Simon, I think you’re right on target with questioning the assumption of pairability. That’s the main problem. Likely some bits will cross over from time to time but they may not be equal crossings-over. How badly that unbalances things would depend on where it happened.
Reticulation I think is weaving back and forth. That is the species complex evolves with repeated inter-crossing. So you end up having a hard time to draw a reliable evolutionary tree.
I can say for sure I have one seedling that has R pomifera (a special one from David Z) as male parent and a “regular” tetraploid out of Carefree Beauty as the female parent. It made it through two seasons and is about 6 inches tall. Foliage and thornage definitely is pomifera. Some day maybe a flower. I had a couple more germinate from that cross (5 of 13 seeds). But don’t seem to have other survivors. Crosses the other direction with assorted pollen onto R pom gave about 150 seeds but no recorded germ. That was before I discovered the nitrate effect. If they were just selfs I ought to be able to get >50% germ with nitrate. Lost a couple seasons for R pom but will attempt it next spring.
Larry, I have tried using Pomifera (duplex) for 3 yrs with out any luck, but this year, I have hips forming on two different cultivars so here is fingers crossed.
Well, the one from David Z is special in that it may have fewer chromosome sets that usual because it was derived from a twinned embryo, and then selfed, if I recall the pedigree correctly. He was giving out the seedlings a few years back and I go a couple.
Good luck with your crosses.
BTW, I was basically right about reticulation. You can read a bunch of articles by googling reticulate evolution. Most are rather theoretical for making trees. But you can get the idea from the pictures.
I hope your CB descendant x R. pom survives!! That’s great it is surviving!!
The story of the 3x R. pomifera is this. There were twin embryos years ago and the smaller twin (same testa- papery outer covering) was 3x while the larger twin was 4x. Likely the smaller twin came from a synergid cell that developed into an embryo. Synergids have the same genetic constitution as the egg cell and basically in this case is like an unfertilized egg. This 3x plant grew fine and is fertile producing selfs readily that are also 3x. The pollen is the expected diameter for 1x pollen, typical for Caninae meiosis. Typically, as we can see from the literature. There is one duplicated genome (or set of chromsomes) that preferentially pair during meiosis and the rest do not pair (univalents). The univalents and one set of the paired chromosomes get packaged in the egg of Caninae section species and in the pollen the univalents are lost and one set of the paired chromosomes are retained and packaged. This way the plant can reestablish its genetic constitution even if its 5x like most R. canina and R. rubiginosa genotypes. In this case with the 3x R. pomifera, we do not have that second set of chromosomes expected from that duplicated genome because it wasn’t fertilized. Somehow, the pattern of having two sets of chromosomes preferentially pair seems like it may have reestablished itself with two sets of the remaining 3 sets of chromosomes. I notice some extra variability in leaf size, etc. in the selfs of the 3x clone than the straight 4x species of R. pomifera. This is likely because those univalent chromosomes that have not likely paired with anything and recombine and were basically transmitted as is through the female generation after generation now may have the opportunity to recombine. There is likely greater segregation of chromosomes now among the selfs of the 3x parent leading to greater variability. I wish I had the resources (time, equipment, additional skill) to document what is happening. I shared this information and idea to collaborate with the Europeans working on Dogroses. They were excited at first, but due to funding, etc. have not followed up on the idea. R. pomifera and other Caninae section species are routinely used for fruit production in Europe. Opening the opportunity for recombination between the once univalent genomes to generate greater segregation among seedlings for fruit traits I think would be of great value. As I’ve found with the 3x parent, it seems possible for Caninae meiosis to be restored at least in some plants and good self fertility retained for fruit production.
In http://www.globalsciencebooks.info/JournalsSup/images/0906/FOB_3(SI1)53-70o.pdf you can see that seedling selection 1I4 page 62 (a 4x seedling of R. pomifera x a polyantha) has pollen diameter expected for pollen being 1x. Perhaps R. pomifera especially has a gene or group of genes that govern the Caninae meiosis and can easily reestablish it with other chromosome sets/genomes. This seedling does make some op hips, but in general they have only 1 or two seeds in them and the pollen has not been successful on other things.
David wrote: “One challenge I have had with putting pollen of Caninae section species on diploid or polyploid roses of other backgrounds is that at least for me the crosses have rarely took, and when they have the seedlings were confused and eventually died. There are some exceptions of course.”
I’ll second that David! And in my opinion, the exceptions have been worth all the trouble. It’s such a strange and mysterious group that it can very frustrating but also equally as fascinating to work with.
The following excerpt has a reference to Carmenetta ploidy. It also mentions some pentaploid hybrids from R. canina x R. rugosa that form more than 7 bivalents at meiosis.
David also mentioned “a 4x seedling of R. pomifera x a polyantha… does make some op hips, but in general they have only 1 or two seeds in them”
That sounds like the about same level of fertility as my F1 glutinosa x palustris, which also sets some open-pollinated seed but generally only one per hip.
Should I understand from Ann P. Wylie’s reference to Carmenetta ploidy (linked in Tom’s post) that Carmenetta might behave as a tetraploid in hybridizing? (I was looking for diploids to nail her with…) Then should the same be assumed for the Skinner’s Red Leaf that Bob has?
Now… this is why I joined RHA in the first place… a little like the forum of old with Robert, Roger Mitchel etc discussing the more in-depth aspects of rose breeding!
So, it appears that the canina-type meiosis might break down in response to hybridisation and climatic pressures. I guess it’s reasonable to expect, therefore, that people growing these roses in areas where they are non-endemic (like Tasmania) might experience more success with this because they are less well adapted to the conditions and responding to changes in these environments is going to place extra challenges on the plants that might result in some ‘creative’ variation in the ploidy of its gametes.
I don’t quite understand what you’re asking, David. I would imagine that given there are no roses native to anywhere in the Southern Hemisphere they would experience challenges anywhere you would choose to grow them. They seem to be very adaptable though as they are a weed in many parts, including Tasmania (i.e. rubiginosa).
Simon this the part I was referring to in your post.
“I guess it’s reasonable to expect, therefore, that people growing these roses in areas where they are non-endemic (like Tasmania) might experience more success with this because they are less well adapted to the conditions and responding to changes in these environments is going to place extra challenges on the plants that might result in some ‘creative’ variation in the ploidy of its gametes”.
I was looking at the different conditions that our roses grow in and whether yours or mine would be more favorable. Just an interest.
What I meant by that statement, David, was not that they would grow better but that it is not their normal environment and because they will experience challenges to which they are not completely adapted then there might be a greater chance of environmental pressures affecting the pattern of meiosis or the chance of wide crosses being successful and having some kind of inheritable impact, etc.
Uhm, Simon, the rest of us are here, too? Thanks, lol. Anyways, Robert does not participate because of a conflict of belief, being that this is a world-wide association, yet specific cultural beliefs are permitted. I dont blame him. That is his right.
The Caninae family are highly productive, except maybe R. glutinosa, which is like 3" tall now, lol . Just keep trying. It will work if it does, or it will not if it wont, but the potential and resources are abundant. That is all that is really needed. ‘Carmenetta’ itself may be tricky simply because 1rst gen rugosa hybrids can prove to be highly unstable as breeding material. If It was Glauca x most other things, I’d have stronger faith. However, the diploid half was matched well, so even though its now and intersection, it will likely blend well down the road, especially since Glauca shares many septet traits with the cinnamonae section. Each Caninae type shares various traits with all other section types. Caninae is the roulette of roses.
Speaking of Robert, I have Kordesii x (R. pedulina x R.glauca). Pretty plant. Iron clad.
Do you think Luther Burbank became successful because he sudied each cross road of likely possibility? This is where my closest friend, a botanist, and I, diverge. He is interested in the science, the talk of science, the what-ifs, and their classifications. I am interested in new actions and efficiency in creation. However, they both relate, and neither are anything to sneeze at.
Yeah, yeah… I know you are all here… just two names I pulled out of a hat… I just miss the really gritty discussions that use to take place on here that don’t seem to happen very often atm. IMO science and creativity go hand-in-hand
An update! I was cleaning the spent flowers off glauca on Sunday (because the advice on here seems to suggest it might self-seed and possibly spread), and noticed that all except one glauca x wichurana hip had shrivelled and failed. The remaining one seems to be developing normally. Maybe I didn’t get it in time and it selfed??? Will be exciting to see.
Caninae x Synstylae had horrible results (hundreds) for me. If I did it again, I’d have tried Synstylae x Caninae. If I couldnt, I’d have picked a mixed Synstylae type, like a groundcover.
I have done this too… Synstylae (wich hybrid) x rubiginosa (I can’t get canina here… it’s banned). I used my rubiginosa seedling that I picked out of 100’s from seed collected off feral plants because it didn’t show any mildew… fingers crossed this is passed on.
