Not meaning to be inflammatory here at all, but I personally could care less if the rose showed visible virus or not in terms of breeding with a rose, I would use it in breeding anyways if I needed to, unless I am convinced in the future it poses a real threat to the breeding program, somehow.
I guess there are so many rose viruses out there in the roses of our gardens / enterprises, some known about and undesirable, others yet to be discovered, and yet others possibly harmless, and who knows some might even be beneficial-contributing to desirable and novel unusual traits in the affected roses.
You know, this interesting topic of possible virus transmission from rose seed and pollen into seedlings, has from memory been a hot topic in the past on this forum.
Apart from anecdotal evidence which is great to hear about, is there any concrete scientific trial/evidence to settle the matter one way or another about whether or not virulent and deleterious rose viruses (i.e. the bad ones, not so much those that don’t cause harm to the roses) are capable of seed and/or pollen transmission in breeding programs…and to what extent this transmisison happens? I mean for example, if it can happen in one in a million frequency, who cares?
Hmmmm…some published data perhaps?
At this point in time, from all I have remembered on this forum, I would not worry much about such transmission in practical terms.
I really would welcome advice on this, in case I am totally off the rails on this topic.
Virus does not really express highly here, with some exception. I usually buy from good sources, but I can never be 100% sure, especially since there are still unknowns concerning the subject.
I fully understand how a grower would reject a seedling with virus stamped all over it, no-one would want that.
But that is exactly what I am asking about… i.e. if I use roses which show virus stamped all over their leaves (as pollen and/or as seed parent) what (if any) hard scientific proof is out there that the progeny will express this same infection, in any significant numbers?
Is the risk of the seedlings acquiring the same infection as the parent so ridiculously low as to not make this an issue in practical terms, or is the risk significant enough for us to totally avoid roses that visually express virus as pollen and/or seed parents, in our breeding programs? (remembering also, as others mention here, the visual absence of virus on a parent rose plant might not be comforting for the likes of me, as there is no guarantee there is no virus present, which makes “virus-free” selecting of parents not reliable based on plant appearances alone).
If it is that significant a risk, I would like to know how significant, as I am using a couple of roses with virus symptoms in my breeding, and am not worried about this yet from what I see coming out the other end in seedlings (small numbers however, so not powerful enough to draw meaningful conclusions).
If I recall correctly, it has been mentioned in the past on this forum or other sites that hybridizers have occasionally seen seedlings showing symptoms of RMV in their seedling beds though neither parent exhibited symptoms. On the other hand, they have also bred with a virused parent and the seedlings showed no symptoms. So it is a gamble.
I bought and grew roses in California (Laguna Hills) which showed no symptoms, moved them to Virginia and bought more in Virginia (colder) and some showed symptoms, and then moved them to New York (even colder). I had Carefree Beauty for about 6 years and Thor about 4 years in Virginia with no evidence of symptoms and moved them to New York. Both show virused leaves in the summer for about the last 2 years. Obviously they were virused when I bought them but I guess the environment was such that they didn’t show symptoms.
My personal feeling is that I would use my virused plants as females only and use the pollen from nonvirused or at least symptomless plants.
This way I am not contaminating the symptomless plant with virused pollen. If both show symptoms then I could go either way.
I have a virused The Fairy, and my uncle has a real grand old Mount Shasta with wicked thick golden zigzagging of its leaves (lesions look quite stunning, almost attractive!!).
I cannot recall seeing virus on the cutting-grown Queen Elizabeth in my uncle’s garden, however I have not looked at it closely anyways as I have not used QE for breeding. I highly doubt that any specimens of Queen Elizabeth would be found to be “virus free” in my country, if subjected to proper lab viral screening.
If there are any of these mentioned roses out there that are confirmed virus free in Australia, please someone let me know about them, I want them!!
“The rootstock mentioned, I have a good idea what it is, I have a preference for using Indica Major.”
aka “Odorata”, aka “Fun Jwan Lo”.
I don’t know about this rootstock on other continents, but I have good reason to believe that in the US, all plants of this are infected with PNRSV. Not a rose I would choose to employ as a rootstock. These days, when I do bud anything (which is rare now) I use one of three near-thornless selections of R. multiflora I grew from seed 12 years ago. Beats me what their infection status is…I kinda don’t care…I assume they are clean. (Cuttings of these selections can be made available to RHA members in June, for the price of postage)
“I cannot recall seeing virus on the cutting-grown Queen Elizabeth in my uncle’s garden, however I have not looked at it closely anyways as I have not used QE for breeding.”
I don’t think you should refrain from using it as a seed parent, since I believe seed transmission of virus is probably a rediculously low risk. That said, you can be almost 100% certain that every plant of ‘Queen Elizabeth’ hot the ground running (or should I say limping?!!) with RMV built in.
I’m looking for this one, Red Knight, as it’s a repeat flowering sport of Dr. Huey. I think we should have it treated then use it for root stock so when the scion is killed off, we all have repeat flowering, cold hardy “door yard” roses to enjoy.
Henry Kuska posted a scientific article about the ability of disease to infect seed material but I cannot find it. Pretty sure it was about more than a yr ago. Here is a photo of a six week old seedling from Walking In Sunshine, which really looks to be mosaic, which seems likely to have been passed on through pollen.
I guessed Prairie Sunrise because your description of your seedlings sounded very much like the seedlings I’ve gotten from Prairie Surnise. My plant is not obviously virused (for what that’s worth) but germination from Prairie Sunrise (as seed parent or pollen parent) has always been low and most of the seedlings have issues of some sort. even the OP ones. I’ve seen wrinkled foliage, fused foliage and just about every other deformity possible. I’d about decided that PS has some issues at the genetic level, even with its own pollen. I have found a few crosses, though, which produced normal seeming seedlings. One was with an old Bourbon, Deuil de Dr. Reynaud, and the other was with a seedling that had another Buck rose (Distant Drums) as a parent. Perhaps PS just has more compatibility issues than some?
I am not doubting your diagnostic skill here for one minute!!! …but……make sure to look at the underneath of the leaves, (in case you already haven‘t done so), mites have caused this appearance in some of my seedlings which had no reason to have virus. It can be a trickster
I don’t think you should refrain from using it as a seed parent, since I believe seed transmission of virus is probably a rediculously low risk.
Thanks for the advice, Paul…umm the reason I have not used QE in breeding is not to do with concerns about virus, as I am pretty sure every local QE specimen if lab tested for virus, would have a very high chance of showing viruses, due to the historical facts mentioned further up here. I guess, the same virus fate would have to be assumed for many of the other roses of earlier last century imported into Australia from overseas for that matter (as well as locally bred roses that were madly bud-grafted in those days)…and, yes, I would still use it as a seed parent with that in mind at this stage of the game.
I haven’t used QE because it just doesn’t grab me. Each to their own.
Great to hear from you. Thanks for the reminder about infected pollens potentially infecting non-virused seed parent recipient roses!! (although I guess it is sometimes hard to know what pollen donor roses are infected, if we have not seen symptoms in them).
I’m still optimistic about my Prairie Sunrise seedlings. The emerging true leaves seem normal, and I’m really curious what it’s characteristic of huge double blossoms will do to crosses with something like my KO X W. Baffin that has tons of smaller single blossoms. I think I have a couple of Distant Drums x PS as well.
I think I tossed the mother plant out due to the virus, so these seedlings will be all that I have left of Prairie Sunrise.
There are several newly characterized rose viruses as well that I’ve been helping Dr. Ben Lockhart and Dimitre Mollov characterize. Some show symptoms during the heat of summer which is different than many of the standard rose viruses that seem to have symptoms clear up with the heat of summer. We are working on a couple articles for the American Rose on them and will encourage people to send symptomatic tissue to Ben for confirmation and to get an impression of how widespread some of these are. Ben and Dimitre are developing diagnostic primers for PCR detection and antibodies too, even though the sensitivity typically is generally less reliable for antibodies than that of a well designed primer. Some viruses have some odd symptoms associated with them that are not the typical mosaic patterns. There is one that we suspect from the data and kind of virus that it is seed transmitted, but typically it does not show noticable symptoms thankfully. I think that as we learn more about all the viruses out there that we will eventually determine some as more problematic than others that we would want to place more effort on eradicating and will choose to live with others. As more tools are developed to index roses for more viruses, the more we will understand is floating around out there. Indexing means that they are screened for the presence of specific viruses using antibodies or PCR. It is misleading to say a rose is virus free, the most we can say it was indexed for such and such virus and tested negative for that virus.
It stressed me out at first working with Ben and Dimitre learning about all these viruses, but as time goes by I’m enjoying the learning process. If they are there, I feel more than ever it is beneficial to learn about them even though sometimes it disappoints me to learn what is positive for this or that.
Wish I had known. No germinations from it yet, too.