What would you conclude if a variety that does show apparent tendencies towards transpoisition didn’t pass on the stripes? Would it just be that the transposons are only mobile within tissue layers 1 and 3 and not 2 from which gametes are formed? ‘Maurice Utrillo’ produced masses of OP hips this year and Ihave about 200-300 seeds in now to see how well they germinate and if the stripes are passed on. So far none are up… but then only a few are so there is plenthy of time yet. If any come up it will be interesting to see if any seedlings show this striping trait. My OP ‘Papageno’ seedlings don’t show any leaf striping. They show various shades of red and green, on separate plants, but not on the same plant. All are at the cotyledon stage-to-2/3 leaf stage so no flowers to speak of yet.
Maurice does seem to have a split personality.
What would you conclude if a variety that does show apparent tendencies towards transpoisition didn’t pass on the stripes?
Small numbers of F1’s would probably give insufficient information to conclude anything. I would want to go two generations of inbreeding to see if stripes manifest themselves.
There may be other mechanisms for variegation as well, including virii and more exotic microbeasts. Folks like David Zlesak, Larry Davis, Henry Kuska and Roger Mitchell would be better informed about these than I am so perhaps they could summerize the state of knowledge of variegation in roses for us.
Don,
I just ordered the second edition of the book (it’s SO up my street!) and can get you the information when it gets here. I assume there’s a bibliography in the back…
For the record, I have a number of striped cultivars that do show mottled pigmentation of the foliage, much like Simon’s leaf illustrated. I absolutely believe this mottling is a phenomenon caused by the striping mechanism. Not all striped roses do it, but many, many do.
Many of my Downy Mildew infected leaves from this spring showed the exact same pigmentation in their early stages. This has been a subject of great interest to me, since here in S.Ca., we have this weather phenomenon called May Grey, and June Gloom. This translates to no sunshine, or limited, high humidity, and cool nights. The perfect storm for D.M. which has a way wider range of transmission than the generally bandied about 64 degrees, with over 85% humidity. I do have some photos, mostly taken between May 1st,09, and June 15,09, that show these same symptoms. I believe that Downy Mildew is underestimated in the damage it does, and since it is asymptomatic at times, it is sometimes present without classical symptoms. Some of the not recognized symptoms are also hip/seed aborting (often accompanied by hip rotting at about 1-1/2-2 months), low to no seed fertility, and low fertility & hip set, and the connection to root(Phytopthera) rot of seedlings. I will see if I can load and post the photos tonight-look just like yours, Simon.
I received plant materials from Northern CA one Winter and I was shocked by the damage Downey Mildew did in the short time it was present.
You have my sympathies. One advantage to gardening in a blast furnace is most fungal organisms can’t prosper once Summer heat sets in. I haven’t seen symptoms of DM here since, so it must not be able to reestablish itself very easily in my area.
This is the back side of a leaf (I have photos of maybe 600+ cultivars infected) that was infected with Downy Mildew. Not all infected leaves get the ghastly lavender backing on their leaves, and in this stage the DM is very easily ‘knocked out’ with heat and dryness in the air. With heat and continued humidity, the DM is quite stubborn about giving up the ghost. I suspect that the mottling/mosaic may be quite typical of striped roses, since many viral causes of striped flowers are quite common, with some passing on the stripe-based virus and others incapable of that.
It’s a good resemblance Jackie! The image is a little small to see clearly but I can definitely see the green/red patches. I guess the thing that caught my eye here is that I have several hundred roses on an acre of rose garden and this is the only one that shows this pattern. If you look closely at it the pattern exactly resembles what one might expect on a variegated leaf… only in green and red. It’s not real clear from the scan… it is very clear when you look at it ‘in the flesh’. Each little line shows clear separation on the upper face of the leaf only with the bottom of the leaf being generally, either green or red. The variegations on the upper surface of the leaf occur in various shades of either green or red. I have mostly non-striped roses, with only a handful of striped roses and I have been curious about this rose for some time now. The other striped roses do not have striped foliage. This is the only one to show it and the ‘symptoms’, for want of a better term, are pretty much only visible on the upper surface of the leaf.
As I mentioned I am testing the germinability of its seeds and the chances of it passing on the stripes but if I was a betting man I would bet it won’t. In fact… I was thinking I might bud a non-striped rose onto a branch and see what happens to it.
For those interested in seeing the flower this is it, from the same plant taken last season:
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Someone asked about the cause of striping. The transposon suggestion in the book chapter cited is interesting and may be right but there is no published evidence I can find for it. I did a search this morning and did come up with an interesting grant proposal, but it has nothing to do with striping. M.S. Dobres at Novaflora in West Grove PA (home of Star Roses) suggests using a transposon based sytem to introduce selected genes into roses and then removing the Tn so that there is no unwanted selectable marker left in the offspring. Antibiotic resistance and such are undesirable things to have floating round in the environment. This looks like a small business initiative proposed to the USDA, phase 1. Dobres knows some things that we don’t.
On Maurice Utrillo, red-leafed rose, the photos look like cyanidin production is unstable both in leaves and flowers. Probably a Tn in an enzyme of the late stage of pigment production as in classic cases of maize seeds. For maize, check out the work of Virginia Walbot on the bronzy locus. Look carefully at coleus and you’ll see this sometimes, in addition to the very regular leaf patterning that is more common.
I’ll keep looking for info on rose striping but don’t think there is much published.
This is the topside of one of the lavender backed leaf-I could not post it last night-and I do not know what is up with the size of the photo. It seems to be self determined to stay small. A computer whiz I am not. I am posting one more of the lavender backed to show a photo of spores that often come with this topside.
IF you can save and enlarge this photo, you will see the lavender coloring that goes hand in glove with a certain strain of DM, and the sporulation is clear on the lower part of the left most leaf. Sorry I don’t know how to enlarge it for attachment, because this is the variety I see a lot in WARM humid weather.
Hi Simon, as Paul noted above, striping on the foliage is a not infrequent occurrence seen mainly in the Springtime as you mentioned. The loss of this characteristic during the heat of Summer, and the fact that the lighter stripe coloration lessens significantly during the hot times of Summer, are what lead me to believe that striping has a viral origin. Transposons, if I remember correctly, may also have a viral origin.
Jim Sproul