had a burst of germination of RKO from some tests I’m doing on improving the nitrate treatment. Those seedlings (>150) are now blooming. Much to my surprise, I’m seeing flowers with a red like DKO, pure deep pink, regular pink. This is not what I’d found in previous years. I can only conclude that weather conditions were such that cross-pollination happened last summer. I am certain that I didn’t mix hips at harvest. I have a separate study going with the limited number of DKO hips that I did get. I have noticed that hip set is much better on DKO close to RKO than further away. I must attribute that to some crossing but everything that I’ve bothered to let grow to blooming looks basically like DKO, so I don’t have any obvious phenotype evidence for crossing. My current observation suggests that RKO may accept pollen sometimes from other CVs. It might be possible to use the old-fashioned strategy of interplanting two desirable parents, and select the seedlings of OP seed. RKO OP does give about 1/1000 pure yellow singles. No luck with fertility on that yet. It can also give very intense reds when crossed with pink kinds.

In my mind, it’s not clear that the low fertility of the KOs is simply triploidy. I think there may be some compatibility factors too. Great for floriferousness, not so good for breeding.

You are probably right about there being more than triploidy involved. Nicolas (1928) wrote, “Paul’s Scarlet Climber as an own root plant may be considered as sterile, but a grafted plant will bear both self- and hand-pollinated seeds.”

‘Paul’s Scarlet Climber’ is also a triploid, so it is obvious that triploidy alone cannot account for its sterility when grown on its own roots.

Also, Stout (1922) reported that Brassica chinensis and its hybrids with B. pekinensis were more self-fertile during the period of mid-bloom, less so earlier and later.

This seems analogous to your plants that were cut back hard in summer, forcing them to throw more effort into the subsequent blooms.

Larry wrote: " I can only conclude that weather conditions were such that cross-pollination happened last summer."

Or that some industrious bee/bumblebee contributed that did not in previous years.


That The Fairy and many other roses occasional fertility is from leaky self incompatibility is possible but there is at times, just as Larry observed, a strong mark from the neighbouring roses.
Such as when collecting OP hips at Hanburry Garden I got seedlings with the long very straight that characterise Banksiae the simple form is growing near by.

Paul, nice to see that Metis is being used. I usually only get OP, little luck with cotroled ones Johannes

I finally remembered this report from Darlington and Mather, Elements of Genetics, (1949) 1969 pp. 255-256:

Ordinary incompatibility is controlled in the same way: it has the same genetic structure as heterostyly. For example, > Petunia violacea > has the usual multiple allelomorph system of pollen-style relationships: self-pollination rarely succeeds. > P. axillaris, > on the other hand, shows no trace of incompatibility: selfing and crossing succeed equally well. In the F1 different S allelomorphs from > violacea > vary in effectiveness and plants differ in the degree of self-compatibility. By crossing together F1 plants with different S allelomorphs, or by backcrossing them to their > violacea > parent, we can get plants with the same S constitution as > violacea > but with other genes, half in the F2 and a quarter, or nearly a quarter, in the backcross, from > axillaris> . Although alike in regard to S these three types of plants show incompatibility relations differing in two ways (Fig. 64).

First, the amount of seed set on self-fertilization increases with the proportion of axillaris genes. These genes must therefore be undermining the operation which the S genes control.

Secondly, the amount of seed set on pollination of backcross or F2 plants by > violacea > is greater than any produced by self-pollination, although the same S genes are at work. Thus the > axillaris > genes not merely weaken the operation of the S genes; they shift their operation so as to put it out of step in plants with different proportions of > axillaris > genes. Or, the other way round, we may the same S genes can not merely control systems of different strengths, but systems which are less efficient with one another than each is within itself.

Now, we may ask, what happens when we cross two self-incompatible species, each with the S genes? This has been done for > Nicotiana alata > and > N. forgetiana > in the production of the garden form > N. sanderae. > Pseudo-compatibility, that is successful fertilization with pollen having an S allelemorph the same as in the style and therefore not legitimately capable of growth, is unknown in > forgetiana> . It occurs only rarely in > alata> . In their derivative it is common, especially with certain of the weaker allelemorphs. Thus the recombination between the general gene systems of two species has robbed each of its efficiency as a basis for the action of the S series.

So, in addition to the influence of environment, the various sterility alleles can differ in their potency.

And regarding temperature, on p. 247, Darlington and Mather wrote:

The S gene tells us many things of importance. Its large number of allelomorphs is without parallel. The specificity of their actions is nearly always complete, since Sx pollen fails on a style carrying Sx no matter what the other allelomorph may be. In some cases this specificity extends to the strength of the action, for some allelomorphs are stronger than others whatever others are present, though in other cases the allelomorphs can strengthen one another’s action. Moreover the propeties of the pollen itself are determined by the single allelomorph carried in its own nucleus after segregation: there is no delayed effect from the other allelomorph present in its diploid parent (and in its sister pollen). The rapid and specific action puts one in mind of the relation between between gene and antigen in the determination of blood groups. The analogy is still more evident from the effect of a rise of temperature which, so Lewis found, speeds up the growth of compatible pollen, yet slows down the growth of the incompatible. Incompatibility is thus due to a positive blocking reaction.

Hi Karl!

Thank you for all you do to archive and preserve these great articles. I wonder (I should look it up…) how much understanding there was at this time between gametophytic and sporophytic self-incompatibility. It’s nice in some ways that roses have gametophytic self-incompatibility that relies more so on suppressing the pollen tube along the way than preventing pollen from generally germinating and get started down the style, so it can more easily (temp., strength of S alleles, early or late pollination, etc.) be overcome.

There are so many breeding systems. It’s hard to keep track of the options. For instance, Heideman (1895) found multiple systems in Prunus americana, none of which (so far as he could suspect) involved multiple sterility alleles.

Jeffrey (1915) reported that with the horseradish it is “possible to bring about the formation of fertile seed by simply girdling the top of the subterranean storage region of the plant, so as to prevent the undue descent of assimilates.” The horseradish will, however, set seed when pollinated by a distinct variety.

This implies that the self-sterility involves a “decision” by the seed parent to withhold or withdraw nutrients to the “illegitimate” seeds. Traub (1935) reported similar results among Amaryllids.

Beaton (1861) also weighed in on the subject:

Mr. Knight made an experiment for getting early Potatoes to seed by planting them on a ridge, and when the plants were ready to bloom he washed away the soil of the ridge to prevent them making young tubers, and so force the whole strength of the plants or roots into the stems and foliage to see if that would force them to seed. Another form of that experiment is applicable to all bulbs and tubers which form roots on the flowering-stems, as the Japan Lilies and others do. Pot such bulbs or tubers with the neck of the bulbs just at the surface, and when the stem is an inch or two put an empty pot over it, introducing the stem through the hole at the bottom of the pot, then earth up the stem, and when it roots and fills the upper pot separate from the bulbs, then cross it.


These may be of particular interest because girdling (or “ringing”) can be done on roses. I haven’t tried it yet, but maybe this year.

Here’s how ringing is done with grapes.

Back on topic, Tom Silvers also reported deficiencies of rebloomers in his breeding.

You know it’s funny that you mention that. I haven’t done actual counts but it’s seemed to me that the rebloomers are always under-represented in the crosses I’ve done. For example, open-pollinated (presumably mostly selfed and sibbed) rugosa X palustris - I would have thought that I should get 1/4 rebloomers in the F2. I don’t recall ever seeing any, though admittedly they suffered a lot. Also, it was rare to find a rebloomer as an F2 from open-pollinated multiflora X Mutabilis. I thought that I’d get at least 1/4, or maybe more since it was right next to Mutabilis itself (so should have had ample opportunity for backcrosses).

It may be relevant to note Wright’s (1960) comment on color inheritance:

“It is more usual for roses which are heterozygous of a color to pass down faint tinges of color than no color at all. In fact, we always tend to get a superabundance of blush-pink varieties in breeding new roses.”
Wright: Inheritance of Color in Hardy Roses (1960)

Would this be analogous to inheriting “tinges” of the once-blooming habit?

Then there is the fact that ‘Schoener’s Nutkana’ bears single flowers. Lammerts (1945) presented a tidy scheme based on the assumption that in the case of doubleness there is a direct correlation between phenotype and genotype. But the neatness of this model does not explain how the cross R. nutkana x Paul Neyron could produce a single-flowered offspring. Or how this (presumably) homozygous-for-singleness plant, when pollinated by ‘Souvenir de Madame Boullet’, could produce a double-flowered ‘Leonard Barron’. By Lammerts’ model, semi-double was the best that could be expected.

Very interesting observations. Let me throw in one of my own. I pollinated Silver Moon with Carefree sunshine and got a hundred-petaled double. It seems sterile so far, with few reproductive parts. Carefree sunshine yields only singles in more than 100 seedlings I’ve grown from it. Silver Moon is a triploid with about 10 petals. A couple of its progenitors are also singles, but somewhere back a couple generations there was a HP reported, probably double given the current fashion around 1900. Other offspring of SM are single or early so. Rebloomers are also rare, though i’ve not kept a careful count. There are enough to keep trying.

The simplest explanation for many of these phenomena is really well known in more amenable breeding systems. It is called linkage disequilibrium. Somewhere I wrote about it in the
RHA Newsletter. Even though in principle we might have simple Mendelian segregation, in practice it doesn’t happen that way. Often only those progeny that retain a whole cluster of traits from different chromosomes are able to survive to germinate. So with Carefree Copper seedlings I typically get thorny, small-leaved, hardy, once-blooming, tall plants, and their opposites. But in between mixtures are hard to find. If the species have diverged enough, they can’t make happy partnerships with others. This happens at the molecular level, when two proteins have to work together to control something. Sometimes the genes for these proteins are linked on one chromosome. Sometimes they are on different one. But either way, they can’t live without each other.

I’m not yet ready to begin thinking hard about where the micro-RNAs enter into all this. We know they are present and important because they were first discovered in plants, though the Nobel prize narrowmindedly excluded David Baulcombe because he worked on plants not animals. But thinking loosely, the RNAs have to find places to match their sequences so they can control gene function, during key stages of development. Too much difference and they’re dead. So even genes on different chromosomes may have to segregate together to make a viable system. Diploid or sniploid, it doesn’t matter the ploidy as much as the polity. Party members hang together.

Trying to blend species is challenging. You probably can’t get equal portions of two (rather?, very?) different species to live together, no matter the ploidy level. But with higher ploidy they are likely to be more able to coexist as two species in a single body. That is what we have in bread wheat with three progenitor chromosome sets still identifiable. Clever breeders now can move things round by brute force selection. But with natural selection, that rarely happens.

Even with brute force its hard. Finding perennial, hardy, high yielding sorghum has challenged The Land Institute for decades.