Quick question about rosa acicularis: does anyone know if the octaploid version’s chromosomes break evenly between seed and pollen parents (4 + 4)? I have been considering using it in my breeding as it grows so prolifically here. My thoughts were to cross it with a tetraploid and then the F1s to a hardy diploid, hoping to eventually get hardy/fertile tetraploid F2s.
Has anyone tried this? What sort of results have others had using rosa acicularis in this way?
Thanks,
CM
Are you sure you have the octoploid version? Apparently hexaploid is a good bit more common, and there may be tetraploids too. Where do you live?
I’m pretty sure it’s the octaploid version. I live in Wasilla Alaska. From what I understand the hexaploid version of rosa acicularis has rounded hips and the octaploid has elongated. Is this correct?
CM
There is enough variability to make ploidy pretty difficult to assign just by location or by hip shape. You might take a look at the references page on HMF and see which description seems to fit your local genotype better. Apparently the pedicels and the sepals may provide hints of which yours is–if you happen to have counted the leaflets, made measurements of the sepals and noted the characteristics of the pedicels this past growing season. Although shape of the hip may be significant, I’d not use that as the only criterion for identification. A species with a relatively elongated hip may have relatively rounded hips if the seed-set has been especially good. Are you familiar with R. woodsii?
The ploidy of rose species can’t be determined from the morphology of the shrub. Populations of Rosa acicularis on the Canadian Prairies having elongated hips appear to be generally tetraploids (tests done by David Zlesak). An exception is the ‘Kinistino’ cultivar (a hybrid of two different Rosa acicularis populations) having elongated hips that is an octoploid.
Rosa acicularis is a neglected species for breeding cold hardy (Zone 3 roses). I hope to develop a ‘Morden Centennial’ x Rosa acicularis breeding line as one route to change this situation. Successful crosses were done this year, and I’ll repeat this cross again next year.
Hey CM,
I grew up in Fairbanks, AK and have wanted to get a selection from there to use in breeding. I remember when I was a kid that we had a ‘volunteer’ Rosa acicularis show up in our backyard. Our family used to go berry picking (blueberries, cranberries and raspberries). They were often mixed in where the raspberries were growing.
Good luck to you!
Jim Sproul
Thanks for the information. The stems are glandular so I will operate on the premise that they are octaploid.
Can I assume safely that the pollen from an octaploid rosa acicularis will create a hexaploid when used on a tetraploid, or is acicularis like the dog rose and separate assymetrically at meiosis?
Those of you that have used any form of rosa acicularis in your work, have you noticed acceptable fertility in its progeny?
Thanks,
CM
Jim,
You’re in zone 9, could you share with me what your vision is with rosa acicularis in your efforts?
CM
Hi CM,
Since R. acicularis is in the section Cinnamomeae (changed to section Rosa officially in the last International Botanical Congress), it should have typical meiosis with the gametes of the octoploid typically being 4x. In visits with Walter Lewis, it sounds like there does tend to be some extra variability and sometimes reduced ploidy level in some gametes from such high ploidy individuals.
I have some open pollinated seedlings germinating of 8x R. acicularis now. I’m excited to grow them on and count them. I suspect they are probably selfs since it does bloom so early. I supposed there is a chance that they are crossed with R. pomifera or R. hugonis in another part of the garden blooming at the same time. Morphology and chromosome counts can help piece together the story if that is the case.
Good luck with your efforts!! I’m in zone 4 and we could sure use more cane hardy roses.
David
Ive always wanted to see if an modern octoploid everbloomer was possible, lol.