Here in the deep south, many of the best performing roses are diploids such as teas, chinas, and banksias. Most modern roses are tetraploid.
I understand that higher ploidy in some plants presumably correlates to larger plants, more vigor, etc., etc., but is there any real reason for folks to focus on higher ploidy beyond the practicality of crossing mismatched ploidies?
The reason most people work with tetraploid is because like you say thatââŹâ˘s what most modern roses are. They have the flower form and growth habits that most people like and want. Tetraploids are generally easier to work with from a fertility standpoint. They typically are more accepting of a wide range of pollen, where as diploids are much pickier of what pollens they accept and they donââŹâ˘t self-pollinate. Incorporating a new trait into a diploid is much easier though than a tetraploid from a numbers standpoint. There are half as many chromosomes in a diploid compared to a tetraploid so you donââŹâ˘t need as many seedlings per cross to see all the possible combinations. And fewer generations are needed to fully incorporate the new trait in a diploid versus what it would take with a tetraploid. If the teas, chinas and banksias are what grows best in your area then by all means work with them. And if there are certain traits typically associated with the tetraploids that you would like to incorporate into those roses then try some crosses with them. Or make use of the many triploids that are available now to cross with those roses.
Incorporating a new trait into a diploid is much easier though than a tetraploid from a numbers standpoint. There are half as many chromosomes in a diploid compared to a tetraploid so you donââŹâ˘t need as many seedlings per cross to see all the possible combinations. And fewer generations are needed to fully incorporate the new trait in a diploid versus what it would take with a tetraploid.
How could someone go about putting yellow genes into an octoploid (moyesii) or decaploid (praleucens) rose, that are pink?
Krylon? Rustoleum?
Krylon
Philistines Are Us.
R. moyesii var Rubra.
[attachment 367 Rosamoyesiirubraphoto1.JPG]
[attachment 368 Rosamoyesiirubraphoto4.JPG]
[attachment 369 Rosamoyesiirubraphoto6.JPG]
Hmmm⌠looking at that one, you could find it easier to try turning it blue.
I posted the moyesii photos to try to help answer Philipâs question.
If you want to chase the huge, dangling anthers, gigantic stipules, completely thornless stems, blackspot tolerance and cinnamomea bloom form then youâre going to have to accept the challenge of working with a very polyploid rose. Some things are worth the struggle.
Classical hybridizing theory says there is really no way to get from an octoploid to a triploid having moyesii in the lineage. However, since we have Bill Radlerâs ancestry of Knockout we know there has to be a way to do it. The obvious mechanism is that some gametes of moyessii are tetraploid or hexaploid, or maybe even diploid - not a stretch because we know many roses make a spectrum of pollen ploidies.
However, if you donât want to wait for Lady Luck then how could you stack the deck?
Philip there are a lot of strong arguments for considering diploid level breeding.
Particularly for the backyard breeder that want to play out of beaten pathes.
There are fertlity issues at all ploidy levels. All species are fertile and with persistence and imagination one can bypass most incompatibilities. There are diploid species or vars with huge anything or every other desirable feature.
That modern tetraploid vars sophisticated flowers are far away from species at many ornamental features is a fact but another is that diploids have a lot to offer.
And that at diploid level introgressing or looking for something like horizontal resistance one need much less seedlings and generations.
Theorical seedling number being only a few percent.
About delays getting results: expression of tetraploid feature in triploids at times is surprisingly good.
Something evidenced from many outstanding vars.
Arenât Natalie and David also going this route?
I think the polyanthus group of roses are a great direction. They are perfect for todayâs garden in many ways. Its a class that reached a certain stage of developement and then got superseeded by floribundas who had a slightly better name, so called better flower form and a wider color range. Even though some floribundas and miniatures are really polyanthus but that is a different topic. But work could still be done here.
Their also a number of species that are miniature that could be looked at. some have not been used at all.
One area that needs to be explored is the genetics in roses. We know certain things but there is plenty to learn and that gets harder for every ploidy level you go up.
Some of the most vigorous seedlings I have ever seen have been diploid. Plus I like the fact diploid roses always look real. Sometimes in tetraploids you get such thick parts the plant looks stiff and and out of place. This happens more in other plants but still seems to occur in roses at times.
I donât follow, can you explain this a bit more, Don?
Okay, so let me just clarify some theoretical crosses and resultant ploidy/feasibilityâŚ
R. glauca x R. moyesii would likely yield a hexaploid, no? (Caninae meiosis = 3 haploid with hexaploid haploid?)
R. glauca x R. rugosa would likely yield a tetraploid with strong glauca characteristics, a la Carmeneta
R. rugosa x R. glauca, on the other hand would yield a diploid as the Caninae pollen would offer a single haploid to Rugosa
And goodness knows what any of those F1 would do trying to go to the F2
THe glauca/moyesii is one that I have really wanted to see. I think I had proposed that to someone here a few years back, but dunno if it was ever attempted. Might end up a dead-end mule with little future potential, but interesting nonetheless. And who knows â with Caninae in it, it could still do some weird meiotic divisions, though Iâll be darned if I know how or which wayâŚ
More to my point as a southerner who wants repeat bloomers with heat tolerance, R. glauca x diploid is a very feasible cross with an offspring having good potential for further use â if the meiosis isnât too screwy still at that pointâŚ
This is the stated parentage for Knock Outâs pollen parent. Razzle Dazzle X [Deep Purple X (Faberge X Eddieâs Crimson)] With Eddieâs Crimson resulting from Donald Prior X a hybrid of Moyesii. Somewhere along the line, Moyesii passed on something of greatly reduced chromosome count.
Adam,
Could you expand on that. Are you thinking along the lines of R. nitida? What other species of smaller stature are you thinking of? Iâm focusing on miniatures. Thanks.
Rob
I know there are dwarf mosses, which have lord knows what in them. I know there are the dwarf synstylae types. Also, I know there are some odd dwarfs like R. spin.
Thanks for explaining, Kim.
Here, right at the top of the page it mentions âR. moyesii LĂŠv. Assigned DNA ploidy=4â⌠can anyone explain what that means?
Philip,
You are correct with the ploidy of the theoretical crosses.
I tried an R.glauca x R.moyesii ââŹĹGeraniumââŹÂ cross a number of years ago and got lots of seedlings. But all of the seedlings looked exactly like the mother. The same thing happened with an R.blanda x Geranium cross that year. I later found out that Geranium is virtually sterile. IââŹâ˘ve tried using my R.glauca as a seed parent several times and the overwhelming majority of the seedlings looked just like mom. I think my R.glauca either self pollinates or is producing unfertilized seed. But I was able to get one seedling last year of an R.glauca x Stanwell Perpetual cross. YouââŹâ˘d think that because this seedling would be 3/5ths R.glauca that its features would predominate, but I would say that I can see more of Stanwell Perpetual in this seedling than R.glauca.
Prior to that I grew some open pollinated R.blanda seeds and a high percentage of these seedlings showed some R.glauca features, like purplish new growth, a more purple color to the stems than pure R.blanda and they were much more vigorous than pure R.blandas, plus the leaves were midway in color between R.glauca and R.blanda. I didnââŹâ˘t keep any of those seedlings because I didnââŹâ˘t think I would use them. I tried some R.glauca pollen on the polyanthas Marie Pavie and La Marne last year, but very few of the attempts took and I only got a few seeds and no seedlings.
Anne Wylie did an excellent paper on caninae meiosis. In it she notes that when you cross a dog rose like R.glauca with a rose that isnââŹâ˘t, the caninae meiosis starts to break down and you get chromosomes pairing up that donââŹâ˘t normally pair up, but only some of them and not all of them. So you can end up with plants that have low fertility.
Repeat bloom is a recessive trait and because R.glauca doesnââŹâ˘t repeat, a cross with a diploid that does repeat isnââŹâ˘t going to have offspring that repeats. It will take several generations of crosses with repeat blooming plants to incorporate repeat bloom into that line.
On my comment I deleted a sentance and rewrote it. that are miniature Was originally talking about polyanthus. This is what happens when you write things before you go to bed. The sentence should be
There is also a number of species that could be looked atand some of them have not been used at all.
Sorry for the confussion. Sometimes my brain is thinking one thing and typing something else.
I know the feeling, Adam. âWindows as second languageâ.
Paul, yes, I understand the R.glauca momma, due to uneven meiosis, has very strong influence on her kids. It might have been worth creating some F2âs of the glau-moy however. Caninae meiosis might have broken down a little, and moyesii might have gotten reinforced in some of the offspring, but thatâs a long line to follow. (Thatâs why I suggest these things to other people! LOL)
If daddy (with glauca mommy) were a rebloomer, then I donât know if his mere contribution of 1/4 of genes to kids would decrease odds of F2 generation having repeat bloomers, or if reboom gene is on a specific chromosome, or what⌠But I would like to try (R. glauca x diploid rebloomer) x (R. glauca x diploid rebloomer) to see if remontant glauca-type could be had, as a tetraploid with normal meiosis.
Might take a few more crosses and result in tons of throwaway seedlings⌠Perhaps no more than 1/16 of F2 would have potential for remontancy?
Sorry, Paul.
I think I just repeated a lot of the stuff you already addressed!
So my (R. glauca x diploid rebloomer) x (R. glauca x diploid rebloomer) will be a difficult cross due to pairing/alignment issues?
Darn!