Canina meiosis: how exactly are the chromosomes distributed through maternal and parental lines?

I have a question about the canina meiosis and I can’t seem to find the answer immediatly. In this paper (Lunerová et al., 2020), they state that

"To cope with the abundant odd-ploidy, sect. Caninae evolved a peculiar reproductive system based on a type of asymmetrical meiosis called ‘canina meiosis’, which was described almost a century
ago (Täckholm, 1920, 1922; Blackburn and Harrison, 1921; Blackburn, 1925). Regardless of ploidy level, only 14 chromosomes pair in meiosis (seven bivalents) and are regularly distributed to the male and female gametes, while the remaining chromosomes are transmitted as univalents via the egg cell (Täckholm, 1922). Thus, male and female gametes contribute unequally to the chromosome complement of the zygote, resulting in a matroclinal inheritance of genetic material. These early cytogenetic observations are supported by molecular studies involving the transmission of microsatellite alleles and randomly amplified polymorphic DNA (RAPD) markers, deviations from standard embryo/endosperm genome size ratios (Kolarčik et al., 2018) and sequences of nuclear ribosomal internal transcribed spacer regions (nrITS) in interspecific hybrids (Werlemark and Nybom, 2001; Wissemann, 2002; Nybom et al., 2004, 2006; Ritz and Wissemann, 2011; Khaitová et al.,
2014). Despite this unique meiotic mechanism, the origin of sect. Caninae is not fully understood."

My question now is… let’s give the chromosomes a letter: A B C D and E. Before yesterday, I thought that during canina meisosis, it was always the same chromosomes, so ABCD that were used for the the matroclinal inheritance, and always E that was going through the paternal (pollen) line. But after a talk yesterday with a very good friend here I’m no longer sure of this.
So could someone help me out on this? Do we actually know if it are always the same chromosomes that are passed trough the maternal line and is it always the same chromosome that is passed through the paternal line or is it always another chromosomes? Or are it always the same 4 through the maternal line but not always the same one through the paternal? But even then… if it is not always the exact same chromosome, then after x generations of chrossings, A B C D and E can be replaced by A A A A A or whatever?

So I’m a bit confused right now… Anyone who can shine some light on this subject?

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From my reading, it seems clear that the pollen is formed only from the recombining bivalent chromosomes and not from the non-recombining univalent chromosomes that are passed exclusively through the egg. One set of each of the five lettered chromosome types in your example would always be passed through the egg, of which just one is subject to recombination during meiosis with its complimentary set that is passed through the pollen. The remaining four are isolated from that process, never pairing and never recombining.

This published commentary on the paper you quoted may answer your question more clearly: love life of a rose. A commentary on: ‘Asymmetrical canina meiosis is accompanied by the expansion of a pericentric satellite in non-recombining univalent chromosomes’ | Annals of Botany | Oxford Academic


Thank you Stefan

So I guess one could say the chromosomes in rosa canina can be symboliswed by A B C D D. The female egg always ends up containging A B C D and the pollen is always D.

So maybe, theoretically if one could find a rose that gives pollen and contains chromosomes that are very much alike as the A of B or C chromosome, it might be possible to break the canina meiosis? That is somehow what must have happened in the past while some breeders were working with rosa rubiginosa and Magnifica.

Caninae meiosis is already understood to break down over a few generations during outcrossing to non-Caninae roses, but I don’t know if anyone has examined what is going on in such hybrids at the chromosome level in recent times. That “alike” chromosomes from the univalents and the unrelated pollen parent could pair up seems like a potentially overly simplistic explanation, and I don’t know that there is any evidence to support that idea. I’m not sure that the univalent Caninae chromosomes are necessarily more like the chromosomes found in pollen from other roses than the bivalent chromosomes are, anyway. It may be that those univalents simply continue to remain so even in hybrids, never directly pairing or recombining with anything, and resulting in something like aneuploid offspring with each generation until perhaps the univalents ultimately fail to be transmitted altogether. It seems to me that Caninae are all sort of like aneuploids, in a way, except that they seem to have evolved a mechanism to promote and regulate this behavior. It is really that special mechanism through which the dog roses transmit univalents to their gametes during meiosis, rather than anything else, that defines Caninae meiosis. The breakdown of Caninae meiosis might then ultimately mean the loss of the ability to transmit such univalents to gametes, even though more typical meiosis continues unabated.


Part of the “mystery” of Caninae meiosis seems a bit less mysterious when we recall that male meiosis and female meiosis are “opposite” processes. On the female side, there is an accumulation of “stuff” into the ovum. On the male side, the “stuff” is being stripped out. The paired chromosomes are obliged to separate, half going one way, the rest going the other way. Unpaired chromosomes drift along with the “stuff”, which pushes them into the ovum, on the female side, but excludes them from microspore on the male side.

Something similar happens in humans. In one region, the leucocytes get packed with “stuff”, while the erythrocytes (red corpuscles) are stripped to the walls … not even chromosomes get in.

Proc. Botanical Soc. of the British Isles (1954/55)

Durham Wild Roses

J. W. Heslop Harrison

Next, taking up the question of rose hybrids, he listed those found in the two counties, and insisted that, contrary to general opinions, many showed limited fertility, although he remarked that Durham R. villosa x spinosissima and R. dumalis x spinosissima were always sterile. Very much different were the cases of R. sherardi x spinosissima, R. rubiginosa x spinosissima, R. caesia x spinosissima, R. canina x sherardi and R. dumetorum x villosa. The first of these crosses he had reared up to the F4 generation, the second to the F3 lots and the third, fourth and fifth to the F2 lots. In each case, the F2 and succeeding lots, when the latter had been obtained, were much more fertile than the F1 generation. At this stage it was indicated that R. spinosissima was self-sterile.

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. Incidentally, the lecturer pointed out that pinkness in all these crosses is dominant.

I wonder whether the lost cell-lines (e.g., diploids) might survive in other environmental conditions. At any rate, Caninae species carry some interesting traits that are stubbornly difficult to isolate. Apple-scented leaves would be a nice addition to hedge roses, and the red-tinted leaves of Rosa glauca would also be welcomed. I wonder how they would work with a surface that is glossy rather than glaucous.

F1’s from a 2013 cross of R. glutinosa onto Mousseux du Japon preserved the pine scent of glutinosa in at least three seedlings from the cross. I have one still, it is mossed but not so heavily as Mosseux du Japon.

Apple-scented leaves would be a nice addition to hedge roses

The canina are the Borg of the rose genus. They assimilate whichever species they cross with. This is described in the paper posted by Roseus on another thread. I PM’d that paper to dgermeys along with a couple of other relevant papers, if anyone else want’s copies let me know.

While describing the Caninae meiosis, I forgot the proper terminology. I wanted to finish my thought, though, rather than search for the right words. Now I’m back with the goods.

Schematic illustration for different types of cell division. (A) Equatorial (E) and meridional (M) cleavages in the two-cell embryo. The red circle is the second polar body. The dashed lines mark the cleavage planes. (B) Symmetric and asymmetric divisions in the eight-cell embryo. Only four blastomeres in the eight-cell embryo are shown. Symmetric division results in two polarized blastomeres with equal position in the embryo, while asymmetric division produces one polarized outer cell and one apolar inside cell.

I have never found another family of plants that have a Caninae-type meiosis. The closest I’ve seen is a strain of hexaploid wheat with an unpaired chromosome borrowed from Elymus trachycaulus.
The borrowed chromosome was transmitted in 20% of the female gametes and 97% of the male gametes in the genetic background of wheat, although the expected transmission frequencies of the alien chromosome through female and male gametes are 25% and 0-5%, respectively.
This is not exactly the same, but it’s the best I can do for now.

Regarding Caninae species crossed with “normal” types, Heslop-Harrison (1921) observed that “glandular leaves are always biserrate”. Can anyone corroborate this?
Has anyone seen the form of Rosa moschata with biserrate leaves?

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So, Ann Endt self 3x, with Rosa pomifera crossed onto that product as a male parent created seedlings with no serration whatsoever. Rosa canina crosses made a lot of biserrated, and a minor amount of slightly smoother edges. Rosa rubiginosa were almost all biserrated (from memory… its kind of crap species to work with). R. glutinosa is harder to tell, like rubiginosa, is mostly biserrated seedlings.

And, no, I dont know why my friend took my Ann Endt self that I selfed once more turned around and selfed it one more time, but I found it hilarious when he showed me lol. Amazing foliage on all of them though! The foliage down on the Ann Endt cubed x Rosa pomifera is so amazing though. Tiny little leaflets, all covered in those grey downy “hairs”, completely semi-dwarf eye internodes. Rosa pomifera itself is not a semi-dwarf, but they can be produced in F1 with the right crosses.

The Dog clan is full of surprises. It just takes patience.

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Is biserrate trait correlated with fragrant leaves?

I am not sure. Fragrant leaves tend to be the first thing to go.

Are these traits linked genetics? I wish I knew.

I own Rosa primula. It’s leaflets are so tiny that I never thought of checking. Completely different type of fragrance and without the foliar texture often associated to scent in dog roses. Canina itself doesn’t really have the scent, but can be highly serrated. Segregating this, is the texture associated with the serration, and I cannot answer this either.

Not all R. rubiginosa have biserate leaves. The majority has, but not all. Found it in a description of a Dutch site with a good reputation in native plants.

Is Applejack biserate? I believe it is, but also irregular. Can’t really tell from the pictures I’ve found online.

I was searching for more info on the topic and stumbled onto this article.

Happy reading!